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    Impact of Kernel Opacity on Protein Content, Some Essential Amino Acids, and Zein Film Properties in Maize
    (Springer, 2025) Gumus, Muhammet; Danisman, Merve; Kibar, Kubra; Yakar, Emin; Oral, Ayhan; Kahriman, Fatih
    Opacity is one of the key indicators of protein quality in maize. Compared to normal maize genotypes, opaque maize contains higher amounts of essential amino acids, contributing to higher levels of lysine and tryptophan, which are limiting in maize diets. These essential amino acids are particularly critical for zeins, the dominant protein fraction in maize, as zeins serve as valuable raw materials with both industrial and nutritional applications. Although zein-based films have been widely studied, there is limited research comparing the properties of zein films derived from maize samples with different kernel opacity levels. In this study, a maize genotype known to possess the opaque trait was used to obtain samples with five different opacity levels. Protein, lysine, and tryptophan content variations were analyzed in flour, raw zein, and zein film samples. Additionally, the dynamic mechanical analysis (DMA) of zein films was performed according to opacity levels. The data obtained were statistically evaluated using one-way analysis of variance (ANOVA), and differences between means were compared using the least significant difference (LSD) test (P < 0.05). The protein content was found to range between 7.6 and 10.14% in flour and 80.6-86.9% in raw zein. Lysine content varied between 1.00 and 1.81% in flour and 0.03-2.28% in raw zein, while tryptophan content ranged from 0.175 to 0.228% in flour to 0.38-2.17% in raw zein. An increase in opacity level led to a decrease in protein content; however, it significantly enhanced the essential amino acid content across all sample types. Furthermore, opacity levels had a substantial impact on the structural properties of zein films. Significant differences were observed among the film samples in terms of color intensity (e.g., L* values ranging from 83.64 in PVA-PEG control to 68.34 in PVA-PEG-Zein100), chroma (2.64 to 40.45), and hue angle (23.30 degrees to 92.43 degrees). Additionally, film thickness varied significantly between 0.028 mm and 0.195 mm across formulations. Mechanical differences were also evident, particularly in storage modulus and flexibility, as quantified through dynamic mechanical analysis (DMA). Although variations in glass transition temperature were modest and appeared to correlate with differences in film opacity-attributable to the lysine-to-tryptophan ratio-a pronounced enhancement in storage modulus was observed. Notably, the formulation exhibiting the highest lysine-tryptophan content showed an increase of up to 1000 times in the storage modulus.The findings suggest that processing and utilizing maize samples separated by opacity level for raw material production could provide important nutritional advantages for food and other applications.
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    In-vitro and In-silico evaluation of the inhibitory effects of Persea americana leaf extract against calcium oxalate stones
    (Springer, 2025) Akyol, Emel; Danisman, Merve; Oner, Mualla
    This study investigated the effects of Persea americana extract (PAE) as a potential inhibitor of calcium oxalate monohydrate growth using both in-vitro and in-silico methods with spontaneous crystallization to evaluate its effectiveness in preventing kidney stones. X-ray diffraction was used to characterize the morphology of calcium oxalate (CaOx) crystals, while scanning electron microscopy (SEM) was used to determine their particle size and crystal formation patterns. SwissADME (Absorption, Distribution, Metabolism, Excretion) computational analysis predicted the biological activity of the extract. The experimental results show that the inhibition of crystal growth increases with the amount of PAE in solution, and crystal growth was almost completely inhibited for 450 min at a concentration of 100 mL of PAE. The in vitro results also revealed that Persea americana leaf promoted the formation of calcium oxalate dihydrate (COD) crystals rather than monohydrate crystals. These findings on PAE's inhibitory effect on calcium oxalate crystallization suggest that natural additives could be valuable in treating kidney stone disease.
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    Surface modification of hydroxyapatite with enzyme-catalyzed reaction: Computation-supported experimental studies
    (Elsevier Science Sa, 2022) Danisman, Merve; Berisha, Avni; Dagdag, Omar; Oral, Ayhan
    Surface modification of the selected particles for different uses (chemical, biological or commercial applications) is a frequently adopted method for industrial and scientific purposes. Thus, the molecules determined for the targeted applications can be attached to particles. However, these methods occur in several steps, at high temperatures, and for long periods of time and require the involvement of chemicals. Chemicals used in the environment and under harsh conditions lead to some restrictions (such as monomer variety and application areas) and cause energy and time loss. Presumably, these problems could be largely avoided by using enzymes, which are natural biocatalysts, in the surface modification of particles. Given this presumption, a surface modification design was devised in this study to modify the hydroxyapatite surface with methacrylic acid using the lipase enzyme. The chemical structures of the particles were characterized through Fourier Transform Infrared and Raman spectroscopy, their thermal behaviors were analyzed with thermogravimetric analysis, and simultaneous molecular modeling studies were conducted to corroborate the experimental studies.