What Are the Uses of Inulin Powder?

Inulin, a white powder, is a mixture of fructooligosaccharides. Inulin is a natural dietary fiber that has excellent functions in promoting the growth of probiotics in the human body, inhibiting the proliferation of harmful bacteria in the intestine, improving intestinal physiological status, and controlling blood sugar. When applied in the food production field, inulin also shows good processing characteristics, such as good solubility, and sweet taste, and can form a delicate and smooth gel. At present, inulin is the most well-known, marketable, and widely developed dietary fiber. Studying the functions, properties, and applications of inulin plays a very important role in expanding its applications and improving the physical fitness of citizens.

1. Overview of Inulin Powder

1.1 Source

Inulin is composed of fructose linked by β-2,1-glycosidic bonds, and its end is a chain polysaccharide [1]. The degree of polymerization of inulin is generally 2-60, with an average degree of polymerization of about 10, and an average molecular weight of about 5,500. Most inulin is derived from plants, and the average molecular weight and degree of polymerization of inulin may vary depending on the time of harvesting and processing methods, more than 36,000 kinds of inulin have been found, including chrysanthemums, lilies, eustoma, gentians, and grasses, etc.[2] .

1.2 Properties of Inulin

1.2.1 Sweetness of Inulin

The degree of polymerization (DP) of fructan has a major influence on the sweetness of inulin, which accounts for about 10% of the sweetness of sucrose. The sweetness of long-chain inulin (DP＞30) is almost no sweetness, and the sweetness of short-chain inulin (DP＜30) is about 30% of that of sucrose. Meanwhile, the purity of inulin also affects its sweetness. The sweetness of high-purity inulin is less than that of sucrose of the same purity, and it has a refreshing taste with no aftertaste.

1.2.2Inulin Solubility and Solution Viscosity

The main factors affecting the solubility of inulin are temperature, molecular conformation, and degree of polymerization. The solubility of inulin powder in hot water is greater than that in cold water. At the same temperature, the solubility of inulin is different depending on its conformation.

The solution of inulin can form a gel, and the molecular mass of the aqueous solution of inulin will change its viscosity. When the content of inulin is 10%-30%, the viscosity of inulin will increase but still can not form a gel; when the content of inulin is higher than 30%, it can combine with water to form a gel. In general, the speed of gel formation increases with the increase of inulin content. Temperature affects the viscosity of inulin solutions, and the two are negatively correlated. At high temperatures, the solubility of inulin in aqueous solutions increases significantly, and therefore gel formation is not possible [3]. The ability of inulin solutions to form gels leads to an increase in the overall viscosity of processed food. In food production, long chain inulin is used for thickening and replacing fats to obtain good texture and taste of processed products, while short chain inulin has good solubility and is mostly used as a filler.

2.Functional Effects of Inulin Powder

2.1 Promoting Intestinal Health

Intestinal flora is the sum of countless microorganisms in the human intestinal tract, including bacteria, fungi, viruses protozoa, etc., with more than 10 kinds of bacteria as the main component. Under the condition of a balanced intestinal physiological environment, the host can maintain normal physiological functions, such as digestion, absorption, immunity barrier, etc. If the balance of intestinal flora is disrupted, the host can maintain normal physiological functions. Disruption of the balance of intestinal flora can lead to a variety of adverse symptoms, such as vomiting, diarrhea, etc., which may have adverse effects on health. Inulin can increase the relative abundance of probiotics in the intestinal tract and inhibit the growth and reproduction of conditionally pathogenic bacteria. 

2.2 Liver Protection

The liver is the largest metabolic center of the human body, its functions are substance metabolism, detoxification, immunity, coagulation, and hematopoiesis. When the liver is abnormal, various physiological functions of the liver will be affected, which may even cause danger to life in serious cases. Clinical use of some hepatoprotective agents can prevent or reduce liver injury. In a study, LIU et al. found that inulin and catechin-grafted inulin (catechin-g-inulin) had a therapeutic effect on acute liver injury in mice, which was caused by carbon tetrachloride (CCl4). The results showed that inulin and catechin-g-inulin could moderately scavenge superoxide radicals, hydroxyl radicals, and hydrogen peroxide (H2O2), and inhibit lipid peroxidation. Therefore, inulin powder has a good protective effect on drug-induced liver injury.

