Changes in Cholesterol and Free Fatty Acid Content of Kars Gravyer Cheese (A Turkish Dairy Product Produced by the Traditional Method)
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─── Food Technology─── Changes in cholesterol and free fatty acid content of Kars Gravyer Cheese (A Turkish dairy product produced by the traditional method) Asya Çetinkaya1, Fatih Öz2 1 – Kafkas University, Kars, Turkey 2 – Ataturk University, Erzurum, Turkey Abstract Keywords: Introduction. This study was carried out to determine Gravyer changing in the ratio of free fatty acids and cholesterol depended Cheese on the maturation period of Kars Graiver cheese produced in the Ripening traditional way, and the affect of the duration of maturation on Fatty acid the fatty acids composition and cholesterol levels. Cholesterol Materials and methods. The fat content of the cheese samples was determined by Gerber's method. Flame Ionization Detector– Gas Chromatography (GC/FID) was used to determine the fatty acids composition and cholesterol content. Article history: Results and discussion. It was found the fat content of Kars Gravyer Cheese samples was between 27.0–38.50%. The Received cholesterol content in the cheese samples ranged from 45.70 to 19.08.2018 55.80 mg/100g during 90 days of maturation. In Kars Gravyer Received in Cheese samples, 16 saturated and unsaturated fatty acids were revised form identified. In Gravyer Cheese samples, the content of volatile 12.09.2018 fatty acids (Butyric acid and myristic acid ) increase up to 25th Accepted day (P <0.01) and decrease from 45th day to 90th day. While 28.09.2018 levels of free fatty acids (palmitic acid and linoleic acid) generally decrease to 25th day, they begin increasing again until Corresponding the end of the maturation period. In the 90 days period of storage author: of Kars Gravyer Cheese, palmitic, oleic, myristic and stearic Asya Çetinkaya acids were found to constitute 74.29% of the total free fatty E-mail: acids content. In the samples studied, the most abundant a_cetinkaya36@ saturated fatty acids were identified as palmitic and stearic hotmail.com acids. Oleic acid was found to be the most abundant unsaturated fatty acid. In cheese samples, the content of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) ranged 28.38–32.37% and 1.59–1.84%, respectively. In Kars Gravyer Cheese sample, the Atherogenicity (AI) index was defined as 2.57–3.04. Conclusion. Fatty acids are precursors of aroma compounds like short and medium chain free fatty acids, ethyl ketones, esters and thioesters, formed in cheese in a result of various biochemical processes. The detection of large amounts of fatty DOI: acids with short and medium chains in Gravyer Cheese samples 10.24263/2304- providing aroma, indicate that this cheese is flavorful cheese. 974X-2018-7-3-6 ─── Ukrainian Food Journal. 2018. Volume 7. Issue 3 ─── 409 ─── Food Technology ─── Introduction Today there are about 4000 different varieties of cheese in the world with different aroma and textural properties [1]. The most important factors affecting cheese quality are flavor and aroma of cheese, texture, and appearance. Unique characteristic properties of cheese are formed by biochemical reactions such as glycolysis, proteolysis, and lipolysis occurring during maturation. Free fatty acid (FFA), which emerges as a result of lipolysis reaction, is effective on the flavor and aroma of cheese. FFA is an important, volatile precursor of catabolic reactions, producing compounds that contribute to aroma [2]. The presence of short, medium and long-chain fatty acids is considered the most important indicator of cheese maturation after the compounds formed by glycolytic and proteolytic reactions [3]. The amount of free fatty acids in dairy products has potential effects not only on the taste and texture of dairy products but also on nutrition and health as antimicrobial agents. Determination of fatty acid profile of cheese is also important in terms of these negativities [4]. Cheese, which is an important source of fat in human nutrition, contains a high level of various fatty acids. From a nutritional point of view, different types of cheese contain a high level of digestible fat. Its digestibility is in the range of 88–94% [5]. However, cheese is usually presented with a negative nutritional image due to the relationship between saturated fatty acids (SFA), the main fatty acids of cheese, and cholesterol, leading to cardiovascular diseases. Although many researchers view SFA as one of the contributing factors in heart disease, there has been no direct link between cardiovascular disease and milk fat, or a real study indicating dairy products' role in heart disease [6]. Cheese is a rich source of some trans-fatty acids and short-chain fatty acids that can be considered as part of a healthy diet [7]. The World Health Organization and the American Heart association have advised that consumers limit their intake of saturated fatty acids and cholesterol to prevent coronary heart disease. The reduction of cholesterol level in dairy