Volume 10 Part 2 Article 61: First Experiments on the Processing of Pleurotus ostreatus Stipes for Human Consumption

Volume 10 Part 2 Article 61
Year 1979
Title: First Experiments on the Processing of Pleurotus ostreatus Stipes for Human Consumption
Author: H. Schmitz

Abstract:

Although fruit bodies of Pleurotus ostreatus are well received by the consumers, there are still problems for the growers. One is the fact that ca. 20-25% of the production consists of tough and therefore inedible stipes. This considerable amount of waste should be reduced drastically to make cultivation of this crop more profitable.

Other problems are the short shelf life and difficulties in preserving. The shelf life of freshly picked mushrooms in the investigation of GORMLEY and O’riordian (1975) was only 1-2 days at 17°C and 3-4 days at 2°C. Refrigerating and packaging prolong it up to 10 days but is expensive and would raise the price of the fruit bodies. By this treatment, however, the mushrooms become tougher, especially the grey strains. Dried mushrooms take on a rubbery consistency after rehydration. Freezing and heat sterilizing are Ii kewise unsuitable as they too enhance toughness.

For these reasons a suitable preservation method was searched. Stipes were used as experimental material because they are the toughest part of the mushroom and they are available for nothing.

One possibility for preservation seemed to be a lactic acid fermentation (silage) because mushrooms contain mannitol and trehalose (Rast, 1965; Hammond and Nichols, 1975) which can be used by Lactobacilli (Bergey, 1974). Preliminary experiments resulted in a product of surprisingly soft consistency. It has been proved later that this change in consistency is independent of the lactic acid fermentation.

This paper reports on the cause of softening and the optimal conditions for processing tough Pleurotus ostreatus stipes (fresh and frozen) to a product of pleasant taste.

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