EVALUATION OF OZONATION TREATMENT EFFECT ON TOMATO FRUITS AND LETTUCE COLOUR

This study was conducted to monitor the effect of ozonation treatment at different ozone concentrations for different periods of time on the red colour of tomato fruits and green colour of lettuce heads using Lovibond colourimeter. The results showed that ozonation is significantly affected all the colour values for both tomato fruits and lettuce heads, it was in a concentration-time dependent manner. The average Brightness for untreated tomato fruits and lettuce samples were 96.254 and 88.862, respectively, and after ozonation for 15 min at concentration of 5 ppm the average brightness were significantly increased (98.397 and 100.846), respectively. On the other hand, redness/greenness and yellowness values of tomato fruits and lettuce were decreased significantly when compared with the untreated samples. The average redness/greenness values for untreated tomato fruits and lettuce samples were -0.815 and 14.629, and after ozonation for 15 min at concentration of 5 ppm the average redness /greenness were significantly decreased to -4.462 and -35.09, respectively, and yellowness values were decreased from 76.536 and 83.249 in untreated tomatoes and lettuce samples to 43.174 and 31.476, respectively. These results indicate that the red colour of tomato fruits and green colour of lettuce degraded significantly with ozone treatment, although this degradation in colour does not affect the marketable value of these products.