Physicochemical properties of dietary fiber

It mainly includes water solubility, water holding power, swelling power, rheological properties, adsorption, ion exchange capacity, gel and particle distribution.

I. Water-holding and swelling power

Dietary fiber structure contains a large number of hydrophilic groups, so it has a strong water holding power. Because of different sources of dietary fiber water holding capacity has a great difference, water holding capacity is roughly in their own mass between 1.5 ~ 25.0 times. Due to the water-holding property of dietary fiber, it can absorb a large amount of water in the human intestinal tract, which increases the volume and speed of human defecation, thus shortening the residence time of toxic substances in the intestinal tract and decreasing the potential chances of diseases.

Rheological properties

According to the different water solubility of dietary fiber, its rheological properties vary greatly, the ratio of SDF/IDF not only affects the physicochemical properties and metabolic properties of dietary fiber, but also has a significant impact on its physiological function. Due to the different composition of dietary fibers prepared by different extraction processes (immersion, extrusion cooking and micron technology), it eventually leads to different SDF/IDF ratios, which in turn affects the nutritional value and functional and physiological properties of dietary fibers. Therefore, modern technical means tend to use physical and chemical methods such as high-pressure homogenization, extrusion cooking, oxidation, cross-linking, etherification, carboxymethylation, fermentation or enzyme treatment to prepare dietary fibers, to strengthen their physicochemical properties, and to carry out research on modification of dietary fibers.

III. Ion exchange capacity and adsorption

In the structure of dietary fiber, it contains some important side-chain groups, mainly including carboxyl and hydroxyl, presenting the role of a weakly acidic cation exchange resin, which plays an important role in cation exchange and can be reversibly exchanged with cations. Dietary fiber ion exchange not only reduces the body’s absorption of ions in a binding manner, but also changes the instantaneous concentration of ions, prolongs the conversion time of ions by diluting the ion concentration, and allows for more beneficial digestion and absorption in a buffered environment.

Some studies have shown that many toxic cations can be exchanged by dietary fiber and then excreted with the feces. At the same time, dietary fiber is also able to absorb NO2- and bind bile acids, thus preventing diseases such as cancer, high blood pressure, and high blood cholesterol.

Application of dietary fiber in food

There are more than 30 kinds of dietary fibers in six categories. These six categories include legume seed and seed coat fibers, grain fibers, fruit and vegetable fibers, microbial fibers, other natural fibers, and synthetic and semi-synthetic fibers. Currently, the following are used in production: wheat fiber, soybean fiber, beet fiber, corn fiber, chitosan, and orange powder.

Dietary fiber has a variety of nutritional functions, is essential to human health, but also a class of more ideal health food ingredients, so dietary fiber in the food industry has gained some application. Dietary fiber is mainly used in staple foods, baked goods, meat products, beverages, dairy products and other foods.

I. Application of dietary fiber in pasta products

Some studies have shown that wheat bran dietary fiber has good water retention, oil retention and expansion. Wheat bran dietary fiber as a food ingredient applied to noodles and other noodle products, to a certain extent, can increase the nutritional value of the product, improve the texture characteristics of noodle products and sensory quality.

Yang Tongshuai compared the noodles without added wheat bran dietary fiber and those with added 3% wheat bran dietary fiber by scanning electron microscope, and found that the starch granules of the noodles with added wheat bran dietary fiber were tightly wrapped by the gluten network, with fewer gap seams of the starch granules, which was more uniform, and did not have any effect on the color and texture.

Compared with the buns without added wheat dietary fiber, the hardness and chewiness of the buns made with wheat dietary fiber added at 8% improved significantly, and the eating quality was improved significantly. After adding wheat bran dietary fiber, the dough formation time increases, the quality of flour is improved.

Second, the application of dietary fiber in baked goods

At present, there are many studies on the application of dietary fiber in baked goods in China, and dietary fiber is added in the production process of cake, bread, cookies, peach crisp, etc., and its application in baked goods is most widely used.

Adding dietary fiber to cakes, breads and cookies, dietary fiber absorbs more water and improves the water-holding capacity of the finished product, which increases the softness and freshness of the finished product, prevents the finished product from drying and hardening during the storage period, and the improvement of the water-holding capacity also reduces the cost of the finished product. Added dietary fiber baked goods, taste delicious, finished product appearance, color, elasticity and product processing technology is basically unaffected. Therefore, the moderate addition of dietary fiber can delay the bread aging rate, increase the volume of bread and pastries, improve the chewiness of cookies, and meet the demand for low-energy, high dietary fiber baked goods.

