ADAPTATION OF SIMPLE METHODS OF PROTEIN DETERMINATION FOR EXPRESS QUALITY CONTROL OF FOODS, INCLUDING ADAPTATION FOR FIELD AND HOME CONDITIONSстатьяИсследовательская статья
Аннотация:The following research was conducted with use of Uniplan (Picon, Russia), a portable microplate photometer, equipped with a special universal light filter with a light transmission range of 550-590 nm. A method of visual semi- quantitative protein content analysis is also developed. Two methods of protein determination were applied: biuret method based on determination of peptide bonds and Bradford method (Coomassie method), using Coomassie pigment for determination of globular non-glycosylated proteins. It is demonstrated that biuret method has some obstacles of application for food analysis due to high concentration of reducing sugars in various objects of analysis. Coomassie method has several advantages, such as low detection limit and absence of interaction with reducing components of the object. An acidic pH value of Coomassie-containing reagent, which is close to pH values of samples analyzed, is also an advantage because addition of the reagent has no significant influence on intrinsic spectra of these samples, which we need to consider during the analysis. Products chosen for research are: chicken egg white, 2 samples of apple juice from different manufacturers, fresh-squeezed apple juice, 4 samples of beer, 1 of kvass, 4 samples of bouillon concentrate from different manufacturers. The approaches proposed in the article are demonstrated to be suitable for rapid control of the authenticity and quality of food products.
