African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6693

Full Length Research Paper

Evaluation of a naturally ventilated solar-venturi dryer environmental effect on the quality of dried sweet-potato slices

Siyabonga Gasa
  • Siyabonga Gasa
  • Institute for Agricultural Engineering, Agricultural Research Council, Private Bag X519, Pretoria, South Africa.
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Sipho Sibanda
  • Sipho Sibanda
  • Institute for Agricultural Engineering, Agricultural Research Council, Private Bag X519, Pretoria, South Africa.
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Tilahun S Workneh
  • Tilahun S Workneh
  • Descipline of Bioresources Engineering, School of Engineering, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg, South Africa.
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Mark Laing
  • Mark Laing
  • Descipline of Bioresources Engineering, School of Engineering, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg, South Africa.
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Alaika Kassim
  • Alaika Kassim
  • Descipline of Bioresources Engineering, School of Engineering, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg, South Africa.
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  •  Received: 08 July 2022
  •  Accepted: 23 September 2022
  •  Published: 30 November 2022

Abstract

A naturally ventilated solar-venturi dryer (NSD) was constructed using locally available materials to improve the quality of dry sweet potato slices (SPS) for small to medium scale farmers. The study investigated the efficiency of the NSD to reduce relative humidity (RH), solar radiation and temperature effect on firmness and color of dried SPS. The maximum temperature inside NSD was 44.4°C (12:00 pm) in an empty dryer and 34.1°C (13:00 pm) for a full filling NSD. The minimum RH in an empty dryer was 13.5 and 15.1% for a full filling NSD. The NSD was able to increase the temperature and reduce the RH at a minimum and maximum efficiency of 38.5 and 84.9% in a fulfilling NSD and 35.2 and 77.6% in an empty NSD. Thickness size and pre-treatment method had a significant (p<0.05) influence on color and firmness of dried SPS. The design of an NSD allows small to medium-scale farmers to process and preserve their produce at low cost, using the already available materials and structures.

Key words: Solar radiation; color; firmness, efficiency.