Investigation of drying kinetics and physicochemical properties of mulberry leather (pestil) dried with different methods

Production of Stevia-Based Persimmon Fruit Leather by Microwave Oven and Its Optimization With Response Surface Methodolog

The consumer preference for low-calorie and nutritious foods has urged the attention of researchers and food designers to develop food products with alternative organic ingredients. For the first time, persimmon is successfully developed into fruit leather (pestil) using a non-caloric stevia sweetener. The study started with the production of persimmon (Diospyros kaki) leather, initially evaluating the compatibility of non-caloric stevia (S T) sweetener with hydrocolloids (corn starch, pectin, and guar gum) by the hot air oven method, in which guar gum exhibited superior flexibility. After setting the leather recipe, the trials were performed in a microwave oven by employing a Box-Behnken experimental design to optimize the drying process. Independent variables including microwave power (MP), microwave time (MT), and leather thickness (LT) have shown their optimum values at 210 W, 30 min, and 3.5 mm, respectively, based on physicochemical analyses focusing on moisture content, texture, color, total phenolic content (TPC), and antioxidant capacity (AC). MP had the most substantial impact on the variables, followed by MT, while LT showed the least influence. Optimized development of microwave products emphasized better physicochemical attributes, highlighting the energy-efficient nature of the resulting product in comparison to hot air-dried product. Sensory evaluation favored the optimized microwave-dried product over the hot air oven leather products. Therefore, utilizing novel processing technologies like microwave drying is recommended for producing functional (S T) based persimmon leather to uphold superior product quality.

Optimization of ohmic heating-assisted osmotic dehydration as a pretreatment for microwave drying of quince

In this study, the ohmic heating system was used as a novel application for osmotic dehydration of quince. After osmotic dehydration, samples were dried by microwave. In this regard, the effects of process variables such as electrical field strengths (20, 30 and 40 V/cm), holding time (10, 20 and 30 minutes), microwave power (90, 180 and 270 W) and sucrose concentration (0%, 25% and 50%) on dielectric constant, dielectric loss factor, rehydration ratios, total phenolic compounds and color values were investigated by response surface methodology (RSM). Optimum conditions were found as 40 V/cm electrical field strength, 30 min holding time, 16.67% sucrose concentration and 270 W microwave power. Total phenolic content, rehydration ratio, color differences and dielectric properties of the novel method were found to be higher than that of control. Moreover, Midilli and Wang & Sing models gave the superior fit to the moisture ratio data obtained during drying.