Production of concentrated cheese aroma from enzyme modified cheese by using supercritical carbon dioxide extraction method

The aim of this study was to obtain concentrated cheese flavor from Enzyme modified cheese (EMC) by using the Supercritical carbon dioxide extraction (SC-CO2) method. For this purpose, cheese flavor extraction was performed from classical Ezine cheese and EMC Ezine cheese by SC-CO2 method. In this study, it was aimed to determine the procedure for the use of SC-CO2 to obtain cheese flavor. For this purpose, the extraction parameters used in the study as follow; temperature of 35 °C, 45 °C, and 55 °C; pressure of 100 bar, 200 bar, and 300 bar; co-solvent concentration of 0%, 4%, and 8%. A total of 54 extractions were made for two types of cheeses in 27 different combinations for 3 levels of 3 parameters. The extraction time was 90 min and the CO2 flow rate was 5 g/min. According to the dry matter results of the pellets, it is observed that the dry matter decreased to 20% in ethanol extractions and increased to 8% in the non-ethanolic samples. The highest percentage of fat changes of pellets was 80.40% in CCC sample and 34% in YZX pellet. The pH value decreased from 4.90 to 4.24 for the BCB sample at Ezine cheese, and decreased from 4,90 to 4,25 for the ZXY sample at EMC Ezine cheese. The titration acidity value in the pellets did not show a significant difference. For Ezine cheese, a relative increase in protein value was observed due to the decrease in the amount of fat in the pellets in terms of % protein. In EMP Ezine cheese, the change in % protein value was limited. It was determined that there was an increase of total free amino acid concentration in the pellets compared to the cheese samples. Free fatty acid analysis was performed on the extracts by a titrimetric method. The highest acid number for Ezine cheese extracts was 2603.4 mg KOH/kg extract, and the highest acid number for EMC Ezine cheese was 6287.1 mg KOH/kg extract obtained from the extraction at 55 °C, 100 bar, and 0 % ethanol concentration. The amount of free fatty acids in the extracts obtained from EMC cheese is approximately 2.5 times higher than in Ezine cheese extracts. Volatile compound analysis (GC-MS-SPME) was carried out to observe the aroma composition of extracts and pellets and the effect of changes in extraction conditions on flavour composition. Principal component analysis (PCA) was used to evaluate the volatile compound analysis. According to the results, the extracts obtained from Ezine cheese clearly differ from EMP Ezine cheese extracts based on volatile compounds. The distinction for Ezine cheese extracts was based on aldehydes (2-nonenal, 2-octenal, 2-nonenal) and fatty acid esters (butanoic acid, pentyl ester, propanoic acid, 2-hydroxy, ethyl ester). For EMP cheese, it was based on fatty acids (heptanoic acid, octanoic acid, butanoic acid). According to the results obtained in the thermal analysis of the extracts with DSC, it was determined that the amount of triglycerides in the Ezine cheese extracts increased due to the increase in pressure. At 55 °C, 300 bar, and 0% ethanol extract (CCA), the Tonset temperature at which crystallization started increased to 4.38 °C. In the CCA sample, it is observed that the final melting temperature rises to 24.06 °C at its maximum point due to the increased amount of triglycerides. On the other hand, the Tonset temperature at which crystallization started at 35 °C, 300 bar, and 0% ethanol extract of EMC cheese (XZX) increased to -6.65 °C. It is observed that at 55 °C, 200 bar, and 0% ethanol extract (ZYX), the final melting temperature rises to -0.60 °C at its maximum point. It is observed that the crystallization and melting temperatures were lower due to the low amount of triglyceride in the extracts of EMC Ezine cheese. According to the results of the sensory analysis of the extracts, Ezine cheese extracts were defined as fruity, sharp, and oxidized. Extracts of EMC Ezine cheese were defined as fruity, sharp, buttery, oxidized, and animal odour. It is seen that the aroma intensity of the extracts of EMP Ezine cheese is higher than the raw material. Considering all the results, it has been determined that the SC-CO2 method can be successful in obtaining concentrated cheese flavour.