Drying date plum (Diospyros lotus L.) fruit: Assessing rehydration properties, antioxidant activity, and phenolic compounds

Abstract

Date plum (Diospyrus lotus L.) is an edible fruit from the Ebenaceae family, rich in nutrients, and having tremendous medicinal properties. This paper attempted to show the influence of different parameters of convective drying such as temperature (50, 60, 70, and 80 • C) and air velocity (0.5, 1.0, and 1.5 m/s) on the shrinkage and microstructure, rehydration properties, antioxidant activity, and phenolic compounds of date plum. The drying caused significant changes in the color, actual size, and distribution of the fruit cells of date plum. The total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) of fresh date plum were 0.81 ± 0.00 mg GAE/g, 0.23 ± 0.10 mg ECE/g, 7.15 ± 1.09 mmol ISE/g, and 14.92 ± 0.88 mmol/TE, respectively. The drying at 70 • C had the highest values of TPC, TFC, gallic acid, chlorogenic and syringic acids, catechin, quercetin-3-glucoside, resveratrol, and DPPH. The drying air velocities showed no significant effects on the antioxidant contents and the antioxidant activity. Of the models applied to the drying kinetics, the Midilli model was found as the best model to describe the drying kinetics of date plum. In addition, the Weibull model was found as the most successful among the models applied to the rehydration kinetics of date plum. According to the achieved findings, the convective drying temperature of 70 • C is the optimum temperature to produce the dehydrated date plum.

Some Aspects of the Modelling of Dried Red Beets Rehydration Process

“…Our results for the rehydration process modelling have been similar to those previously presented [45][46][47]50,74,75].…”

“…The discussed models have been, however, applied also for describing the course of dried material rehydration. A first-order kinetics model, otherwise known as the Lewis (Newton) model, has been adopted to predict the rehydration process of such food materials as carrots [45], date plums [46], ginger [47], mangoes [48], onions [49], pumpkins [50], soybeans [51] and tomatoes [52]. The Page model has been used to describe the rewetting kinetics of such dried products as canola [53], lemon [54], pineapple [55], rough rice [56], Thompson seedless grape [54], and tiger nut [57].…”

Exogenous Application of Melatonin on the Preservation of Physicochemical and Enzymatic Qualities of Pepper Fruit from Chilling Injury

“…On the other hand, the control fruits exhibited the lowest amount of TPC. The increase in TPC levels in the fruits is majorly influenced by temperature stress-induced enzymatic activity, particularly phenylalanine ammonia-lyase (PAL) [63]. Naghizadeh et al [64] reported that MT treatment could significantly enhance PAL activity in plants.…”

Effect of ultrasound‐assisted osmotic dehydration on the drying characteristics and quality properties of goji

“…Therefore, traditional drying methods used for goji, such as sun drying, will consume a lot of time, while hot‐air drying not only consumes a lot of energy but also prolongs the time required for drying (Zhao et al, 2019). Long‐term high‐temperature drying results in fruit quality degradation, which is manifested by dark color, heat‐sensitive nutritional loss, and poor sensory quality (Hassan et al, 2022). To reduce the above deteriorations, the traditional method is to soak the goji in an alkaline solution such as sodium metabisulfite; however, this would result in chemical residues and a decrease in nutritional content (Hassan et al, 2022).…”

“…Long‐term high‐temperature drying results in fruit quality degradation, which is manifested by dark color, heat‐sensitive nutritional loss, and poor sensory quality (Hassan et al, 2022). To reduce the above deteriorations, the traditional method is to soak the goji in an alkaline solution such as sodium metabisulfite; however, this would result in chemical residues and a decrease in nutritional content (Hassan et al, 2022). Currently, the development of new pretreatment methods is necessary to ensure food safety and improve drying efficiency of goji.…”