GIÁO TRÌNH ANH VĂN CHUYÊN NGHÀNH CÔNG NGHỆ THỰC PHẨM

HoChiMinh University of Industry - Institute of Biotechnology & Food Technology Specialized English in Food Science and technology UNIT 1: WHAT IS FOOD SCIENCE?. HoChiMinh University of

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HoChiMinh University of Industry - Institute of Biotechnology & Food Technology

Specialized English in Food Science and technology

UNIT 1: WHAT IS FOOD SCIENCE?

Food Science and Technology is a convenient name used to describe the application of scientific

principles to create and maintain a wholesome food supply Food Science has given us frozen foods,

canned foods, microwave meals, milk which does not need refrigeration, easily prepared traditional foods

and, above all, variety in our diets The Food Scientist learns and applies a wide range of scientific

knowledge to maintain a high quality, abundant food supply Food Science allows us to make the best use

of our resources in a sustainable manner and minimize waste

To be a Food Scientist and help handle the world's food supply to maximum advantage, you need

some familiarity in a number of disciplines including the application of microbiology, chemistry, aspects

of biochemistry and some specialized statistics The investigation of how biological materials behave in

harvesting, processing, distribution, storage and preparation is complex and full awareness of all

important aspects of the problem requires broad-based training

With the special training in the applied science known as Food Science, a wide range of

employment opportunities exist for the trained professional Examples include the Product Development

Specialist, Sensory Scientist, Quality Control and Quality Assurance Specialist, Technical Sales

Specialist, Research and Development Scientist, Marketing, Consumer Behavior and Management to

name a few Food Science can lead to many exciting and productive careers

A number of interesting and unique options in the Food Science and Technology program

Marketing and Consumer Behavior

Human Resource Management and Industrial Relations

Asian Studies

Business Management

Why does there seem to be so much chemistry in Food Science? What if I haven't done well in this

subject before?

Food Science requires about the same amount of basic science as other science programs The

difference is that in Food Science every student gets an exposure to a wide range of scientific disciplines

and has a chance to succeed in more areas The chemistry you study in the program is not pure chemistry

but applied chemistry e.g in studying the formation of alcohol during a wine fermentation or the flavor

components of coffee Food Science classes then allow the student to apply those basic ideas learned in

general science classes

QUESTIONS

1 What do you know about Food Science and Technology?

2 As a Food Scientist, what specialized subjects do you need apply?

3 After the training course in Food Science, what jobs can you get?

4 List some options in the Food Science and Technology program

5 Is it right if chemistry that you study in the program is pure chemistry?

-oooOooo -

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UNIT 3: CARBOHYDRATES

Carbohydrates make up a group of chemical compounds found in plant and animal cells They

have the empirical formula CnH2nOn, or (CH2O)n An empirical formula tells the atomic composition of

the compound, but nothing about structure, size, or what chemical bonds are present Since this formula is

essentially a combination of carbon and water, these materials are called ―hydrates of carbon‖, or

carbohydrates for short

Carbohydrates are the primary products of plant photosynthesis The simplified light-driven

reaction of photosynthesis results in the formation of a carbohydrate: nH2O+ nCO2 -(CH2O)n- + nO2

This type of carbohydrate is found in the structures of plants and is used in the reverse reaction of

photosynthesis (respiration) or is consumed as fuel by plants and animals

Carbohydrates are widely available and inexpensive, and are used as an energy source for our

bodies and for cell structures Food carbohydrates include the simple carbohydrates (sugars) and complex

carbohydrates (starches and fiber) Before a big race, distance runners and cyclists eat foods containing

complex carbohydrates (pasta, pizza, rice and bread) to give them sustained energy

Carbohydrates are divided into monosaccharides, disaccharides, and polysaccharides

Monosaccharides

Monosaccharides are single-molecule sugars (the prefix ―mono‖ means one) that form the basic

units of carbohydrates They usually consist of three to seven carbon atoms with attached hydroxyl (OH)

groups in specific stereochemical configurations The carbons of carbohydrates are traditionally numbered

starting with the carbon of the carbonyl end of the chain (the carbonyl group is the carbon double-bonded

to oxygen).The number of carbons in the molecule generally categorizes monosaccharides For example,

three-carbon carbohydrate molecules are called trioses, five-carbon molecules are called pentoses, and

six-carbon molecules are called hexoses

One of the most important monosaccharides is glucose (dextrose) This molecule is the primary

source of chemical energy for living systems Plants and animals alike use this molecule for energy to

carry out cellular processes Mammals produce peptide hormones (insulin and glucagon) that regulate

blood glucose levels, and a disease of high blood glucose is called diabetes Other hexoses include

fructose (found in fruit juices) and galactose

Different structures are possible for the same monosaccharide Although glucose and fructose are

identical in chemical composition (C6H12O6), they are very different in structure Such materials are

called isomers Isomers in general have very different physical properties based on their structure

Disaccharides

Disaccharides are two monosaccharide sugar molecules that are chemically joined by a glycosidic

linkage (- O -) to form a ―double sugar‖ (the prefix ―di‖ means two) When two monosaccharide

molecules react to form a glycosidic bond (linkage), a water molecule is generated in the process through

a chemical reaction known as condensation Therefore, condensation is a reaction where water is removed

and a polymer is formed The most well known disaccharide found in nature is sucrose, which is also

called cane sugar, beet sugar, or table sugar Sucrose is a disaccharide of glucose and fructose Lactose or

milk sugar is a disaccharide of glucose and galactose and is found in milk Maltose is a disaccharide

composed of two glucose units Disaccharides can easily be hydrolyzed (the reverse of condensation) to

become monosaccharides, especially in the presence of enzymes (such as the digestive enzymes in our

intestines) or alkaline catalysts Invert sugar is created from the hydrolysis of sucrose into glucose and

fructose Bees use enzymes to create invert sugar to make honey Taffy and other invert sugar type

candies are made from sucrose using heat and alkaline baking soda

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Disaccharides are classified as oligosaccharides (the prefix ―oligo‖ means few or little) This

group includes carbohydrates with 2 to 20 saccharide units joined together Carbohydrates containing

more than 20 units are classified as polysaccharides

Polysaccharides

Polysaccharides (the prefix ―poly‖ means many) are formed when many single sugars are joined

together chemically Carbohydrates were one of the original molecules that led to the discovery of what

we call polymers Polysaccharides include starch, glycogen (storage starch in animals), cellulose (found in

the cell walls of plants), and DNA

Starch is the predominant storage molecule in plants and provides the majority of the food calories

consumed by people worldwide Most starch granules are composed of a mixture of two polymers: a

linear polysaccharide called amylose and a branched-chain polysaccharide called amylopectin

