Effects of different pretreatments and proteases on recovery, umami taste compound contents and antioxidant potentials of Labeo rohita head protein hydrolysates.

Effects of the pretreatments namely heating,
microwave (MW), and ultrasound (US), followed by the
enzymatic hydrolysis using different proteases (flavourzyme,
neutrase, and protamex) on the protein recovery,
umami taste compound content, and antioxidant
activities of the Labeo rohita head (LRH) protein hydrolysate
was investigated. US and MW pretreatments
increased the protein recovery, MSG-like amino acid and
flavour 50-nucleotide contents, equivalent umami concentration
(EUC) and antioxidant activities of LRH protein
hydrolysates significantly (p\0.05). The type of enzyme
influenced the protein recovery and EUC significantly but
did not influence the flavour 50-nucleotide content of LRH
protein hydrolysate (p[0.05). The highest recovery yield
of LRH protein hydrolysate (69.75%) was obtained with
the MW pretreatment followed by the protamex hydrolysis,
while the highest EUC (41.82 g monosodium glutamate
(MSG)/kg) was yielded with the combination of the US
pretreatment and the flavourzyme hydrolysis. These results
indicate that US and MW pretreatments can help to
enhance the recovery yield, umami taste compound content
and antioxidant activities of the LRH protein hydrolysate.