Quality retention in pumpkin powder dried by combined microwave-convective drying

• Published in: Journal of food science and technology 2022-04, Vol.59 (4), p.1558-1569
• Main Authors: İzli, Gökçen, Yildiz, Gulcin, Berk, Senel Ecem
• Format: Article
• Language: English
• Subjects: Antioxidants; Bioactive compounds; Biological activity; Bulk density; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Color; Convective drying; Drying; Food quality; Food Science; Furfural; Nutrition; Original; Original Article; Phenolic compounds; Phenols; Physicochemical properties; Porosity; Pumpkins; Vitamin E; Water activity
• ISSN: 0022-1155; 0975-8402
• DOI: 10.1007/s13197-021-05167-5

Three distinct drying methods, microwave drying (MWD), convective drying (CVD) and microwave-convective drying (MWCVD) with a grinding process were applied to obtain pumpkin powder. The effects of CVD (60, 70 & 80 °C), MWD (100 & 200 W) and MWCVD (100 W-60 °C, 100 W-70 °C, 100 W-80 °C, 200 W-60 °C, 200 W-70 °C, and 200 W-80 °C) applications on the physicochemical properties (water activity, bulk, tapped & particle densities, porosity, flowability, cohesiveness, swelling capacity, water holding capacity and water solubility index), color values ( L * , a * , b * , C, α o and Δe ), bioactive compounds (5-Hydroxymethyl-2-furfural (HMF), total phenolic content (TPC) and antioxidant capacity (DPPH and ABTS)) of the eleven pumpkin fruit powders were compared. The MWCVD, namely pumpkin powders dried at 200 W–80 °C resulted in shorter drying times with high‐quality dried pumpkin powders. The bulk, tapped and particle densities of pumpkin powders at 200 W-80 °C by MWCVD were 0.56, 0.66 and 1.74 g/cm 3 , respectively. These values are indicators of the good porosity (61.82%) of pumpkin powders. In addition, the highest TPC (1277.08 mg GA/100 g dw) and ABTS (126.99 ± 3.31 µmol Trolox/g dw) was observed for microwave-convective dried pumpkin powders at 200 W-80 °C. On the other hand, the lowest HMF level (10.12 ± 1.78 mg/kg dw) was found for the pumpkin poowders dried by MWCVD at 200 W-80 °C. In overall, dried pumpkin powders by a MWCVD method can be employed to acquire a high-quality food material along with an enhanced physicochemical properties, color and bioactive components.