Ripening index: a better parameter for colour based assessment of ripening behaviour of tomato fruits

Tomato fruit ripening is a complex phenomenon and throughout its progress it is tightly associated with colour change. Hence, colour change has been considered as an important quality trait to assess ripening behaviour of tomato fruits. Present study depicts the use of two widely used colour based parameters for assessment of ripening behaviour of tomato fruits during storage. Tomato fruits of ten popular Indian varieties were harvested at green mature stage and stored up to 14 days at 22 ± 1 °C with RH of 90 ± 5%. Ripening index (RI %) and red tomato (RT %) were used to determine the progress of ripening at 5, 10 and 14 days after harvest. Out of these two parameters, RI (%) was found to be better for assessment of tomato fruit ripening as it was more sensitive (2.5 times) to the change in rate of ripening than the RT (%). Hence, this colour change based simple, rapid and non-destructive parameter can be used suitably for assessing the progress of tomato fruit ripening. Based on the time-course values of RI (%), tomato varieties were classified as fast ripening, intermediate ripening and slow ripening types. Further, visual colour based evaluation of tomato fruits is discussed and its implications are being highlighted for other colour associated and ripening-related changes (maturity, firmness, nutritional status).