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The process of pasteurization was named after Louis Pasteur who discovered the effects of heat on spoilage organisms in milk.
The process of pasteurization was named after Louis Pasteur who discovered the effects of heat on spoilage organisms in milk.
False
Pasteurization is designed to destroy harmful bacteria in milk to make it safe for human consumption.
Pasteurization is designed to destroy harmful bacteria in milk to make it safe for human consumption.
True
The batch method of pasteurization uses a continuous flow process to heat milk.
The batch method of pasteurization uses a continuous flow process to heat milk.
False
Ultra-high temperature (UHT) processing involves heating milk for a duration of 1–2 seconds at temperatures above 135°C.
Ultra-high temperature (UHT) processing involves heating milk for a duration of 1–2 seconds at temperatures above 135°C.
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Milk is considered pasteurized if it tests positive for alkaline phosphatase.
Milk is considered pasteurized if it tests positive for alkaline phosphatase.
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UHT processed milk typically has a shelf life of six to nine months when unopened.
UHT processed milk typically has a shelf life of six to nine months when unopened.
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The direct heating method for UHT processing includes both injection and infusion techniques.
The direct heating method for UHT processing includes both injection and infusion techniques.
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Membrane processing of milk utilizes heat to separate particles based on molecular size.
Membrane processing of milk utilizes heat to separate particles based on molecular size.
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The main purpose of UHT processing is to kill thermoresistant spores in milk.
The main purpose of UHT processing is to kill thermoresistant spores in milk.
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The temperature during HTST pasteurization is typically 70°C for at least 15 seconds.
The temperature during HTST pasteurization is typically 70°C for at least 15 seconds.
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The keeping quality aspect of milk pasteurization aims to destroy all bacteria present.
The keeping quality aspect of milk pasteurization aims to destroy all bacteria present.
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Indirect heating methods in UHT processing involve direct contact of the heating medium with the product.
Indirect heating methods in UHT processing involve direct contact of the heating medium with the product.
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Frozen dairy dessert mixes require pasteurization at a minimum temperature of 80°C for at least 25 seconds.
Frozen dairy dessert mixes require pasteurization at a minimum temperature of 80°C for at least 25 seconds.
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Milk is composed solely of fat and high-quality protein.
Milk is composed solely of fat and high-quality protein.
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Casein micelles are believed to be composed of smaller units held together by calcium phosphate.
Casein micelles are believed to be composed of smaller units held together by calcium phosphate.
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Whey proteins are less hydrated compared to casein proteins.
Whey proteins are less hydrated compared to casein proteins.
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Centrifuges can separate cream from skim milk by using centrifugal force.
Centrifuges can separate cream from skim milk by using centrifugal force.
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The streams of skim and cream after separation must be discarded without recombining.
The streams of skim and cream after separation must be discarded without recombining.
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The stack of discs in a centrifuge is arranged horizontally.
The stack of discs in a centrifuge is arranged horizontally.
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All milk will be discharged through the cream outlet if the throttling valve is completely closed.
All milk will be discharged through the cream outlet if the throttling valve is completely closed.
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Milk can be concentrated to form products like evaporated milk and cheeses.
Milk can be concentrated to form products like evaporated milk and cheeses.
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Air bubbles in ice cream are stabilized by coalesced fat.
Air bubbles in ice cream are stabilized by coalesced fat.
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Butter is made exclusively from salted cream.
Butter is made exclusively from salted cream.
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Yogurt is a solid fermented product from milk.
Yogurt is a solid fermented product from milk.
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Most industrial yogurt production relies on goat's milk.
Most industrial yogurt production relies on goat's milk.
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Starter cultures for yogurt production include both Streptococcus thermophilus and Lactobacillus delbrueckii.
Starter cultures for yogurt production include both Streptococcus thermophilus and Lactobacillus delbrueckii.
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During fermentation, the pH of yogurt first drops to approximately 7.0.
During fermentation, the pH of yogurt first drops to approximately 7.0.
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The gel formation in yogurt is due to the denaturation of whey proteins.
The gel formation in yogurt is due to the denaturation of whey proteins.
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Cooling the milk to 108°F (42°C) is intended to inhibit starter culture growth.
Cooling the milk to 108°F (42°C) is intended to inhibit starter culture growth.
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Adding fruit during the yogurt manufacturing process should occur only after fermentation is complete.
Adding fruit during the yogurt manufacturing process should occur only after fermentation is complete.
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The fermentation process in yogurt can take several hours to reach the desired pH.
The fermentation process in yogurt can take several hours to reach the desired pH.
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Gelatin and other stabilizers are added to yogurt to decrease the amount of protein.
Gelatin and other stabilizers are added to yogurt to decrease the amount of protein.
