With the gradual increase of people’s attention to dietary structure and nutritional needs, functional oligosaccharides such as fructooligosaccharides (FOS) and galactooligosaccharides (GOS) have become important basic raw materials and food additives by virtue of their characteristics such as low sweetness, low energy, low absorption, promotion of the growth of intestinal probiotic bacteria, regulation of the intestinal micro-ecology, and enhancement of immunity, etc. They have been widely used in the food industry, especially in the dairy products industry.

Oligofructose and oligogalactose

FOS is formed by linking fructose and glucose through β-2,1 glycosidic bond and cannot be digested by enzymes in the digestive tract. FOS is widely found in many plants, such as potato, onion, banana, inulin, rye and so on.

FOS has good solubility and heat stability, and compared with sucrose, it has pure sweetness and lower sweetness, which is effective in enhancing the taste of food, prolonging the shelf life of products, promoting the growth and reproduction of bifidobacteria, and promoting the absorption of trace elements, etc. GOS is composed of galactose or galactosylated glucose.

GOS is formed by galactose or glucose connecting 1 to 7 galactosyl groups. Human breast milk has the highest content of GOS, while animal milk contains less.

Since the digestive system of newborns is still in the developmental stage, the establishment of probiotic flora in infants depends largely on the GOS content in breast milk, so GOS is generally added to the nutritional composition of infant formula milk powder to enhance the digestive ability and immunity level of infants and young children.

In addition, GOS is a nutritional source and proliferator of beneficial bacteria such as Bifidobacteria and Lactobacillus in human intestinal tract, which plays a good role in promoting the establishment of intestinal microecology.

Research progress on the amount of efficacy of oligosaccharides

Regarding the research on the efficacy of functional oligosaccharides FOS and GOS, a search of the literature reveals that there are some differences in the clinical efficacy of FOS and GOS due to the differences in the test population, age group, clinical trial method and purpose, and clinical trial period (Table 1).

Functional oligosaccharides FOS and GOS are mainly used to improve intestinal flora and gastrointestinal symptoms in clinical studies. Overall, the effective dosage increases with age; in addition, clinical trials have proven that FOS and GOS are more effective when used together in certain ratios.

Application of functional oligosaccharide in dairy products

Functional oligosaccharides have obvious advantages in regulating immune function, increasing the number of beneficial intestinal bacteria, and improving the effect of mineral absorption, etc. They are also widely used in infant formula milk powder, children’s milk, yogurt, and milk beverages.

1. Application of oligofructose and oligogalactose in infant formula milk powder

Functional oligosaccharide is a good nutrient fortification ingredient in infant formula milk powder, and its addition in milk powder has gone through the process from single to multiple, and at present, the prebiotics added in most products are mainly FOS and GOS.

In 2004, Abbott took the lead in adding functional oligosaccharides to its infant milk powder, which had a greater impact on the domestic infant formula milk powder market.

With the improvement of consumer health awareness, functional oligosaccharides have become the selling point of infant milk powder for a long time, and functional oligosaccharides are mainly added in the ratio of FOS, GOS, and GOS/FOS in infant milk powder sold in the market at present (Table 2).

2. Application of oligofructose and oligogalactose in children’s milk

Children’s milk is crucial for adolescents aged 3 to 14 years who are in the critical period of development. In addition to the protein and calcium in milk, most children’s milk contains key nutrients such as vitamin D and DHA that will promote the development of children’s bones and intelligence.

With parents’ increasing concern about children’s immunity, the concept of functional prebiotics has gradually become familiar to consumers, and FOS and GOS have been added to the children’s milk sold in the market in the ratio of Future Star Bone Power and Jiazhi; FOS and GOS have also been added to the children’s milk of Nutricia Hi-Q3 Plus Prebio 4 in the Thai market.

3. Application of oligofructose and oligogalactose in fermented milks

At present, consumers’ demand for fermented yogurt is not only satisfied with its taste, but also the functionalization of fermented milk and the segmentation of consumer groups have gradually become the development trend, and functional food ingredients are widely used in fermented milk products.

For example, FOS and Bifidobacterium bifidum BB-12 are added to Kuan Yi Milk to enhance intestinal immunity by adding prebiotics and probiotics at the same time; Bright Healthy Probiotic Yogurt adds oligofructose powder and Bifidobacterium shortum bacteria powder to enhance immunity and promote digestion; Cocoa Zangxiang Plain Yogurt also adds FOS (content ≥1%) to regulate the intestinal environment and enhance the kinetic energy of intestinal tract; Japan Brighten smooth contains 10 billion probiotics and GOS, which play a good role in protecting the intestinal tract of pregnant women, nursing mothers and infants.

4. Application prospect of oligofructose and oligogalactose

FOS and GOS have many incomparable advantages of other sugars, which are new sugar sources integrating nutrition and health care, and have broad application prospects in general food, health care products, special medical food and animal feed.

With low calorific value and good thermal stability, FOS can replace sucrose, which is widely used in bread, cakes, Chinese desserts and other baked goods, and help to improve the color and taste of the products and enhance the health positioning of the products.

The addition of FOS can also be considered in general beverages and alcoholic beverages to meet the demand for taste while adding more versatility options.

FOS and GOS have been widely used in health products, but mainly focus on the protection of the gastrointestinal tract, physiological studies show that it also plays an important role in mineral absorption, lipid metabolism, etc. Therefore, in the development of health products for iron supplementation, zinc supplementation, or the promotion of lipids, we can consider adding oligosaccharides, such as FOS, GOS, etc., to play their synergistic role.

FOS has the effect of proliferating probiotics. Adding a small amount of FOS to fermented products can increase the number of lactic acid bacteria and shorten the fermentation time, so it can be considered to be used in the fermentation process of yogurt, cheese, kimchi, soy sauce, beer and other products.