说明： 1.允许使用中英文字典。 2.原则上，中文题用中文回答，英文题用英文回答 3.选修小语种的同学可不做英语题，但须作附加题。 试题2005 、填空 1.The extent of microorganism inactivation depends on the combination of temperature and holding time.(p.41) 2.Types of single effect evaporators of milk include Batch Pan Rising film,Falling film,Plate evaporators and Scraped surface(58) 3.Concentrated Dairy Products include Evaporated Skim milk Whole Milk. Sweetened Condensed Milk, Condensed buttermilk and Condensed Whey.(p.68) 4.Dried Dairy Products include Milk Powder, Whey Powder and Whey Protein Concentrates(p.68) 5.The following may all be added to the cheese milk:Calcium choride nitrates,colour,hydrogen peroxide and lipases 二、名词解释 1.SMP :Skim milk powder (p.70) 2.WPC:whey protein concentrate(p.53) 3 buttermilk 4.MSNF:The serum solids or milk solids-not-fat(MSNF)contain the lactose,caseins whey proteins,minerals,and ash content of the product from which they were derived(p.86). 5.Cheese:Traditionally,cheese was made as a way of preserving the nutrients of milk.In a 072) cream or partly skimm outtermilk or a mixture of these product 6.UHT:ultra-high temperature(p.48) 7.Plate hea exchanger This piece of equipment consists of a k of corrugate clampe eak ating medium and to prever The he vacuum st r hot water(P 42 8.Yogurt:(also spelled yogourt or yoghurt)is a semi-solid fermented milk product which originated centuries ago in Bulgaria.It's popularity has grown and is now consumed in most parts of the world.Although the consistency,flavour and aroma
说明： 1. 允许使用中英文字典。 2. 原则上，中文题用中文回答，英文题用英文回答。 3. 选修小语种的同学可不做英语题，但须作附加题。 试题 2005 一、填空 1. The extent of microorganism inactivation depends on the combination of temperature and holding time.(p.41) 2. Types of single effect evaporators of milk include Batch Pan , Rising film , Falling film , Plate evaporators and Scraped surface(58) 3. Concentrated Dairy Products include Evaporated Skim milk , Whole Milk, Sweetened Condensed Milk, Condensed Buttermilk and Condensed Whey.(p.68) 4. Dried Dairy Products include Milk Powder, Whey Powder and Whey Protein Concentrates(p.68) 5. The following may all be added to the cheese milk: Calcium choride, nitrates, colour, hydrogen peroxide and lipases 二、名词解释 1. SMP :Skim milk powder (p.70) 2. WPC: whey protein concentrate(p.53) 3. buttermilk: 4. MSNF: The serum solids or milk solids-not-fat (MSNF) contain the lactose, caseins, whey proteins,minerals, and ash content of the product from which they were derived(p.86). 5. Cheese :Traditionally, cheese was made as a way of preserving the nutrients of milk. In a simple definition, cheese is the fresh or ripened product obtained after coagulation and whey separation of milk, cream or partly skimmed milk, buttermilk or a mixture of these products. (p.72) 6. UHT: ultra-high temperature(p.48) 7. Plate heat exchanger. This piece of equipment consists of a stack of corrugated stainless steel plates clamped together in a frame. There are several flow patterns that can be used. Gaskets are used to define the boundaries of the channels and to prevent leakage. The heating medium can be vacuum steam or hot water(p42). 8. Yogurt: (also spelled yogourt or yoghurt) is a semi-solid fermented milk product which originated centuries ago in Bulgaria. It's popularity has grown and is now consumed in most parts of the world. Although the consistency, flavour and aroma
may vary from one region to another,the basic ingredients and manufacturing are essentially consistent(p.75): 9.LA:Lactobacillus acidophilus(p.77) 10.LAB:lactic acid bacteria(p.73) 三、简述题 1.What is the Stoke's Law???(p.39)? ce in density between the two phases .decreasing viscosity of the continuous phas If raw milk were allowed to stand,the fat globules would begin to rise to the surface in a phenomena called creaming.Raw milk in a rotating container also has centrifugal forces acting on it.This allows rapid separation of milk fat from the skim milk portion and removal of solid impurities from the milk. 2.How to Separate the cream from milk?(p.39) Centrifuges can be used to separate the cream from the skim milk.The centrifuge consists of up to 120 discs stacked together at a 45 to 60 degree angle and separated by a 0.4 to 2.0 mm gap or separation channel.Milk is introduced at the outer edge of the disc stack.The stack of discs has vertically aligned distribution holes into which the milk is introduced. Under the influence of centrifugal force the fat globules(cream),which are less dens than the ski axis of 3.What is the Pasteurization of milk?(p.40) The process of pasteur aton wa name d after Louis Pasteur who discovered that applying h ing poin The process was later applied to milk and remains the most the p f od par ut allo owing recontamin milk during th e heat treatment process. 4.How to standardize the milk?(p.40) The streams of skim and cream after separation must be recombined to a specified fat content.This can be done by adjusting the throttling valve of the cream outlet,if the valve is completely closed,all milk will be discharged through the skim milk outlet As the valve is progressively opened,larger amounts of cream with diminishing fat
