Evaluation of the effects of different freezing and thawing methods on the quality preservation of Pleurotus eryngii

Abstract

The individually quick-frozen (IQF) method is used to produce high-quality frozen food by freezing an individual piece of food separately from the remaining food. In this study, the effect of various freezing and thawing combinations on the quality preservation of Pleurotus eryngii (king oyster mushroom) was investigated. For this purpose, diced and mini P. eryngii mushrooms were frozen by natural freezing (NF,-20°C) or IQF (-62.5°C and speed 8.23 m/s) methods and thawed using three thawing methods-flowing water thawing (FT, 4°C), microwave thawing (MT, 620 W), or natural air convection thawing (NT, 20 ± 5°C). Quality characteristics, such as thawing loss, texture, water holding capacity, color, microstructure, and sensory quality, were evaluated. MT showed the most rapid thawing time, followed by FT and NT for all the samples. The results showed that thawing curve, water holding capacity, and hardness of IQF samples were better than those of NF samples after NT, FT, and MT. Scanning electron microscopy analysis revealed that cell integrity of the IQF sample was better than that of the NF sample. MT is the fastest of the thawing methods, but thawing after NF yielded a sample closest to the fresh mushroom sample. Therefore, when combined with NT, IQF minimized the quality changes in frozen diced and mini P. eryngii mushrooms. This study showed that the IQF technology can be used as a new preservation and distribution method of mushroom. Keywords Freezing and thawing methods Á Individually quick-frozen Á Pleurotus eryngii Á Quality changes Á Scanning electron microscopy images & BoKyung Moon

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