Evaluation of the chemical qualities and microstructural changes of Lentinula edodes caused by airborne ultrasonic treatment combined with microwave vacuum drying

Abstract

This study analyzed a new drying method using airborne ultrasound combined with microwave vacuum to study its effect on the quality characteristics and microstructure of dehydrated L. edodes. Ultrasonic treatment resulted in many micropores in the product, forming the sponge effect caused by ultrasonic waves, which can promote the rapid evaporation of water in the product. Samples of Lentinula edodes individuals were dried using four methods: hot air drying (HAD), microwave vacuum drying (MVD), microwave vacuum drying after ultrasonic pretreatment (US+MVD) and airborne ultrasonic treatment combined with microwave vacuum drying (USMVD). The results showed that USMVD can reduced the loss of total sugar, total phenol, and total antioxidants in L. edodes, and increased the relative content of ergosterol, sulfur compounds, and free amino acids (p < 0.05). Scanning electron microscope observation revealed that USMVD resulted in a uniform reticular porous structure, which could better maintain desirable levels of nutrients. Therefore, USMVD can produce high quality products. Practical Application Airborne ultrasonic waves combined with MVD provides an innovative drying method for mushrooms, which has not been studied at present. The mixed drying method has great potential in maintaining product quality. It provides a theoretical basis for studying drying technology in the future.

Effects of combined ultrasonic and microwave vacuum drying on drying characteristics and physicochemical properties of Tremella fuciformis

“…However, polysaccharides obtained by ultrasonic technology are not prone to bubbling, have a small contact area with air, and are not prone to browning, which reduces the degree of the Maillard reaction, so the total sugar loss of USMVD and US + MVD was minimal. Lei et al [33] also drew a similar conclusion that the application of ultrasound could reduce the generation of the Maillard reaction, while increased acoustic energy density could prevent the sugar content in shiitake mushroom from decreasing more than that in the control group. In the dried samples, the protein content was controlled between 5.37% and 5.93%, indicating that MVD with or without ultrasonic treatment had no significant effect on the protein content ( p > 0.05), but the protein content of US3M-TFPs was significantly higher than that of H-TFPs ( p < 0.05).…”

Process effectiveness assessment by modeling the kinetics of lotus seed drying combining air‐borne ultrasound and microwave vacuum

“…Similar results have also shown that microwave and MV drying time can be reduced for pistachio kernel and f honey by applying US pretreatment (Jahanbakhshi, Kaveh, et al, 2020; Jiang, Bai, Sun, & Zhu, 2020). Lei et al (2021) also reported that ultrasonic combination with MVD could promote the rapid evaporation of water in the Lentinula edodes . At identical ultrasonic power, the accelerated drying rate of US + MVD with US pretreatment was slightly higher than that of US + MD with US pretreatment.…”

“…The results of their study showed that the US pretreatment has positive effects on reducing of drying time to dehydrate the samples. The use of ultrasonic combined with drying makes lentinus edodes produce many micropores, forming a sponge effect, which is conducive to the rapid evaporation of water in the product (Lei et al, 2021).…”

Influence of different drying methods on drying characteristics, three- dimensional appearance, physicochemical property and microstructure of Pleurotus eryngii

“…When MD was used to treat P. eryngii, the TPC of P. eryngii slices decreased with increasing microwave power, and the lowest TPC was 28.82 ± 0.50 mg/g. Lei et al (2021) found that after air ultrasonic treatment combined with microwave vacuum drying of lentinus edodes, the retention rate of total sugar could be increased by 25.91% compared with HAD, effectively preventing the reduction of total sugar content.…”