products will be an attractive alternative to satisfy consumer’s concerns and demands [8]. Gravyer cheese is one of the few European-style cheese that has economic value and is appreciated by consumers like domestic cheese varieties in Turkey [9]. Gravyer Cheese, one of the 18 varieties of cheese that is economically important in the world, is in the same group as Emmental (Switzerland), Gruyere (France), Fontina (Italy), Samso (Denmark), Gouda and Edam (Netherlands) [10]. Approximately 90% (544 tons) of the production of Gravyer, which is mostly produced in the Eastern Anatolia Region especially in Kars Province and its surroundings, is carried out in Kars [11]. The industrial production of Kars Grayver Cheese is quite low. Production is mostly carried out by traditional methods in dairy farms [12]. Gravyer Cheese is produced in and around Kars Province and takes the first place after kashar, tulum and white cheese production. It has economic value for the people of the region and Kars Gravyer Cheese has brand awareness throughout the country [9]. Although there are many studies on the fatty acid composition and cholesterol content of various cheeses, no studies have been conducted on the determination of changes in cholesterol and fatty acid content during the production and maturation of Kars Gravyer Cheese. However, there are few studies in which the chemical and microbiological properties of Kars Gravyer Cheese, bought from a point of purchase, are revealed [9,13]. Therefore, the aim of this study is to determine the fatty acid composition and cholesterol level of Kars Gravyer Cheese, which will be produced by traditional methods in dairy conditions, and to determine the effect of different maturation periods on fatty acid composition and cholesterol level. 410 ─── Ukrainian Food Journal. 2018. Volume 7. Issue 3 ─── ─── Food Technology─── Materials and methods Sample preparation Gravyer cheese was produced in a dairy farm in central Boğatepe village of Kars Province according to the flow diagram given in Figure 1. Gravyer cheese production was done in two repetitions. Samples were taken on different maturation days (0th,10th, 25th, 45th, 60th and 90th days) from the produced cheeses and brought to the laboratories under cold chain conditions and fat content, fatty acid composition and cholesterol analyses were performed. Raw milk ↓ Heating (34-37 °C) ↓ Addition of commercial liquid cheese leaven (rennet) ↓ Coagulation (45 min) ↓ Clot segment (In the size of 1 cm3) and Resting ↓ Heating of clot (heating to 55-57 °C and resting for 10 min ) and mixing ↓ Putting clot in cendele cloth and stamping on molds ↓ Changing of cloth in molds (10 min later) ↓ Changing of cloth in molds (4-6 times) ↓ Demolding (24 hours later) ↓ Salinization of top and bottom surfaces (4-5 days) ↓ Transferring salt pools (Holding in 25-30% of Salt concentrations for 7-10 days) ↓ Hot storage of cheese (28-32 oC, 85-90% relative humidity for 10-20 days) ↓ Cold storage of cheese (Maturation at 10-13oC for 3-3.5 months) Figure 1. Production flowchart of Gravyer cheese Methods Determination of fat The fat content of the samples was determined using Gerber method [14]. Determination of fatty acid composition The fatty acid composition of the samples was determined according to the fatty acid methyl ester method (FAME) (AOAC 1996.01) [15]. Approximately 0.1 g of fat obtained as a result of fat determination method was mixed and shaken with 10 ml of n-hexane and mixed again with a 0.5 ml 2 N potassium hydroxide solution with methanol. After standing for 1-2 hours in the dark, 1 μl of the supernatant was taken and directly injected into the gas chromatograph. ─── Ukrainian Food Journal. 2018. Volume 7. Issue 3 ─── 411 ─── Food Technology ─── GC Conditions for the analysis of fatty Acid composition For the fats, the FAME composition was analyzed using a Restek RTX-2330 capillary column (60 m, 0.25 mm id, 0.1 μm film thickness, Bellefonte, PA, USA) in Shimadzu brand gas chromatography (model QP2010 Plus) and a flame ionization detector. The device was given 1 µl as the injection volume from the sample. The column furnace temperature was programmed to reach 240 ° C with an increase of 4 °C/min after kept for 3 minutes at 100 °C and to wait 18 minutes at the last temperature value. The injection temperature was set at 250 °C and the detector temperature was set at 255 °C. Helium was used as a carrier gas. Injection split ratio was used at 1:80 ratio. For the control of the GC/FID system, the LabSolution computer program and FAME Mix standard (37 components) (Restek) were used. FAME peaks were identified by comparing the chain lengths and retention times of the fatty acids specified in the FAME standard. Determination of cholesterol level Cholesterol analysis of samples was done according to [16] with some modifications. According to the method, 1 ml of internal standard (stigmasterol, 0.5 mg/ml) and 0.5 ml of 2 N alcoholic potassium hydroxide solution were added to 0.5 g of fat and the mixture is left to stand in a water bath at 80 °C for 15 minutes.