Amylopectin chains branch approximately every 20-25 saccharide units Amylopectin is the more

common form of starch found in plants Animals store energy in the muscles and liver as glycogen This

molecule is more highly branched than amylopectin For longer-term storage, animals convert the food

calories from carbohydrates to fat In the human and animals, fats are stored in specific parts of the body

called adipose tissue

Cellulose is the main structural component of plant cell walls and is the most abundant

carbohydrate on earth Cellulose serves as a source of dietary fiber since, as explained below, humans do

not have the intestinal enzymes necessary to digest it

Starch and cellulose are both homopolymers (―homo‖ means same) of glucose The glucose

molecules in the polymer are linked through glycosidic covalent bonds There are two different

stereochemical configurations of glycosidic bonds—an alpha linkage and a beta linkage The only

difference between the alpha and beta linkages is the orientation of the linked carbon atoms Therefore,

glucose polymers can exist in two different structures, with either alpha or beta linkages between the

glucose residues Starch contains alpha linkages and cellulose contains beta linkages Because of this

difference, cornstarch has very different physical properties compared to those for cotton and wood

Salivary amylase only recognizes and catalyzes the breakdown of alpha glycosidic bonds and not beta

bonds This is why most mammals can digest starch but not cellulose (grasses, plant stems, and leaves)

Food Uses of Carbohydrates

Carbohydrates are widely used in the food industry because of their physical and chemical

properties The sweet taste of sucrose, glucose, and fructose is used to improve the palatability of many

foods Lactose is used in the manufacture of cheese food, is a milk solids replacer in the manufacture of

frozen desserts, and is used as a binder in the making of pills/tablets

Another useful aspect of some carbohydrates is their chemical reducing capability Sugars with a

free hemiacetal group can readily donate an electron to another molecule Glucose, fructose, maltose, and

lactose are all reducing sugars Sucrose or table sugar is not a reducing sugar because its component

monosaccharides are bonded to each other through their hemiacetal group Reducing sugars react with the

amino acid lysine in a reaction called the Maillard reaction This common browning reaction produced by

heating the food (baking, roasting, or frying) is necessary for the production of the aromas, colors, and

flavors in caramels, chocolate, coffee, and tea This non-enzymatic browning reaction differs from the

enzymatic browning that occurs with fresh-cut fruit and vegetables, such as apples and potatoes

Carbohydrates can protect frozen foods from undesirable textural and structural changes by retarding ice

crystal formation Polysaccharides can bind water and are used to thicken liquids and to form gels in

sauces, gravies, soups, gelatin desserts, and candies like jelly beans and orange slices They are also used

to stabilize dispersions, suspensions, and emulsions in foods like ice cream, infant formulas, dairy

desserts, creamy salad dressings, jellies and jams, and candy Starches are used as binders, adhesives,

moisture retainers, texturizers, and thickeners in foods

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QUESTIONS:

1 What are monosaccharides?

2 What is the most important monosaccharides? What is its role?

3 Explain the term isomers

4 What are disaccharides? Give some examples of disaccharides

5 How is invert sugar created?

6 What are polysaccharides? Give some examples of polysaccharides

7 What are starch granules composed of?

8 Can human digest starch or cellulose? Why?

9 What are the important roles of carbohydrates in food processing?

-oooOooo -

UNIT 4: PROTEINS

Proteins are the most complex and important group of molecules because they possess diverse

functionality to support life Every cell that makes up plants and animals requires proteins for structure

and function Enzymes, specialized proteins, catalyze chemical reactions that are necessary for

metabolism and cell reproduction Our muscles are made from a variety of proteins, and these proteins

allow our muscles to contract, facilitating movement Other types of proteins in our body are the peptide

hormones; insulin and glucagon are two common examples

Proteins are complex polymers composed of amino acids Amino acids contain carbon, hydrogen,

nitrogen, and sometimes sulfur and serve as the monomers for making peptides and proteins Amino acids

have a basic structure that includes an amino group (NH2) and a carboxyl group (COOH) attached to a

carbon atom This carbon atom also has a side chain (an ―R‖ group) This side chain can be as simple as

an -H or a -CH3, or even a benzene group

There are twenty amino acids found in the body Eight of these amino acids are essential for adults

and children, and nine are essential for infants Essential means that we cannot synthesize them in

adequate quantities for growth and repair of our bodies, and therefore, must be included in the diet

Amino acids are linked together by a peptide bond in which the carboxyl carbon of one amino acid

forms a covalent bond with the amino nitrogen of the other amino acid Short chains of amino acids are

called peptides Longer chains of amino acids are called polypeptides Although the term polypeptides

should include proteins, chains with less than 100 amino acid residues are considered to be polypeptides,

while those with 100 or more amino acid residues are considered to be proteins

Many of the major hormones in the body are peptides These hormones can influence enzyme

action, metabolism, and physiology Certain antibiotics and a few anti-tumor agents are also peptides The

artificial sweetener aspartame is a dipeptide composed of aspartic acid and phenylalanine with a methyl

group attached at the carboxyl terminal group (L-aspartyl-L-phenylalanine methyl ester)

The sequence of amino acid residues in a polypeptide chain is critical for biological function A

single structural change resulted in a dramatic alteration in physiological function The ability of an

enzyme to catalyze a particular reaction depends on its specific shape It’s a lot like a key and lock; if the

key is broken or in a different shape, it won’t open the lock The receptor sites on cell surfaces must be in

a specific shape for polypeptide hormones to interact with the cell With twenty different amino acids and

each polypeptide consisting of hundreds of amino acids, it is no wonder that proteins play such a variety

of roles in the human body

Chemistry of Proteins

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The protein backbone is formed from the peptide bonds created from the amino and carboxyl

groups of each monomer that repeat the pattern -N-C-C- or C-C-N- The number and sequence of amino

acids in a polypeptide chain is referred to as the primary structure of a protein The free amino group and

carboxyl group on opposite ends of a polypeptide chain allow proteins to act as pH buffers (resist changes

in pH) inside the cell The amino group (NH2) accepts a proton and becomes (NH3+ ), and the carboxyl

group (COOH) donates a proton and becomes dissociated (COO-)

As noted previously, each amino acid residue in the polymer may have a different side chain or

chemical group attached to it, such as hydroxyl (OH), amino (NH2), aromatic ring (conjugate rings such

as the phenol ring in phenylalanine), sulfhydryl (SH), carboxyl (COOH), or various alkyl (CHn) This

variety of side chain groups on the polymer backbone gives proteins remarkable chemical and physical

properties For example, carboxylate groups can function as carboxylic acids (COO-), or amino groups

can behave as bases (NH3+) This allows protein polymers to be multifunctional molecules, with both

acidic and basic behavior at the same time! Additionally, the presence of hydroxyls, carboxylates,

sulfhydryls, and amino groups allows hydrogen bonding, and the alkyl groups provide hydrophobic

interactions, both within the protein polymer itself and between separate protein molecules

