Comparison of drying kinetics and product quality from convective heat pump and solar drying of Roselle calyx

Norhaida Hanum Ahmad Tajudin, Siti Masrinda Tasirin, Wei Lun Ang, Masli Irwan Rosli, Law Chung Lim

Research output: Contribution to journalArticle

Abstract

This study investigated the effect of temperature (40, 50, and 60 °C) and sample mass (100, 200, and 300 g) on the drying characteristics and product quality of Roselle calyx using heat pump dryer. It was observed that higher drying temperature and lower sample mass led to a shorter drying time (faster drying rate). Higher temperature supplied more heat to the Roselle sample, which increased the activity of water molecules and moisture diffusion. This can be seen where the effective moisture diffusivity increased from 7.87 × 10−10 to 2.05 × 10−9 m2/s when air temperature of heat pump dryer was increased from 40 ᵒC to 60 ᵒC. The drying rates for all samples shared the same drying pattern: warming-up period where the drying rate started to increase due to the breakdown of the waxy layer on Roselle and falling rate period where it decreased gradually as the drying progressed. The Roselle sample dried with heat pump dryer at 40 ᵒC (100 g) possessed the least degradation of quality, maintaining 86.8%, 63.2%, 98%, and 63.3% for color, catechin, protocatechuic acid, and vitamin C, respectively. Overall, heat pump dryer outperformed the sun drying method by recording a much shorter drying period without compromising the product quality.

Original languageEnglish
Pages (from-to)40-49
Number of pages10
JournalFood and Bioproducts Processing
Volume118
DOIs
Publication statusPublished - 1 Nov 2019

Fingerprint

Hibiscus
Hibiscus sabdariffa
heat pumps
solar drying
calyx
product quality
Drying
Hot Temperature
drying
Pumps
kinetics
Kinetics
Temperature
dryers
Catechin
Solar System
Ascorbic Acid
sampling
Moisture
Color

Keywords

  • Colour
  • Drying kinetic
  • Heat pump dryer
  • Roselle
  • Total phenolic content
  • Vitamin C

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Biochemistry
  • Chemical Engineering(all)

Cite this

Comparison of drying kinetics and product quality from convective heat pump and solar drying of Roselle calyx. / Tajudin, Norhaida Hanum Ahmad; Tasirin, Siti Masrinda; Ang, Wei Lun; Rosli, Masli Irwan; Lim, Law Chung.

In: Food and Bioproducts Processing, Vol. 118, 01.11.2019, p. 40-49.

Research output: Contribution to journalArticle

Tajudin, Norhaida Hanum Ahmad ; Tasirin, Siti Masrinda ; Ang, Wei Lun ; Rosli, Masli Irwan ; Lim, Law Chung. / Comparison of drying kinetics and product quality from convective heat pump and solar drying of Roselle calyx. In: Food and Bioproducts Processing. 2019 ; Vol. 118. pp. 40-49.
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