We talked about fermented milk products of Milk-Agro with Ing. Peter Kočiš, head of dairy production in Sabinov.
First, the question: how does the current acidophilus milk differ from the original homemade sour milk…
What came from the cow as homemade production was not acidophilus milk, it was just sour milk. The basic distinction is that sour milk contains only mesophilic cultures that ferment the milk, these are lactobacilli and lactococci. And acidophilus milk differs from the original homemade sour milks in that it contains mesophilic cultures but also Lactobacillus acidophilus, which belongs to probiotics. Lactobacillus acidophilus is classified among probiotic cultures. And these were not naturally present in normal souring, so-called natural souring, of course, they were not added, only what was in the surrounding environment. Therefore, the original sour milk was always different, sometimes less sour, sometimes very sour, sometimes it had a bitter taste or different consistency and taste. But when we produce acidophilus milk industrially, we add besides mesophilic cultures also Lactobacillus acidophilus, which is the probiotic, and it must be present at the end of the shelf life in more than 10 million per milliliter. So this is the basic difference. Other dairies produce so-called "zakysanky" or soured milks, which are only sour milks without added probiotic cultures.
What are mesophilic cultures?
It is a group of dairy cultures that need an optimal temperature from 18 to max 30°C for their activity (lactose fermentation). Thermophilic ones need higher temperature.
So the original homemade milk did not contain thermophilic bacteria since it usually soured at room temperature…
I do not say it could not contain them, but thermophilic dairy cultures need a higher temperature above 30°C for activity.
But it contained a wider spectrum of fermented milk bacteria…
Small dairies or mountain huts still produce soured milks by the original method, let's call it uncontrolled fermentation. But fermented milk products in regular large-scale production are made from pasteurized milk by controlled addition of dairy cultures in a specified amount and quality, meaning that already selected cultures are added, either only mesophilic, then it is just soured milk, or when probiotics are added, these are products with higher added value for the customer, such as acidophilus, kefir or bifidus milks.
The differences are not only in the name…
No, in each of these types of fermented milk drinks there is a different mix of probiotic cultures so that the final customer can choose according to taste, although all have mesophilic fermented milk culture as a base.
What is the history of controlled production of fermented milk products at Milk-Agro?
Our company first started producing Acidophilus milk. There was a tradition from the socialist era when acidophilus milks were produced in polyethylene bags, similar to milk. Shortly after, we started producing Kefir milk, and the newest product we supply to the market only for a few years is Bifidus milk.
Let's start with acidophilus…
In the past, standards were not as strict as now, and acidophilus milk could be milk with varying content of acidophilus culture. Today, strict limits must be met for a fermented milk product to be classified in a certain category. For acidophilus milk, it must contain ten million microorganisms of Lactobacillus acidophilus. It must contain that much also at the end of the shelf life. That means at the beginning there must be much more because they gradually die off. Lactose (a milk component) is the nutrient for them, which bacteria convert to lactic acid, so lactose is gradually consumed, and probiotic cultures start to die off. At the end of the shelf life, there are fewer, but at least the mentioned ten million must be present for it to be called acidophilus milk.
Kefir milk?
The difference between kefir and acidophilus milk is that the base is the same, meaning kefir milk also contains mesophilic dairy cultures, but acidophilus milk must contain Lactobacillus acidophilus, hence the name, while kefir milks contain kefir yeasts and kefir microorganisms.
It is a mix of bacteria and yeasts, so the product of lactose breakdown is lactic acid and also a negligible amount of alcohol along with carbon dioxide…
Yes, also alcohol; in homemade production using the so-called Tibetan mushroom, alcohol content can reach up to 2 percent, in our products the alcohol content is much lower. The mix of bacteria and yeasts gives the drink not only a typical taste but also produces gases, so the drink has a slightly sparkling character. The low alcohol content is achieved by the controlled process at a precisely set temperature, which shortens and optimizes the fermentation process.
We are talking about fermented milk drinks, do you measure acidity in them?
We not only measure acidity but also control it. The acidity of acidophilus milk is from 35 to 50 °SH (Soxhlet-Henkel unit, commonly used in dairying to measure acidity of fermented milk products). The acidity of kefir milk is 38–52 °SH. The acidity of bifidus milk is in the same range. These are not exact values; acidity fluctuates but stays within these limits. It may seem like a wide range, but acidity increases with how much lactose microorganisms consume. Normally, milk contains about 4.7 g lactose per 100 g; after souring, it drops to about 4.2 g, depending on fermentation time. If you put the product in a warm environment, cultures restart and the process continues, lactose is consumed, and acidity increases. Therefore, after controlled fermentation ends, the product must be cooled as soon as possible and kept at 2–8°C.