In the case of macromolecules, such as proteins, the polymeric structure of the macromolecule

allows it to simultaneously carry many different charges (on different amino acid residues) However,

unlike the small single molecules, the amino acid residues are constrained by linear peptide linkages and

thus cannot move freely to randomly associate with other charged molecules Assuming that charged

residues will seek to bond with the nearest convenient counter ion, it is most likely that oppositely

charged amino acid residues located at different points within a single protein chain will bond These

structural differences result in the folding of proteins into a three-dimensional structure, which is, in part,

responsible for their functional properties as biocatalysts, structural materials, muscles, and chemical

receptors Proteins can be shaped as long flat sheets or in globular spheres This leads to the names

fibrous or globular for protein shapes Most enzymes are globular proteins

In standard acid base chemistry, we know that molecules carry electrostatic charges based on the

type of atoms that make up a molecule and the environment of the molecule Given that opposite charges

attract, cationic and anionic atoms can combine to form covalent bonds, in which electrons are shared

between atomic orbitals, or form ionic bonds, in which only electrostatic attractions exist In solution with

smaller molecules, such as HCl (an acid) or NaOH (a base), protein molecules can freely move around

and associate with each other on a more-or-less random basis

Protein polymers extend the simple acid base charged chemical species concepts to explain how

biological systems have greater levels of complexity and can utilize simple, monomeric chemical

structures (like amino acids) to create exquisitely complex biological structures like antibodies, muscle,

and skin Protein polymers have physical structure, even when dissolved in liquids The charged and

hydrophobic residues within a protein tend to associate, causing the protein to fold up When you unfold

the protein molecule (called denaturation), its charged residues can reassociate with other charged

molecules (precipitation or coagulation) Protein precipitation is widely used to recover recombinant

protein products, enzymes, or in the production of many common foods Cheeses and soybean tofu are

examples of coagulated protein food products

Food Uses of Proteins

Proteins also serve important roles in the processing of food products They are used for their

thickening, gelling, emulsifying, and water-binding properties in meats (sausages), bakery products,

cheese, desserts, and salad dressings Proteins are used for their cohesive and adhesive properties in

sausage making, pasta, and baked goods Egg proteins are used for their foaming properties in desserts,

cakes, and whipped toppings Milk, egg, and cereal proteins are used as fat and flavor binders in low-fat

bakery products Proteins are used for texture and palatability in bakery products (breads, cakes, crackers,

and pizza crust) and sausages

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Milk protein consists of 80% casein and 20% whey proteins There are four major types of casein

molecules: alpha-s1, alpha-s2, beta, and kappa Milk, in its natural state, is negatively charged The

negative charge permits the dispersion of casein in the milk When an acid is added to milk, the H+

concentration neutralizes the negatively charged casein micelles When milk is acidified to pH 4.7, the

isoelectric point (the point at which all charges are neutral) of casein, an isoelectric precipitate known as

acid casein is formed Cottage cheese and cream cheese manufacture involves an acid precipitation of

casein with lactic acid or lactic acid producing microorganisms Acid casein is used in the chemical

industry and as a glazing additive in paper manufacturing

Casein also can be coagulated with the enzyme rennin, which is found in rennet (an extract from

the stomach of calves) Rennin works best at body temperature (37°C) If the milk is too cold, the reaction

is very slow, and if the milk is too hot, the heat will denature the rennin, rendering it inactive The

mechanism for the coagulation of the casein by the rennin is different from the acid precipitation of

casein The rennin coagulum consists of casein, whey protein, fat, lactose, and the minerals of the milk,

and has a fluffier and spongier texture than the acid precipitate Rennet is used in the manufacture of

cheese and cheese products, and rennet casein is used in the plastics industry Casein is solubilized with

sodium hydroxide and calcium hydroxide to produce sodium caseinate and calcium caseinate,

respectively Caseinates are added to food products to increase their protein content and are key

ingredients in non-dairy coffee creamers

Approximately 90% of soybean proteins are classified as globulins, based on their solubility in

salts More specifically, the proteins are conglycinin (a glycoprotein) and glycinin Tofu is manufactured

by coagulating the proteins in soymilk with magnesium sulfate As bonding occurs between the positively

charged magnesium ions and negatively charged anionic groups of the protein molecules, the proteins

coagulate

QUESTIONS

1 What are proteins?

2 Why are proteins important group of molecules?

3 Describe a basic structure of amino acid

4 What does essential amino acid mean?

5 How are amino acids linked together in protein molecule?

6 Distinguish the terms ―peptides‖ and ―polypeptides‖

7 What are the important roles of protein in the processing of food products?

8 What is rennin? For what reason we utilized rennin in cheese processing?

-oooOooo -

UNIT 6: ENZYMES

Living systems contain large protein molecules called enzymes Those large globular proteins

range in molecular weight from about 10,000 to several million Each of the thousands of known enzymes

has a characteristic three- dimensional shape with a specific surface configuration as a result of its

primary, secondary, and tertiary structures The unique configuration of each enzyme enables it to ―find‖

the correct substrate from among the large number of diverse molecules in the cell

Although some enzymes consist entirely of proteins, most consist of both a protein portion called

an apoenzyme and a nonprotein component called a cofactor Together, the apoenzyme and cofactor form

a holoenzyme, or whole enzyme If the cofactor is removed, the apoenzyme will not function The

cofactor can be a metal ion or a complex organic molecule called a coenzyme Coenzymes may assist the

enzyme by accepting atoms removed from the substrate or by donating atoms required by the substrate

Some coenzymes act as electron carries, removing electrons from the substrate and donating them to other

molecules in subsequent reactions Many coenzymes are derived from vitamins

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The name of enzymes usually end in –ase All enzymes can be grouped into six classes, according

to the type of chemical reaction they catalyze Enzymes within each of the major classes are named

according to the more specific types of reactions they assist They are:

1 Oxidoreductase: oxidation-reduction in which oxygen and hydrogen are gained or lost

2 Transferase: Transfer of functional groups, such as an amino group, acetyl group, or phosphate

group

3 Hydrolase: hydrolysis (addition of water)

4 Lyase: removal of groups of atoms without hydrolysis

5 Isomerase: Rearrangement of atoms within a molecule

6 Ligase: joining of two molecules (using energy usually derived from break down of ATP)

Mechanism of Enzymatic Action

Enzymes can speed up chemical reaction in several ways Whatever the method, the result is that

the enzyme lowers the activation energy for the reaction without increasing the temperature or pressure

inside the cell Although scientists do not completely understand how enzymes lower the activation

energy of chemical reaction, the general sequence of events in enzyme reaction is as follows:

1 The surface of the substrate contacts a specific region of the surface of the enzyme molecule,

called the active site

2 A temporary intermediate compound forms, called an enzyme-substrate complex

3 The substrate molecule is transformed by the rearrangement of existing atoms, the breakdown of

the substrate molecule, or combination with another substrate molecule

4 The transformed substrate molecules – the products of the reaction – are released from the enzyme

molecule because they no longer fit in the active site of the enzyme

5 The unchanged enzyme is now free to react with other substrate molecules

Enzymes are extremely efficient Under optimum conditions, they can catalyze reaction at rates

