Subject english of food science and technology topic methods of preserving sausages

Preservatives are commonly added to extend shelf life and ensure safety, but fresh sausages are highly perishable due to their high fat content, susceptibility to microbial growth, and s

VNU UNIVERSITY OF SCIENCE

FACULTY OF ENVIRONMENTAL SCIENCE

Se Treen

Subject: English of food Science and Technology

TOPIC: METHODS OF PRESERVING SAUSAGES

Intructors: Assoc Prof Dr Nguyen Thi Lam Doan

PhD Luu Quynh Huong

GROUP7 _ 1 Phạm Thị Mỹ Quyên - 22001497

2 Nguyễn Yến Nhi - 21002407

3 Trịnh Yến Nhi — 22001490

4 Nguyễn Thị Hồng Nhung - 22001493

5 Vũ Quỳnh Như - 22001494

ol, November, 2024

Contents

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Introduction

Sausages are made from fresh ground meats of various animals like pork, beef, chicken, fish, and buffalo, and are processed with different technologies before being stuffed into casings Preservatives are commonly added to extend shelf life and ensure safety, but fresh sausages are highly perishable due to their high fat content, susceptibility to microbial growth, and storage conditions Common chemical preservatives, such as sulphur dioxide and synthetic antioxidants like BHT and BHA, have been scrutinized for potential health risks, including allergic reactions and carcinogenic effects This has led to an increased

demand for natural preservatives, derived from plants, animals, or microbes, which also

offer antimicrobial and antioxidant benefits This review aims to define and classify sausages, particularly fresh sausages, and explore factors affecting their quality, preservation methods, and the use of natural preservatives

I Overview

1.1 Sausages The word “sausage”, however, is derived from saussiche (Old Norman French), salsicia (Late Latin) or from salsus (Latin) which means “salted”

Sausages are defined as comminuted seasoned meats, stuffed into casings, and may be smoked, cured, fermented and heated

1.2 Classification of sausage products

A classification of sausages based on characteristics: raw sausages and heat-processed

sausages

a, Raw sausages

Fresh sausages

Made from fresh comminuted, uncured, non-smoked meats Must be refrigerated prior to heating by the consumer

Eg: Breakfast sausage (USA), boerewors (South Africa), bratwurst (Germany), merguez (North Africa), siskonmakkara (Finland)

Fermented sausages

Made from comminuted, cured or uncured, fermented and often smoked meats Not heat-

processed

Eg: salami, chorizo,

Semidry (quickly fermented) sausages

Stuffed in medium- and large-diameter artificial casings “Tangy” flavour produced by fermentation Length of smoking and fermentation depends on type but rarely exceeds a few days

Eg: Variety of summer sausages, cervelats, mettwursts, Lebanon bologna (USA)

b, Heat-processed sausages

Smoked pre-cooked sausages

Mostly comminuted, cured, non-fermented Final cooking before consumption

Eg: Chinese pork sausages, kielbasa,

Emulsion-type sausages

Made from comminuted well-homogenized cured meats, fat, water and seasoning Usually smoked, slightly cooked Ready-to-eat product

Eg: Frankfurters, wieners, bologna, mortadella,

Cooked sausages

Made from previously comminuted cooked fresh or cured raw materials Final cooking after stuffing With or without smoking Ready-to-eat product

Eg: Liver sausage, BraunschweIger,

II Nutritional composition of sausages

Sausages, a meat product, have a diverse nutritional profile The main components of sausages typically include protein, fat, water, and small amounts of carbohydrates

2.1 Protein

Sausages are a rich source of protein, which plays a crucial role in building and repairing body tissues, as well as supporting immune function and other body processes The protein content in sausages typically ranges from 12-15g per 100g

2.2 Fat

Sausages contain a significant amount of fat, primarily saturated fat from meat and animal fat This fat provides energy and aids in the absorption of fat-soluble vitamins such as A,

D, E, and K The fat content in sausages typically ranges from 20-30¢ per 100g, with about 7-10g being saturated fat However, consuming too much saturated fat can lead to health problems like heart disease, so moderation is key

2.3 Carbohydrates:

Sausages generally have low carbohydrate content, about 1-2g per 100g, although additional sugars or starch may be used in some recipes to improve flavor and texture

