Screening of the compound inhibitor of blackening for damaged lotus rhizome epidermis and evaluation of its fresh-keeping effect on lotus rhizome

The enzymatic browning of fresh-cut lotus rhizomes has been studied extensively at present, but few people pay attention to the quality deterioration of whole lotus rhizomes caused by non-enzymatic browning. In this study, we first screened the compound inhibitors for the blackening of lotus rhizome by color difference and sensory properties and then investigated the effects of blackening compound inhibitors on storage quality and shelf life of lotus rhizome. Results showed that the combination of 0.9% sodium alginate, 2% EDTA-2Na, 5% glycerol and 0.5% potassium sorbate (ENCI-4) had the best color difference and sensory properties of the lotus rhizome. Moreover, after 60 d of low-temperature storage, it was found that the sensory scores, SSC and total phenols contents of the lotus rhizomes treated with ENCI-4 were significantly higher than those in control groups (p < 0.05), while the color difference, total acid, MDA contents, total bacterial, mold and yeast count were significantly lower than those in control groups (p < 0.05). Besides, by comparing the storage quality of bruised lotus rhizomes (CK-1) and mud-treated lotus rhizomes (CK-2), it was found that the formation of epidermal blackening in CK-2 would accelerate the browning and aging rates of lotus rhizomes, thereby having a more negative impact on its storage quality, while the shelf life of lotus rhizome could be significantly extended after ENCI-4 treatment. Overall, the blackening compound inhibitor formula proposed in this study can effectively extend the shelf life of the whole lotus rhizome.