Deamination of Lysine in Soysauce Protein by reaction with active carbonyl Compounds Produced by Maillard Reaction

Dedin F Rosida, Dedi ferdiaz, Anton Apriyantono, dan Nuri andarwulan

Abstract

The development of brown colour during the thermal treatment of many foods, such as coffee, roasted beef, soysauce or evaporated milk, mainly originates from interactions between reducing carbohydrates and amino acids, know as the maillard reaction. It is commonly known at present that one of the causes of changes in colour, aroma, flavour and nutritional value of   food products. The maillard reaction involves condensation, dehydration and polymerization. As a result of this complex reaction, a variety of by products, intermediates and brown pigments.

An amino carbonyl reaction in soysauce yielded a rapid brown coloration. An apparent decrease in the free amino group, determined by the TNBS method, was observed to be associated  in parallel with the brown pigment formation by UV-Vis spectrum, amino acids by HPLC, protein content by lowry method, pH and reducing  sugar.

“Moromi”, moromi with heating and soysauce were examined to effect Maillard reaction. The positive effect of sugar on browning suggested that lysine content decreased from 0.97% to 0.89% and 0.69%, free amino group decreased from 3.16 mg/ml to 2.27 mg/ml and 2.18 mg/ml and their UV-Vis spectrum in 381nm – 400 nm. These results indicate that ε-amino group of lysine in protein could easily be deaminated by the amino-carbonyl reaction.

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