CONICET | Buscador de Institutos y Recursos Humanos

The production of artisan cheeses made with raw milk worldwide has been increasing, due to consumers interest in traditional, fresh, low processing and healthy products. Native lactic acid bacteria (LAB) convert the chemical composition of raw materials during fermentation. LAB improving the nutritional value and are responsible of organoleptic characteristics, such as flavour odour, of many traditional foods. Gas chromatography together with ion mobility spectrometry (GC-IMS) is a sensitive analytical technique that provides information on volatile organic compounds (VOCs) responsible for the aroma in food.The objective was to determine if certain VOCs detected in artisan sheep´s raw milk cheeses are attributed to LAB using GC-IMS. Reference compounds (0.1 mg/L), LAB (L. paracasei, L. plantarum, L. lactis and L. mesenteroides) strains (1 mL) isolated from raw sheep´s milk cheeses: and cured and creamy natural cheese (1 g), both made with raw sheep´s milk, were analysed by GC-IMS FlavourSpec (G.A.S., Germany). Vials heated at 70°C for 5 min at 500 rpm. An aliquot (500 µL) was injected into headspace heated to 80°C and transferred to GC column at 40°C. The N2 flow for the sample was 5 mL/min and the drift flow was 250 mL/min. The drift tube temperature was 65°C, under an electric field of 400 V/cm. The ions arrived at the detector after 30 min. GC-IMS data analysis was performed with VOCal software (G.A.S., Germany).Twenty-seven VOCs (aldehydes, alcohols, esters, ketones and acid) were tentatively identified in the headspace of the cheese samples. No compounds were detected only in LAB. However, 2-heptanone, 2-butanone, 2-pentanone, 3-hydroxybutan-2-one, 2-butanol, 1-heptanol and 3-methyl butanol were tentatively detected in both LAB strains and cheeses. These results indicates that these aromatic compounds in cheeses could be attributed to the presence of LAB. This is essential for the selection of potentially useful strains for the food industry.