Soft cheese production using citric acid and rennet as coagulants

MINISTRY OF EDUCATION AND TRAINING HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING CAPSTONE PROJECT FOOD TECHNOLOGY SOFT CHEESE PRODUCTION U

MINISTRY OF EDUCATION AND TRAINING

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

CAPSTONE PROJECT FOOD TECHNOLOGY

SOFT CHEESE PRODUCTION USING CITRIC ACID

AND RENNET AS COAGULANTS

LECTURER: PhD PHAM THI HOAN STUDENT: PHAN NGUYEN NGOC KHANH

LE THI NGOC YEN

SKL 0 0 8 4 4 3

HO CHI MINH UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY OF HIGH QUALITY TRAINING

GRADUATION THESIS

CODE: 2021-17116013

SOFT CHEESE PRODUCTION USING

CITRIC ACID AND RENNET AS COAGULANTS

HO CHI MINH CITY - 12/2021

Advisor: PhD PHAM THI HOAN Student: PHAN NGUYEN NGOC KHANH Student ID: 17116013

LE THI NGOC YEN 17116045

ACKNOWLEDGEMENTS

Firstly, we would like to express our heartfelt gratitude to all of the lectures at Ho Chi Minh City University of Technology and Education in general and lecturers at the Faculty of Chemical and Food Technology especially We gained valuable knowledge and skills regarding Food Technology throughout our four years at the school

We would like to express our appreciation to PhD Pham Thi Hoan - lecturer at the Department of Food Technology, Faculty of Chemical and Food Technology, Ho Chi Minh City University of Technology and Education She was always enthusiastic in her support and teaching us, mentoring and imparting knowledge and experiences from the idea to the completed graduation thesis We are truly grateful for that, and we will keep her teaching in mind

We would like to show our thanks to Ms Ho Thi Thu Trang, consultant in charge of the Department of Food Technology laboratories and workshops She had been supportive and helpful with tools, machinery and equipment during our experimental research process

We also would like to express our deep sense of gratitude to the instructors in charge of Food Technology workshop 1, workshop 3, Microbiology laboratory, Biochemistry laboratory and Sensory laboratory who created an ideal environment for us to complete this project

We are very grateful to everyone who made my experience at Ho Chi Minh University of Technology and Education very positive and enjoyable; this experience would not have been possible without my friends, family, fellow students and mentors This project has been one of the most challenging things we have done, but also one of the most enjoyable and rewarding It is impossible to prevent faults while implementing the thesis, so we look forward to hearing your feedback on our thesis Once again, we gratefully acknowledge you and wish you all the best

Best regards!