2.3 Improve Constipation

People with poor gastrointestinal function have slow intestinal peristalsis, the feces stay in the colon for a long time, and the amount of feces excreted is small. Consumption of inulin can effectively increase the number of bowel movements improve the quality of bowel movements, and relieve the symptoms. Therefore, for patients with constipation, adding a certain dose of inulin to the diet can change the stool properties and increase the number of bowel movements, thus allowing patients with constipation to return to normal life. Inulin powder can improve the symptoms of constipation patients mainly because it is a probiotic ingredient, which can promote the relative increase of bifidobacteria and lactobacilli in the intestinal flora.

2.4 Enhancement of Immunity

Bifidobacteria have the function of stimulating intestinal immune cells to perform immunity functions in the human body. Inulin powder can promote the growth and reproduction of bifidobacteria, thus enhancing the immune function of the body. SHOAIB M et al. found that inulin can effectively improve gastrointestinal function and prevent and control intestinal diseases. HIJOVÁ E et al. found that in the metabolic activity of β-glucose, when the content of sodium dextran sulfate reaches a certain concentration in the colon tissue and blood of rats, it will make the rats susceptible to acute colitis, and the consumption of inulin can prevent and control acute colitis.

2.5 Promoting the Absorption and Synthesis of Minerals and Vitamins

Relevant studies have found that the fermentation of inulin by beneficial bacteria in the intestinal tract can regulate the pH value of the intestinal tract, making minerals such as calcium, phosphorus, potassium, and sodium more soluble in water, and thus easier to be degraded. Moreover, the short-chain fatty acids produced by the fermentation of inulin can promote the growth of the mucous membrane of the colon and expand the absorption area of the epithelial cells, which is conducive to the transportation of minerals. In addition, the synthesis of B vitamins in the human body can be promoted by the fermentation products of inulin, which can improve the functions of the human body [4].

3.Application of Inulin Powder

3.1 Application of Inulin Powder in Fermented Sausages

In the production of fermented sausage, the use of inulin to partially replace fat can reduce the bitter taste and bring a soft and smooth texture, increasing the flavor of sausage. In the production process, the hardness of fermented sausages is inversely proportional to the amount of inulin added, with an increase in the amount of inulin added leading to a decrease in hardness, and the elasticity is directly proportional to the amount of inulin added, with an increase in the amount of inulin used leading to an increase in elasticity. The addition of inulin to fermented sausages results in the formation of a gel, which improves the ability of the sausage to retain moisture.

The addition of inulin in small doses gives the sausage a better texture, better taste, more attractive color and better properties. However, when the amount of inulin replacing fat reaches or exceeds 10%, the taste and quality of the product will be reduced, and there will be slagging and powdery feeling, etc. Therefore, inulin is used as a low energy substance. Therefore, as a low-energy substance, inulin can only partially replace fat meat to meet the needs of special groups such as those who are suitable for weight loss [5].

3.2 Application of Inulin Powder in Gluten-Free Products

In the processing of pasta products, gluten can increase the elongation of the dough, make the dough bulky and solidify the dough structure, thus giving the dough a good texture and elasticity. Pure grains such as wheat, rye and oats contain gluten, which accounts for about 4/5 of the protein composition of cereals. However, a small percentage of the general population is intolerant to gluten, so gluten-free products need to be developed. Fructans in inulin can slow down the migration of water from the inside of the bread to the outside, thus prolonging the freshness of gluten-free bread.

Maryam et al. found that inulin powder reduced the crystallinity of the starch in gluten-free bread, resulting in a softer crumb, which in turn reduced the hardness and chewiness of the bread. In addition, a 12% inulin fructan level reduced the glycemic index of gluten-free bread, suggesting that gluten-free bread enriched with inulin could be a product that could provide nutritional (11% dietary fiber) and functional benefits to people with celiac disease [6].

3.3 Inulin in Powdered Milk Formulas

Bifidogenic factors are oligosaccharides with the physiological function of stabilizing the structure of intestinal flora and maintaining intestinal health. As a good bifidogenic factor, inulin has all these functions and can also be used to partially replace fat. Inulin powder is one of the natural water-soluble dietary fibers, with good solubility and high affinity to water, so it can be used as a fiber supplement; and inulin can make milk powder get better quality and sensory evaluation, which is beneficial to the health of human diet; in addition, inulin powder can be used as a promoter of bifidus growth and propagation, to make the beneficial bacteria reproduce and grow rapidly in the intestinal tract, and it can make the bifidus bacteria proliferate by 8-10 times, which is beneficial to the distribution of the human flora and the health of the intestinal tract. In particular, it can increase the proliferation of bifidobacteria by 8-10 times, which is beneficial to the distribution of human flora and human health, and at the same time, it can greatly reduce the harmful bacteria.

