MSc

The study on “Process standardisation and varietal screening for osmodehydration
in mango (Mangifera indica.L)” was undertaken at the Department of Processing
Technology, College of Horticulture, Vellanikkara during 2011-13. The main objectives
were to standardise the process variables for osmodehydration in mango and to evaluate
varietal suitability and storage stability of the product.
The temperature and concentration of osmotic solution, duration of immersion
and fruit to solution ratio for osmodehydration in mango were standardised. Local mango
variety „Muvandan‟ was selected for the process standardisation. Sugar was used as the
osmotic agent. The temperatures of the osmotic solution tried were ambient, 20°C, 30°C
and 40°C. Concentration of sugar solution and duration of immersion were 50°Brix and 6
hours respectively. The highest values for dry weight (56.83 g), weight loss (17.38%),
water loss (24.97%), solid gain (7.59%) and TSS (40.6°Brix) were recorded when
osmodehydration was carried out at 40°C. Highest scores for sensory attributes were also
recorded for this treatment.
The effect of four concentrations of sugar solution (40, 50, 60 and 70◦Brix) and
five durations of immersion (4, 6, 8, 10 and 12 hours) on mass transfer and sensory
attributes were studied. T20 (immersion in 70°Brix sugar solution for12 hours) registered
highest values for weight loss (17.84%), water loss (28.56%), solid gain (10.72%), TSS
(68.5°Brix) and sensory attributes.
The fruit to solution ratio was standardised by comparing different ratios of fruit
sample and osmotic solution. Fruit to solution ratio of 1:2 was found to be the most ideal
for osmodehydration with highest dry weight (64.97g), weight loss (19.91%), water loss
(31.02%) and solid gain per cent (11.11%). The maximum TSS (63.1°Brix) was also
recorded for this treatment. Increase in fruit to solution ratio beyond this level resulted in
decrease in dry weight, weight loss, solid gain per cent and TSS. Maximum scores for all
of the sensory attributes was recorded in 1:2 fruit to solution ratio.
Eight varieties of mango viz. Priyur, Muvandan, Neelum, Bangalora, Bennet
Alphonso, Ratna, Banganapalli and Vellaikolumban were evaluated for their feasibility for
osmodehydration. Osmodehydrated mango was prepared by the method standardised in
the first experiment. Among the varieties of mango evaluated, Ratna was found to be the
most suitable for osmodehydration. Highest values for TSS (73.4°Brix), β-carotene (5463
μg/100g) and sensory attributes were recorded for the osmodehydrated product prepared
from this variety.
The effect of different packaging materials (200 gauge polyethylene cover,
metalized polyester cover, PE aluminium foil laminated cover and rigid plastic container)
and methods of packaging (vacuum packaging in PE cover, nitrogen flushing in PE cover)
on biochemical constituents, sensory attributes and microbial count during storage was
studied. Significant variation was not observed in chemical constituents during storage.
Highest values for all biochemical constituents except β-carotene was observed in samples
packaged in PE aluminium foil laminated cover. Vacuum packaged samples and
aluminium foil laminated packed samples recorded the lowest microbial load. Highest
population of microorganisms was recorded in 200 gauge polyethylene cover throughout
the period of storage. The mean ranks for appearance, colour, taste, odour and overall