Demystifying the "black technology" in ultrafiltered milk

Pasteurized milk, high-calcium milk, lactose-free milk.
.
.
There are a wide variety
of milk varieties currently on the market.
Recently, a product called "ultrafiltered milk" has quietly become popular on the Internet, and relevant manufacturers claim that it is more nutritious than ordinary milk, and can drink 1 bottle of milk and absorb 2 times the nutrients
.

The so-called ultrafiltered milk usually refers to milk products
produced by ultrafiltration technology.
So, what is ultrafiltration technology? Can this technology really double the nutrition of milk?

Like a sieve, separate the different components of milk

"Ultrafiltration technology is an industrial technology, which emerged in the 90s of the 20th century and belongs to a kind of
membrane separation technology.
According to the pore size of the membrane, membrane separation technology is divided into four types
: RO (reverse osmosis), NF (nanofiltration), UF (ultrafiltration), and MF (microfiltration).
Yu Jinghua, a professor at Tianjin University of Science and Technology and a member of the expert group for the revision of dairy quality and safety standards of the National Health Commission, introduced that the ultrafiltration membrane used in ultrafiltration technology is a kind of membrane with a pore size between microfiltration and nanofiltration, and it is also a porous membrane with separation function, with a pore size of 1 to 100 nanometers
.
Using the interception ability of the ultrafiltration membrane, substances with different diameters and sizes in the solution can be separated by physical interception, so as to achieve the purpose of
purifying, concentrating and screening different components in the solution.
Membrane technology is often used in various dairy production and processing, such as sterilization, protein content improvement, lactose content reduction, desalination, concentration and other processes
.

"In layman's terms, ultrafiltration membranes are like a sieve, using sieves with different pore sizes to separate substances
with different diameters.
Related milk production enterprises use ultrafiltration membranes to filter out substances such as lactose and salts with smaller molecular diameters, while retaining substances with larger molecular diameters such as
proteins.
Yu Jinghua introduced that the pore size of the general microfiltration membrane is larger than that of the ultrafiltration membrane, and the former can mainly isolate the microorganisms in the milk, including bacteria and spores
.
By borrowing this method, even if it is not treated with high temperature sterilization, the effect of
disinfection and sterilization can be achieved.

Milk that has passed through the ultrafiltration membrane, after removing some water and lactose, contains more protein, calcium and less sugar than before ultrafiltration, and the nutrients are concentrated and the taste is thicker and smoother
.

The production standards of pure milk and fresh milk in China are "GB 25190-2010 National Food Safety Standard Sterilized Milk" and "GB 19645-2010 National Food Safety Standard Pasteurized Milk", according to the above national standards, the minimum protein content of milk should reach 2.
9 grams
per 100 ml.
At present, the protein content of milk on the market is usually between 2.
9 grams and 3.
6 grams per 100 ml, but the protein content of milk after ultrafiltration can reach 6 grams
per 100 ml.

From this point of view, the nutrition of ultrafiltered milk is indeed better than ordinary milk, but in order to maintain human health, it is not enough to rely on high protein, or rely on a balanced diet
.

Ultrafiltration technology is widely used in the food processing industry

In addition to being used in milk production, ultrafiltration technology has been continuously expanded in the food industry because of its advantages of operating at low temperatures, no phase change, better maintaining juice flavor and nutrients, and low energy consumption
.

Ultrafiltration technology is currently used in the production of some new fruit and vegetable juice beverages
.
For example, after watermelon juice is treated by ultrafiltration technology, the retention rate of its main nutrients sugar, organic acid and vitamin C is as high
as 90%.
At the same time, the sterilization rate can reach more than 99.
9%, and it can also meet the national hygiene standards
of beverages and foods without pasteurization.

In addition to sterilization, ultrafiltration technology can also be applied to the clarification
of fruit juices.
Taking mulberry juice as an example, after ultrafiltration clarification, its light transmittance can reach 73.
6%, and there will be no "secondary precipitation"
.
In addition, the ultrafiltration clarification method is simpler than the chemical clarification method, and the quality and flavor of the juice will not be changed
due to other impurities and miscellaneous flavors introduced during clarification.

When making tea beverages, ultrafiltration technology can maximize the retention of active ingredients such as tea polyphenols, amino acids and caffeine in tea on the basis of ensuring tea clarification, which has little effect on color, aroma and taste, and can maintain the flavor substances
of tea to a large extent.
And because the ultrafiltration process is driven by pressure and does not require high temperature heating, it is especially suitable for the clarification
of tea that is sensitive to heat.

In addition, in the brewing process, the use of ultrafiltration technology can also play a role in purification, clarification, sterilization and so on
.

(Source: Science and Technology Daily)

China Food News(Version 04, December 07, 2022)

(Editor-in-charge: Gao Na).