MSc

The study entitled Standardisation of postharvest treatments to extend the shelf
life of rambutan (Nephelium lappaceum L.) was conducted in the Department of Post
Harvest Technology, College of Agriculture, Vellayani during 2019-21 with the
objective to reduce spintern browning and shelf life extension of rambutan through
standardisation of postharvest treatments.
Rambutan fruits of medium size harvested at commercial maturity, as
determined by pericarp colour (redness) were selected for the study. Rambutan fruits
after cleaning and sanitization (ozonation 2 ppm), were subjected to postharvest
treatments viz., edible coating with aloe gel (10, 25, 50%), chitosan (0.5, 1, 2%) and
oxalic acid (5, 7.5 and 10%) as dipping for 5 minutes. The pre-treated rambutan fruits
after air drying to remove excessive surface moisture were stored in CFB boxes at room
temperature. Physiological loss in weight, browning score, general appearance (visual
parameters) and internal fruit quality were analysed daily till the end of shelf life and
biochemical parameters were analysed initially and at the end of shelf life.
Physiological Loss in weight increased during the storage period and after two
days of storage oxalic acid treated fruits recorded the highest PLW (16.74%) with the
highest browning score and were discarded due to spoilage. After fourth day of storage,
the treatment with 50% aloe gel recorded the lowest PLW of 18.19%. Acidity (0.40%),
moisture content (79.05%) of fruits decreased during storage and 50% aloe gel coated
fruits recorded the highest TSS value of 17.98⁰ Brix and lowest value of 15.81⁰Brix was
recorded for the fruits treated with 10% oxalic acid. The highest retention of total sugar
(20.75%), reducing sugar (3.14%), vitamin C (22.69 mg 100g-1
) and antioxidant
activity (68.85%) was recorded for 50% aloe gel treated fruits at the end of shelf life.
Based on the physiological, biochemical and sensory parameters, the best
treatment from each section of chemicals selected for storage studies were 50 % aloe
gel, 0.5% chitosan and 5% oxalic acid. Pre-treated rambutan fruits packaged in
ventilated polypropylene were stored in CFB boxes under refrigerated condition of
12±1⁰ C. The fruits treated with aloe gel 50% recorded the lowest PLW of 9.33 %, and
the highest TSS (16.96⁰ Brix), acidity (0.30 %), moisture content (80.08%), total sugar
(17.67%), reducing sugar (2.84%), vitamin C (19.42 mg 100 g-1
) followed by the
chitosan (0.5%). The postharvest treatments did not show any effect on easiness of
peeling and easiness of separation of pulp from seed. The lowest browning score and
higher score for organoleptic qualities as well as appearance was recorded for the aloe
gel (50%) treated fruits.
Harvested rambutan fruits treated with 50 % aloe gel and pre-packaged in ventilated
polypropylene, stored in CFB boxes under refrigerated storage of 12±1⁰C could extend
the shelf life up to 16 days with minimum spintern browning and nutritional loss.