Adding soy dietary fiber to bread, cookies and other leisure foods can produce high-fiber, high-protein baked goods that can also increase protein content and lower cholesterol.

Addition of dietary fibers from different sources to cookies resulted in a significant increase in protein content and digestibility; cookies with the addition of long bean curd and apple dietary fibers had higher total phenolics and antioxidant activity; and cookies with the addition of inulin had a significant decrease in total energy value.

Bran dietary fiber added to the dough, help to improve the quality of the dough, improve the flavor of the food, but also to improve the nutritional value of the product, regular consumption of the human body has certain health benefits.

Third, the application of dietary fiber in meat products

Meat products are the main food source of protein and fat for human beings, but excessive intake of meat products can be harmful to human health, and it is important to reduce the fat content in meat products. Dietary fiber as a class of functional nutrients has been increasingly used in meat processing to optimize composition, strengthen nutrition, improve product yield and extend shelf life. Dietary fiber has been applied more in ham sausage, sausage, meat floss, salami, meatballs and other products, which are the main representative products of meat products containing dietary fiber.

Oat fiber or oat bran has strong water retention and granularity, and is a more suitable fat substitute. Adding dietary fibers obtained from foods such as soybeans, oats and sweet potatoes to minced meat products such as ham sausage and meat floss as a fat substitute can reduce the fat content of the finished product and increase the content of dietary fibers and proteins, which has a good health effect.

The addition of vegetable oil and rice bran fiber to pork mince reduces the fat content from 30% to 20%. The addition of vegetable oil (e.g., grapeseed oil) mixed with rice bran fiber not only reduces the animal fat, but also enhances the physicochemical properties of the meat product. The same effect can be obtained by adding rice bran fiber to minced meat sausages and meatballs.

Oat β-glucan was added to beef to make low-fat beef patties, and studies have demonstrated that oat β-glucan is a fat substitute for low-fat beef products. Currently, β-glucan has been successfully applied in various meat products such as sausages and meatballs, which effectively reduced the fat content.

In addition to this, reports have suggested that hazelnut skin, legume fiber and wheat fiber can also be used as fat substitutes for beef patties to make low-fat burgers. Water-soluble dietary fiber fibers (e.g., carrot fiber) extracted from olive oil waste liquid can be added to low-fat meatballs as a fat substitute for meatballs.

Fourth, the application of dietary fiber in beverages

In recent years, dietary fiber as a beverage ingredient in China has also been rapid development. Dietary fiber can be added to solid beverages (cereals, etc.), sports drinks, plant protein drinks and fruit juices and other high-fiber beverages, high-fiber beverages with dietary fiber, no odor, lubricated taste, more popular.

Extracted and then processed rice bran dietary fiber for carrot beverage, the results show that the appropriate amount of dietary fiber added to the beverage can improve the quality of the beverage, but it should be noted that the addition of rice bran dietary fiber should not be more than 8%, otherwise the comprehensive quality indicators will be significantly reduced.

Soybean dregs water-soluble dietary fiber in acidic milk beverages in the application of the effect of research, the results show that soybean dregs water-soluble dietary fiber can replace pectin as acidic milk beverage stabilizers, acidic milk beverages have a good stabilizing effect, and the addition of water-soluble dietary fiber to flavored milk beverages, to a large extent, increased the nutritional and health care functions of milk beverages.

V. Application of dietary fiber in dairy products

Dietary fiber can be used as a nutritional source of active bacteria, if you add dietary fiber in dairy products, can increase the validity of the finished product, and the taste is more prominent.

Water-soluble dietary fiber is more suitable to be added in infant formula and milk powder for middle-aged and old people. Infants and middle-aged and elderly people have limited ability to digest and absorb food, and need to store a lot of calcium. Water-soluble dietary fiber can not only laxative, lower blood fat and blood sugar, but also promote the absorption of mineral elements.

In recent years, high-fiber yogurt products are very popular. Adding date palm dietary fiber to yogurt has shown that yogurt with 3% dietary fiber added has essentially the same acceptability as regular yogurt and is more beneficial to health. Some studies have shown that the addition of yam soluble dietary fiber to stirred yogurt significantly reduces the dehydrating contraction effect, and the yogurt tastes better.