Effect thermal ttt on milk
Dr. Dina A. B. Awad discusses the effects of different heat treatments on milk components, highlighting changes in chemical, microbiological, and physical properties. Key findings include that heat affects major proteins, particularly whey proteins, while lactose undergoes Maillard reactions and mineral composition is altered. The presentation emphasizes the significant impact of heat treatment on nutritional properties, particularly for children consuming UHT milk.
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Effect thermal ttt on milk
- 1. Dr. Dina A.B. Awad Lecturer food hygiene and control , faculty of veterinary medicine Benha university, Egypt
- 2. Effect of differentheat treatment on milk components Chemical changes Microbiological changes Physical changes Organoleptic properties Technological propeties Nutritional properties affect N.B : Please read the page 133 and 134 from your CD
- 3. 1- Effect onmicroorganisms Sterilized milk Pasteurized milk Bacterial type Destruction Destruction Pathogenic bacteria Destruction Destruction Spoilage bacteria Destruction Destruction Yeast and mould Destruction resistant Spore forming bacteria Destruction resistant Thermophilic bacteria
- 4. 2- Effect onphysico-chemical properties 2.1 Milk fat - The less component affected by heat treatment. - Creamline formation decreased 10-50% without loss fat %. due to destruction of agglutinin (aggregation) - HTST less affect cream line formation. - MFGM changed due to agitation and foaming . - Above 135C –Protein deposited on FGM forming network –make the membrane denser.
- 5. 2- Effect onphysico-chemical properties 2.2 Milk protein - Major proteins are main affected by heat - Whey proteins the most affected especially beta-lactoglobulin (65 C). (SULPHER BRIDGE with k-casein) - Beta – casein not affected by normal pasteurization. - Most biologically active proteins are denaturated by heat espicially immunoglobulins and vit C. (heat labile). 2.3 Milk lactose - Maillard reaction - Formation of lactulose(absent in HTST) good indicator index betwwen sterilized milk and In container and UHT milk. - Formation of acids : heating above 40 c ---lose of Co2 --- higher pH - Heating above 100C --- degradtion of lactose by formic and lactic acids.
- 6. are less affectedexcept Ca- phospahate in casein micelles ---less soluble– Ca-ortho- phospahate---ppt----impairs cheese making. UHT milk not a good source of Ca. for children. 2- Effect on physico-chemical properties 2.4 Milk minerals 2.5 Milk vitamins All inactivated except VITB2,B12, biotin Vit C and folic acids are affected Vit B1 -------10-20% decreased. 2.6 Milk flavour
- 7. Thank you forattention Presented by : Dr. Dina A. B. Awad Lecturer of food hygiene department Faculty of veterinary medicine Benha university , Egypt Dr.Dina A.B. Awad 7