TABLE OF CONTENT

GRADUATION PROJECT ASSIGNMENT Error! Bookmark not defined

ACKNOWLEDGEMENTS iii

DISCLAIMER iv

TABLE OF CONTENT v

LIST OF ACRONYMS xix

LIST OF FIGURES xx

LIST OF TABLES xxi

ABSTRACT xxii

CHAPTER 1: INTRODUCTION 1

1.1 The study scientific imperative 1

1.2 Objectives and tasks of the study 2

1.2.1 Study objectives 2

1.2.2 Study tasks 2

1.3 Research methodology 3

1.4 Study contribution 3

1.4.1 Scientific potential 3

1.4.2 Practice potential 3

1.5 Study structure 3

CHAPTER 2: LITERATURE REVIEW 4

2.1 Cheese and soft cheese overview 4

2.1.1 General introduction 4

2.1.2 Soft cheese classification 5

2.1.3 Chemical compositions of some soft cheese varieties 6

2.1.4 Soft cheese procedure 7

2.1.5 Cheese production and consumption in Vietnam 9

2.2 Ingredients of cheese manufacturing 12

2.2.1 Fresh milk 12

2.2.2 Skim milk powder 13

2.3 Casein coagulated mechanism 15

2.3.1 Milk protein 15

2.3.2 Casein coagulation types in soft cheese manufacturing 17

2.4 Citric acid 19

2.4.1 Citric acid 19

2.4.2 Citric acid applications 19

2.5 Rennet 21

2.5.1 Rennet introduction 21

2.5.2 Types of rennet or coagulants 21

2.6 Mechanism of gel formation during combined acidification and renneting 23

2.6.1 Primary enzymatic phase 23

2.6.2 Secondary (non – enzymatic phase) 24

2.7 Research situation 24

2.7.1 Overseas researches 24

2.7.2 Domestic researches 26

CHAPTER 3: MATERIALS AND METHODS 27

3.1 Materials, chemicals and equipment 27

3.1.1 Materials 27

3.1.2 Chemicals 28

3.1.3 Equipment 28

3.2 Soft cheese manufacturing 30

3.3 Research plan 34

3.4 Experimental designs 35

3.4.1 Experiment 1: The effect of citric acid concentration on protein coagulation 35

3.4.2 Experiment 2: The effect of incubation temperature on protein coagulation 36

3.4.3 Experiment 3: The effect of rennet concentration on protein coagulation 37

3.5 Analysis methods 38

3.5.1 Cheese yield 38

3.5.2 Cheese solid yield 39

3.5.3 Syneresis 39

3.5.4 Cheese acidity determination 39

3.5.5 Texture analysis 40

3.5.6 Sensory evaluation 41

3.5.7 Microbiological analysis 42

3.5.8 Color space measurement 43

3.5.9 Scanning electron microscopy (SEM) method 44

3.5.10 Determination of chemical compounds 44

3.5.11 Statistical analysis 44

CHAPTER 4: RESULTS AND DISCUSSION 45

4.1 Milk powder’s chemical components 45

4.2 The effect of citric acid and rennet on soft cheese quality 45

4.2.1 The effect of pH renneting on soft cheese criteria 45

4.2.2 The influence of incubation temperature on soft cheese criteria 48

4.2.3 The effect of rennet concentration of soft cheese criteria 50

4.3 Soft cheese technological process 52

4.4 Soft cheese quality evaluation 54

4.4.1 Chemical compositions of soft cheese 54

4.4.2 Microstructure observation of soft cheese 55

4.4.3 Sensory evaluation of soft cheese 57

4.5 Evaluation the quality properties of soft cheese during the storage period 59

4.5.1 Synereris 61

4.5.2 Color 63

4.5.3 Acidity 64

4.5.4 Texture 65

CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 67

5.1 Conclusion 67

5.2 Recommendations 67

REFERENCES 1

APPENDICES 10

LIST OF ACRONYMS

ISO International Organization for Standardization

LIST OF FIGURES

Figure 2.1 Cottage cheese 6

Figure 2.2 Quark cheese 6

Figure 2.3 The general procedure of soft cheese 8

Figure 2.4 Cheese company share 10

Figure 2.5 Fresh/ soft cheese varieties classified through methods of coagulation 17

Figure 2.6 Description of gel formation during combined acidification and renneting 23

Figure 2.7 Summary of the rennet coagulation of milk The primary phase involves enzymatic hydrolysis of κ – casein, while the secondary phase involves aggregation of the rennet- altered (para – casein) micelles into a three-dimensional gel network (coagulum) 24

Figure 3.1 The flowchart of soft cheese production coagulated by rennet and citric acid 30 Figure 3.2 Schematic of cheese curd pressing apparatus 32

Figure 3.3 The cylindrical draining mold (left) and the 1-kg cylindrical block 33

Figure 3.4 Experiment 1 layout 35

Figure 3.5 Experiment 2 layout (A) and milk coagulation image (B) 37

Figure 3.6 Texture analysis layout of soft cheese samples 41

Figure 3.7 Preparation of soft cheese sample for sensory evaluation 42

Figure 4.1 The effect of citric acid concentration on soft cheese quality criteria (A: changes of cheese yield and TSwhey; B: changes of TS cheese and CSY) 46

Figure 4.2 The influence of coagulation temperature on soft cheese criteria (A: changes of cheese yield and TSwhey; B: changes of TScheese and CSY) 48

Figure 4.3 The flowchart of soft cheese production using acid and rennet as coagulants 53

Figure 4.4 Scanning electron microscopy (SEM) micrographs of soft cheese (A) RS; (B) CS and (C) Low-fat cottage cheese Scale bars within the images obtained using x2000 and x5000 magnification are 20 and 10 𝛍m in length, respectively 56

Figure 4.5 Cheese sample during 28 days of storage 61

Figure 4.6 Percentage of separated whey from soft cheese during storage period 61

