Physiological and Physicochemical Changes during Ripening of Tomato Fruit (Assila) Under Greenhouse and Ambient Temperature
Ripening under greenhouse and ambient temperature are common methods used in tomato production ripening but their effects on the quality of the fruit have not been fully investigated. The study aimed to determine the physiological and physicochemical changes in Assila tomato fruits at different ripening stages (breaker, turning, pink, light red and full red) under greenhouse and ambient temperature respectively, using standard methods. Tomato seeds (Assila variety) were planted in rubber containers, the germinated seedlings were transplanted into a greenhouse facility (32°C). Tomato fruits were harvested from the greenhouse at random and transported to a well-ventilated laboratory (25.6 °C/26.4 °C) upon reaching the mature green stage. At each stage of ripening according to the colour index, tomato samples were selected, manually graded, sorted and subjected to physicochemical and physiological analysis. Moisture content among the ripening stages for greenhouse tomatoes were significant (p < 0.05) with a highest of 95.15% at the full red stage and lowest of 91.78% at turning stage in greenhouse tomatoes. For both ripening methods, the highest weight loss (1.33% for greenhouse and 1.58% for ambient temperature) and lowest weight loss (0.34% for greenhouse and 0.35% for ambient temperature) was observed at the breaker stage and full red stage respectively. Firmness decreased from 4.77N to 1.61N and 4.20N to 1.33N for greenhouse and ambient temperature respectively. For both ripening methods, the highest ethylene concentrations (0.808ppm for greenhouse and 0.257ppm for ambient temperature) was in tomatoes at the full red stage whiles the lowest (0.052ppm for greenhouse and 0.110ppm for ambient temperature) was in tomatoes at the pink stage. The highest pH values (4.59 for greenhouse and 4.45 for ambient temperature) were at the breaker stage while the lowest (4.21 for greenhouse and 4.11 for ambient temperature) was at the full red stage. There was an increase in TA (0.54 at breaker to 0.94 at full red) and TSS (3.53 at breaker to 4.93 at full red) for ambient temperature tomatoes but a decrease in TA in greenhouse tomatoes (0.67 at light red to 0.40 at breaker). TSS increased from 2.64 to 4.73. Generally, the different ripening methods had varying influence on the physicochemical and physiological quality of tomato.
A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Science and Technology.