Osmotic, osmovacuum, sonication, and osmosonication pretreatment on the infrared drying of Ginkgo seed slices: Mass transfer, mathematical modeling, drying, and rehydration kinetics and energy consumption

Abstract

This study evaluated the mass transfer, drying, and rehydration kinetics (drying and rehydration curve, moisture diffusivity [Deff]), energy consumption (specific energy consumption [SEC], moisture extraction rate (MER), and specific moisture extraction rate [SMER]), and mathematical modeling of infrared dried Ginkgo biloba seed (GBS) using the various nonthermal pretreatments namely: osmotic (OS), osmovacuum (V + OS), ultrasound (US, ginkgo seed immersed in a distilled water with US), and osmosonication (US + OS, ginkgo seeds immersed in an OS solution with US). Results showed that various pretreatments affected mass transfer, drying, and rehydration characteristics, and energy consumption, which was confirmed by principal component analysis. In terms of mass transfer, US pretreatment recorded the highest weight loss while the osmosonication pretreatment registered the highest solid gain. The entire drying process occurred in the falling‐rate period. The Deff values were within the normal range of agroproducts (10−11 to 10−8 m2/s). The modified Page‐I and Weibull model best fitted the drying and rehydration kinetics, respectively, with the coefficient of determination (R2) > 0.991, root mean square error, residual sum of squares, and reduced chi‐square closer to zero, compared with the other models. The untreated GBS (control) had the lowest energy efficiency (lowest SMER and MER) and the highest SEC than the pretreated GBS. Among the various pretreatments, the US pretreatment of GBS was superior, with the highest Deff, MER, SMER, and drying rate, and lowest drying time and SEC. Based on the findings, sequential US pretreatment and infrared drying is a feasible drying technique for GBS that could be used commercially. Practical Application Ginkgo tree cultivation in China has exceeded market needs with 60,000 tons per annum of GBS produced. Hence, there is a compelling need to explore new chances to use GBS availability irrespective of the seasonality and address the problem where GBS utilization is limited to the early phases of home‐cooked dishes. Although drying increases the shelf life of ginkgo seeds, there is a higher operation cost. Thus, pretreatment can reduce energy consumption and augment the product quality is ideal. This research reported the impact of nonthermal pretreatments on ginkgo seeds’ mass transfer, drying, and rehydration characteristics. The present results will provide a comprehensive understanding of the engineering application of ginkgo seed pretreatment, allowing for the best technique to be selected.

Multi-frequency power ultrasound as a novel approach improves intermediate-wave infrared drying process and quality attributes of pineapple slices

“…Drying curves exhibited a continuous falling rate pattern, which corroborates that moisture mobility was governed by diffusion. Similar scenarios were reported during the drying of Ginkgo biloba seeds [49] , ginger slices [54] , and scallion cylinders [48] . MR curves of pretreated slices were more declined compared to the control group.…”

“…Another explanation could be that the effect of ultrasound was maximized in distilled water than in sucrose solution since cavitation is reduced in viscous solutions [16] . Boateng & Yang [49] and Fernandes et al [43] reported similar trends between US and US-OD during the dehydration of Ginkgo biloba seeds and pineapple slices, respectively.

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“…A similar outcome was reported in osmosonicated and dried pumpkin [56] and quince slices [57] . On the contrary, osmosonication improved the rehydration ratios of Gingko seeds [49] and strawberry slices [25] , [58] . In US and US-ET, ultrasound created microscopic channels which improved the porosity of dried products and reduced the likelihood of shrinkage and product hardening.…”

“…Guo et al [27] , Xu et al [25] , and Zhou et al [31] have also demonstrated the positive effect of multi-frequency ultrasound on the rehydration of agro-products. Generally, ultrasound was found to improve the reconstitution of dried samples due to the rupture of cell walls [40] , [49] , [58] .

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“…The drying rate (g/(g.h)) was computed according to eq. (4) [49] : M 1 and M 2 are the moisture contents on a dry basis of slices (g/g) at times t 1 and t 2 in h, respectively.…”