Identification of Appropriate Postharvest Technologies for Small Scale Horticultural Farmers and Marketers in Sub-Saharan Africa and South Asia - Part 1. Postharvest Losses and Quality Assessments

Abstract

Part 1 of 2. The objectives of the study were 1) to systematically assess and characterize postharvest losses for key horticultural crops in four countries using field based measurements at the farm, wholesale and retail markets, to increase the knowledge base and identify priority postharvest problems that currently limit market access for small farmers and rural marketers, 2) to identify and field test postharvest technology options that could solve priority postharvest problems by conducting field trials in Sub-Saharan Africa and South Asia, and 3) to identify postharvest technology interventions that would specifically address the identified priority problems and serve to reduce food and value losses, and that are of appropriate scale, cost effective, easy to use on a trial basis and capable of generating increased incomes by at least 30% for small farmers. A series of comprehensive postharvest assessments were undertaken in Ghana, Rwanda, Benin and India during 2009 to identify the % physical losses, quality changes and economic value of losses for 16 different crops. Based upon these assessments, supplemented by interviews of various players along the value chains, primary causes and sources of postharvest losses and quality problems were identified. Sampling, objective and subjective measurement of physical losses and quality parameters were conducted at the farm, wholesale and retail markets in each of the four countries by trained data collectors housed at 10 partner institutions. Ten (10) random samples were collected at each of the 3 levels of the value chain for each crop. Tomatoes were assessed in all 4 countries, mangoes in 3 countries, and other crops in one or two countries each. Sample sizes and quality parameters varied by crop type. Sorting was done to determine overall quality, % damaged, % decayed and % with other defects within each sample. Rating scales were developed for visually assessing quality, color changes, stage of ripeness, and degree of package protection. Objective measurements of firmness, SSC%, air temperature, pulp temperature and % RH were made using hand held tools in the field. Postharvest losses were related to one or more of 4 major factors: 1) high temperatures, 2) poor quality packages, 3) poor field sanitation and 4) time required to reach the market.

Use of Insulated Covers over Product Crates to Reduce Losses in Amaranth during Shipping Delays

“…In a study by Kitinoja and AlHassan (2012), it was found that temperatures for leafy vegetables harvested in Rwanda and Benin were generally higher than those recommended for quality maintenance [8]. Pulp temperatures for temperate crops, including amaranth, which were handled without care for shading or temperature control, were found to be 25-30 °C above the recommended lowest safe handling temperatures of 0-2 °C.…”

“…In the study on storage of leafy vegetables conducted in Rwanda, Kitinoja and AlHassan (2012) found that mean weight loss on the farm for 10 samples of amaranth packed in sacks was 10.8% ± 9.1% over up to 240 min directly after harvest [8]. During 6 h display at a retail market, the additional mean weight loss in bunches of amaranth was 11.3% ± 2.8%.…”

“…For example, Kitinoja and AlHassan (2012) found that for amaranth in Benin, economic losses were estimated at 30%, due to the reduction in market value per kg of the produce sold when compared to the highest price per kg offered for higher quality produce on the same day in that market [8].…”

“…Fernando (2006) found that, in Sri Lanka, replacement of poly sacks with plastic crates reduced losses from 30% (poly sacks) to 5% (plastic crates) [7]. In a study of packaging types used in Sub-Saharan Africa and India, Kitinoja and AlHassan (2012) determined that 46% of crops were packed in (too) large sacks or cloth bundles, 31% were packed in open baskets and 8% had no package at all [8]. Only 15% of crops were packaged in plastic crates, and mechanical damage and subsequent weight loss due to poor packaging was extensive.…”

“…In the case of shipping delays, it may be even more important to cover pre-cooled plastic crates with insulating materials, and to package leafy vegetables such as amaranth in separate consumer packages. Kitinoja and AlHassan (2012) found that the percent damage due to delays in the time it takes to market were high [8]. Delays were caused by middlemen not arriving at prescribed times and other reasons.…”