EFFECT OF PACKAGING MATERIALS AND STORAGE ON NUTRIENTS AND AFLATOXIN CONTAMINATION IN DRIED TOMATO FRUITS

Abstract

Fresh tomato fruits are inherently more liable to deterioration under tropical conditions characterized by high ambient temperatures and humidity. The economic loss as a result of spoilage and proliferation of microorganisms on tomatoes with the possible health risks were the justification for this study. The aim of this study was to investigate the effect of different drying methods and packaging on nutritional content, microbial load and aflatoxin level of stored tomatoes. Fresh tomatoes obtained from shasha market, Akure were divided into two lots: one was sun dried for seven days and the other oven dried at 40°C until the moisture content was 13%. Also, dried tomatoes were sourced from Oja Oba market, Akure in Ondo state; Oja tuntun, Ile-Ife in Osun state and Bodija market, Ibadan in Oyo state. All the dried samples were analyzed for moisture content, lycopene, vitamin A and vitamin C contents, fungal load and aflatoxin levels before and after packaging in jute sack, hessian sack and polythene bags, and storage for four months at ambient temperature. An increase in moisture content was recorded after four months storage in jute sack, hessian sack and polythene bag compared to the initial moisture content before storage. Dried tomatoes stored in jute sack had the highest moisture content of 45.66±0.20, obtained from the sun dried samples and the least was 29.17±0.28, obtained from the samples stored in polythene bag. There was a significant reduction in the lycopene (fresh -17.00±0.05; sun dried - 12.00±0.10; oven dried- 11.00±0.02), vitamin A (fresh - 0.55±0.20; sun dried - 0.40±0.03; oven dried- 0.31±0.05) and vitamin C (fresh - 10.00±0.03; sun dried - 8.50±0.51; oven dried - 7.51±0.21) contents of the tomatoes from fresh to dried; with the oven dried tomatoes having the lower contents compared with the sun dried samples. After four months of storage in the three different packaging materials, the laboratory dried tomatoes stored in polythene bags had the highest lycopene and vitamin A contents (5.00±0.01 and 0.13±0.21, respectively), while those stored in jute sack had the highest vitamin C content (8.00±0.03). Similar trend was observed in the samples bought from Ondo, Osun and Oyo states. A total of six fungi were isolated from all the dried tomato samples: Aspergillus niger, Aspergillus flavus, Aspergillus oryzae, Saccharomyces cerevisiae, Rhizopus stolonifer and Fusarium solani. Results of the aflatoxin analysis showed the presence of aflatoxin B1 and B2 in all the samples except dried tomatoes from Oyo state, with dried tomatoes from Ondo state having the highest concentration of the aflatoxins. The data showed that sun drying is better than oven drying because of the effects of oven drying on the nutritional content of the dried tomatoes. Also, polythene bag was the best packaging material in this study. The presence of toxigenic fungi and aflatoxins in the dried samples both from the laboratory and open market in two states is of public health concern. There is need for further research to identify the right processing method and suitable packaging material that would prevent aflatoxin contamination in storage