Screening Antibrowning Agent And Mechanism Of Inhibiting The Browning On Fresh-Cut Lettuce And Chinese Water-Chestnut

Fresh-cut fruits and vegetables have exhibited a promising prospect in recent years due to their potential advantages such as fresh quality, convenient to eat and so on. However, the damage caused by slicing leads to browning, quality decline and other phenomena on fresh-cut fruits and vegetables. In order to explore the effect of ethanol treatment and other common fruit and vegetable preservatives on fresh-cut lettuce and Chinese water chestnut(CWC), replacing sulfate chemical preservation method, and investigating the anti-browning mechanism we have conducted the current study. The anti-browning effect of ethanol was determined by the results of preservation. Subsequently, the polyphenols which leaded to browning of fresh-cut lettuce and CWC were identified during the period of storage. By using the metabolomic technology analyzed metabolites and metabolic pathways. The research provided the theoretical basis and data support for studying on anti-browning of fresh cut fruits and vegetables. The main outcomes of the study were as follows:(1)Four different kinds of anti-browning agents were used to treat fresh-cut lettuce and CWC while the gas composition, color change, activities of browning-associated enzymes, content of browning substrate and total number of colonies during storage were determined. As the results showed, 30% ethanol treatment slowed down the respiration rate and discoloration, repressed the increases of PAL and phenolic content in fresh-cut lettuce and CWC in the storage time. Meanwhile, the certain bactericidal function of ethanol inhibited the growth of spoilage microorganisms. Therefore effectively slowed down the browning processing of fresh-cut lettuce and CWC, and maintained the good quality.(2) Including gallic acid, caffeic acid, chlorogenic acid, p-hydroxybenzoic acid, total 11 kinds of substances were regarded as standards. The polyphenols during storage in fresh-cut lettuce and CWC were separated and identified by HPLC, and then the contents were analyzed and compared. As the results showed that seven kinds of polyphenols such as p-hydroxybenzoic acid, chlorogenic acid, caffeic acid, epicatechin, coumaric acid, rutin, cinnamic were identified in fresh-cut lettuce, while other six kinds of browning substrates including gallic acid, catechin, p-hydroxybenzoic acid, chlorogenic acid, rutin and cinnamic were identified in fresh-cut CWC.(3)Based on the GC-MS data, reduced the dimensionality to decrease the complexity of metabolomics data and focused on the main information of specific data by Principal component analysis(PCA) and Orthogonal to partial least squares discriminant analysis(OPLS-DA). Thus screened the differential metabolites in fresh-cut lettuce and CWC during storage, and further to assume the corresponding metabolic pathways and metabolic networks according to the changes of the type and content. As the results showed, ethanol treatment can improve the resistance of fresh-cut lettuce and CWC by changing the metabolism of amino acid, carbohydrate, organic acid, so as to maintain the good quality.