MSc

ABSTRACT
The present study entitled ―Postharvest quality management of papaya (Carica
papaya L.) cv. Red Lady‖ was conducted at the Department of Post Harvest
Technology, College of Agriculture, Vellayani, Thiruvananthapuram during the year
2018-2020. The objective of the experiment was to standardize postharvest treatments
for delayed ripening and to extend the shelf life of papaya cv. Red Lady with
minimum nutritional loss through postharvest handling practices.
Papaya fruits (cv. Red Lady) of uniform size, shape and maturity at colour
break stage were procured from the field of progressive farmers of Farmer Producer
Organisation, at Pallichal, Thiruvananthapuram. Harvested fruits were sanitized
(ozonisaton 2 ppm) and subjected to hot water treatment (500C for 20 minutes)
followed by postharvest dipping of fruits for 5 minutes using different treatments viz.,
Naphthalene Acetic Acid (NAA 250 ppm), Edible coating (Papaya Leaf Extract Aloe
Gel), Gibberellic Acid (GA3 100 ppm), Calcium chloride (CaCl2 2%), Salicylic Acid
(SA 2 mM), hot water treatment alone and fruits without any postharvest treatment as
absolute control. Treated fruits, after removal of surface moisture, were stored in
corrugated fibre board boxes at room temperature (30±2 ⁰C, RH 80-85%) till the end
of shelf life.
Superiority of postharvest treatments on papaya cv. Red Lady was assessed
based on physiological, biochemical, physical, and sensory attributes during storage at
an interval of 3 days. Papaya fruits treated with Salicylic Acid (2 mM) recorded the
lowest percentage of physiological loss in weight (6.55%), and respiration rate (74.99
mL CO2 kg-1 h-1) after 9th day of storage where as fruits without any postharvest
treatment recorded a weight loss of 16.65% with a respiration rate of 101.92 mL CO2
kg-1 h-1. Fruits with salicylic acid treatment recorded 8.72% total sugars, 6.39%
reducing sugars, 7.66 ˚Brix of total soluble solids with a carotenoid content of 2.09
mg 100g-1, and antioxidant activity of 48.35% after 9 days of storage which increased
with the storage period and the values were significantly lower than the untreated
fruits indicating the delayed ripening of treated fruits. Red Lady papaya fruits without
any postharvest treatment (control) recorded the lowest storage life of 7.38 days due
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to high rate of physiological, biochemical and physical changes which indicated faster
ripening and senescence.
The treatment of fruits with salicylic acid (SA) recorded the lowest respiration
rate of 95.63 mL CO2 kg-1 h-1 and physiological loss in weight (13.10%) after 14 days
of storage at room temperature with the highest fruit firmness (19.89 N) and 8.26%
reducing sugar, 12.73% total sugar, 11.52 ˚Brix of total soluble solids, 0.14%
titratable acidity, 2.55 mg 100g-1 of carotenoid content, and 64.53% of antioxidant
activity. The salicylic acid treatment recorded the highest shelf life of 14.56 days with
acceptable sensory parameters where as fruits without any treatment (control)
recorded a shelf life of 7.38 days.
Papaya fruits cv. Red Lady, harvested at colour break stage were sanitized
using ozonation (2 ppm) and subjected to hot water treatment (50 ˚C for 20 minutes)
followed by dipping for 5 minutes in postharvest treatment with salicylic acid at 2
mM was standardised as the best postharvest treatment for delayed ripening which
recorded the longest shelf life of 14.56 days at room temperature as compared to 7.38
days for fruits without any postharvest treatment.