At present, inulin has become an important bifidobacteria proliferation factor. Due to the above characteristics of inulin, its application in milk powder is very promising, such as improving the intestinal dysfunction and constipation of middle-aged and old people's milk powder for middle-aged and old people, improving the gastrointestinal function of adults' milk powder for adults, lipid-lowering milk powder and low-sugar milk powder and so on [7].

3.4 Application of Inulin in Special Medical Foods

Special medical foods are widely used in health care and treatment, and the people being treated often have the following characteristics: small amount of exercise, limited ability to exercise, or even some bedridden people who cannot exercise, are unable to eat normally, and easily constipated, etc. Inulin can be fermented in the intestinal tract, and can be used to improve the intestinal function of the body. The fermentation of inulin in the intestine can form many kinds of short-chain fatty acids, which have the function of regulating liver metabolism. PEDERSEN A et al. found that the intake of inulin can reduce the content of HDL and LDL. Based on the fact that a large number of people in China are suffering from dyslipidemia, it is necessary to expand the use of inulin in special medical food applications and appropriate medication, which is a life-safety issue.

3.5 Application of Inulin Powder in Noodle Products

The addition of inulin powder to pasta products can promote the enrichment of nutrients in pasta products, so it is widely used in the food industry. Inulin has the characteristics of small relative molecular mass, good hygroscopicity and so on, so it can promote the formation of fascia protein and improve the texture of pasta products. Therefore, adding inulin to bread products can make the bread's water content increase, hardness increase, and the quality of the products better, to prolong the shelf-life of the products. The addition of 6% inulin can make the bread with the best overall sensory evaluation and become a product with more consumer value[8].

Inulin can effectively shorten the baking time of bread and greatly reduce the cooking time of noodles, and it has been widely used in pasta products. Inulin has a high affinity for water, and it can affect protein binding[9].

3.6 Application of Inulin in Animal Feeds

When a certain dose of inulin is added to animal feed, after consumed by animals, the inulin will be digested and decomposed by beneficial intestinal bacteria, producing SCFAs, BA, lactic acid and other secretions, which can improve the immune defense function of the body. Wang et al. found that adding 0.5% of inulin to the daily diet of experimental pigs could effectively reduce serum cholesterol levels, lower blood lipids, and control blood glucose levels. In addition, inulin can promote fat metabolism, reduce fat accumulation, and increase the content of eye muscles in the waist of pigs. Inulin can promote the productivity of chickens and laying hens, increase the laying rate of laying hens, improve the quality of eggs and prolong the shelf life of eggs. Therefore, the application of inulin in animal feed is also quite abundant, which can improve immunity, control lipid metabolism, and improve the production capacity of animals [10-12].

3.7 Application of Inulin in Sweeteners

Stevia is widely used because of its low energy and high sweetness. Sugars such as sucrose and sugar are commonly used as sweeteners in people's daily life, but they are high in energy but not very sweet, and if consumed too much, they may induce high blood sugar, high blood pressure, obesity and other diseases. However, stevia can be used as a sweetening alternative with low calorie content, accounting for only a fraction of the calories of sucrose, and high sweetness. Therefore, stevia has health benefits such as weight control and prevention of hyperglycemia [13].

4.Conclusion

In the new century, dietary fibers have occupied an increasing proportion in the global consumer market, and inulin is one of its representative products. Relevant research found that the market demand for inulin in China is gradually increasing, but the domestic production of inulin is seriously insufficient, so the quantity of imported inulin is large. In China, the function of inulin is gradually known, and the food and medicine fields are actively introducing inulin as an excellent product into their industries, so the development potential of China's inulin industry is huge. Because of the large proportion of oil, salt and sugar in China's diet, adding a certain amount of inulin to daily meals can also prevent the occurrence of various diseases. As time develops and society progresses, and as the standard of living continues to improve, people will be more inclined to low-sugar, low-fat, and high-fiber diets, and it is expected that the future sales market for inulin will increase exponentially every year.

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