Effect of freeze drying, oven drying and their combinations on energy conservation and quality of carrot slices

Z. P. Mina, T. Kaseke, T. Fadiji, O. A. Fawole

Research output: Contribution to journalArticlepeer-review

Abstract

An efficient and effective drying method is desired by food processors to preserve fresh carrots. The present study evaluated the impact of combining oven drying (OD) with freeze-drying (FD) on the drying behaviour, energy requirements, cost implications and physicochemical properties of dried carrots. The drying conditions were as follows: 36 h of FD, 1 h of OD + 21 h of FD, 2 h of OD + 18 h of FD, 3 h of OD + 15 h of FD, and 9 h of OD. Although the OD had the shortest (9 h) drying time, the dried carrot slices were of poor quality. Compared to FD only, the combination of OD and FD (OD-FD) reduced the drying time by 39-50%. When compared to OD and OD-FD combinations, FD carrot slices showed significantly (p<0.05) higher β-carotene (0.30-0.72 mg g-1 DM), lycopene (0.36-0.87 mg g-1 DM), total phenolic content (7.12-10.36 mg GAE 100 g-1 DM), and DPPH antioxidant capacity (6.54-9.88 mM AAE 100 g-1 DM). However, OD-FD significantly decreased energy consumption and cost by 40-56% compared to only FD. Overall, drying at 1 h OD+ 21 h FD produced better β-carotene, total phenolic content and radical scavenging activity retention while reducing energy consumption and costs; therefore, this could be an energy-efficient and time saving drying method to produce good quality and nutrient-rich dried carrot slices.

Original languageEnglish
Pages (from-to)75-82
Number of pages8
JournalActa Horticulturae
Issue number1387
DOIs
Publication statusPublished - 2024

Keywords

  • bioactive compounds
  • carrot slices
  • energy requirements
  • freeze drying
  • oven drying

ASJC Scopus subject areas

  • Horticulture

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