Optimization of the ultrasound-assisted extraction of tryptophan and its derivatives from rice ( Oryza sativa ) grains through a response surface methodology
Penulis/Author
Dr. Widiastuti Setyaningsih, S.T.P., M.Sc. (1); Irfan Estiono Saputro (2); Miguel Palma (3); Carmelo G Barroso (4)
Tanggal/Date
2017
Kata Kunci/Keyword
Abstrak/Abstract
An analytical ultrasound-assisted extraction (UAE) technique has been optimized and validated for the
extraction of tryptophan and its derivatives from rice grains. A Box
e
Behnken design in conjunction with
a response surface methodology based on six factors and three levels was used to evaluate the effects of
the studied factors prior to optimizing the UAE conditions. The signi
fi
cant (
p
<
0.05) response surface
models with high coef
fi
cients of determination were
fi
tted to the experimental data. The most signi
fi
cant
(
p
<
0.0001) effect is the solvent-to-sample ratio while quadratic effects caused by temperature and
solvent-to-sample ratio were of moderate importance (
p
<
0.05). The optimal UAE conditions were as
follows: extraction time of 5 min, ultrasound amplitude of 30%, cycle of 0.7 s
1
, extraction temperature of
30
C, 8% methanol in water as the extraction solvent at pH 3 and a solvent/solid ratio 5:1. The method
validation ensured that appropriate values were obtained for the LOD, LOQ, precision and recovery.
Furthermore, the method was successfully applied to the analysis of a number of rice samples of different
varieties. It was demonstrated that this particular UAE method is an interesting tool for the determi-
nation of tryptophan and tryptophan derivatives in rice grain samples.
