Semih Latif İpEk

Xylitol is a leading low-calorie sugar alcohol worldwide. Industrial production efficiency has become crucial given the increasing global demand. The catalytic hydrogenation of xylose to produce xylitol is a leading method. In this study, xylitol production using a Raney nickel catalyst was optimized in a pressurized batch reactor. The catalyst amount, xylose concentration, hydrogen pressure, and temperature were used as the process variables, and the maximum yield (%) was determined. The experimental design, created using a central composite design (CCD), was optimized using Response Surface Methodology (RSM), and the obtained values were evaluated using ANOVA. The linear regression model was found to be statistically significant. The linear model indicated that temperature had no effect on the model. The optimal conditions determined by the RSM were 40 g of catalyst, 25% xylose, and 60 bar at 400 rpm stirring. The yield was 86.61%, which is quite close to the predicted value of 87.2557%, demonstrating the accuracy of the model. The product was analyzed using HPLC, XRD, DSC, TGA, and ICP-MS to confirm product quality. Under these optimized chemical conditions, increasing the stirring speed to 800 rpm as a post-optimization step led to a further increase in yield up to 98.01%, indicating the presence of mass transfer limitations at lower mixing intensities.

This study aimed to comparatively optimize and evaluate the quality characteristics of Washington Navel orange slices using vacuum microwave drying (VMD) and conventional hot air drying (HAD) systems. Response Surface Methodology based on the Box–Behnken design was applied to both systems. For the models developed in the VMD system, the coefficient of determination (R²) was found to be in the range of 0.96–0.97, and the optimum conditions were determined as 4 kW power, 60 °C temperature, and 2 mm slice thickness. For HAD, the optimum conditions were determined as 78 °C temperature, 1.57 m/s air velocity, of 2.3 mm slice thickness. VMD showed superior performance compared to hot air drying in terms of total phenolic preservation, retention of bioactive compounds, and rehydration capacity. Hydroxymethylfurfural (HMF) formation was higher during hot-air drying. The effective moisture diffusivity (D_eff) was significantly higher in VMD (8.38 × 10⁻¹⁰ m²/s) than in HAD (1.49 × 10⁻¹⁰ m²/s), indicating enhanced internal moisture transport under vacuum microwave conditions. The results revealed that VMD is an efficient technology for producing high-quality dried citrus products with improved bioactive retention and reduced processing time.

L-asparaginase (L-ASNase) is an enzyme that depletes asparagine, a key amino acid for cancer cell survival, producing aspartic acid and ammonia. Beyond its food industry applications, L-ASNase is a clinically important agent against acute lymphoblastic leukemia (ALL). In this study, L-ASNase was produced and purified from Candida utilis via solid-state fermentation. Optimization on wheat bran identified 2 mL inoculation volume, 60% moisture, and a 4-day fermentation period as the optimal conditions, yielding 172.5 U/mL activity. The purified enzyme was tested against glioblastoma (GBM) cell lines, showing IC₅₀ values of 0.4 U/mL for U87MG and 1.8 U/mL for T98G, with minimal toxicity toward normal HaCaT cells. Apoptotic effects were confirmed by DAPI/F-actin and Giemsa staining, while wound healing and clonogenic assays revealed inhibition of cell migration and colony formation. RT-qPCR analysis demonstrated downregulation of the Survivin gene, a key survival regulator. These findings highlight L-ASNase’s potent antiproliferative, anti-migratory, and pro-apoptotic effects, underscoring its potential as an adjuvant therapy for GBM.

Introduction: This study aimed to investigate the anti-carcinogenic effects of recombinant L- methioninase (rBlmet) on the pancreatic cancer cell line MiaPaCa-2. Methods: In this study, rBlmet was initially cloned, expressed, and purified. To increase enzyme activity, the His-tags on the enzyme were removed using thrombin. rBlmet was then applied to MiaPaCa- 2 cells, and the cell viability of MiaPaCa-2 cells was evaluated by neutral red assay after rBlmet treatment. The combined effect of etoposide with rBlmet against MiaPaCa-2 cells was also evaluated for 12 and 24 hours using a neutral red assay. Furthermore, cell morphology was evaluated by Giemsa and DAPI/F-actin staining methods. Survivin and caspase-3 gene expression levels were measured by RT-qPCR. Results and Discussion: The specific activity of the enzyme increased after His-tag elimination to 5.62 μmol/mg per minute. rBlmet showed a significant cytotoxic effect on the MiaPaCa-2 cell line. The IC50 value (24 h) of rBlmet for MiaPaCa-2 cells was 3.02 U/mL. In addition, rBlmet increased the cytotoxic effect of etoposide on the MiaPaCa-2 cell line, while it showed less effect on HaCat, which is a normal human cell line. Furthermore, rBlmet increased caspase-3 expression and downregulated survivin gene expression in MiaPaCa-2 cell lines. It successfully inhibited the growth of Mia-PaCa-2 cells by exploiting exogenous methionine amino acid in the growth medium. This study revealed promising results. However, further studies are needed on additional pancreatic cancer cell lines and in vivomodels. Conclusion: Based on these findings, it can be concluded that rBlmet not only has great potential to treat pancreatic cancer in the future but can also be used as an adjuvant to enhance the effectiveness of chemotherapeutic agents like etoposide.

In this study, bee products such as honey, pollen, and propolis were directly incorporated into the polymer structure prepared based on chitosan and gelatin to obtain biofunctional thin films. Thin fi...

Milk is a complete and incredibly nutritious food supply for humans. Millions of tons of raw milk have been processed by the dairy industry to meet huge public demand. Therefore, there are studies needed related to the classification of raw milks in the supply chain. The aim of this study is to evaluate the quality of raw milk samples in Amasya region. Firstly, raw cow's milk is classified according to its protein and fat values. In the first period, the mean fat value of raw milk collected from three lines was found to be 3.86, 3.89, and 3.87 as (%) the percent value, respectively, while the mean protein value of raw milk collected from three lines was found to be 3.29, 3.28, and 3.25 as (%) the percent value, respectively. In the second period, the mean fat value of raw milk collected from three lines was found to be 3.93, 3.99, and 4.03 as (%) the percent value, respectively, while the mean protein value of raw milk collected from three lines was found to be 3.34, 3.35, and 3.34 as (%) the percent value, respectively. The findings indicated that during both periods, the daily raw milk collected from three lines is class A, where protein value (%) is 3.1 and above while fat value (%) is 3.5 and above. Since the quality of raw milk is important not only for milk consumers but also for the quality of the corresponding dairy products, the quality of raw milk must be controlled correctly. Consumer requirements for high-quality milk and dairy are of importance on dairy products.