Study On The Differences And Changes Of Quality Property Of Different Chestnut Variety Groups During Refrigeration

Chestnuts of 12 typical varieties were harvested from northern, medial and southern variety groups and their nutritional quality, starch property, cell and starch granule structure were analyzied to compare the differences and changes of quality property in storage to provide basis for storage, processing and variety selection.The results showed that:1. Before storage the chestnuts had a high water content of 52.47%~ 61.30%; with fresh weight basis, fat content of 1.15% ~3.00%, soluble sugar content of 6.73%~14.64% and soluble protein content of 51.53 mg·g-1~57.93 mg·g-1were all low; starch was the main stored substance in the nut, corresponding to a content of 56.18%~72.71% with dry weight basis. After 6 months of refrigeration, each of the index was changed, as the water content, fat, soluble protein and starch reduced by 1.23%~5%, 28.5%~70.43%, 0.33%~13.38%, 25.47%~43.8%, respectively, and soluble sugar increased by 23.02%~160.33%. The differences between pre- and post- storage were statistically significant in water content, fat, soluble protein, starch and soluble sugar (P<0.05) of these 12 varieties and they presented a regional relation.2. In these 12 varieties ,"jiujiazhong"and"SQ022"have a high content of fat and"yelicang","qingzha"and"erxinzao"reduced more after storage;"taili 1","yanhong"and"xiaoziyouli"have a high content of soluble protein and"taili 1","yanhong","xiaoziyouli"and"qingzha"reduced more after storage; the starch content of North Variety Group (NVG)were lower than southern ones and"xiaoziyouli","erxinzao","qingzha"and"yelicang"have a higher content; NVG have a higher content of soluble sugar , and the higher varieties were"yanhong"and"erxinzao".Every variety has some Vc and fatty acid .So we should consider more indexes comprehensively to evaluate the quality of fruit to make basis for varity selection. NVG metabolized slower than southern and medial ones and have a higher nutritional quality in storage.3. Differences existed among RVA eigenvalues in different starch of chestnut: the average of peak viscosity, through viscosity, final viscosity and breakdown in NVG were the highest, following with Mid-type Variety Group (MVG) and South Variety Group (SVG); the setback was lowest in NVG and highest in SVG; the peak time of SVG was statistically significant higher than that of NVG and MVG; the pasting temperature of NVG was statistically significant lower than that of MVG and SVG.4. There were differences between starch and amylose content among different chestnut varieties: the starch content of NVG was statistically significant lower than that of MVG and SVG while the amylose content of SVG was the highest. The amylose content showed a positive correlation with setback, pasting temperature and peak time, and a negative correlation with peak viscosity, through viscosity and breakdown.5. Significant differences existed in the size of starch granule among different chestnut varieties: the granule size has a close relationship with variety and the average of granule size has a significant correlation with peak viscosity, while other eigenvalues were based on the varieties to appear correlations with granule size. NVG were featured with low amylose content and high peak viscosity; SVG were featured with high amylose and low peak viscosity; some of MVG were similar with NVG and some similar with SVG. So, the amylose content and peak viscosity can be used as the indexes to measure the waxy quality of chestnut.6. The kernel cell of chestnut contained plenty of starch granules which showed differences in size and shape.Kernel cells presented densely arrangement and regular shape after steamed, and no difference has been identified among varieties.