Inactivation of Dekkera bruxellensis yeasts in wine storage in brand new oak barrels using low electric current technology

Dekkera bruxellensis is one of the species of yeast, which is most damaging to wine quality, and the tools available to control its growth are limited. In previous studies, non-Saccharomyces yeasts and Dekkera bruxellensis have been significantly restricted during wine-making processes using an innovative approach based on low electric current treatment (LEC). In the present study, LEC techniques were assessed for their capacity to inhibit wine spoilage by D. bruxellensis and to prevent formation of undesirable flavours during storage in oak barrels. Although the effect of SO2 treatment on D. bruxellensis viability and ATP content was more immediate, from the 30th day onward no significant variations between LEC and SO2 treatments were observed. At the end of the trial, LEC treatment had had a comparable effect to that of SO2 addition. Acetic acid content was significantly lower after LEC and SO2 treatments than in untreated wines and volatile phenols were also found to be significantly lower in the LEC treated wine. Moreover, the results from the panel test clearly indicate that no significant differences were found between the LEC and the SO2 treated wines. These results clearly indicate that LEC technology could represent a viable tool to limit yeast spoilage caused by D. bruxellensis. The present work represents, to our knowledge, the first attempt to control D. bruxellensis during red wine storage in oak barrels using LEC. The potential industrial applications of LEC technology include the real future possibility of producing a new, marketable range of healthier wines to satisfy the requirements of modern wine consumers

Technological Potential of Lactobacillus Strains Isolated from Fermented Green Olives: In Vitro Studies with Emphasis on Oleuropein-Degrading Capability

Technological properties of two strains of Lactobacillus plantarum (B3 and B11) and one of Lactobacillus pentosus (B4), previously isolated from natural fermented green olives, have been studied in vitro. Acidifying ability, salt, temperature, and pH tolerances of all strains were found in the range reported for similar strains produced in Italy and optimal growth conditions were found to be 6.0-8.0 pH, 15-30 ∘ C temperature, and less than 6% NaCl. Moreover, all strains showed very good tolerance to common olive phenol content (0.3% total phenol) and high oleuropein-degrading capability. It was found that medium composition affected the bacterial oleuropein degradation. B11 strain grown in a nutrient-rich medium showed a lower oleuropein-degrading action than when it was cultivated in nutrient-poor medium. Furthermore, enzymatic activity assays revealed that oleuropein depletion did not correspond to an increase of hydroxytyrosol, evidencing that bacterial strains could efficiently degrade oleuropein via a mechanism different from hydrolysis

Technological Potential of Lactobacillus

Technological properties of two strains of Lactobacillus plantarum (B3 and B11) and one of Lactobacillus pentosus (B4), previously isolated from natural fermented green olives, have been studied in vitro. Acidifying ability, salt, temperature, and pH tolerances of all strains were found in the range reported for similar strains produced in Italy and optimal growth conditions were found to be 6.0–8.0 pH, 15–30°C temperature, and less than 6% NaCl. Moreover, all strains showed very good tolerance to common olive phenol content (0.3% total phenol) and high oleuropein-degrading capability. It was found that medium composition affected the bacterial oleuropein degradation. B11 strain grown in a nutrient-rich medium showed a lower oleuropein-degrading action than when it was cultivated in nutrient-poor medium. Furthermore, enzymatic activity assays revealed that oleuropein depletion did not correspond to an increase of hydroxytyrosol, evidencing that bacterial strains could efficiently degrade oleuropein via a mechanism different from hydrolysis

Exceptional long-term durability of Coratina monovarietal extra virgin olive oil evaluated through chemical parameters and oxidative stability test

Coratina is a very popular olive cultivar, native of the Apulian region (Italy), but today worldwide cultivated and appreciated. In the present study, durability of Coratina monovarietal extra virgin olive oils (CMOO), produced in the Molise region (Southern Italy), was investigated up to 6-years storage in metal tin cans, under room temperature and darkness. Durability was considered the storage time in which an oil remained food grade. Yearly, the free fatty acids, peroxide value, K232 and K270 indices, fatty acid composition, diacylglycerols, phenolic profile and Rancimat induction time at 130 °C were determined on the oil. Free fatty acids and peroxide value increased linearly over time but never surpassing the European limits set for the EVOO category. Conversely, K232 and K270 exceeded the EVOO limits after five and four years, respectively. A linear decrease of phenolic compounds was observed with direct effect on the oil oxidative stability measured by Rancimat test. In conclusion, despite some signs of aging, the CMOO highlighted a remarkable long durability being food-grade up to 6-years