Chemical and microbial properties of shidal, a traditional fermented fish of Northeast India.

Like Southeast Asian countries fermented fish is a
well known strategy of food preservation in the Northeast
region of India. Shidals are mostly preferred salt-free
fermented fish product amongst all. Chemical and microbial
composition, antioxidative potential, fatty acid profile and
proteins profile in gel electrophoresis of shidals were studied.
pH and total titratable acidity (TTA) have been found as
5.86 ± 0.11, 0.115 ± 0.01 and 6.62 ± 0.07, 0.092 ± 0.01 in
punti and phasa shidal respectively. DPPH· radical scavenging
activity of punti and phasa shidal was determined as
80.15 ± 5.67 and 68.30 ± 3.22 respectively. Presence of
eicosapentaenoic, docosahexaenoic, arachidonic, linolenic
and linoleic acid indicate the nutritional significance of shidal.
However, the result showed that punti shidal was rich in
omega-3 but poor in omega-6 fatty acid, whereas, reverse
was observed in respect of phasa shidal. Poly acrylamide
gel electrophoretic study of protein revealed disappearance
of myosin head chain (MHC) in the dry puntius fish (raw
material of shidal). Proteins or peptides with low molecular
weight between 45 and 29 kDa and between 45 and 66 kDa
were noticed in both the shidals and indicative of intensive
protein degradation during fermentation. Therefore,
fermented fish product, shidal could be used as a potential
source of nutrients and natural antioxidants.