Abstract:
A protocol for vacuum impregnation of coconut chips was optimized across
various stages, including the optimization of impregnation and drying parameters,
along with a comprehensive storage study. The vacuum impregnation (VI) process
for coconut slices underwent optimization using a Box-Behnken design, examining
the impact of vacuum pressure (100-300 mbar), vacuum time (10-20 min), vacuum
relaxation time (5-15 min), and solution concentration (50-70OBrix) on various
parameters. The results indicated second-order kinetics for mass transfer, reaching
equilibrium after a vacuum time of 20 minutes. Optimized conditions were
determined as a vacuum level of 229.40 mbar, vacuum time of 12.205 minutes,
vacuum relaxation time of 11.975 minutes, and a solution concentration of
62.609OBrix. Key parameters like water loss (25.033%), solute gain (5.643%),
weight reduction (19.389%), water activity (0.720), pH (5.660), color change
(3.161), total soluble solids (51.120°Brix), ash content (0.825%), and total sugar
(9.255 mg/100g) were observed under these optimum VI conditions. The
subsequent drying process involved a comparison of various dryers (Infra-red,
vacuum, heat pump, and convective) and temperatures (60-800C), with the
optimized parameter being a vacuum dryer at 60OC, exhibiting the least drying time
of 2.5 hrs. The resulting vacuum-dried coconut chips demonstrated high quality,
with desirable characteristics such as moisture content (0.474%), water activity
(0.358), color change (8.48), texture (1.62N), fat content (53.2), protein (4.81), total
sugar (38.5%), fiber (27%), and ash content (1.56%). The VI-processed coconut
chips, developed under optimized conditions, were packed in laminated aluminum
pouches filled with nitrogen and subjected to storage studies. Unlike commercially
available coconut chips that developed a rancid taste after 135 days, the optimized
coconut chips retained acceptable quality attributes for up to 195 days. In summary,
the developed system and process not only reduced processing time but also proved
effective in maintaining quality and extending the shelf life of vacuum-impregnated
coconut chips.
