Growth kinetics and biochemical changes of Grey Oyster Mushroom (Pleurotus Pulmonarius) lyophilized liquid spore induction spawn

Abstract

Grey oyster mushroom (Pleurotus pulmonarius) is a functional food enriched with medicinal properties. Spawns is one of the factors that affected the mushroom growth. Liquid spawns are used as they are more advantageous than solid spawns. However, the disadvantage of the spawn is they cannot be stored for long term. Thus, lyophilization technique is used in this research to examine the possibility of long term preservation of the spawns. Then, growth kinetics and changes of biochemical content of the mycelia are investigated for both untreated and lyophilized mycelia. This is done by growth of tissues of mature P. pulmonarius fruiting bodies on PDA, followed by inoculation of hyphae suspension in stress media, incubation of the spore suspension into PDB and finally transferring of liquid spawns on solid spawns (maize grains). The result shows that lyophilized spawns treated with lyoprotectant (mixture of 10 % of skim milk and 10% of sucrose) has higher recovery percentage than untreated lyophilized spawns. From the growth kinetic study, untreated spawns exhibits higher maximum specific growth rate and lower doubling time (0.5912 day-1 and 1.1725 day respectively) than lyophilized spawns with 0.3724 day -1 of maximum specific growth rate and 1.8612 day of doubling time. In the subsequent biochemical analysis, both treatment spawns show no significant difference (p>0.05) in the aspect of total carbohydrate and total protein content except for lipid content (p<0.05). Hence, lyophilization is considered a reliable preservation technique without significantly destroyed the biochemical content of the spawn.