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    Optimization of protein extraction from halopteris scoparia macroalgae by ultrasonic-assisted enzymatic extraction (UAEE): Bioactive, chemical, and technological properties
    (American Chemical Society, 2024) Yücetepe, Aysun; Aydar, Elif Feyza; Doğu Baykut, Esra; Dinç, Hatice; Onat, İsa Alperen; Demircan, Evren; Şensu, Eda; Okudan, Emine Şükran; Özçelik, Beraat
    Finding alternative food sources is now more crucial than ever because of the ever-growing global population, on the one hand, and the changing climate brought on by global warming, on the other. Macroalgae are currently a viable, novel, and alternative food source for the food industry. This research was centered on the optimization of extraction conditions of protein extracts from Halopteris scoparia by the response surface methodology based on the Box-Behnken design. According to the results, extraction yield (18.31-94.5%), total phenolic content (TPC) (11.70-19.07 mg GAE/g dw), and antioxidant activity (AOACUPRAC: 11.97-17.85 mg TE/g dw, AOAABTS: 45.45-78.02 mg TE/g dw), which were influenced by extraction parameters, were investigated. The optimum extraction conditions were ultrasound application time of 7.46 min, enzyme/substrate of 0.8, and extraction time of 2 h. The water (0.29 ± 0.07 g/g) and oil absorption capacity (1.37 ± 0.06 g/g), foaming capacity (8.50 ± 3.70%) and stability (8.50 ± 3.70%), and emulsion activity (37.5 ± 0.00%) and stability (62.22 ± 7.70%) of the protein extracts obtained under optimum conditions were investigated along with Fourier transform infrared spectroscopy, differential scanning calorimetry, and SDS-PAGE. Protein extracts obtained from H. scoparia showed high TPC and AOA, while the emulsion and foaming properties were found to be lower than those of the algal or plant proteins. The hydrolysis degree of protein hydrolysate from H. scoparia-obtained enzymatic hydrolysis was found to be 61.43%. Sixteen amino acids were identified from the H. scoparia protein hydrolysate. The total amino acid content in the protein hydrolysate was 10.44 mg/g protein. Tyrosine, one of the nonessential amino acids, and leucine and lysine, two of the essential amino acids, were determined as the main amino acids.
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    Production of structured lipids from hazelnut oil with conjugated linoleic acid by lipase-catalyzed esterification: Optimization by response surface methodology
    (Akademiai Kiado Rt., 2018) Bakır, N.; İlyasoğlu, H.; Yücetepe, Aysun; Kasapoglu, K. N.; Demircan, Evren; Özçelik, Beraat
    The aim of this study was to synthesize structured lipid from hazelnut oil with conjugated linoleic acid (CLA) by lipase-catalyzed esterification reaction. The incorporation of CLA into hazelnut oil was optimized by response surface methodology (RSM). Substrate molar ratio, time, and temperature were independent variables chosen for optimization of the reaction. Substrate molar ratio was the most significant variable on the incorporation of conjugated linoleic acid. Good quadratic model was achieved by multiple regression analysis and backward elimination. Optimal incorporation conditions were determined as follows: reaction temperature, 59 degrees C; time, 6 hours; substrate molar ratio, 4. Under these optimum conditions, a maximum incorporation ratio of CLA into hazelnut oil of 49.42% was achieved.
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    The impact of pH and biopolymer ratio on the complex coacervation of Spirulina platensis protein concentrate with chitosan
    (Springer, 2021) Yücetepe, Aysun; Yavuz Düzgün, Merve; Şensu, Eda; Bildik, Fatih; Demircan, Evren; Özçelik, Beraat
    Spirulina platensis is one of the most significant multicellular blue-green Cyanobacterium microalgae with a high protein content. The complex coacervation as an encapsulation technique allows the formation of proteins with improved functional properties and thermal stability. In this study, the effects of pH and Spirulina platensis protein concentrate (SPPC)—chitosan ratio on complex coacervation formation were examined in terms of ?-potential, turbidity, visual observation and microscopic images. Based on the results, the strongest interaction between SPPC and chitosan occurred at pH of 5.5 and SPPC—chitosan ratio of 7.5:1 with a precipitation in the test tubes. Stable dispersions were obtained at a pH range of 2–4 for the SPPC—chitosan ratio of 7.5:1 inhibiting the precipitation which occurs at individual SPPC solutions at this pH range. Characteristic organic groups in the individual SPPC and chitosan solutions as well as the SPPC—chitosan coacervate formed at the optimal conditions were identified by using Fourier Transform Infrared (FT-IR) spectroscopy technique. Furthermore, thermal stability of the individual SPPC and chitosan solutions and the SPPC—chitosan coacervates were investigated using differential scanning calorimetry (DSC). The glass transition temperature and enthalpy were 209.5 °C and ? 3.414 W/g for the complex coacervates and 180.5 °C and ? 0.877 W/g for SPPC. It means that complex coacervation provided more thermally-stable SPPC in chitosan—SPPC coacervate than that of the individual SPPC. Our results might have important implications for the utilization of Spirulina platensis proteins especially for acidic beverage applications.