Yumurta kabuğu zarı proteinlerinin alternatif protein kaynağı olarak değerlendirilmesi

Eggs are the one of the foods with the highest waste capacity, and disposal of these wastes has become difficult due to bad odor and increased bacterial load. Even though eggshell and the three-layer eggshell membrane (ESM) inside the shell are very valuable in terms of protein and calcium concentrations; they cannot be utilized and valorized into new products. Studies with valorization of ESM are very limited because its separation from the shell is very hard and its solubilization is very limited. Thus, separation and solubilization of ESM from the shell, its characterization with functional and textural properties in addition to formulation of soft gel capsules with soluble ESM, determination of its microbial loads, and sensory properties were investigated. The optimal separation conditions at which membranes could be separated from the shells were determined using acetic acid, HCl, EDTA, and water. The highest protein levels of 83.36±0.00, 82.90±0.00, 81.75±0.00, 80.42±0.00, 80.38±0.00, 80.22±1.45, and 79.6±1.98% were obtained from 100 mM EDTA at 1:20 ratio, water at 1:30 ratio, 50 mM EDTA at 1:20 ratio, 100 mM EDTA at 1:40 ratio, 1.25% acetic acid at 1:40 ratio, 1.25% acetic acid 1:30 ratio, and 0.185% HCl at 1:30 ratio, respectively by Kjeldahl method. Solubilization of the highest protein concentrations was performed by means of 0.1, 0.5 and 1% SDS and 0.1, 0.5 and 1% Triton X-100 (T) detergents at 0, 30, 60, 240, 720, and 1440 min in the Lowry analysis. The washing procedure was applied to remove lysis solution and to determine the effect of washing on protein content of the ESM samples. The samples treated with 100 mM EDTA at 1:20 ratio, 100 mM EDTA at 1:40 ratio, and water at 1:40 ratio samples having the highest soluble protein concentrations for further analyses. The samples had a high emulsion stability, low foaming activity index and no foaming abilities. The onset temperature of the samples ranged from 84.60±0.01 ºC to 101.22±0.01 ºC. Rheologial analysis revealed high correlations with Bingham, Herschley-Bulkley, and Newtonian flow models. Moreover, the FT-IR spectra of the samples were similar to each other. 16 different types of aminoacids were identified in soluble ESM samples. The hardness and the springiness values were significantly different from each other (p < 0.05). Soft gels containing 1.45 mg/g ESM protein had lower sensory scores in terms of water 1:40 sample although had a microbiological stability of 32 weeks at +4°C. It was presented by this study that ESM considered as waste can be utilized as a protein supplement in the form of soft gel capsules.