Natural Drying of Astringent and Non-Astringent Persimmon “Rojo Brillante”. Drying Kinetics and Physico-Chemical Properties

Abstract

Persimmon (Diospyros kaki L.f.) crop has markedly increased in Spain, and “Rojo Brillante” persimmon is the main cultivated variety. This astringent cultivar requires de-astringency treatment before commercialization, which may involve an extra cost. Its short commercial season implies handling large volumes of fruits with consequent postharvest losses. Therefore, the development of derived added-value products is of much interest. In this study, astringent and non-astringent “Rojo Brillante” persimmons were dehydrated by following a natural drying method used in Asia. The drying kinetics and physico-chemical properties were analyzed for 81 days. The results indicated subsequent reductions in weight, water content, and water activity throughout the drying process, and the equatorial diameter decreased. All the employed thin-layer mathematical models were suitable for representing the drying characteristics of both products with similar behavior. The effective water diffusivity values were 5.07 × 10−11 m2 s−1 and 6.07 × 10−11 m2 s−1 for astringent and non-astringent persimmon samples, respectively. The drying treatment significantly decreased the soluble tannins content, and the astringent samples obtained similar values to those obtained for the non-astringent samples in 20 days. The external and internal flesh of the astringent fruit remained orange through the drying period, while brown coloration in the non-astringent fruit was observed after 57 drying days. Therefore, prior de-astringency treatment would not be necessary.

Pulsed Vacuum Drying of Pepper (Capsicum annuum L.): Effect of High-Humidity Hot Air Impingement Blanching Pretreatment on Drying Kinetics and Quality Attributes

“…Drying is a complex process involving heat and mass transfer [34] and is influenced by material characteristics, media parameters, process parameters, and environmental conditions [35]. With the development of drying technology and scientific progress, using mathematical models to describe and predict the drying process has become an important part of drying research [36]. Thus, establishing a mathematical model of the drying process can facilitate analysis and evaluation of the entire drying process, optimize the drying parameters, predict the drying end point, and improve the quality of the dried product [37].…”

Thin layer drying kinetics and quality dynamics of persimmon (Diospyros kaki) treated with preservatives and solar dried under different temperatures

“…Persimmon ( Diospyros kaki ) belonging to Ebinaceae family is dicot and astringent fruit with higher flavonoid and lycopene contents, and antioxidant properties [ 1 , 2 ]. This fruit neutralizes the adverse impacts of free radicals responsible for numerous degenerative diseases (i.e., cancer, Parkinson’s disease, vision loss, and pre-mature ageing), enhances the immune system, and reduces cholesterol [ 3 , 4 ].…”

“…Dehydration under sun is one of the most ancient and valuable technique for drying persimmon fruits [ 2 ]; however, it is unhygienic with drying time extended to few weeks under uncontrolled humidity [ 17 ]. The successful dehydration process depends on a slow and steady heat supply to guarantee uniform drying [ 10 ].…”

Valorization of Persimmon Fruit Through the Development of New Food Products

“…In South Korea, however, they are left to hang in a well-ventilated area without being kneaded (Sugiura and Taira, 2009;Hur et al, 2014). González et al (2021b) used the natural drying method without kneading on the persimmon variety Rojo Brillante, comparing the behavior of astringent and non-astringent fruits (subjected to postharvest CO 2 treatment to remove astringency). After 20 days, there was a natural decrease in soluble tannin content; with astringent and non-astringent fruits having similar values (20-30 mg/100 g).…”