Gas chromatography-mass spectrometry characterization of the aroma of Ossetian cheeses

The aim of the study was the qualitative and quantitative determination of volatile aroma compounds and their formation pathways in brine Ossetian cheeses. Volatile components of cheeses were isolated by steam distillation and extraction with dichloromethane, with their subsequent determination and quantification by gas chromatography-mass spectrometry. The results of the analysis are presented according to the structural classes of the main chemical components and the corresponding microbial metabolic processes. Four processes were found to be the main contributors to flavor formation: lipolysis, proteolysis, glycolysis, and a number of oxidative enzymatic transformations. Lipolysis of the fatty fraction of cheeses is a source of formation of volatile carboxylic acids and their esters. Proteolysis of the casein fraction yields branched alcohols, aldehydes, and a number of aromatic and heteroaromatic compounds. Glycolysis of the carbohydrate fraction is a source of ethanol formation, which is the main cause of the dominance of ethyl esters in the ester fraction. Redox enzymatic transformations mainly determine the biosynthesis of unbranched aldehydes, ketones and lactones. A clear distinction between retail and homemade cheeses was observed, due to the different technological approaches to the cheese preparation. The structuralchemical and quantitative evolution of the volatile composition of the studied cheese samples during ripening is tentatively shown. From the authors' point of view, the aromatic composition of the Tib cheese sort is the most consistent with the Ossetian cheese standard. This study represents the first gas chromatographic study of Ossetian cheeses and aims to create objective criteria for controlling technological processes and product quality during production and storage in the food industry.