Abstract:
The processing of spices requires additional care because they are sensitive to
atmospheric parameters like temperature and light. The exposure to temperature
during any of the processing stage may lead to their quality deterioration in terms of
colour, volatile oil, volatile oil constituents, oleoresin content etc. The grinding of
spices at cryogenic temperatures helps in retaining the heat sensitive components in
the spices. This study envisages on the cryogenic grinding of dried ginger in order to
optimize the grinding conditions, considering the important quality characteristics and
compared the cryoground powder with the conventionally ground ginger. The
physical properties which affect the grinding process directly or indirectly were also
determined. The experiments on cryogenic grinding have been carried out for
different feed rates and grinding temperature and the best combination was
determined in terms of product quality as well as grinding characteristics. The
optimized feed rate and temperature were 35 kg/h and -130±5 o C. The lower
temperature in the grinding zone solidifies the moisture and oil components in the raw
material and makes it brittle, which facilitates the grinding easy and faster thus leads
to less energy consumption. The extreme cold condition prevents the volatile oil loss
and lead to their higher retention. The comparison of cryoground powder with the
powder obtained by conventional method has shown that cryogenic grinding
prevented the essential oil and oleoresin loss of ginger considerably and retained its
constituents. The colour of cryoground ginger powder was superior and the particle
size was finer. The time of grinding and specific energy consumption was found
lower in cryogenic grinding. The packaging studies on ginger powder showed that
laminated aluminum foil is suitable for long term storage.
