Research On The Green Storage Of Brown Rice

The green storage of brown rice was studied in this paper. The brown rice samples at (12.5±0.1)%, (13.5±0.1)%, (14.5±0.1)%, (15.5±0.1)% moisture content were stored for 180d at 30℃, 25℃, 20℃, 15℃respectively oxygen concentration were 2%, 5%, 8%, 21% controlled by N2, using the fresh brown rice in 2009 as material . The free fatty acid value, falling number, RVA characteristics were measured every month during the storage. The brown rice odor was also analyzed by using electronec nose .The mainly results as follow:(1) The change of moisture contentThe moisture content was slowly descend in the storage time. The samples stored under high oxygen concentration, the speed of decrease of moisture content was faster than other samples.(2) The change of fatty acid valueThe free fatty acid value changed with storage time prolonged. The effect of storage time, temperature, moisture and oxygen concentration on fatty acid value were significant (p<0.01). The higher moisture content and temperature were, the faster free fatty acid value increased. Low oxygen concentration can delay the fatty acid value decrease.The influence of moisture content,storage temperature, oxygen concentration and storage time were significant on fatty acid value: storage temperature>storage time>moisture>oxygen concentration. The interaction of different storage methods and time were significant on fatty acid value(3) The change ofα-amylase activityThe falling number changed with storage time prolonged. The higher moisture content and temperature were, the faster the falling number increased .Low oxygen concentration can delay the falling number increase. The influence of moisture content,storage temperature, oxygen concentration and storage time were significant onα-amylase activity: storage temperature>storage time>moisture>oxygen concentration. The interaction of different storage methods and time were significant onα-amylase activity.(4) The change of RVA characteristicsThe peak viscosity, hot viscosity, breakdown, final viscosity, setback increased with storage time prolonged. The effect of storage time and conditons on them were significant (p<0.01).The fatty acid and falling number and peak viscosity was negatively correlated (r=-0.487). The peak viscosity and falling number was also negatively correlated (r=-0.608). The fatty acid and peak viscosity were 0.711.(5) The change of brown rice odor stored in different condionsElectronic nose was able to identify the samples stored at different temperature and moisture content by PCA and LDA methods. By comparing, samples stored in different temperature and O2 concentration were better distinguished using Linear Discriminant Analysis (LDA) than Principal Component Analysis (PCA). But the total contribution rates of LDA was lower than the total contribution rates of PCA. The moisture content and temperature had more significantly effect on the result of E-nose response than the oxygen concentration according to the result of the multiple-factor analysis of variance (ANOVA). Moisture content and temperature existed interaction. The Loadings analysis proved that sensors W5C and W1S in the electronic nose PEN3 for samples have a higher influence. This result could be used in further studies to optimize the number of sensors and find better performance.