Effect of Selected Pretreatments on Impregnation of Curcuminoids and Their Influence on Physico-chemical Properties of Raw Banana Slices.

The effect of pretreatments, namely, blanching,
ultrasound, vacuum and their combinations on curcuminoid
impregnation in raw banana slices, was studied in conjunction
with treatments in purewater aswell as in 10%NaCl solution.
The treatments such as ultrasound, vacuum and combination
of vacuum and blanching with ultrasound resulted in higher
curcuminoid infusion compared to control for both pure water
and 10 % NaCl osmotic treatments. The blanching treatment
resulted in lower infusion of curcuminoids as compared to that
of control due to the gelatinisation of starch present in banana.
Further, the increase in surrounding solution concentration
from pure water to 10 % NaCl resulted in enhanced
curcuminoid infusion (e.g. from 85 to 95 mg/100 g for combined
vacuum and sonication treatment). However, the direction
of the mass transfer of water as well as solid was reversed.
The samples subjected to combined vacuum and sonication
treatment resulted in lowest compressive force, highest infusion
of curcuminoids and highest total colour difference compared
to other treatments. Besides, the dehydration of such
product also resulted in the highest retention of curcuminoids
compared to the individual treatments. The present study
concluded that osmotic treatment can be a feasible technology
for the infusion of functional ingredients into foods without
altering its matrix. The extent of infusion can be significantly
enhanced by the application of combined treatment such as
vacuum and ultrasound.