108 to 1010 times (up to 10 billion times) higher than those of comparable reactions without enzymes

In living cells, enzymes serve as biological catalysts As catalysts, enzymes are specific Each acts

on a substrate (or substrates, when there are two or more reactants), and each catalyzes only one reaction

For example, a specific enzyme may be able to hydrolyze a peptide bond only between two specific

amino acids Other enzymes can hydrolyze starch but not cellulose; even though both starch and cellulose

are polysaccharides composed of glucose subunits, the orientation of the subunits in the two

polysaccharides differ Enzymes have this specificity because the three dimensional shape of the active

site fits the substrate somewhat as a lock fits with its key However, the active site and substrate are

flexible, and they change shape somewhat as they meet to fit together more tightly The substrate is

usually much smaller than the enzyme, and relatively few of the enzyme’s amino acids make up the active

site

A certain compound can be a substrate for a number of different enzymes that catalyze different

reactions, so the fate of a compound depends on the enzymes that acts upon it Glucose 6-phosphate, a

molecule that is important in cell metabolism, can be acted upon by at least four different enzymes, and

each reaction will yield a different product

Factors influence enzyme activity

Several factors influence the activity of enzyme The more important are temperature, pH,

substrate concentration, and presence or absence of inhibitors

The rate of most chemical reactions increases as the temperature increases Molecules move more

slowly at lower temperatures than at higher temperatures and so may not have enough energy to cause a

chemical reaction For enzymatic reactions, however, elevation beyond a certain temperature drastically

reduces the rate of reaction This decrease is due to the enzyme’s denaturation, the loss of its

characteristic three-dimensional structure (tertiary configuration) Denaturation of a protein involves

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breakage of hydrogen bonds and other noncovalent bonds As might be expected, denaturation of an

enzyme changes the arrangement of the amino acids in the active site, altering its shape and causing the

enzyme to lose its catalytic ability In some cases, denaturation is partially or fully reversible However, if

denaturation continues until the enzyme has lost its solubility and coagulates (as with cooked albumin) the

enzyme cannot regain its original properties Enzymes can be denatured by concentrated acids, bases,

heavy-metal ions (such as lead, arsenic, or mercury), alcohol, and ultraviolet radiation

Most enzymes have an optimum pH at with their activity is characteristically maximal Above or

bellow this pH value, enzyme activity, and therefore the reaction rate, declines When the H+

concentration (pH) in the medium is changed, many of the enzyme’s amino acids are effected and the

protein’s three-dimensional structure is altered Extreme changes in pH can cause denaturation

There is a maximum rate at which a certain amount of enzyme can catalyze a specific reaction

Only when the concentration of substrate(s) is extremely high can this maximum rate be attained Under

condition of high substrate concentration, the enzyme is said to be saturation; that is, its active site is

always occupied by substrate or product molecules In this condition, a further increase in substrate

concentration will not effect the reaction rate because all active sites are already in use If a substrate’s

concentration exceeds a cell’s saturation level for a particular enzyme, the rate of reaction can be

increased only if the cell produces additional enzyme molecules However, under normal cellular

conditions, enzymes are not saturated with substrate(s) At any given time, many of the enzyme molecules

are inactive for lack of substrate; thus, the rate of reaction is likely to be influenced by the substrate

concentration

Enzyme inhibitors are classified according to their mechanism of action as either competitive or

noncompetive inhibitors Competitive inhibitors fill the active site of an enzyme and compete with the

normal substrate for the active site A competitive inhibitor is able to do this because its shape and

chemical structure are similar to those of normal substrate However, unlike the substrate, it does not

undergo any reaction to form products Some competitive inhibitors bind irreversibly to amino acids in

the active site, preventing any further interactions with the substrate Others bind reversibly, alternately

occupying and leaving the active site, these slow the enzyme’s interaction with the substrate Reversible

competitive inhibition can be overcome by increasing the substrate concentration As active site becomes

available, more substrate molecules than competitive inhibitor molecules are available to attach to the

active sites of enzymes Noncompetitive inhibitors do not compete with the substrate for the enzyme’s

active site; instead, they interact with another part of the enzyme In this process, called allosteric (―other

space‖) inhibition, the inhibitor binds to a site on the enzyme other than the substrate’s binding site This

binding causes the active site to change its shape, making it nonfunctional As a result, the enzyme’s

activity is reduced This effect cab be reversible or irreversible, depending on whether or not the active

site can return to its original shape In some cases, allosteric interaction can activate an enzyme rather

than inhibit it Another type of noncompetitive inhibition can operate on enzymes that require metal ions

for their activity Certain chemical can bind or tie up the metal ion activators and thus prevent an

enzymatic reaction Cyanide can bind the iron in iron-containing enzymes, and fluoride can bind calcium

or magnesium Substances such as cyanide and fluoride are sometimes called enzyme poisons because

they permanently inactivate enzymes

QUESTIONS:

1 What do enzymes generally consist of?

2 What can the cofactor be?

3 How do coenzymes work?

4 What is the important role of enzyme?

5 Describe the general sequence of events in enzyme reaction

6 Why enzymes have their own specificity?

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7 Can a certain compound be a substrate for a number of different enzymes that catalyze different

reactions?

8 What are the important factors that influence the activity of enzyme?

9 What does denaturation of a protein involve?

10 What does denaturation of an enzyme cause?

11 By what factors can arrangement enzymes be denatured?

12 When the enzyme is said to be saturation?

13 How are enzyme inhibitors classified?

14 Are substrate’s shape and chemical structure similar to those of competitive or noncompetive

inhibitors?

