Interuniversity programme master of science in food technology (IUPFOOD):Non-destructive (Laser Induced Chlorophyll Fluorescence) technique for determining tissue integrity in tomato (Lycopersicon esculentum Mill.).

Sorting of the tomato fruit is carried out by using external fruit attributes, such as color,size,firmness or other textural features.However these parameters are differentiated by humans and automatic systems which do not take into account the internal qualities of the fruits which consequently affect fruit quality and uniformity of lots in the consumer market.However, internal characteristics of fruits such as the fluorescence behavior of chlorophyll pigments in their photosynthesizing organelles can be used in quantifying the level of ripening and senescence of fruits.Heence, the puropse of this study was to determine the feasibility of using the technique oflaser induced chlorophyll fluorescence on tomato fruits to follow their repening and predict important fruit quality attributes such as skin color, firmness and soluble solids.The research was conducted in two phases in which following of the repening of 60 tomato samples categorized under 6 repening induces for seven days was followed first(phase one), followed by regression analyssis to predict the important fruit quality attributes, at the last day (phase two). With the progression of ripening in the tomato samples, a decline in color of the peel was associated with decreases in the F690, F740 values with a concomitant increase in the fluorescence ratio F690/740. However, the degree of the above trend was variable as the first three repening stages were observed with increased reate of physiologuc activity, whereas after the light red repening stage tomatoes were observed to have a relatively slower rate of change in tissue integrity. In the second phase of the experiment, determination of correlations among the different variables showed that the highest positive corrleation(0.98) was obtained for F690 and F740 while the lowest was recorded for correlation between color and firmness (0.57).Comparisons of the two mostly used linear regression maodels, PCR and PLSR were carried out to evaluate them for their prediction performance for the fruit quality attributes.These prediction analyses were made by using the peak fluorescence values of chlorophyll at 690nm, 740nm and the fluorescence ratio at 690nm and 740nm.The results obtained revealed that the PLS regression analysis was slightly better in prediction efficiency in all the three prediction models constructed which, combined with its ease of interpretation made it a preferred modeling technique for the experiment.This resulted in comparatively good predition models with the highest correlation coefficient of 0.94 for color and 0.63 for brix(%).