Figure 4.7 Change of titratable acidity of cheese samples during storage 64

LIST OF TABLES

Table 2.1 Soft cheese classification 5 Table 2.2 Chemical composition of some cheese varieties 7 Table 2.3 Top commonplace cheese producers in Vietnam 11 Table 2.4 Chemical compositions of fresh bovine milk 13 Table 2.5 Chemical components of milk powder vary (calculated on %) 14 Table 2.6 Protein compositions of bovine milk 15 Table 2.7 Rennet – coagulated soft cheese and ripened cheese comparison 18 Table 2.8 Acid citric applications in food and beverage industry 20 Table 2.9 Enzyme coagulants varieties of milk 22 Table 3.1 Compositions of skim milk powder 27 Table 3.2 Compositions of whipping cream powder 28 Table 3.3 Parameters and setting values of Brookfield CT3 Texture Analyzer 40 Table 4.1 Chemical compositions of skim milk powder 45 Table 4.2 The effect of citric acid concentration on cheese texture 47 Table 4.3 Influence of coagulation temperature on texture properties 49 Table 4.4 The influence of enzyme concentration on quality of soft cheese 51 Table 4.5 Chemical compositions of some varieties of soft cheese 54 Table 4.6 Color change of cheese samples during storage 63 Table 4.7 Textual properties of cheese samples change during storage 65

ABSTRACT

Cheese is a nutritious dairy product with a wide range of flavours, textures and forms However, cheese is not very popular in Vietnam, and most of the cheese is imported from foreign countries The research “Soft cheese production using citric acid and rennet as coagulants” was done in order to develop a soft cheese that is appropriate for domestic dairy production and it added a new product for cheese category of Vietnam market The soft cheese was made from recombined milk and coagulated by a combination of citric and rennet To develop the soft cheese, we first examined the effect of pH on casein coagulation Next, we evaluated the effect of rennet on casein coagulation Finally, we evaluated the quality of soft cheese and how its quality properties change during 28 days of storage

Analytical results showed that at condition of pH ≈ 5.9 (added 0.1% citric acid) of casein coagulation the obtained soft cheese had a high yield (19.23%), total solid content (TScheese) and cheese solid yield (CSY) of 37.63% and 48.25%, respectively Soft cheese incubated at 37℃ with 0.025% (77 μL) rennet had the high yield (20.74%), total solid of 36.51% and cheese solid yield of 50.49% Regarding the results of sensory analysis, rennet – coagulated cheese (tested sample) was highly evaluated than acid-coagulated cheese (control sample) Analytical results of quality changes during storage (28 days) showed that, tested cheese was firmer than control sample Their colour can be recognized easily Scanning electronic micrographs (SEM) showed that the network structure of the tested cheese was more uniform Additionally, chemical compositions and microbiological criteria

of the research cheese were also determined The results conducted that the cheese quality met QCVN 5-3:2010/BYT (Vietnamese technical regulation for cheese products) From these results, it can be concluded that rennet – coagulated soft cheese can be produced in Vietnam to diversify the cheese products in the marketplace and met domestic’s demand

CHAPTER 1: INTRODUCTION

1.1 The study scientific imperative

The Vietnam government has also launched a project that meets 40% of domestic fresh milk demand (1.4 million litres of milk) in 2025 (Bộ Công thương, 2010) The Vietnam dairy industry has decided to modernize dairy cow farms and improve raw milk productivity

to meet local dairy demand Raw milk materials for dairy products are mostly purchased from small-scale farmers; however, 20 – 50% of the milk from small – scale suppliers did not meet the quality requirement (according to the Institute of Policy and Strategy for Agriculture and Rural Development) Thus, Vinamilk and other local dairy companies began investing in dairy farms and importing cows to Vietnam to ramp up production in 2007 For example, Vinamilk built 12 International standard farms across the country, with 130000 total dairy cows and 950 – 1000 tons of raw fresh milk per day (Vinamilk, 2012) Despite those positive signs, milk domestically production has still been insufficient to meet the growing demand Locally produced milk meets approximately 80% of the drinking milk production and 35% of milk domestic consumption demand Generally, Vietnam does not have favorable conditions for the dairy industry due to the tropical climate, limited land and undeveloped technologies Therefore, exported milk serves as an input to ensure a stable product supply in dairy processing

Compared to milk and other dairy products, cheese is a higher content of protein which is a good source of nutrients for the human daily diet Currently, dairy consumption

in Vietnam has significantly increased because of the increasing concern for health and nutrition However, domestic milk does not provide enough the amount of milk for cheese production Processed cheese and imported cheese are the cheese that is familiar to Vietnamese consumers Processed cheese is natural cheese mixed with non – cheese ingredients such as salt, preservatives, emulsifiers to enhance the texture and flavour of the cheese; therefore, processed cheese is less nutritious than natural cheese In terms of imported cheese, the large amount of imported cheese is hard cheese varieties Hard cheese

is low moisture content, as it is easy to transport and store in tropical regions like Vietnam Compared to hard cheese, soft cheese is rich in protein, and it has lower fat content appropriate for everyone, especially for the elderly, children and those on a diet Besides, soft cheese is well – suited to being processed into cheese preparations or various dishes

such as cheesecakes, sauces, desserts Despite its short shelf – life, there are not many choices of imported soft cheese in the Vietnam market

