| The Yangtse valley, including Hubei Province , Anhui Province, and Guizhou Province are the most important area for rapeseed and double-low rapeseed planting in China. 112 rapeseed meal (RSM) samples and 111 rapeseed cake samples (RSC) were collected in 17 counties whose yield is large in the cited provinces. At the same time , rapeseed samples of 10 double-low cultivars , 34 commercial rapeseed samples and 35 samples from key processing stages of 3 classical processing technics were collected. The quality characters and influencing factors on Chinese RSC and RSM produced were investigated in the study. Chemical analysis acted as our major means of. research, in addition to that, using a two step of pepsin-pancreatin system in vitro , and also using the assay of Sibbald's true metabolizable energy (TME) was adopted to evaluate the effect of major processing technics of Chinese rapeseed and the new dehulling processing technics. The results were presented as followed.By chemical analysis, the contents of ether extract (EE) of Chinese RSC and RSM produced were found to be 9.31-2.69%, 1.87-1.31%, respectively. The former is significantly higher than Canadian canola meal (CM) but the latter was slightly lower than CM. As far as the crude protein (CP) contents of Chinese RSC and RSM were concerned, the former was 34.5 -2.98%, the latter was 36.7 - 1.93%, both of them compared with CM. The contents of neutral detergent fiber (NDF) in Chinese RSC and RSM were 34.45±8.44%, 30.66±3.11%, respectively. And the glucosinolates (GL) content in Chinese RSM was 79.1-44.99umol/g. From the results of chemical analysis cited , we can come to the conclusion that the quality characters of Chinese RSC and RSM were their high protein content as CM and significantly high contents of NDF, GL with great degree of varivance when compared to CM.The effects of cultivar, mixture, planting area, processing technics on the quality of Chinese RSC and RSM was investigated. The results indicated that in major Chinese double-low cultivars' rapeseed, the average contents of CP, GL were 41.7± 2.58%, 35.2±6.52umol/g, respectively. They are all quality ingredients for producing RSC and RSM. But as far as the commodity rapeseed samples were concerned , the average GL content increased to 78.5±21.76umol/g resulting from the mixture of high GL rapeseed.Thus the mixture had been regarded as the most primary reason for the high GL content with great degree of varivance in Chinese RSC and RSM.The results of chemical analysis indicate that cultivar, mixture, planting area, processing technics had no effect on the crude fiber (CF) contents of RSC and RSM. Heat treatment had no effect on CF content, however, heat treatment significantly increased the NDF contents. In the RSC and RSM produced with processing technics of low-temperature-press (LP), prepress-extraction (PE) hydraulic-press (HP), screw-press (SP), the NDF contents were 32.0±2.31%, 34.6±3.40%, 47.2±3.43%, 51.5±7.48%, respectively. There was significantly variance when they were compared to each other. The results indicated that overheating had come to be the primary reason for the significantly higher NDF content with great varivance of Chinese RSC and RSM. The increment of NDF always occured in the stages of cooking/conditioning, pressing, dissolventing where heat treatment was adopted. In these stages, some protein turned to products of maillard reaction which meaned that NDF can act as a right indicator of the quality of RSC and RSM in China.The study was conducted to determine the digestible dry matter(DM), CP contents in Chinese RSC and RSM with different processing techneics and collected from different planting areas using a two step of pepsin-pancreatin system in vitro . From the results, we found that varivance of planting area had no effect on the cited indicators, but varivance of processing technics has significant effects. For a example, the digestible CP contents of samples from Hubei Province produced by the technics of LP, PE, SP are 45.13 - 1.91%, 69.25 -... |
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