Akademik Veri Yönetim Sistemi
Food Biophysics, cilt.20, sa.4, 2025 (SCI-Expanded)
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° to 92.43°). 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.