# Evaluation of a New Bulk Packaging Container for the Ripening of Feta Cheese
## 1 Introduction  
Feta is a white brined cheese, produced in Greece from ewe milk or from mixtures of ewe milk with up to 30% \(v/v\) goat milk. Feta has been approved as a PDO product since 2002 (EU Regulation No. 1829/2002) [1]. As a PDO product, Feta cheese has strict product specifications in terms of its specific composition and method of production within clearly limited production regions in Greece; this provides a substantial added value to the product [1]. Feta production is permitted in specific areas of the Greek mainland and only on the island of Lesvos. Based on this fact, it is quite clear that the composition and the sensory properties of Feta cheese may vary substantially with location but always fall within the legal limits, especially in terms of moisture and fat (moisture \(\leq 56\%\); fat \(\geq 43\%\) fat in dry matter, FDM). Furthermore, the animal breed, type of feeding, the flora of the local pasture, the time of milking, agro-climatic conditions, etc., are expected to affect the composition and the sensory properties of milk and consequently those of the resulting cheese [2]. During the past few decades, the production of Feta cheese has been industrialized and a number of modifications have been introduced to the cheese-making procedure compared to the basic traditional technology [3]. Basic differences between the traditional and modern technologies include: (i) the former uses rennet produced from lamb and kid abomas slaughtered before weaning, but this is substituted by synthetic rennet in modern, industrial-scale Feta cheese production; (ii) the former uses traditional yoghourt as a starter culture instead of the mixtures of commercial mesophilic starters that are used inindustrial production; (iii) the former uses a milder heat treatment than high-temperature short-time (HTST) pasteurization, which is common practice in the industrial production of cheese, resulting in different microflora of the cheese milk; (iv) in the former, the draining and pre-ripening conditions vary according to weather conditions, as there is usually no temperature control in the ripening rooms of traditionally produced Feta cheese as opposed to strict controls in the ripening conditions of industrially produced cheese; and (v) traditionally produced Feta blocks are packaged in beech or oak wooden barrels and dry salted, whereas industrially produced Feta cheese is packaged in parallelepiped tin cans filled with brine. Wood is a porous material, allowing for (1) the gradual inlet of oxygen into the barrel, which interacts with the cheese resulting in the flavor enrichment of the latter, characterizing it as more \"sharp\", (2) the exit of a limited amount of moisture from the product, often resulting in a slightly harder texture, and (3) the formation of a biofilm on the internal surface of the barrel, which immobilizes a large number of microorganisms within a thick layer of polysaccharides. Among these microorganisms, lactococci and lactobacillus are of key importance, contributing to the acidification and additional flavor formation of the cheese. On the other hand, tin cans consisting of two-sided tinned steel protect the cheese from the effects of light, oxygen, moisture, odorous compounds, and microorganisms, resulting in Feta cheese with a softer texture and milder flavor. Both wooden barrels and tin containers result in excellent quality Feta cheese, and the choice of either one by consumers is clearly a matter of individual preference [3; 4]. Recently, a parallelepiped stainless-steel tank with a cover, either internally lined with beech wood or not, has been experimentally used for convenience purposes, and it is being currently tested as a third bulk ripening/packaging material (in addition to tin can containers and wooden barrels), in which the Feta cheese ripens in brine.