| || || Raju, Rupantri Nandika|
| || || Quality evaluation of pre-treated tropical fruits dried in three types of solar dryers |
Author: Raju, Rupantri Nandika
Institution: University of the South Pacific.
Call No.: pac In Process
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: Postharvest losses of surplus seasonal fruits are a major problem in Fiji and other Pacific Islands. Drying is one of the cheapest and most efficient method, to preserve these surpluses, however there are losses with open sun drying due to contamination by pests and dust. Therefore, there is a need to develop a low cost drying system, such as solar drying, to effectively dry fruits, reduce postharvest losses and minimize use of electricity. Three different types of solar dryers were selected to dry papaya (Carica papaya) and pineapple (Ananas cosmusas). These dryers were the indirect dryer with natural convection, solar cabinet dryer and direct dryer with natural convection. Firm and half ripe Hawaiian papaya (Solo and Waimanalo) and pineapple (Smooth Cayenne and Ripley Queen) were selected for drying. Micrometeorological conditions were measured, together with moisture and microbial analysis of the dried fruits to determine the effectiveness of solar drying. Hazard Analysis and Critical Control Points were established as guidelines to ensure quality. Changes in the total sugar content of the dried fruits were determined by High Performance Liquid Chromatography. Sensory evaluation was also conducted using panelists trained to use the hedonic scale. The solar cabinet dryer was the most effective in drying, having the highest temperature (65.0 ºC) and the lowest relative humidity (4.12%). The three types of solar dryers were effective in reducing the moisture content of the fruits to 20%. Sucrose content was high in dried pineapple composites (35g/100g) but low in dried papaya composites (0.1g/100g). The Escherichia coli count in the dried fruits was <3MPN/g, and the sensory evaluation results showed that there was no difference in the level of acceptability between the dried fruit samples (p<0.05). Solar drying can be applied to many other agricultural commodities. The conditions in the Pacific make the use of solar energy for drying food economical and environmentally sustainable as it uses a renewable energy source.