Soft cheese is mainly divided based on the coagulation methods: acid – coagulated, acid/ heat coagulated, rennet – coagulated Rennet – coagulated soft cheese is firmer than other soft cheese varieties because acid and rennet interaction results in better draining than acid-rennet coagulated soft cheese The cheese is better draining resulting in a lower moisture content along with firmer curds that leads to improving cheese texture The high

pH of rennet – coagulated cheese also results in a less acidic flavour of the final cheese product (Fox et al., 2017)

To sum up, cheese is a nutritious food that is an excellent source of protein, calcium, minerals and vitamins Currently, the demand for the rapid cheese consumption growth; however, domestic cheese production is still limited Besides, the advantage of rennet – coagulated cheese far outweighs acid – coagulated soft cheese regarding texture and sensory Thus, we had an idea of developing a kind of rennet coagulated – soft cheese made of skim milk powders that have been suitable for milk production in Vietnam Additionally, the product is locally produced, which is accessible to domestic consumers and is an appropriate option for all aged consumers

1.2 Objectives and tasks of the study

1.2.1 Study objectives

The study was done to build soft cheese technological processing from recombined milk coagulated by rennet and citric acid

1.2.2 Study tasks

The thesis was done with the following study tasks:

- Determining the chemical composition of ingredients

- Investigating the effect of citric acid concentration on casein coagulation

- Investigating the influence of rennet (incubation temperature and enzyme concentration)

on soft cheese criteria

- Evaluating the quality of soft cheese

- Evaluating the quality changes of soft cheese during storage time

1.3 Research methodology

- Documentation method

- Physicochemical and microbiological methods

- Textural characteristics analysis

- Microstructure observation (Scanning Electron Micrograph)

- Color space measurement

- Methods in data analysis

CHAPTER 2: LITERATURE REVIEW

2.1 Cheese and soft cheese overview

2.1.1 General introduction

Dairy products are among the most widely consumed food throughout the world since they are rich in calcium and protein, which increases human metabolism and physical performance (Gharibzahedi and Jafari, 2017) Cheese is one of the popular dairy products, with a complex matrix and a rich supply of nutritious compounds (Nájera et al., 2003) Cheese has a variety of flavors and textures; therefore, it can use as a main course, a dessert,

or an ingredient in other food products (Fox et al., 2017) In comparison to whole milk, with

3 – 4% protein and fat, it has 30 – 40% protein and fat, as well as other minerals and soluble vitamins

fat-Cheese is defined as a product coagulated wholly or parly the protein of milk, skimmed milk, partly skimmed milk, cream, whey cream or buttermilk, or any combination

of these materials, via the action of rennet or other suitable coagulants, and by partially draining the whey resulting from the coagulation, while respecting the principle that cheese-making results in a concentration of milk protein (Codex Alimentarius, 1973) Consequenly, the protein content of the cheese will be distinctly higher than the protein level of the above milk materials from which the cheese was made Cheese is divided into two major groups, namely unripended and ripended cheese Ripened cheese is cheese which is not ready for consumption shortly after manufacture The ripened cheese has to be held for such a period time, at such temperature, and under such other conditions as will result in the necessary biochemical and physical changes characterizing the cheese Unlike ripened cheese, unripened cheese is cheese that can be consumed shortly after manufacture

Our study focuses on unripened cheese type, especially soft cheese Soft cheese is a kind of cheese without ripening, which is produced by coagulating milk, cream, or whey through acid coagulation; coagulation by heating and acidification, a combination of acid and rennet coagulation Soft cheese is ready- to eat after production Some traditional and unique kinds of cheese present the culture and characteristics of their origins These days, these unique soft cheese varieties are widespread due to globalization and tourism increase

In terms of nutritious, soft cheese is rich in proteins, calcium, phosphate and low in calories and it also is easy to digeset Therefore, it is highly recommended for everyone to

use, especially for the elderly, children and those on diet Besides, soft cheese can use on their own or in sweet or savoury dishes Soft cheese is versatile and well – suited to being processed into cheese preparations or various dishes (e.g., cheesecakes, sauces, desserts)

2.1.2 Soft cheese classification

Soft cheese is classified into different groups based on factors such as the method of coagulation: rennet – coagulated cheese, acid – coagulated cheese, acid/heat coagulated; structure of final product: gel, paste, or grain; manufacturing ingredient: whey or milk (Fox

Acid – coagulation, no presence,

or a small amount of rennet is added Acid is created from lactic acid bacteria (Labelle), however, some soft cheese varieties are direct – acidified by gluconodelta – lactone

