Postharvest Dehydration Temperature Modulates the Transcriptomic Programme and Flavonoid Profile of Grape Berries

Abstract

Raisins are a popular and nutritious snack that is produced through the dehydration of postharvest grape berries under high temperature (HT). However, the response of the endogenous metabolism of white grape varieties to postharvest dehydration under different temperature have not been fully elucidated to date. In this study, the white grape cultivar ‘Xiangfei’ was chosen to investigate the effect of dehydration at 50 °C, 40 °C, and 30 °C on the transcriptomic programme and metabolite profiles of grape berries. Postharvest dehydration promoted the accumulation of soluble sugar components and organic acids in berries. The content of gallic acid and its derivatives increased during the dehydration process and the temperature of 40 °C was the optimal for flavonoids and proanthocyanidins accumulation. High-temperature dehydration stress might promote the accumulation of gallic acid by increasing the expression levels of their biosynthesis related genes and regulating the production of NADP+ and NADPH. Compared with that at 30 °C, dehydration at 40 °C accelerated the transcription programme of 7654 genes and induced the continuous upregulation of genes related to the heat stress response and redox homeostasis in each stage. The results of this study indicate that an appropriate dehydration temperature should be selected and applied when producing polyphenols-rich raisins

The role of emerging technologies in the dehydration of berries: Quality, bioactive compounds, and shelf life

“…The same effect was observed in color with higher values of the colour change (ΔE) in samples subjected to prolonged temperature exposure (9.3 vs 5.3 at 50 °C/360 min and 60 °C/300 min, respectively). In the same way, Chen et al (2021) found that the combination of high temperatures/low times (50 °C for 5 days vs 40 °C for 12 days and 30 °C for 30 days) favoured the accumulation of glucose, fructose and total soluble sugars and the contents of citric acid, lactic acid, malic acid, tartaric acid, and gallic acid and its derivatives in grape berries.…”

“… High temperatures favoured the accumulation of some phenols (mainly gallic acid and its derivatives), while the highest accumulation of flavonoids and proanthocyanidins was achieved when lower temperatures were used. Chen et al (2021) Strawberry Convective drying (50 °C and 60 °C, 1.5 m/s) ΔE was greater in strawberries dried longer (9.3 vs 5.3 for 50 °C and 60 °C, respectively). Higher loss of TPC (60.9 % vs 78.1 % for 60 °C and 50 °C, respectively) andanthocyanins (45 % vs 26 % for 60 °C and 50 °C, respectively) with temperature.…”

“…In addition, these products have a very positive image by consumers. In this regard, dehydrated berries have many species that are used per se as food products ( Chen et al, 2021 ), and as an ingredient to obtain functional products ( Oliveira et al, 2021 ) or as natural antioxidants ( Echegaray et al, 2020 , Lorenzo et al, 2018 ) ( Fig. 4 ).…”

“…In recent years, several reports have been published that evaluate grape drying for raisin elaboration ( Barbanti et al, 2008 , Doymaz and Pala, 2002 , Huang et al, 2019 , Pangavhane et al, 1999 , Ruiz-Bejarano et al, 2020 , Wang et al, 2020 ). This popular and healthy snack is a common constituent of many foods due to its high amounts of phenolic compounds, strong antioxidant activity, desirable glycemic index, and long shelf-life ( Chen et al, 2021 ).…”

“…Concerning wines, there are many formulations obtained from dehydrated berries, and an important amount of dehydrated grape berries has been used to produce special wines ( Chen et al, 2021 ). An example of these beverages are sweet sherry wines, a traditional product elaborated from dehydrated grapes in the south of Spain.…”