INVESTIGATION OF BIOCHEMICAL PROPERTIES OF TOMATO JUICE INFLUENCED BY CHEMICAL PRESERVATIVES

Abstract

Tomato (Lycopersicon esculentum Mill.) is one of the most popular and demanding vegetable grown in Bangladesh. The aim of this study was to assess the biochemical properties and the effect of preservatives on the shelf life of tomato juice. The Research work was performed in the laboratory of the Department of Food Processing and Preservation and some analysis were conducted in the laboratory of the Department of Agricultural-chemistry, Hajee Mohammad Danesh Science and Technology University, Dinajpur. The duration of the experiment was 27 March to 27 May, 2018. The fresh, fully ripe and sound tomatoes were collected from local market and then washed, peeled, seeds removed and transferred to the juice extractor. Sugar and preservatives were added to the extracted filtrated juice. Then the juice was heated, cooled and bottled for preservation. Tomato juice was prepared with three different treatments. Among the three treatments T1 sample prepared with no preservative, treatment T2 sample prepared with Sodium benzoate preservative and treatment T3 sample prepared with potassium meta-bisulphite (KMS) preservative. The organoleptic observation of this tomato juice was studied for 60 days storage period. Chemical analysis and sensory tests were carried out during the 30 days at an interval of 15 days to assess the effect of chemical additives on the shelf life of tomato juice. Nutritional value was higher in sample T2 compare to other sample. Negligible change in chemical constituents except vitamin C was observed in the prepared juice throughout the 30 days storage period. Color was gradually faded and slightly off flavor develops at the end of the storage periods. The treatment T2 secured highest score for color, flavor, taste and overall acceptability and ranked as "Like very much" by a taste testing panel. Tomato juice prepared with no preservative (T1) spoiled after 45 days storage and juice prepared with KMS preservative (T3) spoiled after 60 days storage. Total number of viable bacteria were highest in tomato juice treated with no preservative (T1) and KMS preservative (T3). Tomato juice with Sodium benzoate preservative (T2) contained least viable bacteria which was better than T1 and T3 sample. Considering all parameters, Sodium benzoate tends to be better additives than potassium meta-bisulphite for preservation of tomato juice