Effects of Malondialdehyde Modification on the in Vitro Digestibility of Soy Protein Isolate

Soy protein isolate (SPI) was modified by lipid peroxidation product malondialdehyde (MDA), and the in vitro digestibility of modified SPI was investigated. Results indicated that incubation with increasing MDA concentration resulted in significant carbonyl group generation and loss of free amino gr...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2013-12, Vol.61 (49), p.12139-12145
Main Authors: Chen, Nannan, Zhao, Qiangzhong, Sun, Weizheng, Zhao, Mouming
Format: Article
Language:English
Subjects:
amino acid composition
Amino Acids - analysis
Amino Acids - metabolism
beta-conglycinin
Biological and medical sciences
differential scanning calorimetry
Digestion
electrophoresis
enthalpy
fluorescence
Fundamental and applied biological sciences. Psychology
Glycine max - chemistry
Glycine max - metabolism
Humans
in vitro digestibility
in vitro digestion
lipid peroxidation
malondialdehyde
Malondialdehyde - chemistry
Models, Biological
Nutritive Value
pancreatin
pepsin
polymers
schiff bases
Solubility
soy protein isolate
Soybean Proteins - chemistry
thermal stability
tryptophan
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Summary:Soy protein isolate (SPI) was modified by lipid peroxidation product malondialdehyde (MDA), and the in vitro digestibility of modified SPI was investigated. Results indicated that incubation with increasing MDA concentration resulted in significant carbonyl group generation and loss of free amino groups of SPI. Fluorescence loss of natural tryptophan and formation of Schiff base were observed. Noncovalent interaction between molecules was enhanced and became the main force that led to the solubility reduction of MDA-modified SPI. Differential scanning calorimetry (DSC) indicated that SPI had higher thermal stability and lower total calorimetric enthalpy after MDA pretreatment. Electrophoresis showed that β-conglycinin was more sensitive to MDA modification. In vitro digestion indicated that MDA could induce non-disulfide covalent polymer of SPI, which could not be digested by pepsin and pancreatin. β subunits of β-conglycinin became more resistant to digestion with increasing MDA concentration. Evaluation of the free amino acid profile in the digests indicated that MDA-modified SPI had deteriorating nutritive quality.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf404099y