| With the change of people's health concept,cassava in the form of nutrient and healthy coarse food grain slowly return to people's life.But due to the cyanide cassava contains,improper eating can cause poisoning.Therefore,the quality of cassava and other issues have aroused people's attention.In this study,the indexes that influence cassava's quality were divided into bad indexes and good indexes.Meanwhile,this study preliminarily studied and evaluated the quality of 11 kinds of edible cassavas.The poor indexes include hydrocyanic acid,cyanogentic glycosides,cyanogenic glucoside enzyme and other cyanides.The good indexes include dry matter,protein,reducing sugar,crude fiber,total starch,amylose,amylopectin and other nutrients.This study measured and analyzed the contents of hydrocyanic acid in 11 kinds of cassavas.The measured and analyzed methods of cyanogentic glycosides Linamarin were also studied.In the harvest period,the indexes affecting the quality of cassava were determined,that is,the determination of contents of bad and good indexes.The different contents of cyanide and nutrient in different kinds of cassavas were compared.Afterwards,the correlation analysis was carried out.Finally,synthesized all the indicators and carried out the quality evaluation.To provide reference for the selection of excellent cassava germplasm and edible cassava,the varieties of 11 cassava varieties were preliminarily discussed.The main results are as follows:(1)The temporal and spatial variation determiniation of the hydrocyanic acid's content in cassava's pulp and cassava's skin from cassava's growing period to harvest time(August-December)was implemented.The results showed that the content of hydrocyanic acid in different cassava varieties varied with time.And the content of hydrocyanic acid in cassava's skin changed obviously.Most varieties such as SC9,E1424 etc.were increased in general.However,the content of hydrocyanic acid in cassava pulp did not change obviously.The hydrocyanic acid's content in most cassava species slightly decreased in the harvest time.(2)The content of hydrocyanic acid in cassava's skin was significantly higher than that in the pulp.The average content of hydrocyanic acid in cassava's skin was 34.71 mg / kg,the number in pulp was 7.33 mg / kg.The content in the in the cassava's skin is 2 to 3 times than that in the pulp.The highest content of hydrocyanic acid in cassava's skin was E1424,the number was 64.89 mg / kg,the lowest was GR891,the number was 25.88 mg / kg.The highest content of hydrocyanic acid in cassava's pulp was sugar cassava,the number was 10.70 mg / kg,the lowest was GR891,the number was 6.01 mg / kg.(3)The activity of hydrocyanic acid,linamarin and ?-D-glucosidase in the skin and pulp of 11 edible cassava varieties which were in the harvest period were determined.The results showed that the content of hydrocyanic acid and ?-DGlucosidase's activity in cassava's skin is higher than that in the pulp.The linamarin's content in the two parts was similar.(4)The nutritional ingredients in the pulp of 11 edible cassava which were in the harvest period were determined.The results showed that the dry matter rate was 13.78% ~ 42.62%,and the starch's content accounted for 43.44% ~ 89.59% of the dry weight.The amylpectin's content accounted for 39.27% ~ 79.12% of the dry weight.The amylose content accounted for 4.14% ~ 13.75% of the dry weight.The reducing sugar's content occupied 4.53% to 26.46% of dry weight.Protein's content accounted for 0.88% to 3.5% of fresh weight.And crude fiber's content occupied 0.7% to 0.9% of fresh weight.(5)The results of correlation analysis showed that there was a high correlation among the content of hydrocyanic acid content,dry matter rate,total starch content,amylopectin content,amylose content,protein content,reducing sugar content and crude fiber content of the cassava's pulp.The dry matter rate was clearly negative correlated with hydrocyanic acid content and was positive correlated to total starch content,amylopectin content,amylose content;The amylose content was clearly negative correlated with hydrocyanic acid content;The protein content was clearly negative correlated with total starch content;The reducing sugar content was clearly negative correlated with total starch content and was very significantly positive correlated to protein content;The crude fiber content was clearly negative correlated with total starch content and was very significantly positive correlated to protein content,reducing sugar content.(6)The results of the quality evaluation showed that there was obvious difference among the 11 kinds of cassavas' quality.The mean membership index value of SC9,Shatian cassavas,3G were high,which were 0.72,0.63,0.60.And its comprehensive quality was the good,they were suitable for planting.The mean membership index value of GR891,sugar cassava,bread cassava were low,which was 0.45,0.41,0.38.And the comprehensive quality were poor,planting is not recommended. |
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