Everyone may have such an experience: after drinking milk, there is a feeling of the uncomfortable stomach, bloating, screaming and not parking fart; more serious, there will be symptoms of diarrhea and vomiting. What is going on?
As you know, this is caused by a disease called lactose intolerance. Because of the lack of enzymes that break down lactose in the digestive tract, lactose accumulates in the digestive tract. After being fermented by the intestinal flora, a lot of gas is produced, which causes the digestive function to be disordered. I have seen the Big Bang of Life, and the protagonist Leonard has very serious lactose intolerance.
However, what you may not know is that instead of calling infant lactose intolerance "sickness", it is better to call it a "trait". why? Because this situation is so common, there are not many people with lactose tolerance in the world. If we limit our horizons to East Asia, 90%-100% of East Asian populations have more or less lactose intolerance. Therefore, if a reader dares to say that he can completely tolerate lactose, it is one of the best.
Because of this, food scientists have been working to remove the lactose from milk, and it is best not to change the taste of the milk. Removing a thing from a mixture looks very simple, but it's not that easy to do. At present, there are two main ideas for processing lactose-free milk: enzymatic hydrolysis and membrane separation.How is milk made lactose free ?These two terms seem professional, but they are easy to understand. Let me give you a detailed explanation.
Let me talk about enzymatic hydrolysis. As we all know, for people with lactose tolerance, the reason why milk is drunk is that the lactase in the digestive tract breaks down the lactose into galactose and glucose with lower molecular weight. Because these two sugars are directly absorbed by the body, lactose does not accumulate in the body.
Then, a very natural idea is: We add this lactase in the milk during the processing of milk, so that the lactose in the milk can not be decomposed by itself? Yes, this is how the enzymatic method works. The steps to produce this milk are roughly the same as for the production of regular milk, except that there is an additional "enzymatic treatment" step in the middle to add lactase to break down the lactose. So there is no lactose in the finished product we get.
However, although there is no lactose in the finished product, there are more decomposition products of lactose - glucose, and galactose! Does this have any effect?
It has an impact. That is - the milk will become sweeter and the flavor will change a little. However, for the pain of lactose intolerance, a little change in flavor is acceptable. Therefore, in the current market for lactose-free milk, the use of this technology accounts for the vast majority.
So, as a perfectionist, is there a way to remove lactose from milk while maximizing the flavor? This method is available, and that is the membrane separation technology mentioned earlier. This technology is currently not used much, but at least in the United States, there are already some products that use this technology. Therefore, membrane separation technology still has a great development prospect.
What is the separation of membranes? Explain it with a simple example. Now ask everyone a question.
Give you a bottle filled with pebbles, sand, and water, which are evenly dispersed in the bottle. Now your task is to separate the sand. Leave only small stones and water in the bottle. What would you do?
Using two sieves, first sift the stone out with a larger mesh sieve, so I got the stone first. Then pass the remaining mixture of sand and water through the second smaller mesh screen so I get the sand and the leaking water.
Finally, mix the pebbles obtained in the front with the water leaking from the back and pour it back into the bottle.
Yes, this is the basic idea of membrane separation. In plain language, it is filtered with two sieves of different pore sizes.
Milk is what high protein foods and a mixture of water, fat, lactose, inorganic salts, minerals, and the like. Among them, the head (molecular weight) of protein and fat is the largest, which is equivalent to the pebbles in the example; the sugars such as lactose are the first, which is equivalent to the sand in the example, the smallest of water, inorganic salts, minerals, etc. The water inside the example.
In the membrane separation technology, we also use two kinds of "sieves". The one with a relatively large pore size is called "ultrafiltration membrane" (approximately 10-20nm pore size), which can intercept the protein and fat in milk. Other substances flow out. The smaller pore size we call it "nanofiltration membrane" (about 1-2nm pore size), can intercept lactose, let water, inorganic salts, minerals and so on. After the milk passes through the two layers of film, in turn, we add the portion intercepted by the ultrafiltration membrane to the final liquid to be mixed, and the lactose-free milk is obtained.
The advantage of this is that the flavor of the milk is not changed. The disadvantage is that the cost is relatively high. What is the ultrafiltration definition ?For food companies, the purchase of membrane separation equipment, ultrafiltration membranes, and nanofiltration membranes are all a big expense.
Now, some products combine the two technologies and add lactase after the membrane separation process. This has the advantage of further ensuring that no lactose is present in the milk and that it does not produce too much glucose and galactose to change the flavor.