Bài giảng Công nghệ Chế biến và Bảo quản sữa (Milk and Dairy Technology) - Dr. Ing. Thien Trung Le cung cấp cho học viên các kiến thức về các đặc trưng chính của sữa; các cấu phần của sữa/tính chất hóa học của sữa; tính chất vật lý của sữa; vi sinh vật học sữa; các quá trình chế biến sữa;... Mời các bạn cùng tham khảo chi tiết nội dung bài giảng!
Công nghệ Chế biến Bảo quản sữa Milk and Dairy Technology Dr Ing Thien Trung Le Department of Food Engineering Faculty of Food Science and Technology Nong Lam University – HCM City ĐỀ CƯƠNG TỔNG QUÁT (TOPICAL OUTLINE) Chapter 1: Sữa: Các đặc trưng (Milk: Main characteristics) Chapter 2: Các cấu phần sữa (Milk components)/ tính chất hóa học sữa (Chemical properties) Chapter 3: Tính chất vật lý sữa (Physical properties) Chapter 4: Vi sinh vật học sữa (Microbiology of milk) Chapter 5: Các trình chế biến (Milk & dairy processes) Chapter 6: Các sản phẩm sữa (Milk & dairy products) Chapter 7: Tính chất dinh dưỡng (Nutritional properties) References • Dewettinck K., Huyghebaert A., & Rombaut R Milk and Dairy Technology – UGent course 2004-2005 • Walstra P Dairy Science and Technology, Second Edition, CRC 2006 • Tetra Pak Dairy processing handbook, Tetra Pak 1995 • Fox P.F Dairy Chemistry and Biochemistry, Blackie 1998 • … Chapter 1: Milk: Main characteristics • • • • • Introduction Composition and structure Milk formation and excretion Different kinds of milk Factors influencing milk composition Introduction – Milk is defined as the secretion of the mammary glands of mammals – Primary natural function being nutrition of the young – Milk of some animals, especially cows, buffaloes, goats and sheep, is also used for human consumption, either as such or in the form of a range of dairy products – The word ‘milk’ indicates the ‘normal’ milk of healthy cows Composition and structure • Milk Composition and structure • Milk at x 5000 Composition and structure • Milk at x 50,000 Plasma = milk – fat globules Serum = plasma – casein micelles Composition and structure Milk = polydispersed system of water with: – Emulsified fat globules enveloped by a membrane ( 0,1-15 m) – Caseine micelles ( 20-400 nm) – Lipoprotein particles (remnants of mammary secretory cell membranes) ( 10 nm) – Soluble components such as globulins, salts 10 Factors influencing milk composition • Season/ nutrition – is influenced by seasons: different feeding; silaged feed during winter months instead of fresh grass during summer months – Differences are found in fat and protein content has major implications for processing 27 28 Factors influencing milk composition • Season/ nutrition – Homeostasis: i.e., the capability of an organism to maintain a constant composition of body fluids and cells, despite gross differences in food – Nutrition: comparatively small effect on most milk constituents (grass, ensilaged food, hay, ) • Fat content and fat composition are affected distinctly by the feed • A high-protein diet causes nonprotein N content of milk to increase • Several minor components, such as carotene and fatsoluble vitamins, are strongly affected by the content in the feed This is the same for some trace elements 29 Factors influencing milk composition • Season/ nutrition – Climate conditions: little effect on milk composition • High ambient temperatures (>30 C) tend to give higher fat, lower N and lower lactose contents • At temperatures below freezing, fat and N contents both tend to be higher 30 Factors influencing milk composition • Stage and number of lactation – gestation period: months – The period of lactation or milk production: 305 days • the cow produces about 6000 to 8000 kg of milk (note: the calf only needs about 1000 kg of milk for growth) – peak in milk production: ~ the third lactation – the total amount of lactations is around 5-7 31 Factors influencing milk composition • Stage and number of lactation 32 Factors influencing milk composition • Stage and number of lactation – The time elapsed after parturition or calving considerably influences milk composition, presumably because the needs of the calve change with age – Colostrum: differs from normal milk; more salts, proteins (mainly serum proteins) and less lactose – Normal milk: after days further changes occur: decrement in protein content, casein, serum proteins, ashes, fat-free dry matter At the end of the lactation an increment occurs – Lactose content is almost constant during lactation; fat content is correlated to fat-free dry matter during lactation – pH changes: 6,6 6,7 6,9 at the end 33 34 35 Factors influencing milk composition • Age – The age of the cow has a very small but consistent effect on milk composition Fat and fat-free dry matter decrease slightly with each successive lactation 36 Factors influencing milk composition • Mastitis – Several species of pathogenic bacteria may cause inflammation of the udder called mastitis – It causes a decrease in milk yield and a change in milk composition • Decrease in fat content, fat-free dry matter, lactose and casein and increase of serum proteins and chloride content – The number of somatic cells in milk also increases ( > 400.000 cells/ml) – Catalase activity increases – Cl/lactose ratio increases 37 Factors influencing milk composition • Mastitis 38 Factors influencing milk composition • Mastitis 39 Factors influencing milk composition • Mastitis 40 Factors influencing milk composition • • • • Methods of milking Individuals Quarters Other factors 41 ... properties) Chapter 4: Vi sinh vật học sữa (Microbiology of milk) Chapter 5: Các trình chế biến (Milk & dairy processes) Chapter 6: Các sản phẩm sữa (Milk & dairy products) Chapter 7: Tính chất... R Milk and Dairy Technology – UGent course 200 4-2 005 • Walstra P Dairy Science and Technology, Second Edition, CRC 2006 • Tetra Pak Dairy processing handbook, Tetra Pak 1995 • Fox P.F Dairy Chemistry... secretion Digestion: – Food – enzymes simple, soluble, low-molar-mass components: monosaccharides; small peptides and amino acids; and fatty acids and monoglycerides – These are taken up in