Browsing by Author "Çon A.H."

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Optimization of Protective Agents for Freeze-Drying of Weisella cibaria N9 as a Potential Starter Culture
(2021-01-01) Gül L.B.; Gül O.; Dertli E.; Çon A.H.
In this study, it was aimed to determine the optimum cryoprotectant formulation for the lyophilization of Weissella cibaria N9 strain isolated from sourdough as a potential starter culture, the characterization of lyophilized culture and its storage stability. The optimum formulation of skim milk, lactose and sucrose as protective agents was determined by the Box-Behnken experimental design based on viability after lyophilization. The optimal cryoprotectant formulation was identified as 5.65% skim milk, 20% lactose and 20% sucrose for maximum cell survival (>99%). Lyophilized culture obtained by the optimum cryoprotectant formulation had acceptable physicochemical properties in terms of moisture and aw, glass transition, particle surface properties and crystal structure. The highest viability was observed at 4̊C (9.11 log cfu/g) with an inactivation rate of 3.37x10-3 day-1. The fastest cell reduction was observed at 70̊C as the result of an accelerated shelf life storage test, and protective agent effectively decreased thermal death. The culture produced by using cryoprotectant could be stored at room temperature for 18 months. Consequently, this protective agent formulation was an effective in protecting W. cibaria N9 viability during lyophilization and storage while lyophilized culture had ideal properties for powder materials, and accelerated shelf life storage test was a useful technique with certain predictability.
Potential of three different lactic acid Bacteria to use as starter culture for production of type II sourdough breadmaking
(2022-10-01) Gül L.B.; Gül O.; Çon A.H.
The principle objective of this study was to investigate the use of three different lactic acid bacteria (Lactobacillus curvatus N19, Weissella cibaria N9 and L. brevis ED25) lyophilized with optimum cryoprotective agent formulations as Type II sourdough culture to develop sourdough bread in terms of physicochemical, textural and sensory characteristics as well as volatile aroma compounds. Compared to control sample (fermented only commercial yeast), specific volume, crust and crumb color, and textural properties were markedly more acceptable for sourdough bread. The concentration of lactic (2.12–2.87 g/kg) and acetic (0.43–0.77 g/kg) acids in the sourdough bread was significantly higher compared to control sample (0.28 and 0.09 g/kg, respectively). A total of 57 volatile compounds including 13 alcohols, 9 esters, 8 ketones, 13 aldehydes, 10 acid group components, and 4 other compounds (such as oxidation product amine, terpene, sulfur compounds, organic compounds) were detected. Among these compounds, alcohols and aldehydes were significantly higher in control sample, while the ratio of acids was found to be higher in sourdough breads. The evaluation scores of the sourdough breads had desirable sensory features, but in terms of general acceptance values, it was concluded that those containing L. brevis ED25 was more preferred.