How do you control acidity?
This is another example of the difference between controlled and uncontrolled processes. We control acidity basically in two ways. One is the combination of fermentation time and temperature. The longer it ferments, the more it sours and the higher the acidity. So milk enriched with the respective microorganisms ferments for about 12 hours, then acidity is measured, and the fermented milk product is filled into consumer packaging, or fermentation continues until the desired acidity is reached. So it cannot start filling earlier or later.
The second way?
It is the combination of microorganisms. Especially Lactobacillus acidophilus strongly increases acidity. Pure acidophilus fermented milk would probably be undrinkable. It has acidity over 100 °SH. That is so sour that if it were not diluted with milk fermented only by mesophilic cultures, it would be undrinkable. So it is mixed in a ratio of one to eight. One part is pure Lactobacillus acidophilus and eight parts are the mesophilic drink.
Milk is fermented by mesophilic cultures at a lower temperature and then temperature is raised and thermophilic microorganisms are added?
Theoretically, it could be done this way, but in practice, it would be complicated. In production, the mesophilic component is prepared separately in one tank and the thermophilic separately in another, then mixed in a ratio of eight to one and subsequently filled and cooled to stop fermentation.
Flavoring is added during filling…
Yes, we also make flavored acidophilus milk, vanilla and strawberry. Mainly for children, as children prefer sweeter tastes. Acidophilus milk tastes good to adults, but children used to sweets are hard to persuade to drink pure acidophilus milk. That is more an exception than a rule. But if it is sweet, it is consumable for children. Strawberry is included in the school program. Vanilla is not, because it contains no fruit component. It only has sugar and aroma. And although the aroma is natural from vanilla pods, it does not change the fact that the fruit content is almost zero.
New ideas for the school program would be good…
We are thinking about a novelty, banana-peach acidophilus milk. We can include in the school program a product with at least 30 g of fruit per 100 g of product. We want to expand the portfolio of fermented milk drinks for children.
So to summarize, you supply fermented milk drinks in the assortment…
According to fat content, we supply acidophilus milk with three percent and kefir and bifidus milk with one and a half percent. That is the fat content. The more fat, the fuller and tastier the product, but fat content does not affect the health benefits of fermented milk products, which are mainly given by the content of health-beneficial microorganisms.
According to packaging…
Acidophilus and kefir 450 g and 250 g, flavored acidophilus 250 g and bifidus also only 250 g.
According to shelf life?
21 days, flavored 14 days. It should be said that the most probiotic bacteria are present around the third day after production, then gradually decrease. But the declared amount of health-beneficial microorganisms is guaranteed throughout the shelf life. So when a customer buys our product, whether at the beginning or end of shelf life, they still get enough live microorganisms so that even if there are fewer at the end, the product does not lose its nutritional value. Therefore, our philosophy is to produce fresh products with relatively short shelf lives.
We saved the best for last…
Bifidus milk. We are most proud of it. It was developed about twelve years ago. Although it is still relatively unknown among consumers, it is, I would say, a unique product on the Slovak market. As far as I know, nothing similar is produced in Slovakia. It is an ideal combination of probiotic bifidus cultures with fiber. No dairy product naturally contains fiber. That means it is not found in milk or yogurt unless artificially added.
You add inulin…
Yes, we add fiber inulin to bifidus milk. It acts as a so-called prebiotic. We add inulin from the plant topinambur in an amount of half a percent, and it is actually the nutrient base for the growth of probiotics. So the product has an optimal balance of probiotics and prebiotics. And a similar product is not found on the market. Although our bifidus milk is still relatively little known, I highly recommend it because it is healthy, benefits intestinal microflora, and also tastes interesting. It is sweeter than acidophilus, the mentioned inulin gives it a sweeter taste.
So better bifidus milk than bifidus tablets…
Tablets are much more expensive and the effect may not be better. A common mistake is to take one bottle of tablets and think the intestinal flora is fixed. Probiotics must be taken regularly. And choosing suitable foods after their intake is also an art. With fermented milk products, along with beneficial microorganisms, we also take in the substrate on which they survive, the nutrient base. At the same time, we provide nutrition to the body. So from the financial perspective, it is much more effective.
From now on, when we enjoy fermented milk products, we will know that we consume the result of a controlled process, precise procedures, but also the craft of dairy masters.
