The aim of this review was to identify the causes of postharvest losses (PHL) in fruit and vegetables in relation to small-scale farming in sub-Saharan Africa (SSA). The reduction of PHL can improve food security at household level. Farmers involved in small-scale production of fresh produce experience high PHL due to physiological deterioration associated with technical, biological and environmental factors and lack access to postharvest facilities. When these factors are contained, sufficient supplies of fresh produce reach the consumer and improve nutrition, income and food security at household level. This article described the PHL experienced by farmers along the cold chain and explored the advantages and disadvantages of the use of various cooling technologies. There are already existing modern cooling technologies but these are capital intensive and require electricity, which is not always available to small-scale farmers (SSF). This review proposes evaporative cooling as appropriate for SSF in SSA as it has proven to be effective under hot and dry areas and is a simpler and cheaper technology. The review recommends that with the incorporation of a desiccating unit, evaporative cooling could be extended to hot and humid areas. Solar and wind energy can be used to power the desiccating unit in remote and isolated areas with no access to grid electricity. Therefore, research needs to be carried out on developing or adapting a solar or wind powered evaporative cooling system under both hot-dry and hot-humid conditions.

The drying of agricultural produce is an important food preservation measure. However, high energy requirements for drying, limited access to energy sources, small-medium scale farmers experience high post-harvest losses of their produce. Therefore, there is a need to develop and optimize low-cost food preservation technologies. In this study, eleven mathematical models were used to estimate the drying coefficients following non-linear regression method, in hot-air oven and naturally-ventilated solar-venturi drying to find the best fit of the moisture ration models. Sweet potato tubers were sliced at 3, 5 and 7 mm thickness sizes with and without pre-drying treatments. The prepared sweet potato slices were dried in a hot-air oven dryer at a constant temperature of 70 °C in comparison to the naturally-ventilated solar-venturi dryer with a heated ambient air that varied according to the outside environmental conditions. The drying rate of the samples in a hot-air oven dryer was higher than for those in the naturally-ventilated solar-venturi dryer. The results showed that the drying time was significantly (P < 0.05) affected by the thickness size of sweet potato slices (SPS) and that the drying took place at the falling rate period and a constant drying time. The Midilli et al. model was the best fit for predicting the moisture ratio of SPS dried in hot-air oven dryer and naturally-ventilated solar-venturi dryer based on statistical analysis (R² = 0.982–0.999, χ² = 4.60 × 10⁻⁶-5.56 × 10⁻⁵ and RMSE = 0.011–0.067). The D_eff was 3.32 × 10⁻⁹- 6.31 × 10⁻⁹ m s⁻¹ for the naturally-ventilated solar-venturi dryer and 1.02 × 10⁻⁸ - 2.19 × 10⁻⁸ m s⁻¹ for the hot-air oven dryer. According to the results obtained, naturally-ventilated, solar-venturi dryer and lemon juice pre-drying treatment are the suitable application for small-medium scale drying of SPS under Pietermaritzburg conditions.

This study developed an indirect air-cooling combined with evaporative cooling (IAC + EC) system for temporary storage of fruit and vegetables (FV) to improve the shelf life of fresh produce under hot and humid climatic conditions. The aim of the study was to investigate the effect of IAC + EC in providing optimum storage environment of temperature and relative humidity (RH) for the tomato fruit compared to storage under ambient conditions. The IAC + EC system had a 53-m³ storage chamber able to store 3.8 tons of tomatoes. Solar energy during the day and a battery bank facility at night powered the cooling system. The structure was constructed and assembled at Ukulinga research center in Pietermaritzburg. The performance of the IAC + EC was evaluated based on the temperature and the RH measured hourly from 05h00-22h00 daily during a period of 28 days. Temperature and RH were measured in the psychometric unit, various positions in the storage chamber and at ambient conditions. There were significant variations (P < 0.001) in temperature and RH between storage and ambient conditions. The temperature inside the storage chamber was on average 7°C-16°C lower while the average RH was 13%-41% higher than ambient conditions. Temperature and RH at the exhaust end of the IAC + EC storage chamber were 16.40 °C and 88.9% compared to 30.9°C and 47.6% under ambient conditions. Such conditions can enhance the shelf life of FV of moderate respiration rates. Inside the storage chamber, temperature was 15.7°C-16.4°C while the RH was 89.6%-93.8% depending on location. The cooler efficiency varied from 88.04% to 95.6%. The IAC + EC system performed at the same level as evaporative cooling under dry and arid conditions. The results in this study are evidence that IAC + EC system can provide optimum storage conditions for FV as well as being a low-cost technology utilizable in hot and sub-humid to humid areas in sub-Saharan Africa.

CHALLENGES FACED BY SOCIAL WORKERS WORKING IN CHILD PROTECTION SERVICES IN IMPLEMENTING THE CHILDREN’S ACT 38 OF 2005