| In this paper,eight varieties of potatoes grown in Ningxia region were studied,including "Qingshu 9,Qingshu168,Zhuangshu 3,Xiabodi,Daxiyang.Fiureit,Heimeiren and Kexin 1".The basic nutrient composition and antioxidant activity were analyzed."Qingshu 9,Daxiyang,Fiuretta,Heimeiren,Kexin 1" were selected to analyze the change of nutrients and antioxidant activity under different processing methods and establish in vitro digestion model to study changes in GI for laying a foundation of further processing of Ningxia potatoes.The main research results were as follows:(1)The dry matter content of Daxiyang was the highest at 27.44%,followed by Xiabodi 26.94%,and Heimeiren was the lowest at 17.3%.The highest starch content was 16.70%in Daxiyang,and the lowest variety was Qingshu]68(11.90%).Heimeiren in the total sugar content was 7.01%,protein content was 2.16%and cellulose content was 5.07%were all highest,reducing sugar content of the highest variety was 0.49%in Kexin 1,and the lowest content was 0.10%in Daxiyang.The soluble solid content of Qingshu 9 was the highest.The highest content of vitamin C in Heimeiren was 23.26 mg/100g,and the lowest in Fiverite was 11.48 mg/100g.The highest content of carotenoids was 83.47 g/100g in Fiverite,followed by the content of Qingshu168(77.13 μg/100g),and the lowest content was 45.49 μg/100g in Heimeiren.17 amino acids were detected in each of the eight potato species,including 6 essential amino acids and 11 non-essential amino acids.Heimeiren had the highest total amino acid content.Eight mineral elements including sodium,magnesium,potassium,iron,calcium,zinc,phosphorus and selenium were detected.The highest sodium content in Xiabodi was 88.36 mg/kg,and the lowest was 23.30 mg/kg in Zhuangshu 3.The content of magnesium in Fiverite was the highest at 238.56 mg/kg and the lowest at 117.19 mg/kg in Heimeiren.Potassium was the element with the highest content among all mineral elements.The highest content in Zhuangshu 3 was 4328.70 mg/kg,and the lowest content was 2588.43 mg/kg in Heimeiren.Iron content in the Daxiyang was the highest at 142.14 mg/kg,and the lowest at 32.04 mg/kg in Zhuangshu 3.The variety with the highest calcium content was 56.93 mg/kg in Daxiyang and 18.60 mg/kg in Fiverite.The highest zinc content in Heimeiren was 76.66 mg/kg,and the lowest was 15.34 mg/kg in Qingshu 9.The content of phosphorus in Qingshu 9 was 623.05 mg/kg,and the lowest was Fiverite 182.58 mg/kg.Selenium content was very low overall,Qinghsu 9 in the highest content of 4.25 μg/kg.On the whole,the highest content of minerals was found in the Daxiyang,followed by Zhuangshu 3 and Heimeiren was the lowest.(2)The highest polyphenol content in Heimeiren is 400.38 mg/100g,and the lowest in Xiabodi is 233.93 mg/100g.The highest content of flavonoids was 107.39 mg/100g in Fiverite,followed by 94.59 mg/100g in Heimeiren and 33.17 mg/100g for Zhuangshu 3.Chlorogenic acid content in all varieties is the highest,Heimeiren accounted for 91.46%.Five antioxidant capacities of different potato varieties were tested and their correlation with phenolic acid and flavonoids was studied.It was found that chlorogenic acid content was significantly positively correlated with phenolic acid and flavonoid content(p<0.01).The phenolic acid content was significantly correlated with DPPH free radical scavenging ability,superoxide anion scavenging ability,ABTS,and FRAP(p<0.01),with the highest correlation with ABTS scavenging ability,and negatively correlated with hydroxyl radical scavenging ability.Flavonoid content was significantly negatively correlated with hydroxyl radical scavenging ability(p<0.01),superoxide anion scavenging ability and ABTS(p<0.05),but not DPPH and FRAP(p>0.05).The content of chlorogenic acid was significantly correlated with DPPH,and was highly significantly correlated with three antioxidant abilities except hydroxyl radical scavenging ability,with the highest significance with ABTS.(3)Compared with fresh potato,starch content,total sugar content and vitamin C content were decreased in all processing methods.After steaming,boiling,fiying and microwave,the reducing sugar content of all varieties of potatoes decreased significantly,after roasting all varieties except Daxiyang and Heimeiren showed significant increase in content,there was no significant change in Heimeiren after fiying,all varieties were significantly reduced except Fiureit after microwave.Protein increased after stir-frying,fiying,baking and microwaving and decreased after steaming except for Kexin 1,the protein content of Qingshu 9 and Kexin 1 increased after boiling but other varieties were decreased.The content of phenolic acid in all varieties were decreased after processing,especially after frying,followed by roasting,and the loss was lowest after microwave treatment Compared with fresh samples,the antioxidant capacity of processed samples were decreased.After processing,the antioxidant activity of Heimeiren was the highest,followed by Qingshu 9.There were significant differences in the types and content of volatile substances among varieties and processing methods.Potatoes had the largest variety of volatile substances and relatively high content after roasting,while after microwave processing the volatile substances were relatively simple.(4)GI Values were significantly differenu under different processing methods(p<0.05).The highest GI value was 106.44 and the lowest GI value was 58.12 for Qingshu 9 unprocessed.After baking,GI value of Kexin 1 was 91.07,and the lowest was 49.99 after microwave processing.After roasting,GI value of Heimeiren was 98.09 and uncooked value was 63.44.The GI value of the Daxiyang was 103.21 after baking and 65.31 after frying.The highest GI value was 89.13 and the lowest was 58.33.Among all processing methods,the GI value of Qingshu 9 after baking was the highest,followed by Daxiyang after baking,and the GI value of Kexin 1 after microwave was the lowest. |
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