Quark, Cream cheese and Northern- America soft cheese

Rennet – coagulation, no presence, or a small amount of LAB is added

Quesco, Balnco, Quesco Fresco, Halloumi, Cottage

Acid/heat coagulation These products are firm but have a high moisture content

Ricotta (Italy), Channe and Panner (India)

Structure of final

product

double cream cheese

(Schichtkaese)

Adapted from Fox et al (2004)

Cottage cheese, Quark, and Tvorog are the more well-known soft cheese varieties than others in the marketplace (Fox et al., 2004) Quark (in German-speaking countries) or Tvorog (in Eastern European countries) is essentially a milk protein paste It has milky white

to faintly yellowish colour; a smooth, homogenously soft, mildly supple and elastic texture,

Figure 2.2 Quark cheese

mildly acidic and clean flavour Because of the high moisture content (82% w/w), the shelf life of Quark or Tvorog is about 2 – 4 weeks (Guinee et al., 1993) Quark cheese has a high nutritional value due to its high concentration of proteins

Cottage cheese is a soft, unripened, mildly – acid tasting cheese with discrete curd particles of relatively uniform size Cream Cottage cheese is dry- curd Cottage cheese covered with cream dressing Cottage cheese is made by coagulating acidically pasteurized skim - milk or reconstituted extra low – heat skim milk powder Therefore, cottage cheese

is a nutritious and low-calorie food that contains less than 110 kcal/100 g (Farkye, 2004)

2.1.3 Chemical compositions of some soft cheese varieties

Cheese is a nutritious food that has a good deal of calcium, lipid and protein The nutritional value of cheese can be affected by milk such as milk source (cow, goat, or buffalo), milk type (whole milk, part – skim milk, or skim milk), manufacturing and ripening level

Insoluble nutrients of milk (coagulated casein, fat, insoluble minerals, fat-soluble vitamins) exist in final cheese products; whereas, soluble components (whey protein, lactose, water-soluble vitamin sand minerals) dissolve in water (O’Brien and O’Connor, 2004) The total solids content of soft cheese from 14 – 55% (Fox et al., 2004) is lower than that of ripened cheese varieties such as cheddar (66%) (Pastorino et al., 2003), blue cheese (57 – 60%) (Robin et al., 1993)

Figure 2.1 Cottage cheese

Table 2.2 Chemical composition of some cheese varieties

Coagulation by acidification and heating

Adapted from Fox et al (2017)

The chemical compositions of soft cheese in most of the countries has been regularized by Codex Standard For example, in Germany, Quark is defined as cheese with total solid at least 18% (w/w), protein content at least 12% (w/w) and a maximum of 18.5%

of whey protein content in total nitrogen content (Schulz-Collins and Senge, 2004) In some countries, the regulation of cheese definition is less restricted, which moisture and protein content are required For example, Quark or Verse Kaas (Enwa et al., 2013) in Holland requires 87% (w/w) maximum moisture content and 60% (w/w) minimum protein content)

in total non – fat solid (Schulz-Collins and Senge, 2004) American cream cheese (33% lipid, 45% total solids); Neufchatel (20 – 33% lipid, 35% total solid) (Kosikowski and Mistry, 1997)

2.1.4 Soft cheese procedure

Generally, the procedure of cheese production follows the below steps, described in Figure 2.3

Figure 2.3 The general procedure of soft cheese

Cottage cheese is a typical rennet coagulated soft cheese since commercial cottage cheese has been used as a reference product in this study

The official Codex Alimentarius standard for Cottage cheese lists pasteurized bovine skim milk as the raw material for manufacture, as well as the following authorized ingredients: lactic acid bacteria or direct-acidification, rennet or other suitable coagulating agents, CaC12 (maximum of 200 mg/kg milk), NaCl and water The coagulum is sliced into

various – sized curd particles with specific knives, heated, then held for a sufficient amount

of time to allow the curd to firm and the whey to drain The whey is drained until the curds reach the desired consistency (firmness) The curd is then washed, creamed (typically), salted and packed (Bodyfelt and Potter, 2008) Cottage cheese is consumed as soon as it is made (within 3 – 4 weeks)

2.1.5 Cheese production and consumption in Vietnam

a Cheese consumption in Vietnam

Traditionally, cheese is not a staple in the Vietnamese diet since Vietnamese consumers only consume cheese occasionally rather than daily In recent years cheese consumption demand has gone an upward trend in Vietnam In 2019, the cheese sector in Vietnam grew relatively well, with consumption reaching more than 2,000 billion VND, an increase of 11% over 2018 (Virac, 2020) In comparison to other dairy products, consumption value in Vietnam still accounts for a small proportion Despite modest growth, the industry predicts to remain at a consistent growth rate of roughly 13% per year between

