Effect of drying time and temperature, Packaging materials, storage time and Temperature on quality and acceptability Of dried tomato (lycopersicon esculentum l.var Cochoro)

Abstract

Tomato (Lycopersicon esculentum L.) is popular and widely grown vegetable crop in the world as well as in Ethiopia. However, marketing of fresh tomato during peak season is a great problem because of its short postharvest life and traditional ways of managing the post harvest system (inadequate handling, processing and storage facilities). Therefore, drying is one of the most convenient methods in extending the shelf life and minimize postharvest loses. During drying, some physicochemical quality may be degraded and thus affect general quality characteristic of the dried tomato. The main purpose of this investigation was to study the effects of duration and temperature of oven drying on physicochemical property, sensory acceptability and shelf life of dried tomato. Processing type Cochoro variety was collected from Maki (Ziwai). The drying experiment were carried out by two phases, the phase I is the drying studies which were carried out in two factorial design (3*2) which consist three levels of drying temperature (70o C,80o C and 90o C) and two levels of duration of drying (7and 8 hours) based on preliminary trial was arranged in CRD. Phase II(storage study) was selected based on the analysis of phase I (drying study) by comparing physicochemical property and sensory acceptability analysis of dried sample with fresh (control) and then the selected treatments was carried out using 2*3*2*3 factorial CRD arrangement which consist two sample(sample dried at 90°C for 7 hours and 8 hours),three packaging material( Glass jar, plastic jar and plastic bag(low density polyethylene),the storage temperature( room temperature and refrigerated storage) and the storage period(1st, 2nd and 3rdmonths) respectively and three times replicate. The data were analyzed using SAS software (version 9.2).Every significant treatment effect was compared using Tukey at 5% probability level. As the result indicated that the drying processes (interaction effects of duration and temperature) affect the physicochemical and sensory quality of dried tomato. Furthermore, vitamin-C content of the samples dried at 90o C for 7 and 8 hours were badly affected recording an average value of 2.03mg/100g of vitamin-C compared to fresh and those dried at 70o C and 80o C for 7 and 8 hours with average values of 7.03 mg/100g, 3.86 mg/100g, 3.7 mg/100g, 3.16 mg/100g and 2.83 mg/100g respectively. In the storage study (Phase II) also vitamin C and Lycopene contents of tomato powder was decreased more in 3-months of storage period in plastic bag (low density polyethylene bag). But the degradation rate was lower in glass jar and plastic jar for both vitamin-C and Lycopene. In general the result showed that drying can reduce the amount of postharvest losses experienced by farmers and tomato sellers and dried tomato could contribute to daily intake of nutrition especially proximate composition better than fresh tomato.