Adaptation to appropriate sub-freezing temperatures through reduction of mycelial porosity and alteration of cell wall composition in Stropharia rugosoannulata

Abstract

Sub-zero temperatures are avoided for storing mushrooms due to freeze damage. Stropharia rugosoannulata (S. rugosoannulata) often encounter such low temperatures prior to harvest. To preserve S. rugosoannulata, sub-freezing was studied at −2 °C, −6 °C, and −10 °C. The mechanism that caused the differences in the quality was analyzed from the perspective of water distribution and microstructure. The results revealed that at −2 ℃, S. rugosoannulata achieved a firmness and flavor that was comparable to that of the fresh samples. Water migration was observed at −2 ℃. However, at this temperature, S. rugosoannulata exhibited a lower drip loss compared to the fresh samples, and there was no significant variation in the malondialdehyde (MDA) and the electrolyte leakage rate (EL). Despite the swelling of the cells, the mycelial porosity decreased and the cell wall protein and water-soluble polysaccharide content increased to acclimate to the low temperature. In summary, the results of this study imply that it is possible to store S. rugosoannulata at suitable sub-freezing temperatures.