Physico-chemical properties and structure of rice cultivars grown in Heilongjiang Province of China

The relationships between chemical composition,structure and physicochemical properties such as pasting,thermal,and textural properties of 12 temperate rice cultivars grown in Heilongjiang Province,China were investigated in this study.There were significant differences in the content of fat,protein,ash,amylose,damaged starch among 12 cultivars.Brabender Viscograph results showed that gelatinization time,peak viscosity,pasting and peak temperature ranged from 9 min to 15 min,2100 BU to 2500 BU,58.75℃to 72.00℃and 63.75℃to 84.45℃,respectively,except for the waxy one Longjing 9.To,Tp,Tc andΔH were found in the range of 58.34℃to 67.96℃,65.39℃to 75.38℃,78.47℃to 90.69℃and 2.036 J/g to 3.127 J/g respectively.Scanning Electron Micro-photograph results showed that all starch granules were polyhedral with irregular shapes,except Longjing 9 showing signs of the loss of physical integrity.The hardness,adhesiveness,springiness,gumminess,cohesiveness and resilience ranged from 395.87 g to 1161.76 g,-90.842 g·mm to-36.4 g·mm,0.498 to 0.747,78.631 g to 466.837 g,0.199 to 0.569,0.321 to 0.504,respectively.Correlation studies indicated that amylose,damaged starch,protein,fat and ash played a more important role in determining the rice properties of pasting,thermal,crystallinity and texture.