How and how much to store milk and milk products
Educational Program Food / / December 19, 2019
Layfhaker talked to the dairy industry technologist and found out what it depends on the shelf life of milk, yogurt, sour milk, yoghurt, sour cream and cottage cheese.
From what the shelf life depends molochki
On packages often use terms whose meaning we do not know or misunderstand: "Use standardized milk," "ultra-pasteurized", "Made from whole milk," and so on. Let's see a species of dairy raw materials, methods of its processing and packaging, and how all this affects the life of dairy products.
dairy raw materials
Milk is for guests:
- unibody. This natural milk that strain, but was not adjusted for the fat content. Natural balance of fats, proteins and carbohydrates in a milk unchanged.
- normalize. This milk, divided by the inverse (liquid fat zero) and cream, and then reduced to the desired parameters. Milk normalize it to be not too bold and to make sour cream, cottage cheese and other foods with a certain percentage of fat.
- low fat. This milk, from which in the process of separating the cream isolated. On the palate, it is almost the same as a whole, but the energy value is twice lower. Such milk and products based on it produce for people to count calories.
- restoration. This milk made from the concentrated or powdered milk and water.
A method of processing
Depending on the heat treatment of milk is divided into:
- pasteurized - a one-time heating is usually to 60 ° C. When pasteurizing vegetative forms of microorganisms are killed, but the spores remain viable and under favorable conditions occur intensively developed. As a rule, pasteurized whole or skim milk and cream and buttermilk. Pasteurized products were stored at low temperatures for a short period.
- UHT - short heating to 150 ° C and rapid cooling. Bacteria that cause souring of milk are killed, but the flavor and nutrients are retained.
- sterilized - relatively long heating to 100 ° C and above. In fact, it boiled milk, which does not remain nutrients and killing all bacteria, including lactic acid. No yogurt or cottage cheese out of it will not receive. But the store is milk can be very long. In the manufacture of sterilized milk, and ultrapasteurized often apply various salt stabilizers.
Proceeding from the above classifications, all dairy products can be divided into short and long.
Short milk - is unreduced milk with low temperature pasteurization, and products made on its basis. Long milk - it is ultra-pasteurized and sterilized or refurbished from dry milk and products made from it.
Packaging
In addition to raw materials and the processing method for molochki shelf life affect packaging appearance.
- soft packing (Fin-pack, Bertha-pack, etc.). This packets from higher strength polyethylene.
- Semi-rigid packaging (Various types of thermoplastics). It is a usually a plastic cup with a sealed "lid" of the foil or film.
- Semi-rigid packaging sheet and composite materials (Tetra-pack, Tetra Rex and others). This cardboard boxes of various shapes with a multilayer coating inside.
Companies operating in the short milk, typically selected polyethylene plastic and cheap embodiments of cardboard packaging. If the counter milk in plastic and paper bag, most likely before you pasteurized milk with a shelf life of 3-5 days.
Thermoplastics are most often used for yoghurt, sour cream and other dairy products. Here the most important thing - the tightness of the package. If the manufacturer has used a high-quality coating material and strictly followed the gaseous medium in packaging, the product is easy to be stored for 5-7 days.
Seen in the foil slightest hole? 99%, which spoiled product.
Ultra-pasteurization and sterilization requires aseptic filling, which can only provide a tetra-pak. Do not buy such milk in plastic bags and carton cheaper.
How to store milk and milk products
Taking over the counter a bottle of milk or a pack of yogurt, we first look at the shelf life and wonder why such a spread? The product of one brand lives just a couple of days, and seems to be exactly the same product, but a different brand - two weeks.
The shelf life of dairy products is established manufacturers. However, it should not exceed the time limits prescribed in the regulations controlling authorities.
The shelf life of milk, which is only slightly heated to drop off the consumers may not exceed 5 days. the shelf life of dairy products without stabilizers and preservatives - no more than 10 days.
Shelf life long molochki set producers based on what stabilizers, preservatives and thickeners are added to the composition. The manufacturer is obliged to take a test and approve the retention period for each product in your Rospotrebnadzor. Therefore, consumers should focus on the date specified on the package.
The optimum storage temperature short molochki - 2-4 ° C. it third shelf of the refrigeratorAs well as the freshness of the zone. Long jelly can be placed on the top shelf, and even the refrigerator door. For sterilized milk package, for example, is permissible storage temperature to 25 ° C.
After opening the package, the maximum shelf life of pasteurized milk - 48 hours, sterilized - 96 hours. UHT is stored for as long as it is written on the packaging. Dairy products should be consumed within 72 hours.
How to determine the freshness of milk
Sometimes the term did not come out and hold in the refrigerator, but still take a doubt whether it is possible to eat? Determine the adequacy of the product can not only store terms, but also by their appearance.
Fresh milk white, homogeneous, without flakes, huddled fat lumps and foreign tastes and odors (except that melted and sterilized have a taste of boiling).
Natalia Klimova, Chief Technologist "hoe-milk" (holding "Compound")
If milk fat (4.7% and higher), it is acceptable film formation characteristic, which immediately disappears upon stirring. Skim milk may have a slightly bluish tint, and UHT - cream.
We felt sour milk sour, and then a clot appears. It is transformed into yogurt.
How to determine the freshness of yogurt and sour milk
Fresh yogurt has a uniform consistency. Because of mixed (lactate and alcohol) fermentation and special leaven on kefir fungi may flatulence. Natalia Klimova said that small package swelling with yogurt - it is normal.
But for sour milk is, on the contrary, a sign of spoilage. The product produced by fermenting milk with the addition of melted special starter cultures. Fresh ryazhenka absolutely uniform, pale cream-colored and melted with a pleasant aftertaste.
The main sign of deterioration of dairy products - the emergence of top watery whey.
How to determine the freshness of sour cream
Fresh sour cream should be a homogeneous, thick, white or slightly creamy gloss finish. Minimum mass fraction of fat sour cream for - 10%, maximum - 42%. The higher the fat content, the thicker cream.
Natalia Klimova
According to the guests in the cream can not add stabilizers and thickening agents. If the manufacturer he cast a little powder, it does not have the right to write on the package the word "cream". Therefore, in the shops there were all sorts of sour cream, cream products. They are cheaper than natural sour cream, but you need to carefully study the composition: whether in foreign additives.
How to determine the freshness of yogurt
Natalia Klimov explained that, depending on the method of production of yogurt can be a liquid (drinking) and creamy. In any case, fresh product consistency must be uniform. In the production method of the tank (when product first skvashivaetsya a large capacity, and then poured into a container) of protein products may be impaired clot. When thermostat (when starter introduced in the already packaged product) clot should be an integer.
If yogurt with pieces of fruit, it should be moderately sweet and match the color and flavor of the filler.
How to determine the freshness of the curds
Fresh produce soft, spreadable he or crumbly texture. To skim curd normal serum and a small selection weak taste of powdered milk.
Natalia Klimova
Spoiled cheese is easy to recognize the taste: it is bitter.
What if the milk has deteriorated
Do not worry if you missed the deadlines. Natural milk can be processed into yogurt or yogurt. To do this, you need to buy a special starter and mix it with hot sour product.
If yogurt or milk serum is beginning to flake off, make cheese. To this end, the liquid needs to be heated, too, but do not bring to a boil to cereal curds separated from the whey and discard in a colander, the laid gauze. After that you need to tie the cheesecloth and hang it over the sink to the remaining liquid glass.
Also slightly soured milk and a little overdue yogurt - a good basis for pancakes.