Effect of vacuum drying temperature and pressure on the drying and desorption characteristics, and lovastatin content of the oyster mushroom ( Pleurotus ostreatus ) slices

Abstract

The aim of this study was to investigate the effect of vacuum drying conditions on the quality characteristics of oyster mushroom slices. The moisture desorption isotherms and changes in the lovastatin content of samples during drying were also determined. Drying generally took place in both constant and falling rate periods. Page and GAB models with the highest R2 and lowest χ2 and RMSE values were found to satisfactorily describe the drying and desorption behavior of the oyster mushroom slices. An increase in vacuum temperature resulted in a decrease in L and Hue angle, however, the opposite effect was observed for a, b, ΔE, and chroma (p < .05). Lovastatin degradation followed the first-order reaction kinetic and average lovastatin losses were calculated as 69.47%, 73.88%, and 83.98% for 45, 55, and 65°C temperatures and 74.72% and 76.82% for 0.04 and 0.08 MPa absolute pressures, respectively. Practical applications The perishable structure of mushrooms shortens its shelf life and makes postharvest processing methods such as drying, freezing, canning, etc. mandatory. Drying is a common method that is used to extend the shelf life and increase the consumption of oyster mushrooms in the off-seasons. Although the mushrooms are generally dried as a whole or slice, dried mushrooms can be used as ingredients in sauces and instant soups. That is why the drying of mushrooms by an appropriate drying method is essential. The vacuum drying technique generally prefers for oxidizable and temperature-sensitive products. The vacuum drying method has many advantages like low drying temperature, oxygen-free environment, etc. that provides a higher quality product. This study focused on the effect of vacuum drying conditions (temperature and pressure) on the drying kinetics, quality characteristics, moisture desorption isotherms, and changes in the lovastatin content during drying of the oyster mushroom slices.