Effect of drying temperature on color and desorption characteristics of oyster mushroom

Demiray Engin

doi:10.1590/fst.37118

Abstract

Oyster mushroom (Pleurotus ostreatus) slices were dried in a hot air dryer at three temperatures (45, 55 and 65 °C). The sorption isotherm of dried samples in the water activity (aw) range of 0.556-0.970 was also determined at three temperature levels. Moisture desorption isotherms were obtained from changes in water activities of oyster mushroom slices during drying, and the fitness of GAB, BET, Oswin, Henderson and Halsey isotherm equations to sorption data was calculated. The effect of temperature on color change kinetics of oyster mushroom slices was also investigated during drying. GAB model was the best equation for the prediction of the desorption moisture content of samples. Mathematical modeling of color change kinetics indicated that both zero and first order kinetic models were adequate to describe the browning index (BI) value; however, total color change (ΔE) followed zero-order kinetics. The values of the reaction rate constant, found after the drying at 45, 55 and 65 °C, of the ΔE value were respectively 0.058, 0.065 and 0.089.

Highlights

At the present time, thanks to the fact that the importance of mushrooms for the human nutrition and health has come to be understood, there has been an increase in the interest in fungiculture (Politowicz et al, 2018)
The first moisture content of the samples of oyster mushrooms used in the experiments were detected by drying it in the drying oven at 70 ± 1 °C for 24 hours
GAB model was found acceptable for predicting desorption moisture isotherms, while the other models presented a poor fitting to the experimental data

Summary

Introduction

Thanks to the fact that the importance of mushrooms for the human nutrition and health has come to be understood, there has been an increase in the interest in fungiculture (Politowicz et al, 2018). One of the methods for preserving agricultural products to keep the quality and against decaying, is the oldest and the most broadly-practiced method It is this method that is the most practiced though it is possible to preserve agricultural products for an extended period of time by means of cooling, freezing, exposing them to chemical processes, stocking them in an anaerobic environment, making use of ultraviolet and radioactive beams. Mushroom can and quickly decay owing to its content of high humidity and is a product that has shelf life of seven to ten days in cold storage. It is conserved and dried so as to prolong the shelf life (Bano et al, 1992; Rama & Jacob John, 2000). Dried mushrooms are generally used in sauces, instant soups and convenience foods (Yapar et al, 1990)

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Conclusion