may vary from one region to another, the basic ingredients and manufacturing are essentially consistent(p.75): 9. LA: Lactobacillus acidophilus(p.77) 10. LAB: lactic acid bacteria (p.73) 三、简述题 1. What is the Stoke's Law ???(p.39)? Centrifugation is based on Stoke's Law. The particle sedimentation velocity increases with: • increasing diameter • increasing difference in density between the two phases • decreasing viscosity of the continuous phase If raw milk were allowed to stand, the fat globules would begin to rise to the surface in a phenomena called creaming. Raw milk in a rotating container also has centrifugal forces acting on it. This allows rapid separation of milk fat from the skim milk portion and removal of solid impurities from the milk. 2.How to Separate the cream from milk?(p.39) Centrifuges can be used to separate the cream from the skim milk. The centrifuge consists of up to 120 discs stacked together at a 45 to 60 degree angle and separated by a 0.4 to 2.0 mm gap or separation channel. Milk is introduced at the outer edge of the disc stack. The stack of discs has vertically aligned distribution holes into which the milk is introduced. Under the influence of centrifugal force the fat globules (cream), which are less dense than the skim milk, move inwards through the separation channels toward the axis of rotation. The skim milk will move outwards and leaves through a separate outlet. 3. What is the Pasteurization of milk?(p.40) The process of pasteurization was named after Louis Pasteur who discovered that spoilage organisms could be inactivated in wine by applying heat at temperatures below its boiling point. The process was later applied to milk and remains the most important operation in the processing of milk. Definition: The heating of every particle of milk or milk product to a specific temperature for a specified period of time without allowing recontamination of that milk or milk product during the heat treatment process. 4. How to standardize the milk?(p.40) The streams of skim and cream after separation must be recombined to a specified fat content. This can be done by adjusting the throttling valve of the cream outlet; if the valve is completely closed, all milk will be discharged through the skim milk outlet. As the valve is progressively opened, larger amounts of cream with diminishing fat
contents are discharged from the cream outlet.With direct standardization the cream and skim are automatically remixed at the separator to provide the desired fat content Some basic standardization problems including mass balance and Pearson square approach can be viewed here. 5.What is the Pasteurization of milk?(p.40) The process of pasteurization was named after Louis Pasteur who discovered that spoilage organisms could be inactivated in wine by applying heat at temperatures below its boiling poin The process was ater applied to milk and remains the most nt operation in the processing of milk e he milka spe oduct during the hea t treat ent proce 6.What is the Batch method of Pasteurization of milk?(p.42) The batch method uses a vat rizer which consists of a jacketed vat surrounded by either circulating water,steam or heating coils of water or steam. In the vat the milk is heated and held throughout the holding period while being agitated.The milk may be cooled in the vat or removed hot after the holding time is completed for every particle.As a modification,the milk may be partially heated in tubular or plate heater before entering the vat.This method has very little use for milk but some use for milk by-products(e.g.creams,chocolate)and special batches.The d extensivly in the ice cream industry for mix quality reasons other than 7.What is the Continuous method of Pasteurization of milk?(p.42) Continuous process method has several advantages over the vat method,the most important being time and e ergy saving.For m ost con nud us process1n唱，ang npera ort (HTS treatmen ned us g a plate hea exc p Gaske p al flo h 。channels d to prevent leat e The h r hot water. 8.What is Beverage Milks?(p.66) The produc of bev combines the unit operations of clarification. or t produ age milks on of lowe and mogenization ted in the While or mo 34%.Lowe fat alte ativ such as2%fat,1%fat.or skim milk (<0.1%fat)or also
contents are discharged from the cream outlet. With direct standardization the cream and skim are automatically remixed at the separator to provide the desired fat content. Some basic standardization problems including mass balance and Pearson square approach can be viewed here. 5. What is the Pasteurization of milk?(p.40) The process of pasteurization was named after Louis Pasteur who discovered that spoilage organisms could be inactivated in wine by applying heat at temperatures below its boiling point. The process was later applied to milk and remains the most important operation in the processing of milk. Definition: The heating of every particle of milk or milk product to a specific temperature for a specified period of time without allowing recontamination of that milk or milk product during the heat treatment process. 6. What is the Batch method of Pasteurization of milk?(p.42) The batch method uses a vat pasteurizer which consists of a jacketed vat surrounded by either circulating water, steam or heating coils of water or steam. In the vat the milk is heated and held throughout the holding period while being agitated. The milk may be cooled in the vat or removed hot after the holding time is completed for every particle. As a modification, the milk may be partially heated in tubular or plate heater before entering the vat. This method has very little use for milk but some use for milk by-products (e.g. creams, chocolate) and special batches. The vat is used extensivly in the ice cream industry for mix quality reasons other than microbial reasons. 7. What is the Continuous method of Pasteurization of milk?(p.42) Continuous process method has several advantages over the vat method, the most important being time and energy saving. For most continuous processing, a high temperature short time (HTST) pasteurizer is used. The heat treatment is accomplished using a plate heat exchanger. This piece of equipment consists of a stack of corrugated stainless steel plates clamped together in a frame. There are several flow patterns that can be used. Gaskets are used to define the boundaries of the channels and to prevent leakage. The heating medium can be vacuum steam or hot water. 8. What is Beverage Milks?(p.66) The production of beverage milks combines the unit operations of clarification, separation (for the production of lower fat milks), pasteurization, and homogenization. The process is simple, as indicated in the flow chart. While the fat content of most raw milk is 4% or higher, the fat content in most beverage milks has been reduced to 3.4%. Lower fat alternatives, such as 2% fat, 1% fat, or skim milk (<0.1% fat) or also
