# Evaluation of a New Bulk Packaging Container for the Ripening of Feta Cheese
## 3 Results and Discussion
### Volatile Compounds of Feta Cheeses
Classes of volatile compounds identified and semi-quantified on day 60 of storage (the minimum ripening period according to the Greek Codex Alimentarius [16]) in order of decreasing concentration were alcohols > free fatty acids > esters > hydrocarbons > aldehydes > ketones > terpenes for cheeses packaged in wooden barrels and stainless-steel tanks; and alcohols \(\cong\) hydrocarbons > aldehydes \(\cong\) esters >free fatty acids > ketones > terpenes for cheeses packaged in tin can containers. Cheeses packaged in stainless-steel tanks and wooden barrels were the richest in volatile compounds compared to those packaged in tin can containers on day 60 of storage (9770.6, 8865.5, and 4666.3 \(\mu\)g/kg respectively). During ripening, the cheeses packaged in wooden barrels and stainless-steel tanks exhibited a large increase in alcohols, free fatty acids, and esters, and a decrease in aldehydes, hydrocarbons and terpenes compared to the first day of storage. During the same period, cheeses packaged in tin can containers exhibited an increase in esters and free fatty acids and a decrease in hydrocarbons, aldehydes, and terpenes. At this point, it should be mentioned that the cheeses packaged in tin can containers had roughly half the amount of volatiles (day 60) than those packaged in the stainless-steel tanks and wooden barrels. Alcohols were the most abundant volatile compounds in all of the cheeses. Ethanol, the major alcohol in all cheeses, is formed either through lactose fermentation by hetero-fermentative lactic acid bacteria (LAB) or through the metabolism of amino acids or from the reduction of acetaldehyde [5]. [PERSON] et al. [21] also reported that ethanol was the major alcohol in Feta cheese. Primary alcohols, such asbutan-1-ol, pentan-1-ol, and heptan-1-ol, are mainly formed by the reduction of their corresponding aldehydes, following a reduction pathway involving alcohol dehydrogenases. When present above their respective threshold levels, aliphatic primary alcohols, such asbutan-1-ol and heptan-1-ol, contribute fruity and nutty flavor notes to cheese [22]. According to [PERSON] et al. [23], 3-methyl butanol contributes an alcoholic floral note to cheeses and derives from Leucine via Strecker degradation [24]. Pentan-1-ol, which was identified in all of the cheeses, contributes significantly to the aroma of Greek Feta cheese [5]. The amount of alcohol, in decreasing order (day 60), was 2833.2 > 2570.3 > 1069.3 \(\mu\)g/kg for cheeses packaged in stainless-steel tanks, wooden barrels, and tin can containers, respectively. Free fatty acids were the second most abundant volatile compounds in Feta cheeses. In general, short- and medium-chain FFAs are the products of lipolysis and contribute to the background flavors of many cheese varieties due to their low perception thresholds and their characteristic flavor notes. Acetic, butanoic, and hexanoic acids were detected in all cheese samples. Acetic acid, which gives the typical flavor of cheeses ripened in brine, is not a product of lipolysis but is mainly produced by other biochemical pathways, probably from the fermentation of lactate or the metabolism of amino acids by bacteria. It contributes to the final flavor of white brined cheese with \"pungent\" flavor notes and is occasionally detected in brined chees [25]. Butanoic acid is responsible for buttery-chees flavor notes and hexanoic acid creates sweaty and sometimes pungent flavor notes [26]. When excessive lipolysis occurs in cheeses, the product is characterized by rancid flavors, but cheese varieties such as blue cheese, Italian chees, and Greek Feta with a high FFA content are sensorily acceptable [5]. The extensive lipolysis of triglycerides can occur, supported by both microbial and native milk enzymes such as lipases and esterases, and the FFA produced can directly or indirectly contribute to the development of the cheese aroma [26].