·cost hindered whipping ability decreased consumption due to excessive richness ·high caloric value 四、论述题 1.Please describe Advantages of UHT of milk and Difficulties with UHT(p.48) (1)Advantages of UHT High quality: The D and Z valves are higher for quality factors than microorganisms.The reduction in process time due to higher temperature(UHTST)and the minimal come-up and cool-down time leads to a higher quality product. Long shelf life: Greater than 6 months,without refrigeration,can be expected Packaging size independent of llow ge c ce or sale to fo acturers inless steel totes Cheape Both cost of package and storage and transportation costs,laminated packaging allows for use of extensive graphics (2)Difficulties with UHT Sterility: Complexity of equipment and plant are needed to maintain sterile atmosphere between processing and packaging (packaging materials,pipework,tanks. pumps)higher skilled operators,sterility must be maintained through aseptic ackaging Particl ere is a dang rt materialboth limits particle sizesacan tO Equipm e is a lack of settlin of solids and thus nt for pa articulate sterilization,due especially to overprocess Keeping Qualit Heat stable lipases or p s can lead to flavour deterioration.age gelation of the milk over time-nothing lasts forever!There is also a more pronounced cooked flavour to UHT milk. 2.How to produce Stirred style yogurt(p.76) The milk is clarified and sep ated into standardized to acheive the then blended mix tank equipped with vder funnel and an agitation rst em.The mixture is then • cost • hindered whipping ability • decreased consumption due to excessive richness • high caloric value 四、论述题 1. Please describe Advantages of UHT of milk and Difficulties with UHT(p.48) (1)Advantages of UHT High quality: The D and Z valves are higher for quality factors than microorganisms. The reduction in process time due to higher temperature (UHTST) and the minimal come-up and cool-down time leads to a higher quality product. Long shelf life: Greater than 6 months, without refrigeration, can be expected. Packaging size: Processing conditions are independent of container size, thus allowing for the filling of large containers for food-service or sale to food manufacturers (aseptic fruit purees in stainless steel totes). Cheaper packaging: Both cost of package and storage and transportation costs; laminated packaging allows for use of extensive graphics (2) Difficulties with UHT Sterility: Complexity of equipment and plant are needed to maintain sterile atmosphere between processing and packaging (packaging materials, pipework, tanks, pumps); higher skilled operators; sterility must be maintained through aseptic packaging Particle Size: With larger particulates there is a danger of overcooking of surfaces and need to transport material - both limits particle size Equipment: There is a lack of equipment for particulate sterilization, due especially to settling of solids and thus overprocessing Keeping Quality: Heat stable lipases or proteases can lead to flavour deterioration, age gelation of the milk over time - nothing lasts forever! There is also a more pronounced cooked flavour to UHT milk. 2.How to produce Stirred style yogurt(p.76) The milk is clarified and separated into cream and skim milk, then standardized to acheive the desired fat content. The various ingredients are then blended together in a mix tank equipped with a powder funnel and an agitation system. The mixture is then