Biochemical properties of six varieties of tomato from Brong Ahafo region of Ghana as influenced by the ripening condition and drying

Abstract

The study was conducted to assess the influence of the ripening condition and drying on the biochemical properties of six varieties of tomatoes (Lycopersicum esculentum). The six varieties (Tatiana, Techiman, Tropimech, Pectofade, Rodade and Pawa) were obtained from different tomato growing centres of the Brong Ahafo region of Ghana. Fresh fruits were harvested at mature green, half ripe and full ripe conditions using the USDA colour chart for ripening. Fruit samples were sliced and dried in a solar dryer for six days. Biochemical analysis was carried out on samples of both the dried slices and fresh fruits to estimate the vitamin C content, total soluble solids, pH, titratable acidity, moisture and dry matter contents of the six varieties. The results showed significant differences (p<0.05) among the biochemical properties of the six varieties.The vitamin C content of the varieties ranged between 10.37 and 21.25mg/100g. High moisture content, ranging between 83.24 – 96.67 percent was recorded for the six varieties. The means of the vitamin C, moisture content, pH and dry matter content were significantly different among the six varieties studied. Although the total soluble solids ranged from 2.70 to 4.17%, there was no significant difference among the varieties. The ripening  condition of the fruits did not have any significant effect on the biochemical properties studied. The study revealed that drying significantly affected the biochemical properties of tomato, except the titratable acidity and the total soluble solids. Drying significantly (p<0.05) reduced the vitamin C, total soluble solids, and the moisture contents of the six varieties. As expected, the pH and the dry matter content increased significantly (p<0.05) after drying. Significant correlations were observed among the biochemical properties studied. It can be concluded that some of the six varieties studied have appreciable levels of vitamin C, dry matter, total soluble solids and titratable acidity which could be improved for industrial purposes. In respect to the biochemical properties studied, Pawa appears to be the best  variety for industrial processing because of the high Total Soluble Solid (TSS) as well as lower pH and TA values, which are important quality attributes of tomato meant for processing. Tropimech and Techimanare are recommended for fresh market because of the high vitamin C and moisture contents. Although drying could be used to preserve the nutritive value of tomatoes meant for food, it is not  recommended for fruits meant for processing because it reduces the TSS content.

Key words: Tomato, varieties, drying, ripening, pH, vitamin C, biochemical  properties, titratable acidity