Abstract
In this study, the changes in chemical and microbiological composition of two olive varieties, Edincik and Gemlik, have been examined during fermentation at industrial scale. Prior to processing, the olives have been thoroughly characterized chemically and microbiologically. Then, the nature of the fermentation process has been investigated during the 9 months of fermentation period by taking samples at certain intervals. The most important characteristics of the two varieties before processing were determined as follows: Edincik variety was found to have relatively higher reducing sugar (5.94%) and moisture (59.53%) contents than that of Gemlik variety (4.45% reducing sugar and 43.18% moisture). Polyphenol concentrations of two varieties were 2.50% and 2.40%, respectively. During fermentation, reducing sugar and polyphenols contents were decreased gradually in the fruit, while other constituents were slightly changed or remained almost unchanged. While reducing sugar decreased to the values of 0.98% and 0.65%, free acidity in brine increased to 0.41% and 0.35%, pH value of brine were 4.4 and 4.9 and salt content in fruit were reached to the final values of 7.4% and 6.9% for Edincik and Gemlik varieties, respectively. Microflora of the raw samples was consisted of various bacteria mainly, lactobacilli, Gram-negative, anaerobic sulfide producing, coliform bacteria and yeasts. During the fermentation of both varieties, yeasts were dominated starting from the 40th days of fermentation.
Highlights
Olive is one of the major agricultural products of Turkey and Turkey has the second place among olive cultivating countries in the world [1]
The principle characteristics of the olive fruit to be considered during fermentation are the type and the quantity of microorganisms, reducing sugar, moisture and polyphenol contents
According to the results of chemical analyses it was observed that Edincik variety has higher reducing sugar (5.94%) and moisture (59.53%) content than that of Gemlik variety which is more nutritive with regard to its oil and protein content (Table I )
Summary
Olive is one of the major agricultural products of Turkey and Turkey has the second place among olive cultivating countries in the world [1]. The most common two Turkish olive varieties, namely Gemlik and Edincik, constitutes the major part of the olive production in the region of the Sea of Marmara (North-West of Turkey), and are best suited for processing natural black olives. With an average size of 270-280 olives/kg has a high oil content. With an average size of 230-400 olives/kg is characterised by firm flesh, comparably low oil, high moisture and sugar contents. The olives are packed in tin containers with the capacities of 1-10 kg, using freshly prepared brine of 1112% NaCI. This is the most common process in Turkey and the process is based upon traditional practices. Intensive researches have been conducted on olive fermentation in Turkey to produce high quality table olives
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