2020 and 2024 The steady growth of the segment reflected a gradual change in local tastes

as more locals became exposed to new international foods

Demand for dairy products in Vietnam, cheese varieties especially, involves the general economic situation Vietnam has been growing young population (an estimated 56%

of the Vietnam population is under 30 years old) and heightening income levels are good conditions for Vietnam to become a market for prospective consumption in the area According to YCP Solidiance Research and Analysis, the biggest motivators for people to purchase dairy were overwhelmingly health advantages and nutrition Furthermore, long shelf – life and ease of corporate with other foods may have contributed to dairy products being more than a staple in an average Vietnamese family

Processed cheese is the most familiar cheese variety consumed by Vietnamese people The global company named Bel Vietnam retains dominance of cheese through its well-known processed cheese, namely The Laughing Cow, which accounts for 79% of the cheese market The remaining percentage of this segment consists of mass-produced cheese

by other international brands such as Lactalis Group and Fonterra or imported specialty cheese from all over the world These cheese varieties are extensively high – end products; therefore, they are consumed mostly by high-income people Locally – produced cheese has

a limited consumption Vinamilk had tried tapping into the cheese segment with limited success gaining 3.0% of the market Another local dairy company named TH True Milk also launched its first cheese product – mozzarella in 2017 Figure 2.5 shows cheese company shares in the Vietnam cheese market “Other” defines mainly imported specialty cheese worldwide

Figure 2.4 Cheese company share

Adapted from Euromonitor, YCP Solidiance Research and Analysis

b Cheese production in Vietnam

Regarding production, cheese accounted for 0.4% of total dairy production in 2016 Local cheese production grew to 8.3% in 2020 and is expected to increase faster to 9.3% in

2023 (Virac, 2020)

According to Euromonitor, more than 90% of the Vietnam cheese segment is dominated by international companies such as The Bel Group, Lactalis Group, Fonterra Brands and others with extensive experience in cheese production Domestic enterprises such as Vinamilk and TH True Milk are catching up to overseas competitors Local cheese production accounted for approximately 14% of the cheese market Besides processed cheese from Vinamilk and TH mozzarella cheese, local cheese is mainly from small artisanal producers, such as Pizza 4Ps, that cater to their restaurant supply chain Table 2.3 compares the most commonplace cheese producers in the regions of Vietnam ("Vietnam Market Study

on Cheese & Dairy Product," 2020)

Table 2.3 Top commonplace cheese producers in Vietnam

Vietnam

Vietnam Dairy Products JSC TH Food Chain JSC

Lactalis International Vietnam

Fonterra Brands (Vietnam) Co

Ltd

Paysan Breton

Natural cheese

Cow Vinamilk Cheese

TH True Milk cheese President Anchor

Paysan Breton

produced

locally

All of “Vinamilk Cheese” brand is currently produced locally

All of “TH True Milk Cheese” brand

is currently produced locally

Local entity to handle all importing and distributing matters

Local entity to handle all importing and distributing matters

Imported from France and distributed

by New Viet Dairy

Adapted from Euromonitor, YCP Solidiance Research and Analysis

There are three types of cheese in Vietnam: processed, natural and mass – produced Processed cheese alone accounts for 90% of the cheese market Laughing Cow brand from The Bel Group is a kind of processed cheese that is the most popular cheese consumed in local cuisine Vinamilk also produced low – end price processed cheeses aimed at local consumers; however, its production into the large dairy market was still few; and the cheese sector is not the primary focus of Vinamilk's development Traditional cheese varieties such

as brie, camembert and cheddar are examples of mass – produced and natural cheeses Mass – produced cheeses such as Bottega Zelachi, Anchor, Kraft and President, are often packed

in slices, small blocks, or shredded packets in price ranges suited to the mainstream Unlike mass-produced cheese, natural cheeses are exported from artisanal dairy farms specializing

in cheese making

In general, cheese production has still not satisfied the cheese consumption increase

of locals Local – produced cheese accounts for a relatively small percentage, and 80 % of cheese in the market is exported, mainly from the following markets: New Zealand, Germany, France and Australia Processed cheese plays a dominant role in the Vietnamese cheese segment, leading the Laughing Cow brand of Bel Vietnam Thus, we had an idea that develops a kind of soft cheese that aims to produce in local and accessible to local consumer

