İspirli, Hümeyra; Dertli, Enes

Recently, branching sucrases encoded in the genomes of certain Lactic Acid Bacteria (LAB) strains have become novel enzymes to obtain branched α-glucans. In this study an active α-(1 → 2) branching sucrase from Apilactobacillus kunkeei PDER37 was expressed, characterised and distinct branched dextrans was obtained with reactions under different sucrose: dextran ratio. Structural characterisation by 1H and 13C NMR analysis demonstrated the branching of the dextran with (1 → 2)-linked α- d -glucose units with no alteration in the final structure depending on sucrose: dextran ratio (D0) but this ratio was effective for the determination of the molecular weights of the branched dextrans (D1, D2 and D3). FTIR analysis further supported the dextran structures and suggested the higher accumulation of the α-Glc units in the branched dextrans. Thermal characterisation of the branched dextrans obtained by TGA and DSC analysis suggested the increased hygroscopicity of the branching units. Both SEM and AFM analysis demonstrated more porous chain like structures in the branched dextrans. This study provides valuable information on the role of active α-(1 → 2) branching sucrase (BS37) for the production of branched dextrans with potential increased physicochemical status applicable for food and other industries.

İncele

Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Alamoudi, Mohammed; Dertli, Enes

A slimy-mucinous-type colony of EPS-producing Weissella cibaria PDER21 was isolated and identified. The monomer composition was glucose, showing that the EPS is a glucan type homopolysaccharide, The core structure of (1 → 6)-linked α-D-glucose units including (1 → 3)-linked α-D-glucose branches at a ratio of 93.4/6.6 was revealed by 1H and 13C NMR spectra and confirmed by FTIR analysis. The glucan showed a superior thermal stability with almost no degradation in structure up to 300 °C. XRD analysis revealed the amorphous structure while SEM analysis confirmed the layer-like morphology. The glucan had an antioxidant activity (89.5%), water-holding capacity (103.7%) and water solubility index (80.7%) values, suggesting that the glucan had a strong level of antioxidant properties; good water binding capacity and excellent solubility. The glucan PDER21 is a polysaccharide possessing a good combination of technical and functional attributes, suggesting a great deal of potential for use in the food industry.

AtıfScopus42·WoS41·OpenAlex40

İncele

Dertli, Enes; Toker, Omer S.; Durak, M. Zeki; Yilmaz, Mustafa T.; Tatlisu, Nevruz Berna; Sagdic, Osman; Cankurt, Hasan

This study aimed to investigate the role of in situ exopolysaccharide (EPS) production by EPS+ Streptococcus thermophilus strains on physicochemical, rheological, molecular, microstructural and sensory properties of ice cream in order to develop a fermented and consequently functional ice-cream in which no stabilizers would be required in ice-cream production. For this purpose, the effect of EPS producing strains (control, strain 1, strain 2 and mixture) and fermentation conditions (fermentation temperature; 32, 37 and 42°C and time; 2, 3 and 4 h) on pH, S. thermophilus count, EPS amount, consistency coefficient (K), and apparent viscosity (η50) were investigated and optimized using single and multiple response optimization tools of response surface methodology. Optimization analyses indicated that functional ice-cream should be fermented with strain 1 or strain mixture at 40-42°C for 4 h in order to produce the most viscous ice-cream with maximum EPS content. Optimization analysis results also revealed that strain specific conditions appeared to be more effective factor on in situ EPS production amount, K and η50 parameters than did fermentation temperature and time. The rheological analysis of the ice-cream produced by EPS+ strains revealed its high viscous and pseudoplastic non-Newtonian fluid behavior, which demonstrates potential of S. thermophilus EPS as thickening and gelling agent in dairy industry. FTIR analysis proved that the EPS in ice-cream corresponded to a typical EPS, as revealed by the presence of carboxyl, hydroxyl and amide groups with additional α-glycosidic linkages. SEM studies demonstrated that it had a web-like compact microstructure with pores in ice-cream, revealing its application possibility in dairy products to improve their rheological properties.

AtıfScopus86·WoS74·OpenAlex98

İncele