| Due to abnormal physiological changes and improper preservation processing,the quality of cowpeas postharvest loss then affect the commodity value,so we need to find a non-toxic,natural preservation technology.Currently,at home and abroad preservation technology of cowpeas focus on physical means,chemical reagents,etc,but natural antistaling agents,such as Chinese herbal medicine,film-forming agent is few study,so we can study natural antistaling agents on keeping fresh cowpeas.In this research,using cow-28 cowpea as the research object,under 20 r℃ elative humidity is 75% of the storage conditions,daub processing methods,using such as fructus forsythiae,fructus ligustri lucidi,fructus schisandrae 16 kinds of Chinese herbs and such as pullulan polysaccharides,guar gum,locust bean gum 8 kinds of film former as raw material,screening with good preservation effect of herbal water extract and film former,then on the single factor basis of herbal water extract concentration,film former concentration and daub amount using the response surface to optimize the compound preservative formula,which discusses it keeps fresh on cowpea quality during storage.The results of this research as follows:1.Daub processing method is adopted to weightlessness rate and decay index as the index,early screening concentration is 0.10 g/ml(Chinese herbal medicine powder quality and constant volume volume 16 kinds of water extraction liquid of Chinese herbal medicine,the concentration of 1.00%(film-former quality and constant volume volume 8 kinds of film-former on cowpea postharvest fresh-keeping effect,the results showed:fructus ligustri lucidi,fructus schisandrae,pullulan polysaccharides and locust bean gum have significant effect,12 d,which compared to CK1(don’t do any deal with the blank control group),weight-loss rate respectively have fallen by 44.15%,46.94%,28.72% and 44.15%,rotting index respectively have fallen by 56.87%,59.74%,53.30% and 59.74%,significant difference(P＜0.05).On that basis,single factor experiment was performed on herbal water extract best concentration,film former best concentration,herbal water extract best daub amount and film former best daub amount,the result showed:the best concentration of fructus ligustri lucidi,fructus schisandrae,pullulan polysaccharides and locust bean gum were: 0.20 g/mL,0.10 g/mL,2.00% and 3.00%,which compared to CK1,weight-loss rate respectively have fallen by 44.75%,46.94%,45.63% and 44.84%;rotting index respectively have fallen by 61.58%,59.74%,62.66% and 59.32%,significant difference(P＜0.05);the best daub amount of fructus ligustri lucidi,fructus schisandrae,pullulan polysaccharides and locust bean gum were: 8:1,which compared to CK1,weight-loss rate respectively have fallen by 42.42%,49.57%,44.84% and 44.71%;rotting index respectively have fallen by 63.27%,61.68%,66.21% and 62.07%,significant difference(P＜0.05).Based on the results of single factors,which taking 4 natural preservatives on cowpeas to keep it fresh.The results show that:0.10g/mL+fructus ligustri lucidi+2.00%pullulan polysaccharides fresh effect best,which compared to CK1,weight-loss rate and rotting index respectively have fallen by 54.10% and 68.84%,significant difference(P＜0.05).2.Taking schisandrae chinensis concentration,pullulan polysaccharide concentration and as response factor,weight-loss rate and decay index as response values,to conduct response surface test design experiment.The result of optimization experiments and validation showed that:0.10 g/mL fructus ligustri lucidi,2.00% pullulan polysaccharides and 8.15:1 compound daub amount,reducing weightlessness rate and decay index of cowpeas significantly,weight-loss rate and rotting index is 9.69%,16.83%,which compared to CK1(don’t do any deal with the blank control group),respectively have fallen by 54.10%,60.66%,significant difference(P＜0.05);which closer to through the design-expert 8.0 software the predicted values 8.78% and 17.01%,no significant difference(P＞0.05).3.Taking 0.10 g/mL fructus ligustri lucidi+2.00% pullulan polysaccharides+8.15:1 compound daub amount antistaling agent to treat with cowpeas,the results showed that:after 12 d,which compared to CK1(don’t do any deal with the blank control group),antistaling agent treatment can significant restrain weight-loss rate,rotting index,and respiratory intensity raise during cowpeas storage,respectively have fallen by 44.18%,63.16% and 65.41%(P＜0.05);restrain rusty spot-rate not significant,compared to CK1,has risen by 4.16%(P＞0.05);significant maintain the higher content of soluble solids(TSS),vitamin C and chlorophyll,compared to CK1,respectively have fallen by 12.60%,15.92% and 43.24%(P＜0.05);significant restrain the accumulation of propanedial(MDA),compared to CK1,respectively fell by 20.00%(P＜0.05);compared to CK1,which respectively rised by 5.98% of peroxidase(POD);significantly reduce polyphenol oxidase(PPO),catalase(CAT)activity,compared to CK1,respectively fell by 74.68% and 26.72%(P＜0.05);fell by 7.08% of total phenol,but not significant;significant maintain the higher anthocyanins content,activity of cellulase and 4-the coenzyme A ligase(4-CL),compared to CK1,respectively fell by 38.89%,32.77% and 11.86%(P＜0.05);to maintain phenylalanine deaminase(PAL)activity and lignin content was not significant,compared to CK1,respectively rised by 6.18% and 5.70%(P＞0.05);significantly reduce the cinnamate-4-hydroxygenase(C4H)activity,compared to CK1,respectively fell by14.78%(P＜0.05). |
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