Dual role of reusable Zingiber officinale in microwave synergistic drying of Pleurotus eryngii: Dielectric regulation and composite flavor formation

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Abstract

Microwave drying dehydrates rapidly but is limited by uneven heating and quality loss. To tackle this challenge, a mixed material system was designed by combining Pleurotus eryngii with reusable Zingiber officinale, where Z. officinale served both as a dielectric regulator to improve thermal uniformity and as a sustained source of volatile compounds for stable composite flavor formation. Within this system, Z. officinale alleviated the dielectric responsiveness of P. eryngii, enhancing thermal uniformity by 23.1 % and reducing overheating. The enzyme activity retention rates of polyphenol oxidase and peroxidase in P. eryngii showed strong negative correlations with heat accumulation, with both correlation coefficients exceeding 0.9. Under an optimized pretreatment of 2.0 W/g for 8 min, both enzymes were efficiently inactivated, the moisture ratio declined to 68.5 %, and the pore structure was preserved. Consequently, the dried products exhibited desirable properties, with a rehydration ratio of 84.4 % and a shrinkage ratio of 91.2 %. Nutritional constituents were retained, including sugars at 114.8 mg/g, phenolics at 30.5 mg/g, and acids at 23.6 mg/g. Volatile profiling revealed the long term contribution of Z. officinale, as 86.5 % of volatile species and 64.3 % of total content were preserved even after four reuse cycles.