Technological and enzymatic characterization of the yeasts isolated from natural fermentation media of Gemlik olives

Abstract

Aim: To determine the technological and enzymatic characteristics of 54 yeast strains belonging to 16 species previously isolated from natural fermentation media of Gemlik olives. The distinguishing feature of these strains, according to their selective technological and enzymatic properties using principal component analysis (PCA), was also intended. Methods and Results: The technological properties of yeast strains, growth characteristics at different temperatures, pH and salt concentrations were examined. Besides, yeast strains' abilities to use oleuropein as a sole carbon source, to assimilate citric acid and to produce H 2 S were examined and their catalase, pectolytic, proteolytic and killer activities were also tested. All strains could grow between 15 and 28°C which are favourable temperatures for natural olive fermentation and they were able to tolerate high salt concentration and low pH in the brine of natural fermentation media. As a result of enzymatic characterization with API-ZYM test system, all strains have esterase activity, which is an important feature for developing table olive aroma. In this research, b-glucosidase activity, which contributes to removing bitterness out of olives, was one of the main distinguishing features of yeast strains. Several strains of Candida hellenica, Pichia anomala and Candida pelliculosa species had b-glucosidase activity. PCA tested yeasts and several strains belonging to C. hellenica (AF84-1), P. anomala (BF1-1, BF46-2) and C. pelliculosa (BF46-3, BF143-2) species have promising technological and enzymatic properties for natural table olive production. Conclusion: Five promising strains belonging to C. hellenica, P. anomala and C. pelliculosa species may be suitable adjunct starter cultures with lactic acid bacteria in natural fermentation media of table olive. Significance and Impact of the Study: This study has been the first contribution to the enzymatic and technological characterization of yeasts isolated from Gemlik olives in Turkey. Some strains could be proposed as a promising adjunct culture in the production of table olives. Aureobasidium pullulans AZ-6Candida famata BZ-2Clv. lusitaniae BF1-2 C. hellenica AF28-4 P. anomala BZ-1 C. hellenica AF46-5 P. anomala BZ-4 C. hellenica AF46-6 P. anomala BF0-5 C. hellenica AF84-1 P. anomala BF1-1 C. membranifaciens AF164-1 P. anomala BF1-4 Cry. laurentii AF46-3 P. anomala BF18-2 D. hansenii AF28-2 P. anomala BF27-3 D. hansenii AF60-3 P. anomala BF46-2 D. hansenii AF191-2 P. anomala BF63-2 D. hansenii AF211-1 K. apiculata AF211-2

Impact of oleuropein on rheology and breadmaking performance of wheat doughs, and functional features of bread

“…However, hydroxytyrosol was not found in OP2B bread. Three mechanisms were proposed to describe the loss of polyphenol compounds during the process: (i) oxidative reactions (Stamatopoulos et al ., 2014); (ii) several yeast strains utilise OP as a carbon source for their metabolism and further biological activities (Mujdeci & Ozbas, 2020), probably causing OP degradation during dough fermentation and proofing; (iii) thermal degradation during baking (Sui et al ., 2015; Lin & Zhou, 2018). Previously, OP thermal degradation was observed during simulation of home‐cooking process at 120–170 °C for 15–60 min (Lozano‐Castellόn et al ., 2020) and 80–230 °C for a sufficient period of time (Attya et al ., 2010).…”

Current Status, Recent Advances, and Main Challenges on Table Olive Fermentation: The Present Meets the Future

“…For all the aforementioned, last decade, the interest of the scientific community was focused on the isolation of autochthonous microbes, to study beyond their technological characteristics described above, their potential probiotic properties. Indeed, there are several studies dealing with the probiotic characterization of LAB ( Bevilacqua et al, 2010 ; Ghabbour et al, 2011 ; Abriouel et al, 2012 ; Argyri et al, 2013 ; Bautista-Gallego et al, 2013a ; Bleve et al, 2014 , 2015 ; Botta et al, 2014 ; Montoro et al, 2016 ; Anagnostopoulos et al, 2018 ; Guantario et al, 2018 ; Yalçınkaya and Kılıç, 2019 ; El Issaoui et al, 2021 ) and yeast/mold ( Hernández et al, 2007 ; Bevilacqua et al, 2009 , 2013 ; Silva et al, 2011 ; Bonatsou et al, 2015 , 2018a ; Bavaro et al, 2017 ; Oliveira et al, 2017 ; Porru et al, 2018 ; Mujdeci and Ozbas, 2020 ; Simões et al, 2021 ) strains, isolated from several olive varieties, in order to select and use those with the most promising features to produce table olives with potential health benefits. It is crucial to point out that in the majority of the studies, strain selection is based on the most combined range of both technological and probiotic features.…”

The fermentation conditions of low alcoholic three-leaved (Cayratia trifolia (L.) Domin) cider using Saccharomyces cerevisiae HG1.3

“…This initiative reflects the industry's commitment to harnessing microbial diversity for enhanced and diversified fermentation processes [6]; for instance, 21 Saccharomyces strains were found during cider production [7]; 2 thermotolerant yeasts were reported to have a high-temperature limit of 47°C among the total of 34 strains isolated from Indonesian rice wine [8]. In addition, yeasts were also isolated from different kinds of fruit such as watermelon [9], Cayratia berry [10], dragon fruit [11], Gemlik olives [12], and soursop [13,14].…”