Characteristics of Cell Wall Structure of Green Beans During Controlled Freezing Point Storage

Abstract

Controlled freezing-point storage means that the storage temperature is in a non-freezing temperature zone between the freezing point of water and food. It has been demonstrated that controlled freezing-point storage can prolong the storage-life of fresh food. Green beans (Phaseolus vulgaris L.) have been planted extensively in the northeast region of China and harvested seasonally. Degradation of cell wall polysaccharides has greatly affected the texture properties of the green bean cell walls. During controlled freezing-point storage, activities of cellulase, pectin methyl esterase, and polygalacturonase were inhibited effectively. It resulted in a slow degradation of cellulose and pectin, less expansion of the cell wall, and less dissolution of pectin layers. As a result, the web structure of the cell wall was preserved. At controlled freezing temperature, the hardness of green beans decreased slightly. Homogalacturonan of chelate pectin was degraded into galacturonic acid, and the side chains of the soluble alkali pectin were degraded into arabinose and galactose. At the later stage of controlled freezing-point storage, the web structure of the cell wall polysaccharides was destroyed. However, the pectin degradation in the green beans was inhibited significantly during controlled freezing-point storage.