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PIGMENTS AND ANTIOXIDANTS IN RELATION TO RIPENING OF TOMATO (Solanum lycopersicum L.) FRUITS

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Title PIGMENTS AND ANTIOXIDANTS IN RELATION TO RIPENING OF TOMATO (Solanum lycopersicum L.) FRUITS
 
Creator LAXMI SHARMA
 
Contributor Vijay Paul
 
Subject Antioxidants, chlorophylls, glutathione, pigments, ripening, storage tomato, tomato fruit, varietal variability
 
Description T-8461
Tomato (Solanum lycopersicum L.) fruit is one of the most important vegetable world
over. This fruit is considered as a model system of climacteric fruit ripening but at the same
time due to its climacteric nature itself, the postharvest losses are huge (up to 25 to 40 % or
even more). Being a climacteric fruit, ethylene (a natural plant growth regulator) plays major
role in the ripening of tomato. But, besides the ethylene, free radicals also influence the
ripening and therefore they got the especial attention in the literature. Keeping in view the
importance, regulatory role and antioxidative properties of different pigments, vitamin C,
phenolics, flavonoids and glutathione this study was taken up. The study looked into the
changes in the levels of above said bioactive compounds during fruit ripening and their role in
governing the rate of ripening. Initially, tomato fruits of 10 commercial varieties [at green
mature (GM) stage of harvest)] were evaluated for their ripening behaviour during storage (in
dark at temperature of 25±1.0 0
C and RH of 45±5.0 %). Based on ripening index (RI %),
varieties were grouped into three categories i.e., 1. Fast ripening type (Pusa Ruby and Pusa
Sadabahar), 2. Slow ripening type (Pusa Gaurav and Roma) and 3. Intermediate ripening type
(Pusa Sheetal, Pusa Uphar, Pusa Early Dwarf, Pusa Selection-8, Pusa-120 and Pusa Rohini).
For analysis of bioactive compounds, varieties with fast and slow ripening types were used.
Different pigments and non-enzymatic antioxidants were estimated in the pericarp of tomato
fruits at immature and GM stages of plant-harvested fruits and with the progress of ripening
of fruits (harvested at GM stage) during storage. With the transition of fruits from immature
to GM stage, pigments showed no change but, changes in the levels of antioxidants indicated
(i). Increase in the level of oxidative stress and (ii). Tendency of tomato fruit to acclimatise
against this change by enhancing the levels of antioxidants. With the progress of ripening of
stored fruits, on the other hand, bioactive compounds showed decreasing (chlorophyll a,
chlorophyll b and total chlorophylls, oxidized glutathione and ratio of oxidized to reduced
glutathione), increasing (total carotenoids and lycopene, vitamin C, total soluble phenols, total
flavonoids, total glutathione, reduced glutathione, glutathione redox ratio and reduced to
oxidized glutathione) or static (chlorophyll a/b and total chlorophylls/total carotenoids)
trends. Correlation studies (between the levels of pigments and antioxidants present at GM
stage and the rate of ripening) pointed out the need for better protection of tomato fruits from
oxidative stress right at the GM stage because this capacity was found to provide the tomato
fruit an attribute of delayed ripening during storage. In this context, glutathione appeared to
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play an important role because enhancement and reduction in the levels of oxidized
glutathione and reduced glutathione respectively were recorded during the transition of
tomato fruits from immature stage to GM stage. The study in totality pointed out that the
higher levels of total chlorophylls, oxidized glutathione and lower levels of vitamin C, total
flavonoids and total soluble phenols in the pericarp of tomato fruit at GM stage facilitate the
delay in the ripening of tomato fruits. The obtained results are being discussed in view of 1.
Triggering of senescence/ripening process due to decrease in the level of chlorophylls below a
certain threshold level and 2. Increase in the level of oxidative stress at the onset and with the
progress of ripening and tendency of tomato fruit to acclimatise itself against this change by
enhancing the levels of antioxidants.
 
Date 2016-11-23T09:28:25Z
2016-11-23T09:28:25Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/87160
 
Format application/pdf
 
Publisher IARI, DIVISION OF PLANT PHYSIOLOGY