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

Abstract

The effects of microwave (90 and 180 W), hot air (60 and 70°C) and vacuum (60 and 70°C with 250 mbar) drying techniques on drying characteristics, total phenolic content (TPC), antioxidant capacity (AC), color and texture of mulberry pestils were investigated. L*, b*, C*, and h° decreased while a* value was generally increased in pestils. Hardness, springiness, chewiness, and gumminess of the samples were found to be significantly different (p < 0.05). Between the applied seven thin layer drying models, Page and Modified Page were best fitted with the highest R2 (0.9997) and the lowest values of RMSE (0.000927) and χ2 (0.000011). Effective moisture diffusivity (Deff) of pestils ranged from 4.42 × 10−8 to 8.47 × 10−7 m2/s. Drying treatments caused an increment in TPC (1.41%–57.13%) and AC (0.37%–72.79%). These highest results were both obtained from microwave 180 W (TPC: 209.14 mg GAE/100 g dw and AC: 181.37 μmol TE/100 g dw). Practical applications Mulberry is a perishable fruit with several health benefits. It can be consumed raw or in the form of fruit leather (pestil), jam, jelly, marmalade. By pestil production, in which fruit pulp is dehydrated into leathery sheets, mulberry can be processed into a nonseasonal shelf life prolonged product for markets without the additon of preservatives. In this study, drying kinetics of mulberry pestil by microwave, hot air, and vacuum methods were evaluated via mathematical modeling. Page and Modified Page were the best thin layer drying models for pestil production. Drying characteristics were assessed for the development of food specific system in industrial usage and the simulation and optimization of the drying process. Drying treatmens affected texture and color of pestils significantly while exerting higher total phenolic content and antioxidant capacity when compared to non‐dried formulation. Microwave was determined as a promising method to yield high‐quality pestils with greater nutritional properties and the advantage of reduced drying times.

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

“…Similar results were also reported in literature. Suna and Özkan-Karabacak (2019) applied microwave drying to obtain mulberry leather at microwave powers of 90 and 180 W. They have stated that total phenolic compound increased with increasing microwave power. On the other hand, the extremely high microwave powers may cause decrement in total phenolic compounds due to a sudden increase in temperature.…”

Moisture sorption isotherms, drying behavior, and quality attributes of mango sheets dried using hot air combined with relative humidity control

“…The application of drying air at 80°C in the first stage resulted in the higher firmness and adhesiveness values compared to single‐stage drying at 60°C and 15% RH, although the drying time was a little shorter. Suna and Özkan‐Karabacak (2019) studied mulberry leather drying and reported that the hardness (firmness) and adhesiveness of the dried mulberry leather product increased when dehydration occurred at a higher temperature. The drying condition in the second stage was expected to be more significant to the mango sheet texture than that of the first drying stage.…”

“…Plus, Stable Micro Systems Ltd., Godalming, UK) equipped with a light knife blade probe. The measurement method was modified from Suna and Özkan‐Karabacak (2019). The samples were cut into a rectangle shape and stacked one mango sheet upon another.…”

Changes in Antioxidant Activity and Organoleptic Quality of Mixed Fruit Leather during Drying and Storage

“…Phương pháp này thường được sử dụng chế biến trái cây sấy khô, đặc biệt phù hợp cho các doanh nghiệp chế biến quy mô vừa và nhỏ áp dụng. Trái cây sấy dạng miếng được chế biến chủ yếu từ trái cây có hoặc không bổ sung thêm các chất tạo cấu trúc, chất điều vị; do đó sản phẩm được xem là nguồn cung chất nhiều hợp chất có lợi cho sức khỏe như: các chất chống oxy hóa, vitamin C, chất khoáng, chất xơ [3,4]. Sản phẩm này có thể xem như là món ăn vặt có lợi cho sức khỏe thay thế cho các món ăn vặt giàu chất béo khác.…”