Total sugar determination
Total sugar content was determined by the phenol-sulphuric acid method (Dubois, M., et al. 1956) Absorbance was measured with a JENWAY 6300 spectrophotometer at a wavelength of 480 nm and total sugar content was calculated on fresh weight basis.
Total acidity
Titratable acidity was estimated by a standard titrimetric method. 20 grams of extracted juice was mixed with 250ml of distilled water. In the presence of phenolphtalein as an indicator, the mixture was titrated by adding 0.1 N NaOH until the break of light pink color. The volume of NaOH added to the solution was multiplied by the correction factor of 0.064 for the calculation of total acidity as percentage of citric acid.
Dry matter determination
Dry matter was determined with a hand-held refractometer KRUSS HR10, calibrated with distilled water. Measurements were made on at least 10 fruit at botanical maturity, taken from the second cluster. Each fruit was longitudinally cut at two and juice was extracted. Approximately equal number of drops of tomato juice was placed on the prism of the refractometer and the percentage was directly noted from the measuring scale of the instrument.