Evaluation of blanching effectiveness and optimal temperature and time conditions to minimize browning of commercial mushrooms

Abstract

The bleaching operation has been utilized to increase the shelf life, reduce enzymatic activity, and lower the microbial load of foods. This study aimed to investigate the effects of blanching time and temperature on three commercial mushroom varieties' lightness and color variation and determine the optimal operation conditions. Three specimens were collected: Agaricus bisporus Paris Champignon, Agaricus bisporus Portobello, and Lentinula edodes Shiitake. The composite central rotational design and the response surface methodology were employed to evaluate the combined effects of blanching temperature (ranging from 53.8°C to 96.2°C) and time (ranging from 10.3 seconds to 349.7 seconds) on the color parameters L* (lightness), a* (redness-greenness) and b* (yellowness-blueness) of mushrooms slices. Cutting, oxygen exposure, and temperature below 75°C significantly affected the color by reducing L* and b* values and increasing a* values, favoring the mushrooms' darkening (higher △L). The bleaching operation optimized to minimize color variation (△E) was at 80°C for 170 seconds for Champignon, 83°C for 209 seconds for Portobello, and 82°C for 186 seconds for Shitake. Blanching fresh mushrooms under these operational conditions can help prevent the development of dark color, thereby improving their quality for human consumption, extending their shelf life, and reducing waste caused by unsightly appearance.