Research On The Influence Factors Of Oat Grain Hardness And Its Relationship With Quality

The hardness of oat grain has much effect on grain processing,It determines the pulverizing rate,the smoothness of oat flakes,and the elasticity of oats.The explanation of the relationship between hardness and quality of oat kernel is beneficial to the development and utilization of oat.In this experiment,three types of hardness measuring methods of oat grain(JYDB/SCKS/Texture Analyzer)were investigated,and made the comparative analysis.The microstructure of oat grain(including endosperm structure and aleurone layer structure)with different hardness was observed by SEM(scanning electron microscope).The mechanism of grain hardness formation from the perspective of microstructure composition was compared.The effects of various quality indicators(β-glucan,protein,fat,etc.)on the hardness of oat grain were investigated.The analysis of rheological properties of different hardness oat flour were analyzed could provide the rational choice of oats grain for production and processing of guidance.The main results are as follows:Three methods(JYDB/SCKS/Texture Analyzer)were used to measure the hardness of oat grain.The results showed that there was significant positive correlations(r=0.823**)between hardness tested with JYDB by 40 mesh screen and hardness tested with Texture Analyzer by repeating 300 times,the linearity regression equation was as follows:y=1227.1x+1123.7(y was hardness tested with Texture Analyzer,x was hardness tested with JYDB by 40 mesh),and the determinate coefficient was 0.7217.The HI value measured by 40 mesh screen can describe the actual value of oat grain hardness more accurately.Two oat varieties with large difference of hardness were selected to observe the transverse section of the endosperm through SEM.There was large gap between the starch granules and the protein matrix,the starch granules were separated from the protein,the aleurone layer is mostly like empty a shell,and the starch particles in the aleurone layer are less distributed in soft oat.But in hard oat variety,the starch granules were close to each other,and the protein matrix is relatively close to the starch grains,most aleurone layer are filled with starch granules starch grains,and the structure is relatively completed.The thickness of the aleurone layer and the cell wall thickness of the aleurone layer were measured.It showed that the thickness of the hard oat aleurone layer(41.25±8.23μm)was significantly higher than that of the soft oats(38.75±7.85μm),also the thickness of the hard oat aleurone layer cell wall(5.35±2.07μm)was significantly higher than that of the soft oats(3.74±1.48μm).The correlation analysis was made between the HI value measured by JYDB 40 and the physicochemical properties and rheological properties of oat powder.JYDB 40 is negative correlation with protein content(r=-0.775**),and significantly negative correlation with ash content(r=0.599**).JYDB 40 was significantly negative correlation with the water absorption rate(r=-0.828**),which was also significantly positively correlated with the viscosity of the regenerated endpoint(r=0.785**)and the return value(r=0.771**).