2.4 Vitamins and Minerals:

Sausages provide some vitamins, including vitamin B12, which is essential for nerve function and red blood cell production Vitamin B12 in sausages can range from 0.6- 1.5mcg per 100g They also provide minerals like iron (1-2mg) and zine (2-3mg), which are important for immune function and maintaining healthy bones and teeth

HH Factors influencing the quality of fresh sausages

3.1 Microbial composition

Meat in general is an ideal growth medium for a wide range of microorganisms Aerobic colony counts may range from 1.5x10° - 2.1x10* cfu/g for fresh sausage, to 1.4x10° - 3.1x10’ cfu/g for frozen sausage and yeast counts varying from 5.0x10° - 4.7x10° efu/g for fresh sausages

The intrinsic factors affecting bacterial growth, and therefore the spoilage potential of fresh sausage products, include:

+ pH, which should not be less than 5.5

+ nutrient availability

+ water activity which is equal to, or higher than 0.97

+ oxidation/reduction potential

The extrinsic factors :

+ temperature where fresh sausages are usually stored at or below 4 C before consumption + particle surface area where grinding of the meat increases the spoilage characteristics

+ gaseous environment and packaging material

3.2 Free radicals

Apart from microbial spoilage, lipid oxidation or oxidative rancidity is the second most known spoilage factor of fresh meat and fresh meat products The grinding of meat disrupts the integrity of muscle membranes and exposes the lipid membranes to metal ions, which facilitates interactions between prooxidants and unsaturated fatty acids Lipid oxidation therefore depends on light and oxygen access, the chemical composition of the meat, storage temperature and technological processes (e.g., grinding) This will have a negative effect on the quality of the meat leading to changes in sensory (colour, texture and flavour) and nutritional quality

Fresh meat cuts and meat products owe their bright red colour to the presence of oxymyoglobin During chilled storage, this red colour is lost due to exposure to high levels

of oxygen The red oxymyoglobin is then transformed to the brown-coloured metmyoglobin

IV Methods of sausage preservation

4.1 Bio-Preservation by Lactic Acid Bacteria Strains and Their Antibacterial

Metabolites

Bio-preservation implies the application of microorganisms or their metabolites to extend the shelf life of food products.In this regard, according to the ancient and safe use of fermentation by lactic acid bacteria (LAB), their application in the bio-preservation of

meat and meat products, their metabolites, their antibacterial mechanism and_ their

combined use with other novel technologies or natural antibacterial compounds as hurdle technology is a more effective method that can compete with synthetic preservatives, the high potential of various LAB strains and their metabolites especially bacteriocins as bio- preservatives in meat and meat products for extending their shelf life and is gaining more

attention

LAB are part of the natural microbial flora of fermented meats and the intestinal microbiota of humans These aerotolerant bacteria are mainly non-sporing, Gram-positive, Catalase-negative, and have either a spherical-shaped or rod-shaped cell LAB are microaerophilic organisms and preferably require anaerobic conditions for growth

+ LAB Strains Involved in Fermented Meat Products

Members of the genus Lactobacillus are usually the dominant species in most fermented meat products, but in some slightly acidified sausages, both Enterococcus and Lactobacillus are present in similar amounts ; nevertheless, Lactobacillus plantarum and Lactobacillus curvatus are the most common LAB species in fermented sausages It has been reported that in many fermented sausages, Lactobacillus sakei has the most adaptability due to a higher maximum growth rate, higher final cell density, and a shorter lag phase It should be noted that in Southern European sausages, the most and least common species are Lactobacillus sakei and Pediococci spp., respectively Also, molds, such as Penicillium chrysogenum and Penicillium nalgiovense, are commonly used for sausage ripening in Southern Europe In artisan sausages from Southern Europe, a strain of Enterococcus faecium grows increasingly during the early stages of fermentation, producing a bacteriocin It has been reported that yeast genera, especially Debarvomyces hansenii, can be found in fermented meat products with appropriate organoleptic characteristics

