Influence of Storage Temperature on the Qualities of Fresh Soybeans during Storage

The aim of this study was to investigate the influence of storage temperature on the qualities of fresh soybeans during storage and to determine the optimum storage temperature for fresh soybeans. Fresh soybeans were stored at 1, 5, 9 and 13 ℃. During storage, the sensory indicators (weight loss rate, hardness, browning index, brightness, red-green value and yellow-blue value), nutritional indicators (soluble protein content, total sugar content and reducing sugar content) and physiological indicators (respiration intensity and malondialdehyde content) of fresh soybeans were monitored, and the correlation analysis of these indicators was carried out. Finally, the optimal storage temperature was determined by principal component analysis. The results showed that compared with the storage temperatures of 9 ℃ and 13 ℃, 1 ℃ and 5 ℃ low storage temperature were significantly conducive to reducing the weight loss rate, delaying the browning, maintaining the colours, keeping the appropriate hardness, holding the contents of soluble protein, total sugar and reducing sugar of fresh soybeans relatively stable. And after 15 days of storage, it still retained its edible value. While the storage time of fresh soybeans stored at 9 ℃ and 13 ℃ shall not exceed 9~12 days. The start time of malondialdehyde accumulation was delayed in fresh soybeans stored at 1 ℃. Its accumulation amount (only twice that of the fresh samples) was much lower than that in the other three storage temperatures after 15 days of storage. Meanwhile, its respiration intensity remained at 40% when the fresh soybeans were returned to room temperature. Correlation analysis showed that the sensory index, nutritional index and physiological index were closely related. PCA analysis showed that among the four storage temperatures, 1 ℃ had the best freshness preservation effect, followed by 5 ℃.