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ORIGINAL RESEARCH article

Front. Hortic.
Sec. Postharvest Physiology, Management and Technology
Volume 3 - 2024 | doi: 10.3389/fhort.2024.1447957
This article is part of the Research Topic Sustainable Approaches to Food Loss and Waste Reduction in Smallholder Horticulture: from Proof of Concept to Scale View all 4 articles

Combined oven/freeze drying as a cost and energy-efficient drying method for preserving quality attributes and volatile compounds of carrot slices

Provisionally accepted
Zobabalo Progress Mina Zobabalo Progress Mina 1Tafadzwa Kaseke Tafadzwa Kaseke 2Tobi Fadiji Tobi Fadiji 3Yardjouma Silue Yardjouma Silue 1Olaniyi Amos Fawole Olaniyi Amos Fawole 1*
  • 1 University of Johannesburg, Johannesburg, South Africa
  • 2 University of Belgrade, Belgrade, Serbia
  • 3 Cranfield University, Cranfield, East of England, United Kingdom

The final, formatted version of the article will be published soon.

    An effective and efficient drying method for preserving fresh carrots is essential in food processing. Combined drying represents the next generation of novel drying methods that can potentially overcome the shortcomings of conventional drying methods. This study evaluates the impact of combining oven drying (OD) with freeze-drying (FD) on drying behaviour, energy requirements, costs, enzyme activity, and the physicochemical and sensory properties of dried carrots. The drying conditions included 36 hours of FD, combinations of OD and FD (OD-FD) at 1 h of OD + 21 h of FD (OD1-FD21), 2 h of OD + 18 h of FD (OD2-FD18), 3 h of OD + 15 h of FD (OD3-FD15), and 9 h of OD. Compared to FD alone, the OD-FD combination reduced drying time by 39–50% and decreased energy consumption and cost by 40-56%. FD and OD-FD reduced polyphenol oxidase activity by 71–85% and peroxidase activity by 29–52% compared to OD. FD carrot slices retained significantly higher levels of β-carotene (11.67–25.96 mg/100g DM), lycopene (9.91–21.85 mg/100g DM), total phenolic content (7.12–10.24 mg GAE/100g DM), and DPPH radical scavenging activity (16.44–19.38 mM AAE/100g DM) than OD and OD-FD slices. Volatile compounds such as aldehydes, terpenes, esters, alcohols, ketones, and acids were detected in all drying methods. The OD-FD process exhibited the highest percentages of these volatile compounds, indicating its effectiveness in preserving flavour components. Overall, the combination of OD2-FD18 significantly reduced energy consumption and costs while maintaining better β-carotene, total phenolic content, DPPH radical scavenging activity and volatile compounds.

    Keywords: bioactive compounds, energy consumption, Carrot slices, Freeze-drying, Oven drying, Quality attributes

    Received: 12 Jun 2024; Accepted: 16 Dec 2024.

    Copyright: © 2024 Mina, Kaseke, Fadiji, Silue and Fawole. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Olaniyi Amos Fawole, University of Johannesburg, Johannesburg, South Africa

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.