Effect of Vacuum Pre-cooling on Postharvest Storage Quality of Fresh Lotus Seeds

In order to investigate the effect of vacuum precooling on postharvest quality of fresh lotus seeds, different final pre-cooling pressures (500, 750, 1000 Pa) and water replenishment rates (0%, 2%, 4%, 6%) were set respectively, and no pre-cooling was used as control. Then, the effects of different vacuum pre-cooling conditions on the cooling rate and storage quality of fresh lotus seeds were studied. The results showed that compared with the control, vacuum pre-cooling reduced the heat and respiration rate of fresh lotus seeds in a short time. The pre-cooling time and weight loss in the pre-cooling process for the final pressure of 750 Pa were 780 s and 4.51%, respectively. Water replenishment treatment before vacuum pre-cooling not only prolonged the storage period, but also maintained better storage quality. Among of them, the treatment group (750 Pa, 4%) was the best, which could maintain the good appearance quality of fresh lotus seeds during storage, significantly reduce weight loss and respiration rate, and inhibit lotus seeds browning, maintain higher content of total chlorophyll, chlorophyll a, chlorophyll b and carotenoids. Therefore, vacuum pre-cooling conditions with a final pressure of 750 Pa and water replenishment rate of 4% could effectively delay the yellowing and senescence of fresh lotus seeds, maintain better storage quality, and extend the storage period.