Effects of Different Pre-Cooling Methods on the Shelf Life and Quality of Sweet Corn (Zea mays L.)

Abstract

The strong wind pre-cooling (SWPC), ice water pre-cooling (IWPC), vacuum pre-cooling (VPC), natural convection pre-cooling (NCPC), and slurry ice pre-cooling (SIPC) techniques were used to pre-cool the fresh sweet corn (Zea mays L.), and then the pre-cooling treated sweet corn samples were stored at 4 °C for 28 days. During refrigeration, quality indicators, such as hardness, water loss, color, soluble solids content, and soluble sugar, were determined. In addition, oxidation indicators, such as peroxidase, catalase, ascorbic acid-peroxidase activity, and carotene content, were also measured. The results showed that the main problems of sweet corn during cold storage were water loss and respiration. The pre-cooling speed of SWPC is the fastest, and the latent heat of sweet corn can be removed in only 31 min. SWPC and IWPC could reduce the loss of fruit quality, maintain good color and hardness, inhibit the decrease of water, soluble solids, soluble sugars, and carotenoid contents, maintain balance between POD, APX, and CAT, and extend the shelf life of sweet corn. The shelf life of SWPC and IWPC corn reached 28 days, 14 days longer than SIPC and VPC treated samples, and 7 days longer than NCPC treated samples. Therefore, SWPC and IWPC are the appropriate methods to pre-cool the sweet corn before cold storage.

Influence of different pre-cooling methods on the freshness preservation of bok choi(Brassica rapa var. chinensis)

“…Every three days, measurements were taken on indicators such as weight loss rate, conductivity, hardness, color, total viable count (TVC), respiration rate, chlorophyll, titratable acid (TA), soluble sugar, soluble solids, Vitamin C (VC), total phenols (TP), malondialdehyde (MDA) and antioxidant enzyme activity of the bok choi samples. Different pre-cooling methods were analyzed as follows ( Zhang et al, 2023 ), and all vegetables were cooled from the initial temperature of 25 °C to 4 °C.…”

“…The purpose of pre-cooling is to eliminate field heat from freshly harvested vegetables, cool them to the appropriate temperature after harvesting and before transporting them to cold storage warehouses or markets, slow down the physiological and biochemical activities of the vegetables, and prepare for subsequent storage or shelf life ( Zhang et al, 2023 ). In addition, pre-cooling can preserve fruit and vegetables from physiological disorders, postpone aging or maturation, decrease post-harvest spoilage, and conserve vegetable quality.…”