Detection of volatile organic compounds in artisanal raw sheep's milk cheeses attributable to lactic acid bacteria

RUIZ M. JULIA; AVILA, SANDRA; CARDADOR, MARIA JOSÉ; ARCE, LOURDES; FRIZZO, LAUREANO; JORDANO, RAFAEL; MEDINA CANALEJO, LUIS

Madrid

Congreso; VI Congreso de Internacional de Calidad y Seguridad Alimentaria; 2022

ACOFESAL Asociación de Consultores y Formadores de España en Seguridad Alimentaria

INTRODUCTIONThe production of artisan cheeses made with raw milk worldwide has been increasing, due to consumers are interest for 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 and odour, of many traditional foods. Gas chromatography together with ion mobility spectrometry (GC-IMS) is a simple and 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. MATERIAL AND METHODSGC-IMS analysis conditionsThe analyses of the VOC profiles were made on a HS-GC-IMS instrument (FlavourSpec®, G.A.S. Gesellschaft für analytische Sensorsysteme mbH. Dortmund, Germany). Working conditions were used according to Gallegos et al. (2017, Food Chemistry) with modifications.Identification of VOCs Chemical standards were used to unequivocally confirm the presence of volatile compounds in the LAB and cheese samples. The identification of volatile metabolites was carried out by analysis of individual standards at 1 or 2 mg/L by GC-IMS and confirmed by GC-IMS Library version 1.01 (G.A.S. Gesellschaft für analytische Sensorsysteme mbH. Dortmund, Germany). The different analytical grade VOCs (Sigma-Aldrich, St. Louis, MO) were chosen according to studies based on the detection of VOCs in LAB samples and in cheese samples made from raw sheep's milk. SamplingSix samples of cheese made from raw sheep's milk were analyzed. Three samples corresponded to creamy natural cheese called "Torta del Casar", from Extremadura, Spain. Other three samples were extracted from a matured cheese from Navarra, Spain. In both cheeses, the samples were taken from different parts (center, inner and surface areas).CONCLUSIONVOCs detected in cheeses were Ethyl hexanoate, ethyl propanoate, propyl butanoate, 2-methyl butanal, hexanal, 2-methyl propanal, 2-butanol, 2-methyl propanol and pentanol were tentatively detected in cheeses. None of these compounds were detected only in LAB. However, 2-heptanone, 2-butanone, 2-pentanone, 3-hydroxybutan-2-one were tentatively detected in both in LAB strains and cheeses were detected. These results indicate 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.