Influence of heat treatment on function characteristics of tartary buckwheat protein

Abstract: Tartary buckwheat protein is the main bioactive substance in tartary buckwheat. It has the advantages of antibacterial activity, anti-tumor, lowering blood pressure, and inhibiting serine protease and other physiological activities. It is an ideal healthy food raw material. At present, the heating treatment methods are wet-heat, dry-heat and microwave method. In order to maximize the maintenance of food functional characteristics, it is very important to study the effect of different heating treatment methods on the tartary buckwheat products. Wet-heat treatment: Tartary buckwheat protein were mixed with water according to the ratio of solid to liquid 1:10, the temperature of water bath was 80、100 ℃, the treatment time was 20 min, 40 min, 60 min, freeze-dried. Dry heat treatment: the tartary buckwheat protein tile on the enamel plate, placed in the oven, the temperature 80、100 ℃, treatment time was 20 min, 40 min, 60 min. Microwave heating treatment: the tartary buckwheat protein placed in a microwave oven (700 W), treatment time was 2 min, 4 min, 6 min. In this paper, tartary buckwheat seeds were crushed, degreased, with flavonoids removed, then the supernatant was taken and the pH value was adjusted to the isoelectric point, and the precipitate was freezing-dried in vacuo to give tartary buckwheat protein. The tartary buckwheat protein was prepared by wet-heat, dry-heat, microwave treatment. The changes in physical and chemical properties and functional properties of tartary buckwheat protein, such as hydration properties, emulsifying activity, foaming activity, in vitro digestibility, antioxidant activity and bile salt adsorption capacity were measured. The experimental results show that the traditional heating methods (wet-heat, dry-heat) and short-term microwave treatment have a certain improvement on the functional properties of tartary buckwheat protein. Among them, the wet-heat treatment has positive effects, especially for emulsification, emulsifying stability, foaming property, foam stability, hydroxyl radical (·OH) scavenging ability, and sodium taurocholic acid adsorption ability, which were increased by 28%, 22%, 22%, 23%, 9.75% and 28%, respectively. Dry-heat treatment can improve the water holding capacity and the reducing power of tartary buckwheat protein, which are 31% and 16.34% higher than that of untreated tartary buckwheat protein. For short-term microwave treatment (2 min), the water holding capacity of tartary buckwheat protein was increased by 51%. And long-term microwave treatment (4、6 min) has a greater negative impact on the tartary buckwheat protein performance, especially for emulsification, emulsifying stability, foaming ability, and foam stability, which were reduced by 62%, 77%, 66% and 54%, respectively; ABTS radical scavenging ability, .OH scavenging ability, and reducing power were reduced by 48.79%, 63.49% and 49.18%, respectively; adsorption ability of sodium bile acid, sodium deoxycholic acid and sodium taurocholic acid was reduced by 64%, 55% and 41% respectively. In summary, in the process of tartary buckwheat protein processing, you can choose the traditional heating method or strictly control the microwave time to avoid the damage of long-term microwave heating to the buckwheat protein functional characteristics. The results can provide theoretical and experimental basis for the further study of the application of tartary buckwheat protein in functional food.