Research On Fresh-cut Potato Browning Mechanism

Fresh-cut potato has a huge market demand. However, just like many fruits and vegetables, fresh-cut potatoes are prone to browning after cut. This turns out to be the major limitation for their shelf life. For this reason, to discover the biochemical mechanisms of potato browning is necessary. To explore the mechnism of browning formation of fresh-cut potato, the curing treatment was studied in this paper. The differences in gene expression between two varieties and between curing treatment and control were investigated by RNA-Seq analysis. Some interesting information were found out in the result. And it has been experimentally verified in this paper.1. Curing treatment could improve the color of potato after 12 days shelf life. HPLC analysis revealed that amounts of total phenolics, chlorogenic acid, gallic acid and protocatechuic acid were induced by curing and highly accumulated in the curing treated potatoes. Significantly higher PPO activities in curied potatoes were detected compared to the control, which lead to the lower browning in the slices from curing treated potatoes. Our results suggests that the activity of PPO and the content of the phenolics are not the key factor for fresh-cut potato browning.2. To reveal the potato browning mechanism. The differences of gene expression between two varieties, as well as control and curing treatment were analyzed in the paper. The sequence saturation analysis, randomness analysis and qRT-PCR results suggest that RNA-Seq results are appropriate for functional genomics studies of potato tubers. From expression pattern analysis and GO enrichment analysis, over 10 protease inhibitor genes were showing very significant up-regulated in curing treatment group and Kexin#13. This results indicated that protease inhibition gene may play an important rule in potato browning.3. Proteinase inhibitor cocktail test and amino acid analysis results are confirmed that the protease inhibitor is important factors in potato browning. At frist we treated potato juice with Protease Inhibitor Cocktail. The result show that the potato juice with Protease Inhibitor Cocktail has much lower browning degree than control. This results to some extent prove that protease inhibitors has the effect of inhibiting Browning(ex vivo). And then warming-up treatment has been studied, through the qRT-PCR and free amino acid analysis, found that lower PIs expression will significantly increase the content of free tyrosine(Browning substrate), and further aggravate the browning of fresh-cut potato.