15 What do competitive inhibitors do?

16 What is the difference between competitive inhibitors and noncompetitive inhibitors?

-oooOooo -

UNIT 8: STERILIZATION VERSUS PASTEURIZATION

Thermal processing covers the broad area of food preservation technology in which heat

treatments are used to inactivate microorganisms to accomplish either commercial sterilization or

pasteurization Sterilization processes are used with canning to preserve the safety and wholesomeness of

ready-to-eat foods over long terms of extended storage at normal room temperature (nonrefrigerated)

without additives or preservatives, and pasteurization processes are used to extend the refrigerated storage

life of fresh foods Although both processes make use of heat treatments for the purpose of inactivating

microorganisms, they differ widely with respect to the classification or type of microorganisms targeted,

and thus the range of temperatures that must be used and the type of equipment systems capable of

achieving such temperatures

SECTION I: PASTEURIZATION

Pasteurization is a relatively mild heat treatment given to foods with the purpose of destroying

selected vegetative microbial species (especially the pathogens) and inactivating the enzymes Because

the process does not eliminate all the vegetative microbial population and almost none of the spore

formers, pasteurized foods must be contained and stored under conditions of refrigeration with chemical

additives or modified atmosphere packaging, which minimize microbial growth Depending on the type of

product, the shelf life of pasteurized foods could range from several days (milk) to several months (fruit

juices) Because only mild heat treatment is involved, the sensory characteristics and nutritive value of the

food are minimally affected The severity of the heat treatment and the length of storage depend on the

nature of the product, pH conditions, the resistance of the target microorganism or enzyme, the sensitivity

of the product, and the method of heating

Most pasteurization operations involving liquids (milk, milk products, beer, fruit juices, liquid

egg, etc) are carried out in continuous heat exchangers The product temperature is quickly raised to the

pasteurization levels in the first heat exchanger, held for the required length of time in the holding tube,

and quickly cooled in a second heat exchanger For viscous fluids, a swept surface heat exchanger is often

used to promote faster heat transfer and to prevent surface fouling problems In-package pasteurization is

similar to conventional thermal processing of foods except that it is carried out at lower temperatures The

thermal processing of high acid foods (natural or acidified) is also sometimes termed pasteurization to

indicate that relatively milder heat treatment is involved (generally carried out at boiling water

temperatures)

SECTION II: STERILIZATION

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Sterilization implies the destruction of all viable microorganisms and is not the appropriate word

to be used for thermal processing of foods, because these foods are far from being sterile in the medical

sense of the word The success of thermal processing does not lie in destroying all viable microorganisms

but in the fact that together with the nature of the food (pH), environment (vacuum), hermetic packaging,

and storage temperature, the given heat process prevents the growth of microorganisms of spoilage and

public health concern In essence, it presents a thermal process in which foods are exposed to a

high-enough temperature for a sufficiently long time to render them commercially sterile The process takes

into account the heat resistance of the spore formers in addition to their growth sensitivity to oxygen, pH,

and temperature The presence of vacuum in cans prevents the growth of most aerobic microorganisms,

and if the storage temperature is kept below 250C, the heat-resistant thermopiles pose little or no problem

From the public health perspective, the most important microorganism in low-acid (pH > 4.5) foods is

Clostridium botulinum, a heat-resistant, spore-forming, anaerobic pathogen that, if it survives processing,

can potentially grow and produce the deadly botulism toxin in foods Because C botulinum and most

spore formers do not grow at pH < 4.5 (acid and medium-acid foods), the thermal processing criterion for

these foods is the destruction of heat-resistant yeasts and molds, vegetative microorganisms, or enzymes

Because spore formers generally have high heat resistance, the low-acid foods that support their growth

are processed at elevated temperatures (115-1250C), whereas acid foods need only to be brought to

80-900C for adequate inactivation of enzymes or destruction of vegetative cells, yeasts, and molds

QUESTIONS

1 What is the difference between sterilization and pasteurization?

2 The main purpose of sterilization and pasteurization

3 Are spore –former microorganisms destroyed in pasteurization?

4 Can pasteurized foods be preserved in normal storage condition?

5 Does the pasteurization process affect greatly the sensory characteristics and nutritive value of the

food?

6 Are enzymes inactivated in the pasteurization process?

7 Give example of food products which is treated by pasteurization

8 Describe the stages in the pasteurization process

9 What is the equipment for holding the pasteurization temperature called?

10 What does the term ―pasteurization‖ mean for heat treatment of high acid foods?

11 Are all viable microorganisms destroyed by sterilization or pasteurization?

12 What microorganism is considered as the most important in terms of public health concern,

especially in low acid foods ? Why?

13 What are the ph values for low-acid and acid foods?

14 What target microorganisms are destroyed by heat processing for acid foods?

15 Why is temperature requirement of thermal processing for acid foods lower than for low acid

foods?

-oooOooo -

UNIT 9: MAKING PEANUT BUTTER

The first step in making peanut butter is growing the peanuts, of course!

From the harvest the nuts go to shelling operations These plants, located near the growing fields,

remove the shells, clean the nuts, and pack them into huge bags for shipment to the peanut butter plant

Each bag holds more than 2,000 pounds of peanuts!

At the plant, the bags are unloaded into bucket conveyors that move the nuts from each processing

step to the next one The first step is to insure that all impurities, such as stems and sticks from the peanut

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plants, are removed from the product stream This is done by gravity separators, which sort out objects

that are heavier or lighter than peanuts

The peanuts are now ready for roasting This is done by a continuous roaster The nuts are slowly

carried through the roaster on a belt while hot air is circulated It is extremely important that the nuts be

roasted evenly and properly so that flavor and color are just right The roaster operator adjusts the roast as

required by changing the air temperature, belt speed or peanut layer thickness on the belt

The peanuts are cooled and conveyed to the blanching machines, which remove the skins This

prevents the peanut butter from having dark specks from the skins

The last step before the peanuts can be ground into peanut butter is the final inspection for quality

The nuts are conveyed through an electronic color sorter which removes nuts that were under or over

roasted The peanuts also pass a trained inspector who looks them over and picks out any that do not look

right

The peanuts are now ready to be conveyed to the grinders (If we are making 'chunky' peanut

butter, some of the nuts are diverted to a chopper, and are then added back to the peanut butter just before

filling the jars.) The grinders are like giant milkshake machines

Although peanut butter consists of mostly peanuts (at least 90%), small amounts of other

ingredients are added while the nuts are being ground In the case of 'old fashioned' peanut butter, we add

a little bit of salt for flavor and a special vegetable oil called a stabilizer This keeps the peanut oil from

separating out to the top of the jar

At this point the peanut butter is pumped through a metal detector to insure that no metal got into

it during the grinding Then it is pumped into a deaerator, which removes trapped air Finally, the peanut

butter, quite hot from all that grinding, passes through a heat exchanger to cool it down so it can be

packed into containers on the filling line

The filling machine is carefully timed to put the correct amount of peanut butter in each jar The

jar then is conveyed to the capping machine

Capped jars are sent through an induction sealer, which seals the inner liner to the top of the jar

Then, another machine applies the label to the jar

The jars are now ready for packing into the shipping case This is done by hand so that the packer

can inspect each jar's label and general appearance

All that's left is to glue the cases closed and put the peanut butter in the warehouse, then wait a few

days before shipping it to the stores This allows for 'microbiological tests to make sure no molds or

bacteria have found their way into the peanut butter After the tests come back 'clean' we can release it for

our customers to enjoy

QUESTIONS:

1 What are the major processing steps in producing peanut butter?

2 What are the reasons for roasting peanuts?

3 What is the important consideration one should be taken during roasting step?

4 Why do we often add vegetable oil to peanut butter?

5 Why the peanut butter is pumped through a metal detector after grinding?

6 Why do we have to keep peanut butter jars at warehouse a few days before shipping them to the

stores?

