Non-thermal pretreatment affects Ginkgo biloba L. seed's product qualities, sensory, and physicochemical properties

Abstract

Drying plays a significant role in Ginkgo biloba seed's (GBS) processing, and the previous research showed drying affected the product quality. A combined hurdle drying technology (integrated non-thermal pretreatment and drying) could be applied on GBS to achieve better product quality. Osmotic (OS), osmo-vacuum (OS + V), sonication (US), and osmosonication (OS + US) pretreatment followed by infrared drying was performed on GBS, and the product qualities (texture, color, enzyme inactivation, water activity, and microstructure), physicochemical properties (titrable acidity, reducing sugar, soluble solids, total sugar, free amino acid, and ascorbic acid), and organoleptic qualities were evaluated. Results showed pretreatment had various effects on physicochemical and product quality, and was confirmed by principal component analysis (PCA). The sensory scores, acceptability index combined with Pearson's correlation, and PCA showed that different pretreatments influenced the likeness and acceptability, and color, taste, and odor were the key determinants and strongly associated with the consumers' preferences. The untreated GBS (no pretreatment before drying) had a higher color change and lower enzyme inactivation. Pretreatment increased texture preservation after thermal processing, although it had a negative effect on soluble solids, reducing sugar and total sugar content. While the US improved the texture, it resulted in shrinkage (from the microstructure) and total sugar degradation. Among the various hurdle technologies, osmosonication (OS + US, followed by infrared drying) had the highest sensory attributes, free amino acid, slight structure deformation, and lowest water activity. The present study showed that osmosonication is a promising hurdle technology for GBS because it provides better quality attributes. PRACTICAL APPLICATION: Previous research showed that Ginkgo biloba seed (GBS) drying has an impact on product quality, which will ultimately determine GBS acceptance. This research was set out to envisage and advance current dryer design by merging the sequential operations (integrated non-thermal pretreatment and drying), also known as hurdle drying technology on GBS, to achieve better process efficiency, product quality, and make GBS's drying process more sustainable. The various pretreatments improved ginkgo seed's product qualities compared to the control (no pretreatment prior to drying). Osmosonication is a promising hurdle technology for GBS processing.

Keywords: enzyme activities; ginkgo seed; hurdle technology; microstructure; product quality; sensory analysis; ultrasound-assisted pretreatment; vacuum-assisted pretreatment.