Effect of relative humidity on the microbial and physicochemical characteristics of 'Samnamul' (Aruncus dioicus var. kamtschaticus) during storage

The effect of relative humidity (11-96%) on the numbers of microorganisms, color values, total phenolic contents, antioxidant activities, and oxidative enzyme activities of 'Samnamul' (Aruncus dioicus var. kamtschaticus) was examined during storage at 10°C. It was found that an increase in the relative humidity led to increases in the number of aerobic bacteria, yeast, and mold during storage, while the samples stored at a higher relative humidity exhibited lower L and b values, in addition to higher a values, thereby indicating progressive browning. Furthermore, the total phenolic contents and antioxidant activities decreased upon increasing the relative humidity during storage at 10°C, and storage at a higher relative humidity resulted in increases in the oxidative enzyme activities (e.g., polyphenol oxidase and peroxidase activities) over 4 weeks. The obtained result therefore indicate that the low oxidative enzyme activities of samples stored at a low relative humidity restrict enzymatic oxidation and browning, thereby maintaining the sample color and nutritional quality. As a result, storage at a lower relative humidity is considerably effective for extending the shelf life of 'Samnamul'.