Research On Quality Characteristics Of Different Varieties Of Lotus Root And Low-temperature Instant Lotus Root Powder Technology

Lotus root is the most widely planted aquatic vegetable in China.It is not only rich in nutrients,but also has high edible and medicinal value.The lotus root is prone to browning during storage,resulting in huge losses.Processing it into lotus root powder,beverages,crisps and other products will not only broaden the space for development and utilization,but also extend the relevant industrial chain.However,there are many varieties of lotus roots in China with great differences in quality between different varieties.The suitable raw materials are the basis for the production of high-quality processed products.Therefore,in this study,28 widely cultivated and local varieties were collected to determine their postharvest quality,and starch was extracted to study their characteristics,then the varieties suitable for processing lotus root flour were selected.On this basis,the pre-gelatinization processing technology of starch was optimized and the products of low temperature instant lotus root powder were developed.The main results are as follows:(1)In this study,6 indexes on morphology,browning degree,vitamins,soluble-sugar,total sugar,soluble protein,total phenols of 28 lotus root shoot cultivars were analyzed.The varieties with better comprehensive quality were selected by principal component analysis.The result indicated that there were significant differences(P<0.05)observed in the contents of browning degree,vitamins,soluble-sugar among different cultivars of lotus root.Under principal component analysis,the cumulative variance contribution rate of the first three principal components was 66%,which basically reflected most of the information of the original indexes.The cultivars with higher comprehensive score were Donghezaoou,E'lian 6,Wuyiliuchengshiyongou,Suzhoushiyongou,Huhzouzaobaihe.(2)Through the determination of the composition and content of free amino acids in different varieties of lotus root,and the comprehensive evaluation by correlation analysis,principal component analysis and cluster analysis,the content,composition and variety diversity of free amino acids in lotus root were determined.Results showed that total of 17 free amino acids were found in 28 different lotus roots.The average content of total essential amino acids,non-essential amino acid and total free amino acids was 2.05 mg/g,12.27 mg/g and 14.33 mg/g respectively.The cumulative variance contribution rate of the three principal components is80.16%,which better reflects the comprehensive information of amino acids in lotus root,The top five varieties with comprehensive scores were Jinhua seedless lotus root,Xibu,E'lian5,Wuyi Baimu edible lotus root and Jinhua red lotus root.Cluster analysis divided 28 lotus root varieties into three categories,which was consistent with the results of principal component analysis,which well reflected the difference between free amino acid composition and flavor varieties of lotus root.(3)Different varieties of lotus root were used to analyze the diversity in the composition,content and taste of lotus root starch content,amylose,gelatinization characteristics,texture characteristics,thermal properties,and their comprehensive quality was evaluated to select cultivar with better quality by principal component analysis.The results showed that there were significant differences in starch content,amylose content,gelatinization and texture properties among different lotus root varieties(P < 0.05).Based on the principal component analysis of each quality index,three main factors were extracted,and the cumulative variance contribution rate was75.66%,which basically reflected the information of the original index.The varieties with better comprehensive quality are Jinhua seedless lotus root,golden lotus root No.4,golden lotus root No.1,Jinhua Honglian' and 'Elian No.7.(4)The pre-gelatinization processing technology of starch was optimized,and the products of low temperature instant lotus root powder were studied and developed.Taking the sensory quality of pre-gelatinized lotus root powder as the evaluation index,on the basis of single factor experiment,three factors of gelatinization time,gelatinization temperature and sample concentration were selected to design the Box-Behnken response surface method to optimize the processing technology.The results show that the best processing technology of low-temperature instant lotus root powder is as follows: gelatinization time 10 min,gelatinization temperature 75?,sample concentration 8%.Under this condition,the sensory evaluation of low-temperature instant lotus root powder is better.