Study On Effects Of Non-starch Component On The Physicochemical Properties Of Starch And Quality Of Rice Noodles In Heat-moisture Rice Flour

Rice,which is nutritious,convenient to eat and widely distributed,is the main food of people in most parts of China.The non-starch components of rice flour not only affect the structure of the starch but may also have a significant impact on its structure and physicochemical properties during the modification process.Based on this,the effects of non-starch components on the physicochemical properties and rice noodle quality of heatmoisture treatment(HMT)rice flour were explored.Taking the protein and lipids in rice as the influencing factors,combined with the pre-and post-treatment sequence of HMT,the effects of non-starch components on the starch properties of HMT rice flour were explored,and the effects of fresh rice noodles on the quality of the finished product were explored.The main conclusions are as follows:(1)Non-starch components(proteins and lipids)of rice flour have a major influence on the structure,physicochemical properties and digestive characteristics of HMT rice starch.According to the results,HMT caused the adhesion and agglomeration,Increased particle size and weakened polarisation structure of the rice flour,Increases the thermal stability of the rice flour granules and significantly reduces the crystallinity,pasting viscosity,pasting enthalpy and pasting temperature range of the rice flour,promoted the binding between starch,protein and lipid molecular chains and lead to the formation of complexes(especially starch-lipid complexes),which hindered the removal of non-starch components.At the same time,HMT conditions with too high a moisture content can lead to partial starch pasting and an increase in its Rapid Digestion Starch(RDS).Compared to the untreated rice flour,the HMT treated lipid-removal rice flour had less changes in their crystallinity,gelatinization temperature and viscosity property.After protein removal,the crystallinity,peak viscosity,final viscosity,breakdown and starch digestibility were sharply increased.These findings are helpful in understanding the contribution of removing endogenous proteins and lipids to the physicochemical changes of HMT treated rice flour during its heating process and thus can be helpful in controlling the quality of rice flour through HMT.(2)HMT has a significant impact on the structure,physicochemical properties and digestive characteristics of rice flour with non-starch components(proteins and lipids)removed.According to the results,HMT resulted in reduced binding of starch granules to protein and lipid molecular chains and increased interactions between starch molecules,resulting in agglomerative adhesion between rice starch granules,increased particle size and weakened polarisation structure.In addition,the high moisture content conditions of the HMT can lead to a slight pasting of the rice flour,resulting in an increase in RDS.Removal of the lipids and protein layer from the rice flour as a "strong barrier" to the starch before HMT leads to an increase in the crystallinity,enthalpy of pasting,peak viscosity and disintegration value of the rice starch,and a decrease in pasting temperature and setback value;at the same time,the removal of the protein and lipids results in the lowest thermal stability of the rice flour.(3)HMT and non-starch components of rice flour have a significant impact on the quality of fresh and wet rice noodles.Combining the samples studied in parts(1)and(2),they were prepared into fresh wet rice noodles by process processing.The results showed that the content of non-starch components(especially protein)in rice flour was significantly and positively correlated with the indices of hardness and chewiness of fresh wet rice noodles,and significantly and negatively correlated with the cooking loss rate and color difference value.After HMT,the existence of proteins and lipids made the gel structure of fresh wet rice noodles internally disorganized and with different pore sizes,the cooking loss rate increased significantly,and the light transmission and hardness decreased,indicating that the gel quality of the modified rice flour was significantly reduced.In addition,the fresh wet rice noodles with non-starch components removed first and then HMT had better cooking quality,microscopic morphology and sensory quality compared to the samples with non-starch components removed after HMT.The texture,cooking quality and color difference values of the fresh wet rice noodles were combined,and the best quality was obtained from the fresh wet rice noodles with protein removed and then HMT.