-oooOooo -

UNIT 10: BREAD PREPARATION

Preparing bread involves many ingredients and advance preparation steps Flour is received by

bulk rail or truck and stored in 100,000 pound bins All other raw materials are received by truck Two

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hours before production begins, a liquid sponge or broth is prepared and allowed to ferment to ensure that

the finished loaf will rise properly The broth is a blend of flour, water, sugar, salt, yeast and yeast foods

To combine the ingredients necessary for bread making, a scaler measures out the smaller

increments of the mix, some as little as one ounce A dough mixer operated by a control panel takes the

ingredients from the scaler and adds the larger increments to the mix to create the proper dough

consistency

This mixture can weigh anywhere from 400 to 2,000 pounds The dough is then 'kicked' out of the

mixer into a trough and allowed to 'relax' and ferment This is called floortime Then it goes to a hopper

and is divided into loaf-sized pieces, then to the rounder for shaping

Once again the dough is set aside in an overhead proofer to relax and continue fermenting for

approximately 10 minutes The dough is then sent to the head rollers for flattening and removal of excess

air This is a key step in bread making Removing excess fermenting gas helps ensure good inner structure

and grain in the finished loaf

The next stop is the moulder, where the bread is shaped for the final baking process The moulder

is also helpful in removing air from the dough Once molded, the bread is dropped into a large pan

divided into five separate loaf pans These pans travel along a conveyor to another proof box Here they

will stay for 55 minutes The temperature in the proof box is monitored closely to maintain 90% humidity

level and 105º temperature level at all times

Now the bread is sent to the ovens for baking The oven temperatures and baking times will vary

as to size and density of the loaf The loaves bake for 22 minutes at approximately 400º The baked bread

is conveyed to a depanner This is just what it sounds like; suction cups and vacuum pressure remove the

baked loaf from the pan The pan is sent back to storage to be used again, and the loaf is sent to cool

The bread cools for about an hour and is then sent to be sliced Once sliced, the bread is wrapped

by an automatic bagging machine Now that the loaf is in the bag, it is sent to be tied and fastened The

finished product is conveyed to where it is sorted and stacked for store distribution Total production time

for a loaf of bread is about three hours The total lapsed time from the beginning of production to when

the bread is on the shelf in the store is 24 hours

QUESTIONS:

1 What are the major processing steps in preparing bread?

2 Definition the term ―a liquid sponge‖ or ―broth‖ in bread preparation

3 What does a broth consist of?

4 What is floortime in bread preparation?

5 What do baking temperatures and times depend on?

-oooOooo -

UNIT 12: MILK PROCESSING

Milk fresh from the cow is virtually a sterile product All post-milking handling must maintain the

milk's nutritional value and prevent deterioration caused by numerous physical and biological factors In

addition, equipment on the farm must be maintained to government and industry standards Most cows are

milked twice a day, although some farms milk three or four times per day The milk is immediately

cooled from body temperature to below 40°F (5°C), then stored at the farm under refrigeration until

picked up by insulated tanker trucks at least every other day The milk tanker driver records the amount of

milk and notes the temperature and the presence of any odors If the milk is too warm or has an

off-odor, it will not be picked up, and the farmer will have to feed it to his animals or dump it When the milk

is pumped into the tanker, a sample is collected for later lab analysis

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When the milk arrives at the milk plant, it is checked to make sure it meets the standards for

temperature, total acidity, flavor, odor, tanker cleanliness, and the absence of antibiotics The butterfat and

solids-not-fat content of this raw milk is also analyzed The amounts of butterfat (BF) and solids-not-fat

(SNF) in the milk will vary according to time of year, breed of cow, and feed supply Butterfat content,

solids-not-fat content, and volume are used to determine the amount of money paid the farmer

Once the load passes these receiving tests, it is then pumped into large refrigerated storage silos

(nearly half-million pounds capacity) at the processing plant

All raw milk must be processed within 72 hours of receipt at the plant Milk is such a nutritious

food that numerous naturally occurring bacteria are always present The milk is pasteurized, which is a

process of heating the raw milk to kill all "pathogenic" bacteria that may be present A pathogen is a

bacteria that could, if allowed to grow and multiply, make humans sick It should be noted that

pasteurization is not sterilization (sterilization eliminates all viable life forms, while pasteurization does

not) After pasteurization, some harmless bacteria may survive the heating process It is these bacteria that

will cause milk to "go sour." Keeping milk refrigerated is the best way to slow the growth of these

bacteria Some bacteria do not cause spoilage, but are actually added to milk or cream after pasteurization

to make "cultured" products such as cheese, cottage cheese, yogurt, buttermilk, acidophilus milk and sour

cream

There are different ways to pasteurize milk The "batch" method heats the milk to at least 145° and

holds it at that temperature for at least 30 minutes

Since this method may cause a "cooked" flavor, it is not used by some milk plants for fluid milk

products

High Temperature/Short Time (HTST) pasteurization heats the milk to at least 161° for at least 15

seconds The milk is immediately cooled to below 40° and packaged into plastic jugs or plastic-coated

cartons Most milk plants have at least one HTST processor This piece of equipment is considered the

"heart" of the plant

Butterfat content accounts for several different types of products Whole milk, 2%, 1%, Nonfat,

and Half & Half are some examples A machine called a separator separates the cream and skim portions

of the milk A separator is really a large centrifuge that spins about 2,000 rotations per minute The

different types of milk products are then "standardized" by blending the components (skim milk, raw

milk, cream) in the correct proportions to yield the desired end-products Water is never added to lower

the butterfat content of fluid milk Excess cream is used to make ice cream and butter

Milk is homogenized to prevent the cream portion from rising to the top of the package The

expression "cream rises to the top," is accurate because cream is lighter in weight than milk The cream

portion of un-homogenized milk would form a cream layer at the top of the carton A "homogenizer"

forces the milk under high pressure through a valve that breaks up the butterfat globules to such small

sizes they will not "coalesce" (stick together) Homogenization does not affect the nutrition or quality of

the product; it is done entirely for aesthetic purposes

Vitamin quantities may be reduced by the heating process and removal of the butterfat Therefore,

to replace the natural nutrition of nature's perfect food, liquid vitamins are added to fortify most fluid milk

products Many states have milk standards that require the addition of milk solids These solids represent

the natural mineral (i.e calcium, iron), protein (casein), and sugar (lactose) portion of nonfat dry milk

You will see this shown as an ingredient on those products needing fortification

Quality Control personnel conduct numerous tests on the raw and pasteurized products to insure

optimum quality and nutrition A sample is analyzed for the presence of microbiological organisms with a

standard plate count (SPC) and ropey milk test The equipment used to analyze butterfat and solids-not-fat

is calibrated on a regular basis to insure a consistent, quality product that meets or exceeds government

requirements

All milk products have a sell-by date printed on the package This is the last day the item should

be offered for sale However, most companies guaranty the quality and freshness of the product for at

