FUNGI ASSOCIATED WITH ANAEROBIC METABISULPHITE PRESERVATION OF TOMATOE PUREE

ABSTRACT

Food spoilage is a major agricultural and economic problem. The search for techniques to prevent or control spoilage is an ever present endeavor. It is estimated that over 40% of total harvest tomato world wide, indeed Nigeria , is the wasted due to spoilage. This study aimed to determine the preservation effectiveness of sodium metabisulphite treated tomato samples at varying concentrations pasteurized at 65ºC for 15min. The samples were stored for a total of 21 days with analyses done every 7days. The analyses include microbiological (cultural) analysis, pH, titratable acidity, lycopene content and ascorbic content. Cultural analysis was done using pour plate technique with potato dextrose agar (PDA). Fungal isolates were identified based on cultural, morphological and microscopic characteristics. pH was measured using pH meter, titratable acidity by titrating the sample extract against sodium hydroxide, using phenolphthalein indicator. Lycopene and ascorbic acid contents were determined spectrophotometrically at 540nm. After 21 days of storage, the highest count recorded was 7.6±1.15×103 cfu/ml by sample Pv0.2g/l, while the lowest count 1.3±0.58×103 was recorded by sample Pv0.3g/l. The fungi isolated from this study were Asperagillus niger, Asperagillus flavus, Penicilleum sp, Candida tropicalis, Fusarium oxysporum and Geotrichum sp. Samples pasteurized and treated recorded no growth after 21 days of storage. The highest lycopene content recorded was 22.01±0.15×103 cfu/ml by sample Pv0.2g/l, while the lowest content recorded was 7.71± 0.15 ×103 cfu/ml by sample Ps65oC. The highest ascorbic acid content recorded was 0.74±0.07×103 cfu/ml by sample Pv0.1g/l and 0.74±0.07×103 cfu/ml by sample Pv0.2g/l, while the lowest content recorded was 0.17 ± 0.01×103 cfu/ml by sample Ps65oC. Combating spoilage in tomato due to fungal contamination by treating tomato products with concentration of 400 mg/L has been shown to be possible in the present study. More studies are necessary to explore even longer duration for preservation.