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Yogurt should be pasteurized after fermentation to ensure bacteria are killed.
Yogurt should be pasteurized after fermentation to ensure bacteria are killed.
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One of the fermentation products in yogurt that contributes to flavor is lactic acid.
One of the fermentation products in yogurt that contributes to flavor is lactic acid.
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Homogenization in yogurt production is carried out at pressures above 3000 psi.
Homogenization in yogurt production is carried out at pressures above 3000 psi.
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Heat treatment during milk powder production is less severe than that used for pasteurization.
Heat treatment during milk powder production is less severe than that used for pasteurization.
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Whey is a by-product of cheese production.
Whey is a by-product of cheese production.
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The process of crystallization in whey powder production increases its hygroscopicity.
The process of crystallization in whey powder production increases its hygroscopicity.
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Lactic acid is produced by bacteria during cheese ripening and helps in coagulation.
Lactic acid is produced by bacteria during cheese ripening and helps in coagulation.
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Homogenization is often used for cheesemilk to create a strong curd.
Homogenization is often used for cheesemilk to create a strong curd.
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Heat-acid coagulation can recover more protein than rennet coagulation.
Heat-acid coagulation can recover more protein than rennet coagulation.
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Milk powder production requires evaporation before drying to save energy.
Milk powder production requires evaporation before drying to save energy.
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Cheese ripening is a process that takes place after coagulation and curd treatment.
Cheese ripening is a process that takes place after coagulation and curd treatment.
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The process of syneresis involves the absorption of whey into the curd.
The process of syneresis involves the absorption of whey into the curd.
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Traditional cheese making methods have led to thousands of varieties worldwide.
Traditional cheese making methods have led to thousands of varieties worldwide.
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Acid treatment coagulates milk by destabilizing all proteins indiscriminately.
Acid treatment coagulates milk by destabilizing all proteins indiscriminately.
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Condensed buttermilk is one of the concentrated dairy products.
Condensed buttermilk is one of the concentrated dairy products.
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Lactose crystallization is induced before whey concentrate is spray dried.
Lactose crystallization is induced before whey concentrate is spray dried.
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Sweetened condensed milk is more concentrated than regular milk.
Sweetened condensed milk is more concentrated than regular milk.
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The increase in temperature causes the protein matrix to expand.
The increase in temperature causes the protein matrix to expand.
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Cheese varieties such as Gouda and Colby include a curd washing process.
Cheese varieties such as Gouda and Colby include a curd washing process.
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Milk solids-not-fat are a significant source of total solids in ice cream.
Milk solids-not-fat are a significant source of total solids in ice cream.
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Excessive use of butterfat in ice cream can decrease its caloric value.
Excessive use of butterfat in ice cream can decrease its caloric value.
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The final moisture content of curd does not influence the residual amount of fermentable lactose.
The final moisture content of curd does not influence the residual amount of fermentable lactose.
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Stabilizers are responsible for decreasing the viscosity of the unfrozen portion of ice cream.
Stabilizers are responsible for decreasing the viscosity of the unfrozen portion of ice cream.
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Rennet is one of the ripening agents used in cheese production.
Rennet is one of the ripening agents used in cheese production.
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Locust bean gum is derived from the leaves of plants.
Locust bean gum is derived from the leaves of plants.
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The characteristic flavour, body, and texture of cheese are achieved during the curing stage.
The characteristic flavour, body, and texture of cheese are achieved during the curing stage.
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Emulsifiers are primarily used to enhance the stability of fat emulsion in ice cream.
Emulsifiers are primarily used to enhance the stability of fat emulsion in ice cream.
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High overrun in ice cream is desirable for a texture that is snowy and flaky.
High overrun in ice cream is desirable for a texture that is snowy and flaky.
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Butterfat contributes to the richness of flavour and smooth texture in ice cream.
Butterfat contributes to the richness of flavour and smooth texture in ice cream.
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The curd is separated from the whey after it has reached the desired moisture and acidity.
The curd is separated from the whey after it has reached the desired moisture and acidity.
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Polysorbate 80 is a naturally occurring emulsifier found in eggs.
Polysorbate 80 is a naturally occurring emulsifier found in eggs.
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Environmental contaminants play no role in the microbiological content of curds.
Environmental contaminants play no role in the microbiological content of curds.
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Study Notes
Dairy Products Technology
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Milk is a mixture of fat, high-quality protein (casein and whey), water, lactose, vitamins, and minerals produced by female mammals' mammary glands.
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Milk products include various forms like fluid milk, evaporated milk, and cheeses used globally as drinks, cheeses, yogurts, and ingredients in soups/sauces.
Casein Micelle Structure
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Casein micelles are complex structures, thought to be composed of smaller submicelles held together by calcium phosphate.
