Effect of postharvest treatments and storage temperature on the physiological, nutritional, and shelf-life of broccoli (Brassica oleracea) microgreens

Abstract

Microgreens are categorized in the class of ‘super foods’ due to their high content of phytochemical and bioactive compounds. Rapid senescence and short life span are the restrictive parameters for the industrial production and marketing of these immature greens. Hence, there is a need to improve the production and storage conditions of microgreens to magnify postharvest quality, life span, and safety of microgreens, thereby emerging markets. To prolong their shelf life, effect of different postharvest treatments (MAP (modified Atmospheric Packaging) and GRAS chemical treatments) and storage temperature on physiological, nutritional and shelf life of broccoli (Brassica oleracea) microgreens studied. The effect of ascorbic acid + citric acid (0.25 % w/v each) along with MAP conditions (15 % CO2 + 5 % O2 + balanced N2) stored at 5 °C was used for post-harvest quality evaluation of broccoli microgreens. Microgreens treated with an organic acid in high CO2 conditions retained significantly (p < 0.05) higher bioactive compounds in terms of total phenols (1247.68 mg GAE/100 g FW), flavonoids (56.9 mg QE/100 g FW), and chlorophyll (42.12 mg/100 g FW) with better antioxidant activity (44.78 % inhibition). In addition, MAP conditions in the package significantly (p < 0.05) suppressed the weight loss that helped to retain better firmness. The combined effect of organic acids and MAP conditions significantly (p < 0.05) reduced the microbial load with better color quality and higher overall acceptability. The results indicate that post-harvest treatment of ascorbic acid + citric acid along with MAP conditions could be the practical approach to enhance the shelf life of microgreens up to 12 days while maintaining the nutritional quality, to provide avenues for better marketability and commercial gains.