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View the PDF document Mechanical cleaning for improved quality of Pacific Island export taro
Author:Malaki, Ioane
Institution: University of the South Pacific.
Award: M.Agri.
Subject: Taro -- Postharvest technology -- Oceania, Taro -- Processing -- Machinery -- Oceania
Date: 1997.
Call No.: pac SB 211 .T2 M35
BRN: 919787
Copyright:This thesis may NOT be copied without the authors written permission.

Abstract: All Pacific countries exporting fresh rootcrops face strict quarantine requirements in their target markets. For taro, Colocasia esculenta (L). Schott var. esculenta, the major market is New Zealand followed by Australia and the United States, Quarantine standards stipulate the removal of all soil and other surface debris from taro corms in the country of origin. Cleaning the corms to meet these standards is one essential part of the whole post-harvest handling chain. At present all taro is cleaned by hand scraping and or washing in water at export packhouses. This system involves much hard work and is one where uniformity of quality is difficult to achieve and maintain. The taro export industry in the Pacific has identified this part of the process as a major constraint. This study aimed to quantify the existing post-harvest handling systems for export taro to identify problems in these systems, and to specify, assemble, modify and test an improved post-harvest handling system incorporating an appropriate mechanised cleaning module. The overall performance of the modified system was assessed. Factors affecting storage quality were identified and the effects of impact damage of the taro corm were investigated. Literature investigations identified only one machine designed to clean harvested taro corms in Hawaii. This machine was evaluated from literature reports. Circumstances dictated that its specific assessment not be pursued in this study. However an assessment of the cleaning principle incorporated in its its design (parallel rollers) was assessed and found unsuitable. Corm cleaning trials in New Zealand using the Transverse-Brush Machine, the Longitudinal Parallel Brushes with Auger Drive, the Onion Topper using parallel pinch rollers and the Horizontal Rotating Barrel xiii Washer are described. Best results were obtained from a Horizontal Rotating Barrel Washer. Extensive tests using this type of machine in Fiji are described. Quantitative results and observations of the present system were obtained and compared to machine washing. The modified system had a higher throughput, is cheaper and imposes less human hardship. An impact damage trial concluded that the taro corm does not suffer internal bruising when subjected to surface impact; damage was manifested only as surface wounds. Key words: Taro, Colocasia esculenta, root-crop post-harvest handling, root-crop export, root-crop cleaning, Barrel Washer, impact damage, bruising.
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