Pasteurisation and UHT Processing

Study Notes

Pasteurisation involves heating milk to 72°C for 15 seconds to destroy pathogenic bacteria and increase shelf life.
Pasteurisation also destroys spoilage-causing enzymes, but has no significant effect on nutritional value.
Ultra High Temperature Processing (UHT) involves heating milk to 138-149°C for 2-6 seconds, allowing for storage without refrigeration for at least 3 months.
UHT gives milk a slightly cooked taste, but no significant effect on nutritional value.
Homogenisation reduces fat globules in whole milk, preventing them from clumping and rising to the surface.

Fluid milk should be refrigerated at or below 4°C to prevent bacterial growth.
Shelf life is reduced by half for every 5°C rise in temperature above 4°C.
Milk containers should be kept closed to prevent absorption of odours or flavours.

Concentrated milk products are produced by removing water from whole milk using a vacuum.
Resulting products have a high concentration of milk fat and solids, and an extended shelf life.

Condensed milk has 60% of its water removed and contains 40-45% sugar.
Sweetened condensed milk is canned and has a caramel flavour, but cannot be substituted for whole milk due to its sugar content.

Paddle: used for generic mixing applications, particularly those that are too heavy for whips.
Hook or dough arm: used for mixing and kneading bread doughs, developing gluten quickly and efficiently.
Bench models range in capacity from 4 to 18 litres, while floor mixers can hold up to 140 litres.

Food processors are similar to blenders, but require little to no liquid during use.
Used for blending, chopping, dicing, and slicing, allowing for quicker meal preparation.

Immersion blenders are kitchen blade grinders used to blend ingredients or purée food in the container.
Can be used while a pan is on the stove.

Ice cream churners are electric or manual equipment that freezes a mixture and simultaneously churns it to aerate and keep ice crystals small.
There are three types: countertop, floor, and manual.

Use a double-walled bowl filled with a liquid of urea and distilled water to freeze the machine to well below the normal freezing range of water in about 24 hours.

OTG (Oven Toaster Grill) uses heating coils, radiation, and conduction to bake, toast, grill, or reheat small amounts of food.

Use microwaves (radiowaves) at a particular frequency to break water molecules, releasing heat and cooking food.

The Dough Sheeter is an electric appliance that mechanically rolls dough and pastry to a uniform thickness.
Consists of a cloth conveyor belt that moves beneath a stationary rolling pin.

The electric mixer is indispensable in the commercial kitchen, with several types found in most professional kitchens.
Selection of mixer depends on various factors such as the type of products being mixed and the volume of production required.
Vertical planetary mixers are most common due to their versatility and come in various sizes.

Whisk: used for aeration or foaming applications, such as egg whites for meringue or whipping cream.
Paddle: used for generic mixing applications.
Hook or dough arm: used for mixing and kneading bread doughs.