Grape drying is a slow and energy intensive process because the waxy peel has low permeability to moisture.\ud Therefore, peel chemical and physical pretreatments are considered before drying in order to facilitate\ud water diffusion. However, they cause heterogeneity in the waxes removal and problems during\ud shelf-life.\ud In this paper an alternative abrasive pretreatment of grape peel, for enhancing the drying rate and preserving\ud the samples, was applied to Red Globe grapes. Convective drying experiments were carried out at\ud 40–70 !C and at 2.3 ms!1 air velocity. The effect of wax abrasive pretreatment on the drying kinetics and\ud quality parameters of raisins was investigated. The results were compared with those of samples pretreated\ud by dipping in alkaline ethyl oleate solution and untreated grapes. All the dried samples are darker\ud than fresh one and shrunked. The samples pretreated by peel abrasion and dried at 50 !C showed the lowest\ud color changes, less shrinkage and the best rehydration capacity. The drying kinetics and shrinkage\ud curves were also analyzed using some commonly available empirical models

Abstract:Loquat is a non-climacteric fruit consumed fresh for its essential nutrients and phytochemical compounds. In this study, the effects of chitosan coating (1% w/v) on changes in the enzymatic antioxidant and membrane damage in three loquat selections (CREAFRC-S18; CREAFRC-S35 and CREAFRC-S36) and three loquat cultivars (Golden Nugget, Algerie and Nespolone rosso di Trabia) stored at 7 • C over 21 days were evaluated. Chitosan treatment enhanced the activities of superoxide dismutase, catalase and ascorbate peroxidase. Moreover, this treatment inhibited polyphenol oxidase and guaiacol peroxidase activities, extending the storage life of loquat. Chitosan also preserved membrane integrity by inhibiting lipoxygenase activity and malondialdehyde accumulation. Principal component analysis provided a global view of the responses of both loquat selections and cultivars to the postharvest chitosan coating and storage temperature. These findings suggest that chitosan treatment could be a valid tool for improving the activity of antioxidant enzymes, preserving the enzymatic browning of loquat fruits.

No abstract

Chitosan-based coatings are used as a postharvest treatment to extend the shelf-life of several fruits. In this study, the effectiveness of chitosan-based coating to preserve the physico-chemical (weight loss, soluble solid content, and titratable acidity) and nutraceutical traits (total polyphenol, anthocyanin, flavonoid, ascorbic acid content, antioxidant capacity) in fresh fig “Troiano” has been evaluated. Furthermore, antioxidant enzyme activities, such as catalase (CAT) and ascorbate peroxidase (APX), were evaluated as well as the enzymes activities involved in fruit browning (polyphenol oxidase (PPO), guaiacol peroxidase (GPX)). Fruits were treated with 1% chitosan and 1% ascorbic acid coating, stored at 4 °C for nine days, and sampled every three days. Chitosan-based coating significantly reduced the weight loss and the qualitative changes, improving the total polyphenol, anthocyanin, and flavonoid contents and the antioxidant activity in stored figs. The higher activity of antioxidant enzymes allowed to reduce oxidative stress and prevent the browning reactions in chitosan-coated figs. The principal component analysis allowed to distinguish different behaviors among uncoated and chitosan-coated figs, indicating that the combined effects of chitosan-based treatment and storage time influenced the physico-chemical, nutraceutical and antioxidant system of figs during storage.

No abstract