2.2 Ingredients of cheese manufacturing

Most cheeses in the world are made from bovine milk, and the remains are made from goat’s milk, buffalo’s milk and others The percentage of bovine milk made cheeses in the world accounts for 81%; while, percentages of cheese made from buffalo, sheep, goat’s milk is 11%, 2% and 1.5%, respectively (Fox et al., 2017)

2.2.1 Fresh milk

Milk is the secretion of mammary glands in mammals, with the function of nourishing the young Milk from some animals such as cows, buffaloes, goats and sheep has been consumed by humans as milk liquid and other dairy products The main composition

of milk is water, and the remains include lipid, lactose and protein (whey protein and casein) (Robinson et al., 2002) Lipid plays a significant role in human nutrition Unlike lipid from flora and fauna sources, milk lipid contains several fatty acids, vitamins (Thanh, 2003) Milk lipid absorbs easier than lipid of animals and plants because of its lower melting point Triglycerides have the highest amount in milk lipid, about 98% and 2% of milk lipid is phospholipids, monoglycerides, ganglioside and free fatty acid (Robinson et al., 2002)

Good-quality milk is a must for good – quality cheese production The milk for cheese production has to be free of contaminants, off – flavors, abnormal colour and odour The main factors include genetic factors, the stage of lactation, illness of the cow and feed

is responsible for natural variation in milk composition These mentioned factors can affect the quality properties and functionality of cheese (Farkye, 2004)

Table 2.4 presents chemical compositions of fresh bovine milk

Table 2.4 Chemical compositions of fresh bovine milk

Composition Content (% w/w)

Moisture 84.93 – 85.07 Minerals 2.87 – 2.89 Proteins 3.27 – 3.31 Lipids 2.75 – 2.79 Lactose 4.96 – 4.98 Total solid 12.43 – 12.57

Adapted from Siddig et al (2016)

As fresh milk is considered as a perishable product, cheese made of fresh milk is produced mostly in countries or regions there are self – sufficient in raw milk production

2.2.2 Skim milk powder

Many developing countries such as East and Southeast Asia, North Africa and sub – Saharan Africa are unlikely to achieve self – sufficiency in dairy products because they could not be able to increase production as quickly as population and economic growth requirements In non – self – sufficiency dairy countries, the local milk businesses produce with imported milk powders material Processors prefer imported milk powder because they are often price-competitive compared to local suppliers, convenient, consistent in quality, constantly available and can be used to make almost every dairy product Skim milk powder

is more likely used in dairy products production because it is easy to substitute and adjust fat

Skim milk is milk separated fat from the milk Skim milk powder is manufactured

by evaporating skim milk into concentrated skim milk and subsequently drying it into powders The purpose of milk powder production is to turn a perishable liquid raw material into a commodity that can store for a couple of years without any quality loss Besides, milk powder is easy to handle, which decreases transportation costs

One of the crucial characteristics of powder products is insolubility It is the powder dispersion, meaning that the powder particles will become thoroughly wetted As a result,

the soluble components dissolve and the colloidal particles (fat globules and casein micelles) disperse throughout the solution The insolubility index can be estimated by the fraction that cannot dissolve after centrifugation when milk powder dissolve in standardized conditions (Walstra, 1999) Insolubility varies from different kinds of milk, depending on drying method For example, the insolubility index of drum drying is 80 – 85 %, compared with 98 – 99.5 % of spray drying (Thanh, 2003)

Table 2.5 Chemical components of milk powder vary (calculated on %)

Components Whole milk powder Skim milk powder

Adapted from Thanh (2003)

In Vietnam, the current Vietnamese domestic raw milk has only been able to fulfil 30-40% of consumer demand has met the only production of drinking milk; therefore, the import of milk powder for dairy production is inevitable Milk powder is used widely in the Vietnamese food industry; for example, a) reconstituted milk and formulated milk production; b) chocolate production; c) a substitute of egg in the bakery industry; d) dairy products manufacturing (Thanh, 2003)

Milk powder has a low moisture content, about 2.5 – 3.0%, which is easy to handle and long self-life, making research more convenient Besides, it is easier to adjust the fat of reconstituted skim milk powder than reconstituted whole milk powder Based on practical and current trends in domestic production, in this research, we built a process of producing soft cheese using whole milk powder

Recombined and reconstituted milk provide a nutritious and high – quality source of dairy products in areas where a fresh raw milk supply is not readily available or is in short supply Reconstitued milk are prepared by dissolving single dried ingredient (e.g., whole

milk powder or skim milk powder) into water; while recombined products can be prepared

by combining more than one liquid or dried ingredients Recombined milk refers to the product obtained from recombining dairy fat source, skim milk powder and water in correct proportion to obtain fluid milk (Walstra, 1999) Within this research, we use recombined milk to produce soft cheese

