# Evaluation of a New Bulk Packaging Container for the Ripening of Feta Cheese
## 3 Results and Discussion
### Volatile Compounds of Feta Cheeses
Butanoic acid was identified as the most abundant volatile fraction in Feta cheeses [5], while other carboxylic acids, including acetic and hexanoic acids, were found to be the major acids in Turkish white-brined cheeses [27]. The amount of free fatty acids, in decreasing order (day 60), was 2661.9 > 2263.9 > 654.2 \(\mu\)g/kg for cheeses packaged in stainless-steel tanks, wooden barrel, and tin can containers, respectively. Esters were the third most abundant group of compounds on day 60 of storage. Esters are mainly produced by the enzymatic or chemical reaction of fatty acids with primary alcohols [23] and also by the transesterification of partial glycerides to ethanol [4]. The majority of the esters identified in the present study were ethyl and methyl esters of butanoic, hexanoic, and decanoic acids. [PERSON] et al. [5] reported similar differences in ester content for Feta cheeses packaged in wooden barrels and tin can containers. Most of the identified esters have low perception thresholds, with floral and fruity notes, and they probably contribute to the balance of the cheese flavor by minimizing the sharpness imparted by the FFA [28]. [PERSON] et al. [29] reported that high-quality ewes' milk cheees also contained significant amounts of ethyl esters, including ethyl lactate, which are positively correlated with the following sensory attributes: lactic, fruity, floral, and clean cheese flavors. [PERSON] et al. [19] reported ethyl esters, including ethyl acetate, ethyl butanoate, ethyl octanoate, and ethyl hexanoate in cow white-brined cheeses. The amount of esters, in decreasing order (day 60), was 2486.8 \(>\) 1936.4 \(>\) 788.0 \(\upmu\)g/kg for cheeses packaged in stainless-steel tanks, wooden barrels, and tin can containers, respectively. Straight-chain aldehydes, such as propanal, pentanal, hexanal, heptanal, octanal, and nonanal, were detected in the chees in different amounts. These aldehydes may be formed via the \(\beta\)-oxidation of unsaturated fatty acids [22]. Aldehydes may make an important contribution to cheese flavor due to their low perception thresholds. Among aldehydes, [PERSON] et al. [19] also identified 3-methyl-1-butanol in white-brined cheeses; it is responsible for spicy, cocoa, unripe, apple-like, cheesy, green, malty, and harsh flavors in many cheeses such as Proosdji, Parmesan, Camembert, blue and cheddar. 3-methyl-1-butanal, also detected in cheeses in the present study, is derived from Leucine [30]. The amount of aldehydes, in decreasing order (day 60), was 882.4 \(>\) 689.3 \(>\) 383.0 \(\upmu\)g/kg for cheeses packaged in tin can containers, wooden barrels, and stainless-steel tanks, respectively. Ketones were not among the major groups of volatile compounds found in the Feta cheeses. In brined cheeses such as Feta, ketones may be produced by the enzymatic decarboxylation of fatty acids by lactic bacteria [28]. Ketones usually play an important role in the flavor of mold-ripened cheeses and they are formed by the action of _Penicillium roqueforti, P. camemberti_, and _Geotrichum candidium_[31]. Among ketones, 3-hydroxy-2-butanone was the most abundant ketone identified in all cheese samples. 3-hydroxy-2-butanone was also determined by [PERSON] et al. [5] in Feta cheese and by [PERSON] et al. [19] in white-brined cow chees. The amount of ketones on day 60 was 202.8 and 83.6 \(\upmu\)g/kg for chees packaged in wooden barrels and tin can containers, respectively. No. ketones were detected in stainless-steel tanks on day 60 of storage. A number of miscellaneous compounds were determined in the cheeses (Tables 1-3). Of these, two terpenes, \(\alpha\)-pinene and limonene, with citrus-like flavors, were identified and semi-quantified. Terpenes are transferred into the milk through the grazing of animals in mountain pastures and are finally detected in the cheese [32]. The linear hydrocarbons detected in the chees were probably produced during ripening due to lipid autoxidation [9].