Effect of calcium and salicylic acid on cell wall hydrolyzing enzymes and biochemical characteristics of tomatoes during post harvest storage

Major Advisor: Presented by: Dr.(Mrs.)Surekha Bhatia Jyoti Kalra L-2011-BS-174-M

INTRODUCTION:

•Tomato (Lycopersicon esculentum Mill.) is one of the most important and widely cultivated vegetables in India with an annual production of 11.488 million tones.

•Tomatoes are major contributors of carotenoids especially lycopene, phenolics, vitamin C and small amounts of vitamin E in daily diets. Water comprises about 90% of its fresh fruit, which makes it highly perishable.

Process of fruit ripening and senescence increases as soon as a fruit is harvested and involves several bio-chemical changes which are softening of cell walls, loss in chlorophyll, changes in lycopene content and changes in color, flavor and texture with the involvement of several classes of enzymes.

Polygalacturonase (PG), pectinmethylesterase (PME), cellulose, β-D-galactosidase are important cell wall hydrolysing enzymes involved in fruit softening.

The deterioration of tomato fruits following harvest is influenced by many factors such as storage conditions, packing conditions and post harvest treatments.

• Calcium is involved in change of fundamental physiological process of plants involving cell walls, membranes, chromosome structures and enzyme activity. Post harvest calcium application maintains cell turgor, membrane integrity, tissue firmness, delays lipid catabolism, inhibits ripening and senescence .• Salicylic Acid is an endogenous growth regulator, which participates in the regulation of physiological process in plants. Exogenous applications of salicylic acid may influence stomata closure, ion uptake and transport, inhibition of ethylene biosynthesis, transpiration and stress tolerance.•These post harvest treatments by calcium and salicylic acid have the potential to extend the shelf life of the tomatoes. So understanding the mechanism involved in the action of these ions in relation to quality maintenance during storage is important in order to reveal strategies for improving the shelf life of tomatoes.

Knowledge Gaps: Little information is available regarding the harvest treatments of Ca2+ and salicylic acid on the cell wall hydrolyzing enzymes in relation to the quality parameters. A better understanding of mechanism of action of these treatments is necessary to formulate more targeted strategies for increasing the shelf life of tomatoes.

Objectives:

• To evaluate the effect of Ca2+ , salicylic acid on the activities of the cell wall hydrolyzing enzymes and associated biochemical changes as a function of the time of storage.• To find out the suitable post harvest treatments for extending the shelf life of tomatoes under different environmental conditions.

Expected New Knowledge:

Calcium and salicylic acid may enhance the shelf life of tomatoes by effecting cell wall hydrolyzing enzymes.

Technical Program:

Tomato variety: Punjab Ratta will be grown under natural field condition following recommended culture practices. Crops will be grown in the research field of Department of Vegetable Crops, PAU, Ludhiana

Experiment No.1Name of Experiment: Effect of Ca2+ and salicylic acid treatment on the quality changes during storage of tomatoes under different environmental conditions.

Location-field/Lab: Department of Processing and Food Engineering, PAU, Ludhiana.

Methodology: Tomatoes from the chosen variety will be harvested at a pink stage, washed and will be treated with Ca2+ (1, 1.5, 2.0%) and salicylic acid (1, 1.5, 2.0 mM). Each of these treatments was given by dipping the fruits of each set comprising seven fruits in the treatment solution for half an hour. Dried tomatoes will be placed in open tray and polythene bags and will be stored under ambient and refrigerated conditions till the edible state .

Samples will be analyzed for its weight loss, pH, TSS (Total Soluble Solids), titrable acidity (Znidarcic and Pozrl, 2006), ascorbic acid, carotenoid, lycopene(Sozzi et al 1999), total sugar (Dubois et al 1956) , total soluble flavonoids, total anti-oxidant activity (Marcello et al 2006).

Observations to be recorded: Changes in the weight loss, pH, TSS (Total Soluble Solids), titrable acidity, ascorbic acid carotenoid, lycopene , total sugar , total soluble flavonoids and total anti-oxidant activity.

Statistical Analysis: Data of standard error of three independent replicates will be evaluated. Analysis of variance (ANOVA) will be done.

Experiment No.2

Name of the Experiment: Effect of Ca2+ and salicylic acid on the activity of cell wall hydrolases during post harvest storage of tomatoes.

Location-field/Lab: Department of Processing and Food Engineering, PAU, Ludhiana.

Methodology: Tomatoes from the chosen variety will be harvested at a pink stage, washed and will be treated with Ca2+ (1, 1.5, 2.0 %) and salicylic acid (1, 1.5, 2.0 mM). Each of these treatments was given by dipping the fruits of each set comprising seven fruits in the treatment solution for half an hour. Dried tomatoes will be stored in open tray and polythene bags. Samples will be stored under ambient and

refrigerated conditions cooling till the edible state. Enzymes will be extracted from fresh samples at weekly intervals and enzymes extracts will be analyzed for the activity of polygalacturonase (PG), pectinmethylesterase (PME), cellulases (Ianattea et al 1999),β-D-galactosidase (Biswas 1985). Proteins from enzyme extracts will be estimated by Lowry et al (1951).

Observations to be recorded: Changes in the activity of Polygalacturonase (PG), pectinmethylesterase (PME), cellulases, β-D-galactosidase will be measured as a function of time.

Statistical Analysis: Data of standard error of three independent replicates will be evaluated. Analysis of variance (ANOVA) will be done.

Collaboration with other departments:

Help will be sought from :Department of Vegetable crops in

growing and maintaining the tomato crop during the period of study.

Department of Processing and Food Engineering, PAU ,Ludhiana in using the facilities during period of study.

THANK YOU