Yazar "Simsek, Mehmet Ali" seçeneğine göre listele

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    Improving nutritional quality, aroma profile and bioactive retention of rocket juice via thermosonication: a support vector regression-based optimization
    (Frontiers Media Sa, 2026) Levent, Okan; Simsek, Mehmet Ali; Yikmis, Seydi; Demirel, Selinay; Turkol, Melikenur; Demirok, Nazan Tokatli; Er, Hatice
    This study investigates the application of thermosonication (TS) to improve the functional properties of roka (Eruca vesicaria subsp. sativia) water. Processing parameters, including time (8-16 min), amplitude (60-100%), and temperature (40-60 degrees C), were optimised using a comparative approach combining the response surface method (RSM) and support vector regression (SVR). The total phenolic content (TPC) increased to 86.04 mg GAE/100 mL with TS, representing an 8.1% rise compared to the control group and an 18.3% increase over pasteurization. Likewise, the total chlorophyll level reached 16.98 mmol TE/L from 9.67 g/100 mL, and beta-carotene rose to 24.90 mg/100 mL (p < 0.05). Pasteurization caused losses of 15-30% in these components. In the phenolic profile, significant increases were observed in chlorogenic acid (42.05 mu g/mL), caffeic acid (15.66 mu g/mL), and quercetin (4.28 mu g/mL). A total of 31 compounds were identified in aroma analysis; with TS treatment, levels of 3-Hexen-1-ol (15.70 mu g/kg) and 1-hexanol (2.01 mu g/kg) were preserved or increased. In in vitro digestion tests, the TS group demonstrated the highest bioavailability, even during the intestinal phase. For example, RSM demonstrated high compliance coefficients (R2 = 0.99), while SVR showed strong predictive performance (CV R2 = 0.84), particularly for FRAP. Overall, the results suggest that thermosonication is an innovative method for protecting and enhancing bioactive compounds in rocket juice.
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    Ultrasound-Assisted Sustainable Processing of Garden Cress Juice: Enhancing Bioactive Compounds and Bioaccessibility through XGBoost Optimization
    (Amer Chemical Soc, 2025) Levent, Okan; Simsek, Mehmet Ali; Yikmis, Seydi; Demirel, Selinay; Tokatli Demirok, Nazan; Turkol, Melikenur; Aljobair, Moneera O.
    This study aimed to improve the functional and nutritional properties of garden cress (Lepidium sativum) juice using ultrasound and optimize process parameters by modeling them with advanced machine learning algorithms. Using a Box-Behnken experimental design, the effects of sonication time (8-16 min) and amplitude (60-100%) on total chlorophyll, total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) were investigated. Nonparametric, high-accuracy estimations were made using the XGBoost algorithm. Optimum conditions were determined to be 12 min and 80% amplitude. Under these conditions, TPC (78.44 mg GAE/mL), FRAP (59.80 mg TE/mL), and chlorophyll (7.15 g/100 mL) values were significantly higher than those in control and pasteurized samples (p < 0.05). HPLC-DAD analysis showed that ultrasound treatment positively impacted the phenolic profile by increasing the release of quercetin, quercetin derivatives, caffeic acid, and chrysin. GC-MS data revealed that volatile aroma compounds (especially 1-hexanol, benzaldehyde, and cinnamaldehyde) were preserved mainly by ultrasound. In vitro digestion simulation showed that total postdigestion recovery rates in ultrasound-treated samples were 34.96% for TPC, 32.50% for chlorophyll, and 28.81% for FRAP, demonstrating a significant increase in bioaccessibility. PCA and hierarchical clustering analyses confirmed a significant biochemical separation of ultrasound-treated samples. The findings indicate that ultrasound technology is a superior method for preserving bioactive compounds, maintaining the aroma profile, and enhancing bioaccessibility compared to heat treatment. This enables data-driven process design. The developed model showed a strong predictive performance under optimal conditions. However, the study is limited by the relatively small data set used for model training.