Evaluation of Finger-Feel Firmness as a Subjective Measurement of Tomato Quality Degradation in the Retail Market

Abstract

The versatility of the Finger-Feel-Firmness (FFF) test method has been proved with a series of panel evaluations. Judgment of the panel on the pattern of the variation of FFF, agrees with that of the author. An individual can be trained to monitor the pattern of variation of FFF. Absolute values of FFF however, depend on the personal force- sensitivity of the individual. Degradation of the firmness due to squeezes made in FFF test itself has also been investigated. Retail market tomatoes registered a rate of loss of average FFF from 60 to 65 g/d and the level of ripeness of the sample had no significant effect on this rate. On repeated squeezing in the FFF test itself, the rate of loss of FFF was only about 4 g/squeeze. Development in red colour with shelf-life in less-ripe tomatoes was nearly 3 times faster compared to 0.5 rank/d in red-ripe tomatoes. However, the loss of FFF with the development in red colour in less-ripe tomatoes was 40 g/rank and it was more or less 3 times slower compared to 121 g/rank in red-ripe tomatoes. It was clear that the natural deterioration does about 15 times severe damage to the whole fruit, compared to the induced local damage by squeezing in the FFF test. With knowledge of colour and FFF value, it is possible to estimate the expected shelf life of tomatoes. Tomatoes ripened up to colour rank 10 would spend a shelf-life till they reach a range of FFF as low as 100 to 200 g (subject to personal force-sensitivity, tomato variety and post-harvest management methods.)