+ Bio-Preservation of Fermented Meat Products by Starter LAB

The bio-preservation of meat and meat products by starter LAB has been reported in different studies as summarized For example, Nikodinoska et al [evaluated the effect of L plantarum PSC20 on microbial quality (2 monocytogenes and Salmonella) of Chorizo sausage They reported that LZ plantarum PSC20 caused a significant reduction in L

monocytogenes but did not have a significant effect on Salmonella In another study, Lucumi-banguero et al revealed that Lb plantarum and Lh sakei have the maximum inhibition effect on P aureus and the minimum effect on S typhimurium and S marcescens,

+ Bio-Preservation of Meat and Meat Products by Bacteriocins from LAB

LAB produce antimicrobial compounds such as bacteriocins that have the potential to limit the growth of pathogen or spoilage microorganisms

Ren et al reported the noticeable antibacterial activity of 1 rhamnosus sp AS against FE coli, B subtilis, Salmonella, and S aureus They revealed that its purified bacteriocins have a pronounced inhibitory effect against £ coli and B subtilis

+ Bio-Preservation of Meat and Meat Products by Biosurfactants from LAB

LAB produce different bioactive compounds including bacteriocins and bio-surfactants Bio-surfactants are non-toxic, biodegradable, and amphiphilic compounds that are produced by various microorganisms such as LAB as secondary metabolites

They exert their antimicrobial potential through various mechanisms such as: (1) The prevention of biofilm formation by the reduction of the bacterial interaction with the surface through alteration of the charge and wettability of the surface ; (2) Interference in the normal function of the microorganisms by interaction with their intracellular constituents ; (3) Destruction of the cell walls and membranes of microorganisms

Application of bacteriocin from Lactobacillus plantarum SRCM I 004 34 strain isolated from okara as a natural preservative in beef sausage

LAB isolated from okara (soy milk pulp) produces antimicrobial compounds called bacteriocins which can be used as natural preservatives in sausages Thisstudy aims to determine the effectiveness of this bacteriocin from LAB as a natural preservative in sausages The bacteriocin was isolated from Lactobacillus plantarum SRCM 1 004 34

strain isolated from Okara

The study used a Completely Randomized Design(CRD) in 4x4 factorial pattern by three

replicates The first factor was four levels of bacteriocin addition (B), ¡.e., 0%(B0), 0.3%

(B1), 0.6% (B2) and 0.9% (B3) The second factor was the length of sausage storage time (L) at 4°C: Odays (L0), 4 days (L1), 8 days (L2) and 12 days (L3)

The results showed that the content of protein, fat, and the bacterial count was significantly influenced by the interaction of the percentage addition of bacteriocin and storage time pH was significantly affected by bacteriocin dose and storage time but was not affected by the interaction of other factors The moisture content of the sausage was significantly affected

by storage time The results of this study showed that sausages treated with 0.9% bacteriocin (B3) with a maximum storage time of 12 in the refrigerator was still safe to be

consumed

The bacteriocins produced by LAB can inhibit the growth of pathogenic microbes and those involved in decomposition such as_ Bacillus cereus, Clostridium botulinum,Clostridium perfringens, Listeria monocytogenes, and Staphylococcus aureus (Diop et al 2007) The application of bacteriocins in food does not affect the taste and appearance of the product Bacteriocins produced by LABcan be utilized in the form of supematant, partially purified, or more completely purified products (Woraprayote et al 2016) Bacteriocins are commonly used in the food industry especially in fermented foods

to inhibit the growth of bacterial contaminants that cause food spoilage and food-borne diseases (Abdelbasset et al 2008).The antimicrobial compounds may affect bacterial metabolism and toxin production (Rolfe 2000)

According to the USDA (2001), fresh sausages stored in the fridge(40C) have a shelf life

of 1-2 days.The shelf life of fresh sausages can be extended byadding nitrite, but excessive consumption of nitrites can beharmful to health (Stringer and Pin 2005)

Theuse of nitrite as a preservative in making sausages can bereduced by the addition of bacteriocin The addition of 0.3% bacteriocin extracted from Lactobacillus plantarum 2C 12 was able to inhibit the growth of Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium inmeatballs without any changes of the taste (Arief et al.2012),

Bacteriocin used in this study was isolated from L.plantarum strain SRCM | 004 34 from okara (Aritonang etal 2017) Lactiplantibacillus plantarum is a beneficial bacterium

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