Acidity and related properties of tomato fruits as influenced by genetic, environmental, and cultural factors

The purpose of this study was to determine the influence of cultivars, fertilizer rates, ripeness levels, methods of training, shade and moisture relationships, and processing on certain quality factors of tomato fruits. The quality factors studied were pH, percent titratable acid, percent soluble solids, soluble solids-titratable acid ratio, and percent reducing sugars.

There were significant differences among cultivars for pH, titratable acidity, soluble solids, and soluble solids-titratable acid ratio. There were differences among cultivars within two harvest dates and two growing locations and a significant interaction between harvest date and location for pH and soluble solids.

There were no significant differences in quality factors due to fertilizer treatments nor was acidification of samples affected by fertilizer treatments.

Overripe fruits had a considerably higher pH, lower acid content, and higher soluble solids-titratable acid ratio than fruits analyzed when at a ripe stage of maturity. There was a significant interaction between maturity levels and harvest dates.

Four training systems did not influence fruit pH and reducing sugars but did influence titratable acidity, soluble solids, and soluble solids-titratable acid ratio. Four different fruit maturities from four training systems influenced all quality factors studied. There was no interaction between factors studied due to system of training and stage of maturity.

Moisture levels during the growing period influenced pH, titratable acidity, soluble solids, soluble solids-titratable acid ratio, and reducing sugars. Shading plants influenced only soluble solids. There was no moisture and shade interaction for any quality factor studied.

The only difference in factors studied between tomatoes at various stages of maturity when analyzed fresh or 24 hours after canning was reducing sugar content.

Generally, in these experiments, pH and titratable acidity were related to each other but neither was related to soluble solids and reducing sugars.