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least 7 days past the date printed on the package Samples of each product packaged each day are saved to

confirm that they maintain their freshness 7 days after the sell-by date

Once the milk has been separated, standardized, homogenized and pasteurized, it is held below

40°F in insulated storage tanks, then packaged into gallon, half-gallon, quart, pint, and half-pint

containers The packaging machines are maintained under strict sanitation specifications to prevent

bacteria from being introduced into the pasteurized product All equipment that comes into contact with

product (raw or pasteurized) is washed daily Sophisticated automatic Clean-in-Place (CIP) systems

guarantee consistent sanitation with a minimum of manual handling, reducing the risk of contamination

Once packaged, the products are quickly conveyed to a cold storage warehouse They are stored

there for a short time and shipped to the supermarket on refrigerated trailers Once at the store, the milk is

immediately placed into a cold storage room or refrigerated display case

QUESTIONS:

1 What are requirements for handling fresh milk?

2 Which parameters must be checked when receiving raw milk at factory?

3 Explain the difference between pasteurization and sterilization

4 Explain the difference between the batch and the HTST method of pasteurization

5 For what reason do we homogenize milk?

6 What is SPC abbreviated for?

7 What is CIP abbreviated for?

8 What is HTST abbreviated for?

9 What is BF abbreviated for?

10 What is SNF abbreviated for?

11 What is a sell-by date?

-oooOooo -UNIT 13: THE BISCUIT INDUSTRY

WHAT ARE BISCUITS?

Biscuits are small baked products made principally from flour, sugar and fat They typically have

a moisture content of less than 4% and when packaged in moisture-proof containers have long shelf lives,

perhaps six months or more The appeal to consumers is determined by the appearance and eating

qualities For example, consumers do not like broken biscuits nor ones that have been over or under

baked

Biscuits are made in many shapes and sizes and after baking they may be coated with chocolate,

sandwiched with a fat-based filling or have other pleasantly flavored additions

HOW ARE BISCUITS MADE?

Biscuits are a traditional type of flour confectionery which were, and can still be, made and baked

in a domestic kitchen Now they are made mostly in factories on large production plants These plants are

large and complex and involve considerable mechanical sophistication Forming, baking and packaging

are largely continuous operations but metering ingredients and dough mixing are typically done in

batches

There is a high degree of mechanization in the biscuit industry but at present there are very few

completely automatic production plants This means that there is a high degree of dependence on the

operators to start and control production plant It is essential that operators are skilled in the tasks they

have to do and this involves responsibility for product quality As part of their training they must know

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about the ingredients and their roles in making biscuits They must be aware of the potential ingredient

quality variations and the significance of these

There are basically two types of biscuit dough, hard and soft The difference is determined by the

amount of water required to make dough which has satisfactory handling quality for making dough pieces

for baking

Hard dough has high water and relatively low fat (and sugar) contents The dough is tough and

extensible (it can be pulled out without immediately breaking), like tight bread dough The biscuits are

either crackers or in a group known as semi-sweet or hard sweet

Soft doughs contain much less water and relatively high levels of fat and sugar The dough is

short, (breaks when it is pulled out) which means that it inhibits very low extensible character It may be

soft that it is pourable The biscuits are of the soft eating types which are often referred to as ―cookies‖

There are a great number of biscuit types made from soft doughs and a wide variety of ingredients may be

used

The machinery used to make biscuits is designed to suit the type of dough needed and to develop

the structure and shape of the individual biscuits

Secondary processing, which is done after the biscuit has been baked, and packaging of biscuits

are specific to the product concerned There is normally a limited range of biscuit types that can be made

by given set of plant machinery

Many biscuit production plants bake at the rate of 1000-2000 kg per hour and higher rates are not

unusual Given this and the sophistication of the production line it is most economical to make only one

biscuit type for a whole day or at least an eight hour shift

QUESTIONS

1 Which ingredients are biscuits made from?

2 What moisture do biscuits typically have?

3 In terms of packaging, how is the shelf life of biscuits prolonged?

4 Due to a high degree of mechanization in the biscuit industry, how important is the role of the

operators?

5 What requirements do operators in biscuit production need to meet?

6 Describe the main differences between hard and soft dough

7 What types of biscuit are referred to as ―cookies‖?

-oooOooo -

UNIT 18: FOOD PRESERVATION

Food preservation is the process of treating and handling food in such a way as to stop or greatly

slow down spoilage to prevent foodborne illness while maintaining nutritional value, texture and flavor

Preservation usually involves preventing the growth of bacteria, fungi and other micro-organisms,

as well as retarding the oxidation of fat which cause rancidity It also includes processes to inhibit natural

aging and discolouration that can occur during food preparation such as the polyphenoloxidase reaction in

apples which causes browning when apples are cut Some preservation methods require the food to be

sealed after treatment to prevent re-contamination with microbes; others, such as drying, allow food to be

stored without any special containment for long periods

Preservation processes include:

 Heating to kill or denature organisms (e.g boiling)

 Oxidation (e.g use of sulphur dioxide)

 Toxic inhibition (e.g smoking, use of carbon dioxide, vinegar, alcohol etc)

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 Dehydration (drying)

 Osmotic inhibition ( e.g use of syrups)

 Low temperature inactivation (e.g freezing)

 Many combinations of these methods

One of the oldest methods of food preservation is by drying, which reduces water activity

sufficient to delay or prevent bacterial growth Most types of meat can be dried and this is especially

valuable in the case of pig meat since this is difficult to keep without preservation Many fruits can also be

dried and the process is often applied to apples, pears, bananas, mangoes, papaya, coconut etc Drying is

also the normal means of preservation for cereal grains such as wheat, maize, oats, barley, rice

Probably as old as drying, many Arctic communities would preserve food in holes or larders dug

into the ice There is a tradition in Scandinavia of preserving fish and especially herrings in this way

Freezing is also one of the most commonly used processes commercially and domestically for preserving

a very wide range of food stuffs including prepared food stuffs which would not have required freezing in

their unprepared state For example, potato waffles are stored in the freezer, but potatoes themselves

require only a cool dark place to ensure many months' storage Cold stores provide large volume,

long-term storage for strategic food stocks held in case of national emergency in many countries

