Milk different types

Pasteurized and sterilized sound like the same thing, to me.

Homogenized means that the cream/fat will not separate out from the rest of the milk.

I have no idea what uht is.

c'mon DD, pronounce it like nosey is from Longwood


Uht?

drank milk, it's gud fer ya. Uht cha waitin' fer?

ennybody seed my car keys?

UHT Milk
UHT MILK= Ultra Heat Ttreated MILK

Ultra Heat Treatment basics


Introduction
While pasteurization conditions effectively eliminate potential pathogenic microorganisms, it is not sufficient to inactivate the thermoresistant spores in milk. The term sterilization refers to the complete elimination of all microorganisms. The food industry uses the more realistic term "commercial sterilization"; a product is not necessarily free of all microorganisms, but those that survive the sterilization process are unlikely to grow during storage and cause product spoilage.
In canning we need to ensure the "cold spot" has reached the desired temperature for the desired time. With most canned products, there is a low rate of heat penetration to the thermal centre. This leads to overprocessing of some portions, and damage to nutritional and sensory characteristics, especially near the walls of the container. This implies long processing times at lower temperatures.
Milk can be made commercially sterile by subjecting it to temperatures in excess of 100° C, and packaging it in air-tight containers. The milk may be packaged either before or after sterilization. The basis of UHT, or ultra-high temperature, is the sterilization of food before packaging, then filling into pre-sterilized containers in a sterile atmosphere. Milk that is processed in this way using temperatures exceeding 135° C, permits a decrease in the necessary holding time (to 2-5 s) enabling a continuous flow operation.
Some examples of food products processed with UHT are:
· liquid products - milk, juices, cream, yoghurt, wine, salad dressings
· foods with discrete particles - baby foods; tomato products; fruits and vegetables juices; soups
· larger particles - stews


Advantages of UHT
High quality:
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


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.


UHT Methods
There are two principal methods of UHT treatment:
1. Direct Heating
2. Indirect Heating
Direct heating systems
The product is heated by direct contact with steam of potable or culinary quality. The main advantage of direct heating is that the product is held at the elevated temperature for a shorter period of time. For a heat-sensitive product such as milk, this means less damage.

Indirect vs Direct Heating
There are two methods of direct heating;
1. injection
2. infusion
Injection - High pressure steam is injected into pre-heated liquid by a steam injector leading to a rapid rise in temperature. After holding, the product is flash-cooled in a vacuum to remove water equivalent to amount of condensed steam used. This method allows fast heating and cooling, and volatile removal, but is only suitable for some products. It is energy intensive and because the product comes in contact with hot equipment, there is potential for flavour damage.

Infusion - Food in a free falling film is pumped into a chamber of high pressure steam. The time of the fall matches the desired holding time. The product, therefore, falls onto a cooled surface, followed by flash cooling in vacuum chamber. This method has several advantages:
· instantaneous heating and rapid cooling
· no localized overheating or burn-on
· suitable for low and higher viscosity products


Indirect heating systems
The heating medium and product are not in direct contact, but separated by equipment contact surfaces. Several types of heat exchangers are applicable:
· plate
· tubular
· scraped surface
· double-cone


Plate Heat Exchangers

Similar to that used in HTST but operating pressures are limited by gaskets. Liquid velocities are low which could lead to uneven heating and burn-on. This method is economical in floor space, easily inspected, and allows for potential regeneration.


Tubular Heat Exchangers

There are several types:
· shell and tube
· shell and coil
· double tube
· triple tube

All of these tubular heat exchangers have fewer seals involved than with plates. This allows for higher pressures, thus higher flow rates and higher temperatures. The heating is more uniform


Scraped Surface Heat Exchangers

The product flows through a jacketed tube, which contains the heating medium, and is scraped from the sides with a rotating knife. This method is suitable for viscous products and particulates (< 1 cm) such as fruit sauces, and can be adjusted for different products by changing configuration of rotor. There is a problem with larger particulates; the long process time for particulates would mean long holding sections which are impractical. This may lead to damaged solids and overprocessing

Double-Cone Heat Exchangers

eg APV Jupiter: Suitable for large particulates because it involves separation of solids/liquids and combines indirect heating in double cone (batch) with direct heating of liquid portion (maybe also scraped surface if too viscous). The solid pieces are fed into a double-cone, rotated slowly on horizontal axis with steam injection and heated surfaces. There is no burn-on because they are the same temperature. The liquid is directly heated with steam separately, then added after pre-cooling. The double cone acts as a blender and coats solids. The product is then discharged to an aseptic filler by overpressure with sterile air. Used for soups, stews, carrots, and vegetables.


Packaging for Aseptic Processing


The most important point to remember is that it must be sterile! All handling of product post-process must be within the sterile environment.
There are 5 basic types of aseptic packaging lines:
1. Fill and seal: preformed containers made of thermoformed plastic, glass or metal are sterilized, filled in aseptic environment, and sealed
2. Form, fill and seal: roll of material is sterilized, formed in sterile environment, filled, sealed e.g. tetrapak
3. Erect, fill and seal: using knocked-down blanks, erected, sterilized, filled, sealed. e.g. gable-top cartons, cambri-bloc
4. Thermoform, fill, sealed roll stock sterilized, thermoformed, filled, sealed aseptically. e.g. creamers, plastic soup cans
5. Blow mould, fill, seal:


There are several different package forms that are used in aseptic UHT processing
· cans
· paperboard/plastic/foil/plastic laminates
· flexible pouches
· thermoformed plastic containers
· flow molded containers
· bag-in-box
· bulk totes

http://www.dairyconsultant.co.uk/pages/UHT_Process.htm

you said blow mould.


this seems like a lot of work.

I'll stick to soy milk thanks.

I growed up drinking milk as it comes from the cow. the stuff you buy is coloured water.

I growed up having to get up extra early to shoo in all the soys from where they hid in the sand dunes over night.

Then my sister and I would get to work.

Being the big sister, and protective, I always milked the ones who were skittish.

thanks for sharing chai tea

speaking of tea

do you take milk?

Ernie:- "I can give you pasteurised, 'cos pasteurised is best"

Sue:- "Ernie, I'll be happy if it comes up to me chest!"

"I growed up"
You making fun of the Dys?

I forgot that! Or maybe too young or innocent to appreciate it

Ernie..And he drove the fastest milkcart in the .... where was that exactly Ealing, Hounslow?

<sigh>
if you kept up on your threads, you would see that Boomer made me a very special medical alert bracelet that explains my gastrointestinal relationship with milk.

I don't know how to link...boomer, if you head this way, could you Please show steverino my wrist band?

I dont think that will be necessary. I have to maintain a professional disinterest in your gastrointestinal relationship with milk. Unless soya...that would be quite astounding.

There's another type of milk on the market, so to say situated between pasteurised milk and UHT: high temepered milk, which tatses very nearly like 'normal' milk but can be kept longer than that (about 14 days).

i use just a little milk in tea and too much sugar, in the far east as im led to believe tea is drunk cold with nothing added to it.
Soy milk is ok but im not keen on the sweetened variety

I use soy for my cereal and cooking.

The choclate type is for dessert. Tastes like yohoo.

Thanks for reminder, out of soya milk.

Milk different types
I would much prefer a 6-oz. glass of well-chilled Liebfraumilch, with an apple and Gruyere cheese...