MSc

The study entitled “Postharvest handling studies for extending shelf life of
rambutan (Nephelium lappaceum L.)” was conducted in the Department of Post
Harvest Technology, College of Agriculture, Vellayani, during 2015-17 with the
objective to extend the shelf life of rambutan with minimum nutritional loss through
postharvest handling practices.
Good quality rambutan fruits of uniform size and maturity with red skin colour,
collected from the homesteads of Thiruvananthapuram and Pathanamthitta districts
were used for the study. The harvested fruits dipped in 1% wax formulations viz.
KAU wax (bee wax), palm wax (carnauba wax) and paraffin wax were air dried and
stored under room temperature (30±2oC; RH 80-85%) for standardizing the best wax
formulation. Fruits coated with 1% paraffin wax had the lowest physiological loss in
weight (PLW) (18.36%), retained highest total soluble solids (TSS) (18.46 oB),
acidity (0.40%), vitamin C (22.05 mg/ 100g), total sugar (16.78%), reducing sugar
(5.33%) and antioxidant activity (66.60%) with lowest browning score (3.43) and
superior in general appearance, taste and flavour with minimum pulp browning at the
end of shelf life. Hence 1% paraffin wax was selected for further pre-treatment
studies.
Harvested rambutan fruits subjected to various pre-treatments viz. 1% paraffin
wax, sulphitation (350 ppm) and ozonization (2 ppm) were stored at room
temperature. Ozonization at 2 ppm was adjudged as the best pre-treatment as it
recorded the lowest PLW (20.24%), highest TSS (18.70 oB), acidity (0.51%), vitamin
C (22.20 mg/ 100g), total sugar (15.58%), reducing sugar (5.74%), non reducing
sugar (9.84%) and antioxidant activity (70.64%). The lowest mean score (4.10) for
browning and highest for general appearance (4.83), taste, flavour and reduced pulp
browning were also observed in fruits pre-treated with ozonization (2 ppm) and hence
selected for pre-packaging and storage studies.
Rambutan fruits subjected to 2 ppm ozonization for 5 minutes were pre-packaged
in different packaging materials viz. ventilated low density polyethylene (LDPE),
ventilated polypropylene (PP), polystyrene tray with cling film wrap and shrink wrap.
The pre-packaged fruits were stored at room temperature (30±2 oC; RH 80-85%) and
refrigerated condition (10±2 oC; RH 90-95%) till the end of shelf life. Pre-packaging
of pre-treated rambutan in ventilated PP (100 guage) had discerned lowest PLW
(3.23%), highest vitamin C (21.43 mg/ 100g), total sugar (15.70%) and antioxidant
activity (66.34%) whereas TSS, pH, acidity, reducing and non reducing sugars were
not affected by pre-packaging treatments after 8 days of storage at room temperature.
Better physical quality with the lowest score for browning (2.86) and highest for
general appearance (6.90), taste, flavour and least pulp browning were also perceived
for fruits in ventilated PP (100 guage) stored under room temperature.
Under refrigerated storage, ventilated PP was ideal as it registered the lowest
PLW (3.38%) and pH (3.90) with highest acidity (0.44%), vitamin C (22.27 mg/
100g), total sugar (15.45%) and antioxidant activity (64.23%) after 14 days of
storage. Excellent physical quality with lowest score for browning (2.90) and the
highest for general appearance (6.40), internal fruit quality viz. taste, flavour and
lowest pulp browning were also noticed for fruits in ventilated PP after 14 days of
storage. Rambutan fruits without any postharvest treatments had limited shelf life of
only 3 days with diminished nutritional and organoleptic qualities.
Ozonization of harvested rambutan fruits at 2 ppm for 5 minutes and prepackaging
in ventilated polypropylene (100 guage) could extend the shelf life of
fruits up to fourteen days when stored under refrigerated condition and eight days
under room temperature storage with minimum nutritional loss.