title: Comparative Evaluation of Physicochemical Properties of Pine Needle Powders Prepared by Different Drying Methods.
abstract: Systematic study of how different drying methods, namely hot-air drying, vacuum-drying, and freeze-drying, affect color, browning index, degree of rehydration, water solubility, and vitamin C content is critical for utilizing pine needle powders (PNP) as a novel ingredient in functional foods. Samples prepared by vacuum-drying showed a significantly higher L*-value, whereas higher a*- and b*-values were detected in the hot-air dried samples (P<0.05). The browning index was significantly higher in samples prepared by vacuum-drying compared to samples prepared by freeze-drying (P<0.05). Freeze-dried PNP exhibited a significantly higher degree of rehydration than hot-air dried samples (P<0.05). Water solubilities of freeze-dried and hot-air dried samples were significantly higher than that of vacuum-dried sample (P<0.05). Vitamin C was less destroyed during freeze-drying compared to hot-air or vacuum-drying (P<0.05). Freeze-dried samples displayed a clear porous structure and appeared to have a bigger space, whereas hot-air dried samples showed lower porosity than vacuum and freeze-dried samples.
authors.affiliation: Department of Food and Nutrition, Duksung Women's University, Seoul 132-714, Korea.
authors.forename: Ha-Sook
authors.initials: HS
authors.lastname: Chung
authors.affiliation: Department of Food Science and Engineering, Daegu University, Gyeongbuk 712-714, Korea.
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
keywords: drying methods; physicochemical properties; pine needle; powder