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Chemical processes in peanut under thermal treatment

Miyagi, Atsushi, Ogaki, Yoshihiro
Journal of food measurement & characterization 2014 v.8 no.4 pp. 305-315
Maillard reaction, absorbance, consumer preferences, consumer satisfaction, free amino acids, frying, heat treatment, p-anisidine value, peanut oil, peanuts, peptides, protein hydrolysates, sucrose, wavelengths
Raw peanuts are processed to satisfy consumer preference; therefore, it is important to research their nutritive and physiological qualities during processing. In the present study, the changes in the peanuts properties have been investigated during frying period (2, 4, 6, 9, 12, and 15 min) at 150 °C. The amino acid content of hydrolyzed proteins, except for basic amino acid content, and the fatty-acid composition did not change during frying. After 15 min frying, sucrose content was reduced by 25 %, free amino acid content was reduced by 89 %, and basic amino acid content of hydrolyzed proteins was reduced by 12 %, due to the Maillard reaction and caramelization. In the peanut oil, the characteristic spectra in the visible range (absorbance decreased with an increase in the wavelength without any peaks) and increase in the p-anisidine value (aldehyde index) implied that a Maillard-like reaction may have occurred during frying. The nutritive function and/or physiological function based on fatty-acid composition and amino-acid composition consisting of proteins and peptides were scarcely affected during frying.