Research On Non-sulfur Anti-browning Of Canned Agaricus Bisporuss And Litchi

Disodium Stannous Citrate Stannous is a kind of food additive with a strong reducibilityand used as antioxidants, preservatives and anti-browning agent owing to its inoxidizability.However, this new color retention agent has not yet been widely used, and its anti-browningmechanism has not yet been studied both at home and abroad. The research is aimedat its application effects and anti-browning mechanisms in fruit and vegetable products inorder to provide a theoretical basis for it being a new safe, efficient, non-toxic and non-sulfurcolor retention agent and to promote the development of the agro-processing exports.This paper was mainly to have a research on the anti-browning effect of DSC, used as anew color protection additive for Agaricus bisporus and litchi both in the pretreatment andcanned products storage period. Besides, the anti-browning effect of DSC was compared withother commonly used color fixative. Different color protection formulations of DSC weredesigned respectively for canned Agaricus bisporus and litchi. Meanwhile, there werepreliminary studies about the inhibition mechanism of DSC on fruits and vegetables.Firstly, the anti-browning effect of DSC used in Agaricus bisporus products was studied.Compared with other common color fixatives such as phytic acid, citric acid, ascorbicacid and calcium chloride etc., the inhibitory effects of DSC on polyphenol oxidase activityand browning were studied,which showed the result that DSC got a better inhibitory effect onpolyphenol oxidase activity and browning up to the ones of sodium metabisulfite.Thecompound color fixative of DSC for fresh-cut Agaricus bisporus pretreatment was citric acid0.2%+DSC0.03%+phytic acid0.02%+Vc0.03%; Besides, the optimal parameters forblanching process was determined to be: blanched in95℃liquid with0.1%citric acid for9minutes; During the storage period, the compound color fixative of DSC for canned Agaricusbisporus was: DSC0.03%+citric acid0.5%+CaCl20.5%.Secondly, it discussed the anti-browning effect of DSC used in litchi products. Comparedwith other common color fixatives such as phytic acid, citric acid, ascorbic acid and calciumchloride etc, the inhibitory effects of DSC on polyphenol oxidase activity and browning werestudied, which showed the result that DSC got an inhibitory effect on litchi polyphenoloxidase activity and browning, up to the ones of sodium metabisulfite but remarkablely betterthan other common color fixatives such as phytic acid, citric acid, ascorbic acid and calciumchloride etc.. The compound color fixative of DSC for fresh litchi pretreatment was: DSC0.02%+citric acid0.3%+calcium chloride0.4%; Besides, the compound color fixative forcanned litchi during the storage period was DSC0.03%+citric acid0.5%+CaCl20.5%.Finally, there was a preliminary exploration on browning inhibition mechanism of DSC.The absorption peak of enzymatic browning products of PPO with DSC was significantlyweakened at410nm in UV spectrophotometric, which indicated that DSC could effectivelyinhibit the enzymatic browning reactions to reduce the formation of precipitation recognizedas the browning products. In the other hand, PPO activity remained25.30%residual afterreducted by DSC. Reducted by DSC, the amount of α-helixreduction in the secondarystructure of PPO decreased as opposed to the increase of β-sheet. The circular dichroism showed that DSC might reduce PPO activity by changing its molecular conformation. In ESRspectra, the signal of Cu(Ⅱ)was a little bit of weakened, when DSC was added to PPO. Theresult indicates that DSC may have a direct effect on PPO through the reduction of Cu(Ⅱ)inthe active center to Cu(Ⅰ), but not obviously. In conclusion，not only by consuming O2, DSCmay also inhibit PPO activity by changing the molecular conformation of PPO and revertingCu(Ⅱ) in the active center to Cu(Ⅰ), for the purpose of browning control.