Cambios en la composición química y microbiológica de dos variedades de aceituna durante la fermentación

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.En este estudio, se han examinado los cambios en la composición química y microbiológica de dos variedades de aceituna, Edincik y Gemlik, durante la fermentación a escala industrial. Las aceitunas se caracterizaron química y microbiológicamente antes del tratamiento. Posteriormente, la naturaleza del proceso se investigó durante ios nueve meses del periodo de fermentación tomando muestras cada ciertos intervalos. Se determinaron las características más importantes de las dos variedades antes del tratamiento: la variedad Edincik tuvo un mayor contenido relativo en azúcares reductores (5.94%) y humedad (59.53%) que la variedad Gemlik (4.45% azúcares reductores y 43,18% humedad). Las concentraciones de polifenoles de las dos variedades fueron 2.50% y 2.40% respectivamente. Durante la fermentación, los contenidos en azúcares reductores y polifenoles disminuyeron gradualmente en el fruto, mientras que otros constituyentes cambiaron ligeramente o permanecieron casi inalterados. En la salmuera los azúcares reductores disminuyeron hasta valores de 0.98% y 0.65%, aumentando la acidez libre hasta 0.41 % y 0.35%, con unos valores de pH de 4.4 y 4.9, alcanzando el contenido en sal en el fruto valores finales de 7.4% y 6.9% para las variedades Edincik y Gemlik respectivamente. La microflora de las muestras originales estuvo constituida por bacterias, principalmente del tipo: lactobacitos, Gram-negativo, anaerobios productores de sulfuro, bacterias coliformes y hongos. Durante la fermentación de ambas variedades, los hongos fueron controlados a los 40 días de fermentación

Bacterial production of polyesters from free fatty acids obtained from natural oils by Pseudomonas oleovorans

The carboxylic acids derived from olive oil, hazelnut oil, sesame oil and hamci(anchovy) oil were evaluated as substrates for cell growth and the production of reserve polyesters by Pseudomonas oleovorans. Poly-3-hydroxyalkanoates containing both saturated (mainly 3-hydroxy-octanoate and 3-hydroxy-decanoate) and unsaturated repeating units with 8 to 20 carbon atoms, or more, were produced in 26 to 61% yields based on cell dry weights. The number average molecular weights of these polymers varied from 45,000 to 68,000 Daltons.The carboxylic acids derived from olive oil, hazelnut oil, sesame oil and hamci(anchovy) oil were evaluated as substrates for cell growth and the production of reserve polyesters by Pseudomonas oleovorans. Poly-3-hydroxy alkanoates containing both saturated (mainly 3-hydroxy-octanoate and 3-hydroxy-decanoate) and unsaturated repeating units with 8 to 20 carbon atoms, or more, were produced in 26 to 61% yields based on cell dry weights. The number average molecular weights of these polymers varied from 45,000 to 68,000 Daltons.Support for this work was provided by NATO Col-loborative Research Grant. The authors gratefully acknowledge Mine (Tir)Bilsel and Cemil Nas for GC-MS, GC and GPC measurements

Microbiological, physico-chemical, nutritional and sensory characterization of traditional Matsoni: selection and use of autochthonous multiple strain cultures to extend its shelf-life.

Matsoni, a traditional Georgian fermented milk, has variable quality and stability besides a short shelf-life (72–120 h at 6 °C) due to inadequate production and storage conditions. To individuate its typical traits as well as select and exploit autochthonous starter cultures to standardize its overall quality without altering its typicality, we carried out a thorough physico-chemical, sensorial and microbial characterization of traditional Matsoni. A polyphasic approach, including a culture-independent (PCR-DGGE) and two PCR culture-dependent methods, was employed to study the ecology of Matsoni. Overall, the microbial ecosystem of Matsoni resulted largely dominated by Streptococcus (S.) thermophilus and Lactobacillus (Lb.) delbrueckii subsp. bulgaricus. High loads of other lactic acid bacteria species, including Lb. helveticus, Lb. paracasei and Leuconostoc (Leuc.) lactis were found to occur as well. A selected autochthonous multiple strain culture (AMSC) composed of one Lb. bulgaricus, one Lb. paracasei and one S. thermophilus strain, applied for the pilot-scale production of traditional Matsoni, resulted the best in terms of enhanced shelf-life (one month), sensorial and nutritional quality without altering its overall typical quality. This AMSC is at disposal of SMEs who need to exploit and standardize the overall quality of this traditional fermented milk, preserving its typicality