Common Questions

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Why industrial yogurt, in contrast to home-made yogurt, does not become sour in the refrigerator after a while?

Home-made yoghurt is prepared in the absence of temperature control and precise industrial inspections. The starter used in this yogurt is usually a spoon of purchased industrial yogurt or traditional yogurt, whose type, nature, and how it is acidified are not known, and the milk specifications are also not known to the housewife.

Each packet of starter used in dairy industry is presented at the time of purchase with unique certificate, in which the type and characteristics of its subspecies, the temperature range of its addition to the milk (in what is called inoculation), the amount of use or dose addition, the diagram of the effects of changes in ambient temperature on its activity and the final production acidity are determined.

After a full food and microbial analysis of the primary milk and its processing, it is time to prepare the starters in a sterilized environment in accordance with the characteristics of the type of microorganism in the identification sheet by the starter specialist, based on the exact amount calculated in accordance with the weight of the milk, and then added to milk inoculation tanks. These tanks are three-walled and maintain the temperature at the desired temperature until the preparation of the yogurt under constant control by production experts, which is not possible at home. The unknown nature of the starter used, the high temperature of inoculation and disproportion between the starter type and appropriate temperature for it, slow and long process of cooling after fermentation, long storage at ambient temperature after the preparation of yogurt are some of the reasons for the yogurt being sour at home.


Why does a layer of fat remain on top of home milk but this fat layer does not exist in the industrial milk?

Industrial milk is homogenized in order to properly distribute fat throughout the product tissue and prevent its exit from tissue and accumulation at the surface, increase yogurt consistency, improve the tissue before inoculation, and other technical reasons (Homogenizer is a device that breaks the fat globules of milk into smaller droplets through mechanical impulses so that they stay suspended in the milk rather preventing the separation of milk into two phases), which is not possible at home. Homogenization by equalizing the size of the fat globules eliminates the possibility of accumulation of fat globules at the surface and its exit from the tissue as a layer.


Why is traditional milk yellow, and does this yellow color indicate a high quality milk?

Fat globules are one of the main causes of the yellow color of milk, and in industrial milk, they are broken down into uniform sizes when passed through homogenization device and are distributed with balanced weighing in the tissue, but these globules are different in size in the milk used at home. Accumulation of a large number in one place reflects the darker color of the yellowish fats, and since light is reflected in all directions, the milk with smaller fat cells will have greater surface for reflection, wider reflection of light and brighter color, while milk with larger and more heterogeneous globules will have a lower surface for reflection. The presence of milk fat in the vicinity of the air is another reason for changing the color of the fat, which leads to early milk putrefaction.


   What is the cause of traditional products’ smell and why does not this smell exist in industrial products?

Traditional milking does not take much of the steps of washing the cow’s breast and disinfecting it in the industrial milking process, so the smell of the livestock that comes from the animal itself and the remaining residues from the previous milking comes into the milk. In the industry, maintaining health principles and using deaerator, all undesired smells and naturally some desirable smells are eliminated from the milk.


  Is bleach poured in milk?

Bleach, javel water, or sodium hypochlorite is an antiseptic material and bleach agent that has a yellowish color and a strong taste and smell. According to the characteristics of this chemical material, it does not have any application in industrial milk and dairy industry. If, for example, it is used in washing lines and milk pipes and leaves residues, it is detectable in the laboratories of reputable dairy companies, so it will be isolated and returned before entering the production cycle of these companies.


What does starter mean in dairy products?

The addition of the starter is the same as the action of inoculation. The starters are microorganisms from the group of lactic acid bacteria that start to produce lactic acid and increase the acidity of the milk by consuming the lactose of the milk, which results in the production of protein, fat and milk water, which is known as gel or clot.


What is the cause of using powdered milk in dairy products and is it right to use powdered milk?

Livestock milk does not always have the same nutrition parameters. Race, season, food consumption, and so forth are the factors affecting the nutritional value of the milk produced. In the dairy industry, in order to preserve the quality of a product throughout the entire year of production, increase the dry matter of the final product which results in more consistency of the product, increase the nutritional value of the product and enrich it, powdered milk is added to the milk, which is a non-fat powdered milk type. Furthermore, due to the legal requirements regarding the product’s characteristics in the formulation, the reason for the misconception that adding powdered milk to dairy products is unclear, while this material is a large amount of milk whose water is taken and 10 times more than milk, with 34 percent of protein per 100 grams of it.


Does removing fat from milk changes milk characteristics?

Let’s take a look at the ingredients of these two products; low-fat and high-fat milk. Both products contain 9 effective nutrition material; calcium, vitamin D, protein, potassium, vitamin A, vitamin B12, riboflavin, niacin and phosphorus, and each has its own benefits.

Their difference is only in the amount of fat content received by the body.

By removing fat, only, the product is felt to be less fatty in terms of smell and taste, but in terms of nutritional characteristics, changes exist in the amount of calories of the product, and no effect on the characteristics of the milk is created.