Combined Hot Air and Microwave-Vacuum Drying of Cranberries: Effects of Pretreatments and Pulsed Vacuum Osmotic Dehydrat
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Combined Hot Air and Microwave-Vacuum Drying of Cranberries: Effects of Pretreatments and Pulsed Vacuum Osmotic Dehydration on Drying Kinetics and Physicochemical Properties Zi-Liang Liu 1 & Izabela Staniszewska 2 & Danuta Zielinska 3 & Yu-Hao Zhou 1 & Konrad W. Nowak 2 & Hong-Wei Xiao 1 & Zhongli Pan 4 & Magdalena Zielinska 2 Received: 19 December 2019 / Accepted: 23 July 2020 # The Author(s) 2020
Abstract The aim of the study was to evaluate the effect of sonication (S), microwave-vacuum (MWV), convective freezing (F), cryogenic freezing (N), and their combinations, as well as pulsed vacuum osmotic dehydration (PVOD) on the drying kinetics, bioactive compounds, texture and color of whole cranberries during combined hot air convective drying, and microwave-vacuum drying (HACD+MWVD). Drying of berries took from 20 to 493 min. Drying rate was enhanced by 23% and drying time of nonosmotically dehydrated fruits was shortened by 33% using F treatment, while MWV decreased moisture content before drying by 68% and shortened the drying time of PVOD berries by 96%. Generally, total phenolic (TP) content increased during processing, total flavonoids (TF), and total monomeric anthocyanins (TMA) contents decreased, while the values of ferric reducing antioxidant power (FRAP) of dried fruits depended on the initial pretreatment. F and HACD+MWVD yielded fruits of the highest L* (33.8 ± 0.7), a* (25.2 ± 1.0), and b* (7.3 ± 0.6), inflated oval shape, and a small amount of wrinkles on the surface. PVOD and HACD+MWVD resulted in flat and wrinkled fruits. Keywords Cranberries . Ultrasound . Microwave-vacuum treatment . Freezing . Hybrid drying . Quality attributes
Abbreviations C S MWV N F S+F MWV + F PVOD
HACD+MWVD control (raw, non-treated) sonication microwave-vacuum treatment cryogenic freezing convective freezing sonication and convective freezing microwave-vacuum treatment and convective freezing pulsed vacuum osmotic dehydration
* Magdalena Zielinska [email protected] 1
College of Engineering, China Agricultural University, Beijing, China
2
Department of Systems Engineering, University of Warmia and Mazury in Olsztyn, Heweliusza 14, 10-718 Olsztyn, Poland
3
Department of Chemistry, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
4
Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA, USA
TP TF TMA FRAP MR DRAVG t MC(t) MCe MC0
hot air convective drying and microwavevacuum drying total polyphenols, mg GAE/g DM total flavonoids, mg CAE/g DM total monomeric anthocyanins, mg Cy3G/g DM ferric reducing antioxidant power, mg TE/ g DM moisture ratio average drying rate, kg H2O/kg DM/min drying time, min moisture content of fruits at any level and any time, dry basis (db) equilibrium moisture content (db) the initial moisture content of the material (db)
Introduction Cranberries (Vaccinium macrocarpon) contain high level of bioactive compounds, which poses health-promoting
Food Bioprocess Technol Table 1
Parameters of initial treatments befor
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