2.3 Casein coagulated mechanism

2.3.1 Milk protein

Milk protein has a high biological value, making it a great source of essential amino acids Milk protein, making up 3.3 – 3.9% of milk, is divided into two primary categories consisting of casein and whey proteins (also called serum proteins) Protein accounts for 3.3 – 3.9%, including 80% casein and 20% whey protein in bovine milk Casein and whey protein in milk can change during the feeding period Table 2.6 shows the concentration of milk protein compositions

Table 2.6 Protein compositions of bovine milk

Major milk protein Grams/ liter % of Total protein

79.5 30.6 8.0 28.4 10.1 Total whey proteins

𝛂-Lactalbumin 𝛃-Lactaglobumin BSA Immunoglobulins Protease peptone

6.3 1.2 3.2 0.4 0.7 0.8

19.3 3.7 9.8 1.2 2.1 2.4

Adapted from Walstra (1999)

2.3.1.1.Casein

Casein is a protein that precipitates from milk near pH 4.6 Casein is extensively associated and found in milk in the large aggregates, known as casein micelles containing colloidal calcium phosphate The biological functions of casein are to transport calcium and phosphate and form a clot in the stomach for efficient digestion

Casein micelles are hydrophobic and slightly charged These micelles exhibit considerable linkages, including both self-linkage and linkage with one another via hydrophobic links The phosphate groups contribute to casein's high charge The groups bind divalent ions like Ca2+ efficiently, especially at higher pH Because of the highly charged,

casein remains in the solution (Walstra, 1999)

Casein is formed from numerous components, mainly αs1-, αs2-, β-,k-casein with the molar ratio, is about 11 : 3 : 10 : 4 respectively The αs- and β- phosphoproteins with phosphate groups esterified to serine residues They precipitate with Ca2+, but k – casein prevents them from precipitation However, k-casein is easily attacked by rennet enzyme chymosin which splits off a portion of the k – casein molecules; it thereby loses its protective ability Since the caseins precipitate in the presence of Ca ions These reactions are the basis

of the clotting of milk by rennet and thus cheese making At pH = 4.6 and above 20℃, casein is coagulated, which leads to curd formation during yoghurt or cheese making (Walstra, 1999)

2.3.1.2 Whey proteins

Whey proteins have the following properties including heat-sensitive, globular,

water-soluble proteins and enzymes (Hui, 1993) The main components of whey proteins are β-lactoglobulin, α-lactoglobulin, albumin and immunoglobulin (Walstra, 1993) Whey

proteins are capable interact with themselves and k – casein to form heat – induced protein

aggregates

β-lactoglobulin is the predominant serum protein, therefore, its properties tend to dominate those of whey protein preparations, particularly the reactions with k- casein

occurring during heat treatment (Walstra, 1999) Small β – lactoglobulin aggregates form,

leading to larger β -lactoglobulin aggregates are formed (Jang and Swaisgood, 1990) during heat treatment Once the heating temperature and/ or heating duration are raised further, forming complexes with large denatured β – lactoglobulin aggregates and both proteins bind

to the surface of casein micelles (Fox, 2003) Following denaturation of whey proteins, a reaction between the whey proteins and the k-caseins initially happen on the surfaces of the

casein micelles, resulting in complexes of whey protein and k – casein (Oldfield et al., 2000)

Additionally, whey protein aggregates form alone (Mahmoudi et al., 2007; Vasbinder and

De Kruif, 2003) Furthermore, hydrophobic interactions or disulfide between the casein

fraction and the heat-denatured and whey proteins form when k – casein is present

(Guyomarc'h et al., 2009)

2.3.2 Casein coagulation types in soft cheese manufacturing

Coagulation of casein of the milk protein system is a crucial step in the production

of all cheese varieties, forming a gel that entraps the fat if present Coagulation can be accomplished by: a) limited proteolysis by rennet; b) acidification to pH 4.6; c) acidification

to a pH value greater than 4.6 (perhaps 5.2) with heating to 90 ℃ Likely other cheese varieties, soft cheese is also produced by coagulation of milk, cream, or whey through acidification, acidification with a small amount of rennet, or acid and heat combination Soft cheese is ready for consumption once its production finishes

Adapted from Fox et al (2017)

Soft cheese

Acid-coagulated

cheese

Quark Chakka Labneh

Acid/ heat coagulated cheese

RicottaMascaponePaneer