Canning involves cooking fruits or vegetables, sealing them in sterile cans or jars, and boiling the

containers to kill or weaken any remaining bacteria Various foods have varying degrees of natural

protection against spoilage and may require that the final step occur in a pressure cooker High-acid fruits

like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal fruits

such as tomatoes require longer boiling and addition of other acidic elements Many vegetables require

pressure canning Food preserved by canning or bottling is at immediate risk of spoilage once the can or

bottle has been opened Lack of quality control in the canning process may allow ingress of water or

micro-organisms Most such failures are rapidly detected as decomposition within the can causes gas

production and the can will swell or burst However, there have been examples of poor manufacture and

poor hygiene allowing contamination of canned food by the obligate anaerobe, Clostridium botulinum

which produces an acute toxin within the food leading to severe illness or death This organism produces

no gas or obvious taste and remains undetected by taste or smell

Pickling is a method of preserving food by placing it or cooking it in a substance that inhibits or

kills bacteria and other micro-organisms This material must also be fit for human consumption Typical

pickling agents include brine (high in salt), vinegar, ethanol, and vegetable oil, especially olive oil but

also many other oils Most pickling processes also involve heating or boiling so that the food being

preserved becomes saturated with the pickling agent Frequently pickled items include vegetables such as

cabbage, peppers, and some animal products such as corned beef and eggs

Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle The

vacuum environment strips bacteria of oxygen needed for survival, hence preventing the food from

spoiling Vacuum-packing is commonly used for storing nuts

Modified atmosphere is a way to preserve food operating on the atmosphere around it Salad crops

which are notoriously difficult to preserve are now being packaged in sealed bags with an atmosphere

modified to reduce the oxygen concentration and increase the carbon dioxide concentration There is

concern that although salad vegetables retain their appearance and texture in such conditions, this method

of preservation may not retain nutrients, especially vitamins Grains may be preserved using carbon

dioxide A block of dry ice is placed in the bottom and the can is filled with grain The can is then

"burped" of excess gas The carbon dioxide from the sublimation of the dry ice prevents insects, mold,

and oxidation from damaging the grain Grain stored in this way can remain edible for five years

Some foods, such as many traditional cheeses, will keep for a long time without use of any special

procedures The preservation occurs because of the presence in very high numbers of beneficial bacteria

or fungi which use their own biological defences to prevent other organisms gaining a foot-hold

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Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots,

plums or in crystalized form where the preserved material is cooked in sugar to the point of crystalization

and the resultant product is then stored dry This method is used for the skins of citrus fruit (candied peel),

angelica and ginger The use of sugar is often combined with alcohol for preservation of luxury products

such as fruit in brandy or other spirits

Food may be preserved by cooking in a material that solidifies to form a gel Such materials

include gelatine, agar, maize flour and arrowroot flour Some foods naturally form a protein gel when

cooked

QUESTIONS:

1 What is food preservation?

2 What is foodborne illness?

3 What do preservation processes include?

4 How can drying method preserve foods?

5 What is the role of cold stores in food preservation?

6 What is pickling method?

7 How can grains be preserved by using modified atmosphere?

-oooOooo -

UNIT 19: FOOD PACKAGING

Food packaging development started with humankind’s earliest beginnings Early forms of

packaging ranged from gourds to sea shells to animal skin Later came pottery, cloth and wooden

containers These packages were created to facilitate transportation and trade

Utilizing modern technology, today’s society has created an overwhelming number of new

packages containing a multitude of food products A modern food package has many functions, its main

purpose being to physically protect the product during transport The package also acts as a barrier against

potential spoilage agents, which vary with the food product For example, milk is sensitive to light;

therefore, a package that provides a light barrier is necessary The milk carton is ideal for that Other

foods like potato chips are sensitive to air because the oxygen in the air causes rancidity, which is a

condition of spoiled oil characterized by objectionable odor and flavor The bags containing potato chips

are made of materials with oxygen- barrier properties Practically all foods should be protected from filth,

microorganisms, moisture and objectionable odors We rely on the package to offer that protection

Aside from protecting the food, the package serves as a vehicle through which the manufacturer

can communicate with the consumer Nutritional information ingredients and often recipes are found on a

food label The package is also utilized as a marketing tool designed to attract your attention at the store

This makes printability an important property of a package

The food industry utilizes four basic packaging materials: metal, plant matter (paper and wood),

glass and plastic A number of basic packaging materials are often combined to give a suitable package

The fruit drink box is an example where plastic, paper and metal are combined in a laminate to give an

ideal package This concept can be easily seen in your peanut butter jar The main package containing the

food (primary package) is made of glass (or plastic), the lid is made of metal lined with plastic, and the

label is made of paper

Each basic packaging material has advantages and disadvantages Metal is strong and a good

overall barrier, but heavy and prone to corrosion Paper is economical and has good printing properties;

however, it is not strong and it absorbs water Glass is transparent, which allows the consumer to see the

product, but breakable Plastics are versatile but often expensive Therefore, combining the basic

materials works well in most cases So, for a product like milk, which is an essential food for children and

young adults and therefore cannot be very expensive, paper makes a good economical material It also

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provides a good printing surface However, since paper absorbs water, it will gain moisture from the milk,

get weaker and fail, thereby exposing the milk to spoilage factors It may even break and waste the

product When a thin layer of a plastic called polyethylene is utilized to line the inside of the milk carton,

it serves as a barrier to moisture and makes an economical, functional package

After making a food product and placing it in the appropriate package, a number of these

individual packages must be placed in a large container to facilitate shipment These larger containers are

called secondary packages The paperboard box is a very common secondary package Plastics also can

serve as secondary packages The milk case in which a number of milk cartons are delivered to the

supermarket is a good example

We cannot discuss food packaging without discussing the effects of packaging waste on the

environment Clearly, recycling is a sound approach However, the problem often lies in feasibility of

collection, separation and purification of the consumer’s disposed food packages This mode of recycling

is called post-consumer recycling While it offers a logistic challenge, recycling is gaining in popularity,

and the packaging industry is cooperating in that effort Aluminum cans are the most recycled container at

this time Plastic recycling is increasing, yet most plastic is recycled during manufacturing of the

containers; not as post-consumer recycling For example, trimmings from plastic bottles are reground and

reprocessed into new ones

The plastics industry is helping to facilitate consumer recycling by identifying the type of plastic

from which the container is made A number from 1 to 7 is placed within the recycling logo on the

container’s bottom For example, 1 refers to PET (Polyethylene Terephthalate), the plastic used for the

large 2 liter soft drink bottles Plastics have the advantage of being light This helps to conserve fuel

during transport and also reduces the amount of package waste

There are many interesting packaging concepts being explored by the industry to keep up with the

changing life style of the consumer and new technologies Many professionals are involved in designing

and manufacturing the modern package Today's package is designed with the consumer's safety and

convenience in mind Examples are microwaveable popcorn packages, squeezable ketchup bottles and the

tamper-proof milk bottle cap

QUESTIONS

1 In term of packaging, what does barrier mean?

2 What does Primary Package mean?

3 What does Secondary Package mean?

4 What does Printability mean?

5 Explain about rancidity

6 What is PET abbreviated for?

7 What is PE abbreviated for?

8 What does laminated package mean?

9 What are the three basic packaging materials that make up the fruit drink box?

10 Which plastic is utilized to line the inside of the milk carton?

-oooOooo -

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