PHYTOCHEMICAL CONTENT, PHYSICOCHEMICAL AND MICROSTRUCTURAL PROPERTIES OF APPLE POWDER AS AFFECTED BY DRYING METHOD

  • Seyed‑Ahmad Shahidi Medicinal Plants Research Center, Ayatollah Amoli Branch, Islamic Azad University
  • Shiva Roshani Department of Food Science and Technology, Ayatollah Amoli Branch, Islamic Azad University
  • Azade Ghorbani-HasanSaraei Department of Food Science and Technology, Ayatollah Amoli Branch, Islamic Azad University
  • Shahram Naghizadeh Raeisi Department of Food Science and Technology, Ayatollah Amoli Branch, Islamic Azad University
Keywords: Apple powder, drying method, physicochemical properties, microstructure

Abstract

Apple in forms of slice and juice dried through methods of freeze drying (FZD), microwave drying (MWD), oven drying (OVN), spray drying (SPD) and foam mat drying (FMD) and the resulted powders were characterized in terms of water activity, vitamin C (Vc), phenolic compounds (TP), anthocyanin (TA), density, porosity, color, glass transition temperature and microstructure. The nutritional quality of apple powders expressed by the amount of Vc, TP and TA was found to be in the highest level in samples obtained after FZD followed by SPD. The minimum shift of color indexes from fresh apple observed for FZD followed by MWD. The highest and lowest bulk and true density were noted after OVD and FMD, and FZD and SPD, respectively. DSC analysis showed the powders obtained from apple slice through FZD, MWD and OVD have significantly lower Tg than those of produced from apple juice, by SPD and FMD. Scanning electron micrograph confirmed the porous structure of FMD and FZD and the dense structure of OVD.

Published
2020-12-24
Section
Heat and Mass Transfer