| Rice is one of the most important cereal crops in China. Due to its fragility, the broken-rice can be applied for preparation of modified starch to enlarge its application scope. Indica rice starch was hydrolyzed by high temperature ?-amylase to prepare hydrolysate with low DE(dextrose equivalent). Meanwhile, the structure and properties of production were analyzed in detail. This properties indicated that hydrolysates can be used as fat substitutes. The effects of hydrolysate as fat substitutes on ice-cream and low-fat emulsified sausages were investigated. The whole research aimed to provide theoretical basis and specific methods for comprehensive development and utilization of broken-rice.According to the results of single factor test, response surface methodology was employed to determine the process conditions for preparation of different hydrolyzing degree of indica rice starch. The regression equation of the reaction conditions of different hydrolizing degree of Indica rice starch were obtained through the response surface methodology. Verification test shows that the prediction of reaction conditions is accurate. Under the conditions of keeping the concentration of the starch solution was 10%, the enzymolysis temperature was 95 ?, p H 6.5, as well as the enzyme supplementation was 6 U/g, hydrolysates with DE 2.07, 2.96, 3.93 and 5.07 were obtained by changing the enzymolysis time(4, 6, 10, 14 min). The hydrolysates with DE 2.07-5.07 were characterized by FTIR, XRD and SEM. Texture properties of hydrolysates were systematically investigated. The FTIR spectrometry illustrated that hydrolysates kept pyran structure of glucose. Compared to native starch, X-ray diffraction of hydrolysates revealed the peak at 18° were retained, and this indicated that the crystalline pattern of the hydrolysates partially retained the typical A-type pattern of indica rice starch. The SEM pattern exhibited that the hydrolysates displayed a cavernous rock structure which provides plenty of space for retaining moisture. Textural data indicated that hydrolysates can be used as fat substitutes.The main physicochemical property of fat substitutes and rice starch were studied and compared. Pasting properties of fat substitutes, including peak viscosity, cool viscosity, breakdown, setback and gelatinization temperature, were significantly weakened after hydrolysis. Based on above, the anti-aging ability of fat substitutes was improved. The results showed an increase of the solubility, swelling degree and water holding capacity, and a decrease of retrogradation and freeze-thaw stability.The applicability of fat substitute in ice cream was investigated by comparing the expansion rate, melting rate, and sensory evaluation of ice cream. The results showed an increase of the expansion rate, structural state, and a decrease of melting rate, smell and colour with the higher degree of substitution. In consideration of the expansion rate, melting rate, and sensory evaluation, when fat substitute adding quantity was 75% the ice cream' sensory quality was best.The product was used as pork backfat replacers in low-fat emulsified sausages. The effect of mass ratio of fat substitute and water, degree of substitution and starch-based fat substitutes with DE 2.07-5.07 to low-fat emulsified sausages has been investigated by single factor test. The applicability of fat substitute in low-fat emulsified sausages was investigated by comparing the cooking loss, pressing loss, thermal stability, deformation force, carrying power, chromatic aberration and sensory evaluation of low-fat emulsified sausages. The results showed that the physicochemical property and sensory quality was best with the mass ratio of fat substitute and water was 1:2, degree of substitution was 50%, DE of fat substitute was 2.07. |
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