available in most markets.These products are either produced by partially skimming the whole milk,or by completely skimming it and then adding an appropriate amount of cream back to achieve the desired final fat content. Vitamins may be added to both full fat and reduced fat milks.Vitamins A and D(the fat soluble ones)are often supplemented in the form of a water soluble emulsion to offset that quantity lost in the fat separation process. 9.What is Recombined Milk?(p.67) Beverage milks can also be prepared by recombining skim milk powder and butter with water.This is often done in countries where there is not enough milk production to meet the demand for beverage milk consumption.The concept is simple.Skim milk powder is dispersed in water and allowed to hydrate.Butter is then emulsified into his mixt丸re by either blending melted butter into the liquid mixture while hot,or by dispersing solid butter into the liquid through a high shear blender device.In some cases,a non-dairy fat source may also be used.The recombined milk product is then pasteurized, homo enized and pa ged as in regular mi produ e fina mpo mately and eithe 2% ole milk,approx T30 he n and g must be lumping of the powder.Its disper sal in water is the key to su 10.How to treatment of Milk for Cheesemaking?(p.72) oducts st first be clarified, ay then be subiected to a sub-pasteu ent of 63-65 C for 15 to 16 sec.This thermization trea atment results in a reduction of high initial bacteria counts before stor age it must he followed by oner pasteurization While HTST pasteurization (72C for 16 sec)is often used,an alternative heat treatment of 60 C for 16 sec may also be used.This less severe heat treatment is thought to result in a better final flavour cheese by preserving some of the natural flora.If used,the cheese must be stored for 60 days prior to sale,which is similar to the regulations for raw milk cheese. 11.Why is milkfat important to ice cream ?(p.85) Milkfat is important to ice cream for the following reasons ·: increases the e rich hness of flavou to to its r aids in melting rtie also e to its role in fat destabilization aids in lubricating the free ezer barrel during manufacturing (Non-fat mixes are extremely hard on the freezing equipment) The limitations of excessive use of butterfat in a mix include:
available in most markets. These products are either produced by partially skimming the whole milk, or by completely skimming it and then adding an appropriate amount of cream back to achieve the desired final fat content. Vitamins may be added to both full fat and reduced fat milks. Vitamins A and D (the fat soluble ones) are often supplemented in the form of a water soluble emulsion to offset that quantity lost in the fat separation process. 9. What is Recombined Milk?(p.67) Beverage milks can also be prepared by recombining skim milk powder and butter with water. This is often done in countries where there is not enough milk production to meet the demand for beverage milk consumption. The concept is simple. Skim milk powder is dispersed in water and allowed to hydrate. Butter is then emulsified into this mixture by either blending melted butter into the liquid mixture while hot, or by dispersing solid butter into the liquid through a high shear blender device. In some cases, a non-dairy fat source may also be used. The recombined milk product is then pasteurized, homogenized and packaged as in regular milk production. The final composition is similar to that of whole milk, approximately 9% milk solids-not-fat, and either 2% or 3.4% fat. The water source must be of excellent quality. The milk powder used for recombining must be of high quality and good flavour. Care must be taken to ensure adequate blending of the ingredients to prevent aggregation or lumping of the powder. Its dispersal in water is the key to success. 10. How to treatment of Milk for Cheesemaking?(p.72) Like most dairy products, cheesemilk must first be clarified, separated and standardized. The milk may then be subjected to a sub-pasteurization treatment of 63-65° C for 15 to 16 sec. This thermization treatment results in a reduction of high initial bacteria counts before storage. It must be followed by proper pasteurization. While HTST pasteurization (72° C for 16 sec) is often used, an alternative heat treatment of 60° C for 16 sec may also be used. This less severe heat treatment is thought to result in a better final flavour cheese by preserving some of the natural flora. If used, the cheese must be stored for 60 days prior to sale, which is similar to the regulations for raw milk cheese. 11. Why is milkfat important to ice cream ?(p.85) Milkfat is important to ice cream for the following reasons: • increases the richness of flavour in ice cream • produces a characteristic smooth texture by lubricating the palate • helps to give body to the ice cream, due to its role in fat destabilization • aids in good melting properties, also due to its role in fat destabilization • aids in lubricating the freezer barrel during manufacturing (Non-fat mixes are extremely hard on the freezing equipment) The limitations of excessive use of butterfat in a mix include:
·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