Postharvest physiology of fresh cut tomato slices.

Abstract

Fresh-cut products are becoming increasingly popular as an option for processing fruit and vegetable commodities. Rapid deterioration during storage of tomato slices is the main problem with fresh-cut tomato. Slicing disrupts the plant tissue so the products become more perishable, which leads to a relatively short storage life, tissue softening, and results in tomato slices with poor quality. The scientific basis for maintaining quality of tomato slices during storage, and postharvest handling techniques to extend storage life, is the focus of this thesis.The major research objectives of this study focused on the physiological (ethylene and respiration), quality (firmness, colour, soluble solids, titratable acidity, and electrolyte leakage) and nutritional (ascorbic acid and lycopene) changes that occur in fresh- cut tomato slices from cv. 'Revolution' during storage. The specific objectives of the research were:1. To determine the effects of slicing on the postharvest physiology of tomato slices2. To study the quality changes in tomato slices taken from fruit at different stages of maturity and stored at different storage temperatures3. To characterise the involvement of ethylene in the loss of slice quality4. To determine the efficacy of 1-MCP in maintaining quality of tomato slices5. To determine the effect of fruit maturity and 1-MCP on the quality of tomato slices6. To evaluate the effect of applying a brief heat shock to intact tomatoes on the quality of slices.Study of the physiology of fresh-cut of tomato slices was started with comparisons of ethylene production and respiration between intact tomatoes and sliced tomatoes (arranged stacked or scattered in storage containers). Ethylene production and respiration initially increased in response to slicing. The rate of ethylene production and respiration by tomato slices was higher than in intact fruit. Slices arranged in stacks had lower rates of ethylene production and respiration compared with slices that were scattered. To reduce ethylene production and respiration rates by tomato slices, regrouping slices into their original shape is desirable during storage.Tomato fruits at different stages of maturity have different physiological and metabolic activities when stored at different temperature regimes. Slices taken from fruit at four stages of maturity, characterized by colour as 'turning', 'pink', 'light-red', and 'red', were evaluated for quality when stored at 0, 5 or 10 oC. The slices taken from the 'turning' stage of maturity were firmer and had longer storage life compared with those slices taken from the 'red' maturity tomatoes. Tomato slices stored at 0 oC were firmer and had longer storage life compared with those slices stored at 10 oC. Storage life of tomato slices could be maintained for 12 days at 0 oC, 10 days at 5 oC, or 8 days at 10 oC. Tomato slices obtained from the 'pink' and 'light-red' stages of maturity would be acceptable for marketing.n n n n Experiments were conducted to investigate whether ethylene absorbents and ethylene influence the quality of tomato slices. Ethylene absorbent resulted in reduced ethylene, less CO2 accumulation, and firmer slices. In contrast, ethylene applied 2 days after slicing stimulated the rate of ethylene production, CO2 production, and produced softer slices during storage. These experiments show that endogenous ethylene produced by slicing of intact tomatoes or application of exogenous ethylene to slices in containers had the undesirable effects of inducing softening during storage.n n n nn n n n n n n nn