| Fat is an essential nutrient for human health, which can provid 37.8kJ/g of heat, while protein and carbohydrates only produce 16.72kJ/g of heat. However, excessive intake of fats will be hazardous to human health, increase the incidence of cancer, and would easily lead to obesity,cardiovascular diseases, such as fatty liver, high blood lipids, high blood pressure. How to replace high-calorie fats in food, reduce fat intake, has becom a popular research direction. In recent years, many countries have commited to research develop fat substitutes; fat substitutes have been widely used to replace part of the fat in food formulations. Low DE maltodextrins can form soft, stretchable, heat reversible gel, and melt in your mouth, make the products taste like fat, so it can be a good fat substitute.In this paper, heat-stable a-amylase was adopted to hydrolysis rice starch become low DE maltodextrins. Processing conditions of low DE maltodextrins prepared from rice starch were studied by orthogonal experiments.The rheological properties and pasting properties of low DE maltodextrins were determined. It was aimed chiefly at providing theoretical basis for comprehensive developing and utilizing rice starch.The main conclusions as follows:1,The processing parameters as follows:rice starch concentration 25%,24U of the heat-stable a-amylase per one gram starch, the time is 10 minutes and the temperature is 90℃. Under this condition, the dextrose equivalent of the maltodextrins is 2.9.2,Rice starch and maltodextrins are the properties of non-Newtonian pseudoplastic fluid. At the same temperature, the sample shear stress increases with increasing shear rate. Viscosity was decreased with increasing temperature and shear rate, shear thinning; maltodextrins concentration increased, the impact of viscosity with increasing temperature and become smaller; DE increases, that is, the increase in the degree of starch hydrolysis to decrease viscosity of maltodextrins, at low temperature and low shear rate conditions, the performance was relatively clear.3,Starch paste is a phase transition process, different factors can be studied with the DSC phase transition resulting from the different dffects. DE was greater, the degree of aging was lower, the stability of maltodextrins was better. As the sample flow increases, DSC gelatinization curves of the absorption peak gradually be wider and shorter, shift the direction of high temperature, gelatinization temperature range was peogressively larger. It reflected the high degree of hydrolysis seriously damaged the internal structure of starch granules, starch degradation was larger, gelatinization process even more complicated.4,Rice starch viscosity with temperature was a regular increase (up to maximum viscosity), down (up to hot paste viscosity), and then increase (up to cold plastic viscosity) process, thereby constituted a typical RVA spectrum.RVA spectral characteristics of maltodextrins is not obvious, in the starting temperature of 50℃to operate the first 1 minute, viscosity reaches its maximum and then quickly drop, the viscosity is no longer rise, RVA eigenvalue spectrum is almost constant.5,The low DE maltodextrins were used as fat substitutes to replace part fat in the bread. Through texture analysis and sensory evaluation, the influence on the bread quality by adding the low DE maltodextrins into the bread were studied. The results showed that: in this experimental condition, adding 30%DE2.9 maltdextrins into the bread have good texture properties and sensory evaluation.
|
PDF Full Text Request