Citation
Ong, Lisa Gaik Ai
(2001)
Proteolytic Hydrolysis of Rice (Oryza Sativa Basmati).
Masters thesis, Universiti Putra Malaysia.
Abstract
Protein hydrolysate has been produced a long time ago. It is normally
use as animal feed or as a substitute for dietary patient and the protein used
is usually obtained from seafood. In this study, we are more interested in the
production of protein hydrolysate from rice. The rice that was used in this
study were obtained form BERNAS, Padi National Bhd, and it was pretreated
by first grinding it into fine powder, prior to analysis. The rice flour
was found to consist of 11.77% of moisture, 0.46% of ash and 5.79% of
crude protein. The commercial enzyme that was used for this study were
Flavourzyme, Alcalase (Novo Nordisk, Denmark) and Papain (Sigma, USA).
The enzyme activities and the stability of the enzymes were determined first
before they were used for the "production of protein hydrolysate. From the
enzyme decay experiment, three of the enzymes were found to be stable at
55°C. Flavourzyme was totally denatured at 100°C, but for Alcalase
(0.624%) and Papain (2.104%), some activity was still detected. Therefore,
Alcalase and Papain can be clarified as being thermostable. Papain was
used as comparison with Flavourzyme and Alcalase, to determine which
enzyme performed better in producing the hydrolysates. From the correlation between the free amino group, Flavourzyme ( R2 value is 0.9291) and
Alcalase ( R2 value is 0.6719) were found to have a better correlation and
they give a higher degree of hydrolysis compared with Papain ( R2 value is
0.5152). Therefore, Flavourzyme and Alcalase were selected for further
study. The protein hydrolysate that was produced from Flavourzyme and
Alcalase gave lower molecular weight subunits, which was 342 Da and
161.46 Da, respectively as detected by size exclusion high performance
liquid chromatography. The free amino acids that were present in the
hydrolysate were hydrolysed by the commercial enzymes and detected using
the PICO-Tag method. From the kinetic analysis, Alcalase was found to form
enzyme-substrate complex easier compared to Flavourzyme. However, the
production rate for Alcalase was lower compared with Flavourzyme, which
was 8.14 for Alcalase and 34.80 for Flavourzyme using Eadie-Hofstee equation.
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