Investigations into the shelf life and nutritional quality of fresh tomato fruit (solanum Lycopersicon) following two post-harvest treatments

Tomato production in Ghana is characterized by a glut and high post - harvest losses during the major season followed by scarcity and high prices during the off season. This is the result of the absence of a standard method for preservation of fresh fruits. This research was conducted to determine an effective method for the post - harvest treatment of fresh tomato fruits to enhance shelf life while preserving its physiochemical and nutritional properties. Two experiments were conducted, each with a factorial design of 5x2. In experiment one, the fruits were subjected to 0,1,2,3,and 4 kGy gamma radiation and stored at 10±1°C and 28±1°C. In experiment two, CaCl2 dissolved in distilled water at 0, 1.00, 1.50, 2.00 and 2.50% concerntrations were used to coat tomato fruits and stored at 10±1°C and 28±1°C. Gamma radiation at 4kGy extended the shelf life of tomato by 5 and 9 days above control when stored at 28±1°C and 10±1°C respectively. The use of CaCl2 at 2.5% greatly extended the shelf life of tomato by 11days and 18 days above control when stored at 28±1°C and 10±1°C respectively. For both treatments, shelf life increased with increasing dose of radiation/ concentraionn of CaCl2. Weight loss was higher in control fruits as well as fruits treated with gamma radiation or CaCl2 coating stored at 28±1°C temperature than treated fruits stored at 10±1°C. Tomato fruits treated with gamma radiation at 1 and 2 kGy and untreated fruits showed an increased in pH and Total Soluble Solids (TSS) which was paralleled by a decrease in Total Titratable Acidity (TTA) as storage period advance at both storage temperatures. However, fruits treated with CaCl2 at 1.00% had little effect on pH and TTA of tomato during the storage period. Nutritionally, CaCl2 coating significantly maintained the vitamin C and Iycopene concentrations in tomato fruit more than control and gamma irradiation which reduced vitamin C and Iycopene contents in the fruits significantly with days of storage. Storage at 10±1°C better preserved the antioxidants properties of the fruits better than storage at 28±1°C. Elemental composition (Na, K, Zn. Cu, and Mn) of the tomato fruits analysed on the initial and final days of storage showed K to be the element with the highest concentration whilst Zn was the least. Generally, gamma radiation led to an increased in the concentration of Na and K for all doses whilst CaCl2 coating significantly decreased the concentration of the same element at both storage temperatures. Concentrations of Zn, Cu and Mn reduced significantly in the tomato fruits by the final day of storage for all treatments following storage at 10±1°C whilst there were inconsistencies in the contents of the elements in the tomato fruits stored at 28±1°C. Gamma radiation and CaCl2 significantly reduced the microbial load in the tomato at both temperatures compared to the control. The reduction was proportional to increasing dose of irradiation and concentration of CaCl2. However, CaCl2 significantly reduced Total Aerobic Mesophiles as well as Mould and Yeast growth in tomato fruits compared to gamma irradiation at both temperatures. In general, treated tomato fruits stored at lower temperature (10±1°C) had more suitability and longer shelf life as well as the ability to maintain nutritional properties than those stored at 28±1°C. (au)