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They have negatively charged regions (exposed casein protein chains) on their surfaces.
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Electron micrographs demonstrate their structure (scale bar represents 100 nm).
Whey Protein
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Whey, comprising approximately 20% of milk protein, includes lactalbumins and lactoglobulins.
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Whey proteins are more hydrated than casein and denature by heat rather than acid.
General Milk Processing
Separation
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Centrifuges separate cream (less dense) from skim milk.
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The process utilizes a disc stack with a specific gap, introducing milk at the outer edge, and separating the components via centrifugal force.
Standardization
- Separated skim and cream are recombined to the desired fat content by adjusting cream outlet throttling valves.
Pasteurization
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Pasteurization, named after Louis Pasteur, inactivates spoilage organisms by heating below boiling point.
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Key Purposes include: public health (eliminating harmful bacteria) and improving keeping quality.
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Common regulations for milk, (63°C for 30min, 72°C for 16sec, or equivalent pathogen/enzyme inactivation), and milk-based products at different temperatures for specific time periods.
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Methods include batch (jacketed vat) and continuous.
UHT Processing
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UHT (Ultra-High Temperature) processing sterilizes food by heating for a short time (1-2 seconds) above 135°C.
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It significantly extends the shelf life as it eliminates many microorganisms, including spores.
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Techniques include: direct heating (injection/infusion) and indirect heating (heat exchangers such as plate, tubular, and scraped surface).
Membrane Processing
- Membrane processing concentrates/separates milk components (proteins, lactose) via semi-permeable membranes without heat, increasing efficiency.
Concentrated and Dried Dairy Products
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Fluid milk is high in water (approximately 88%).
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Concentration/drying reduces water content for extended shelf life, convenience, reduced transport, and storage costs.
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Concentrated products include evaporated milk, sweetened condensed milk and condensed buttermilk, while dried products include milk powder, whey powder, and whey protein concentrates.
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Milk powder production involves clarification, standardization, heat treatment to destroy enzymes (lipids) and microorganisms, and evaporation before drying.
Whey Powder
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Whey, a byproduct of cheesemaking, often has disposal and environmental concerns.
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Whey powder production utilizes reverse osmosis, vacuum evaporation followed by rapid cooling (crystallization), and fluidized bed for drying for consistent product quality.
Cheese Production
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Cheesemaking traditionally involves preserving milk nutrients by coagulation and whey separation of milk, cream, or mixtures.
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Key steps include milk treatment, additives, inoculation & milk ripening, coagulation (enzyme, acid, or heat-acid treatments), curd treatment, & ripening.
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Treatment of milk for cheesemaking includes clarification, separation, standardization and pasteurization using HTST or a milder, alternative treatment.
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Coagulation methods (enzyme, acid and combined heat-acid) create different types of cheeses.
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Curd handling varies with cheese types, involving cutting, draining, washing, salting and pressing (like cheddaring).
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Ripening is a crucial step to develop flavor, body, and texture using various agents like bacteria, enzymes, molds, or yeasts.
Ice Cream Formulations
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Key components include milkfat (10%-16%), milk solids-not-fat (9%-12%), sugar, corn syrup solids, stabilizers, emulsifiers, and water.
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Milkfat enhances richness, smoothness, body, and melting properties (though excessive fat limits whipping ability, costs, and overall appeal).
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Milk solids-not-fat (MSNF) improve texture, body, overrun capability and can be a source of total solids. Good sources include concentrated, condensed, or spray-dried skim milk.
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Stabilizers (CMC, locust bean gum, guar gum, carrageenan) add viscosity and prevent ice crystal formation, while emulsifiers (mono- and di-glycerides, polysorbate 80) reduce fat emulsion stability, for smoother texture.
Butter Manufacture
- Butter is essentially milk fat, usually made from sweet cream and salted. Salted and unsalted options exist.
Yogurt Production
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Yogurt, a fermented milk product, uses various types of milk (cow's, whole/skim, or cream).
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Crucial to ensure low bacteria count, absence of antibiotics, sanitizers, and other contaminants in the raw milk for successful yogurt fermentation.
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Common ingredients include stabilizers, sweeteners, and flavorings.
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Starter cultures ( Streptococcus thermophilus and Lactobacillus bulgaricus) are pivotal in the fermentation process to produce lactic acid, acetaldehyde, acetic acid, and diacetyl, resulting in characteristic flavor.
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Description
Explore the various methods of pasteurization, including the batch and ultra-high temperature (UHT) techniques. Learn about the importance of pasteurization in ensuring milk safety and its impact on shelf life. This quiz will test your knowledge on the process and significance of pasteurization in dairy products.
