| Fermented rice cake is a traditional food that originated in the south of China.The texture is soft and the production process is simple.The main components of fermented rice cakes are rice starch,protein,and fat.Rice starch is prone to aging during production and storage,resulting in dehydration and dryness and yellowing and hardening.Common methods for anti-aging of starchy foods include controlling water,low-temperature storage（-20°C）,adding protein,carbohydrates,lipids,acid,salt,etc.These methods have some shortcomings in the food industry,such as high storage costs,lack of cleaning labels,and a large number of unhealthy additives.Enzymes are widely used in industrial production due to safety,efficiency,and environmental protection,and they are often used in rice noodle products to delay aging.At present,the quality of fermented rice cake products is mostly used in the quality of chemical additives and enzyme method.This topic uses fermented rice cake as the research object,and has studied the effects of maltoseα-amylase and neutral protease coordinating the impact of fermented rice cake molecule structure,rebirth properties and consumption quality.The main research content is as follows:（1）Effect of maltogenicα-amylase on the physicochemical and retrogradation properties of fermented rice cakes.The rice cakes were modified by maltogenicα-amylase at concentrations of 0,1.5×10-3,4.0×10-3,7.0×10-3,9.5×10-3 U/g.The results of high performance size exclusion chromatography（HPSEC）showed that the molecular weight of fermented rice cakes did not change significantly after being treated with maltogenicα-amylase.Amylase could hydrolyze the long chains in amylopectin and increased the content of the chains with DP≤9.High performance liquid chromatography（HPLC）analysis showed that maltogenicα-amylase increased the maltose content,which affected the fermentation of fermented rice cake.Gelatinization performance and thermal properties showed that maltogenicα-amylase effectively inhibited the retrogradation of fermented rice cake.Differential scanning calorimetry（DSC）result showed that the gelatinization enthalpy of rice cake after storage for7 d decreased to 0.83 J/g.Rapid viscosity analyzer（RVA）result showed that the viscosity of fermented rice cake decreased to 181 c P after being treated with 9.5×10-3 U/g maltogenicα-amylase.（2）Effect of maltogenicα-amylase on the edible quality of fermented rice cakes.The fermented rice cake was stored in the refrigerator at 4°C for 7 d,and then taken out to room temperature before testing.Texture profile analysis（TPA）result showed that maltogenicα-amylase could reduce the hardness and chewiness of fermented rice cakes.In vitro digestibility result showed that maltogenicα-amylase increased the slowly digestible starch（SDS）content in fermented rice cakes.Maltogenicα-amylase(9.5×10-3 U/g)increased the SDS of fermented rice cakes from 11%to 23%,decreased the rapidly digestible starch（RDS）from 68%to 57%,and maintained the resistant starch（RS）.The chromaticity result showed that maltogenicα-amylase had a certain loss of the L*in fermented rice cakes.The specific volume result showed that the addition of maltogenicα-amylase was increased,the smaller the specific volume.The sensory evaluation result showed the acceptability of rice cake was the highest at the concentration of 4.0×10-3 U/g.（3）Effect of compound enzymes on the physicochemical properties and edible quality of fermented rice cakes.DSC showed that the gelatinization enthalpy of fermented rice cake modified by neutral protease decreased to 1.03 J/g after 7 d,and the gelatinization enthalpy of fermented rice cake treated with 16 U/g neutral protease was 77.40%,which was lower than that of the control group.TPA result showed that the hardness of fermented rice cake increased continuously by the addition of neutral protease,but the increase of hardness was smaller compared with that of the control,the elasticity did not change much,the chewiness decreased gradually,and the recovery was not much different;the result of color showed that the L*value of fermented rice cake treated with neutral protease decreased,but the L*value increased compared with that of fermented rice cake treated maltogenicα-amylase.The specific volume result showed that the specific volume of the fermented rice cake decreased.The sensory evaluation showed that the highest acceptable level of neutral protease was added at 8 U/g.The maltogenicα-amylase(4.0×10-3 U/g)and neutral protease（8 U/g）were employed simultaneously to explore their effects on the quality of fermented rice cakes.TPA result showed that the hardness of fermented rice cakes treated with the two enzymes decreased,and the recovery value did not change much.DSC result showed that the gelatinization enthalpy of fermented rice cakes treated with compound enzymes decreased to 2.08 J/g.Compared with the enzyme used alone,the compound enzyme improved the color of the fermented rice cake.The L*value increased to 42.48.The specific volume was also increased,indicating that the compound enzyme could make up for the deficiencies of the first two enzymes.The sensory evaluation result showed that the pores of the fermented rice cake modified by the compound enzyme were evenly distributed,the color was bright,and the taste was soft. |
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