Obtaining protein from black cumin seed meal and investigating the possibilities of its use in bread

Problems in access to food with increasing consumer demand, malnutrition, difficulty in accessing animal-based foods, changing consumption habits of people, changing protein sources, and turning to more easily available plant protein sources. Various functional properties of proteins that can be used in the food industry play an important role in maintaining their quality during shelf life. The most common plant-based protein shown as an alternative source to animal-based proteins is isolated from soybeans. Apart from soybean, other legumes and oilseeds are also used as new protein sources, and research on the structure, composition and functional properties of these proteins is constantly renewed and updated. This study aimed to first determine the composition of black cumin meal, which is a by-product in cold press oil production of black cumin, and protein isolates produced from this meal as a result of different ultrasounds, and then to determine various physicochemical and functional properties of these proteins and to determine the possibilities of using these protein isolates in bread making. The analyses started with the procurement of black cumin meals from Bursa artisans. After grinding and pulverizing the meal, protein isolates were obtained by alkaline extraction and the isoelectric precipitation method. Moisture, ash, protein, and fat ratios of the bagasse and protein values of the protein isolates were determined. According to the results of the composition analysis, it was determined that the meal contained 7.42% moisture, 6.0% ash, 11.22% fat, and 33.87% protein. The protein isolates obtained were determined to contain 74.83-77.19% protein. When the amino acid composition of the protein isolate was examined, it was found that 33% of the protein isolate consisted of essential amino acids and contained glutamic acid at the highest concentration. The known functional properties of the proteins obtained as a result of isolation were analyzed for solubility, water retention, emulsion properties, gel-forming capacity, and foam-forming properties. According to the results of the analysis; the water retention capacity of the protein isolate varieties was between 104.38-182.18%. Changes in ultrasound amplitudes caused a statistical difference between the results. The solubilities of the proteins were analyzed at pH 3, 5, 7, and 9 and the values at these pHs were determined as 35.51-39.59% at pH 3; 13.15-19.59% at pH 5; 56.06-57.91% at pH 7; 72.25-81.68% at pH 9. To examine the emulsion properties of the obtained protein isolates, the emulsion activity index and emulsion stability index were measured respectively. The emulsion activity and stability index values of the isolates were determined as 93.0-214.7 m2 /g and 10.76-12.27 g fat/g protein, respectively. Statistical differences were found between different ultrasounds in terms of emulsion properties. To examine the foam properties of the studied black cumin meal proteins, foam forming capacities and foam stability values were determined. Foam forming capacities ranged between 68.89-104.44% and foam stability values were determined as 91.11-93.47%, 82.23-88.15%, and 75.57-84.87% at 0, 30, and 60 minutes, respectively. Gel-forming properties of proteins were determined by determining the lowest gelation concentration. The low gelation concentration of the proteins indicates that the proteins have good gelation properties. The minimum gel concentration was 12% at 75G and the highest was 18% at 0 and 25G. DSC was used to study the thermal properties of the proteins. The initial denaturation temperature, enthalpy, and temperature of the protein isolates were determined as 67.67 °C, 61.28 J/g, and 90.7 °C, respectively. Rheological properties of bread doughs prepared by adding certain ratios (5%-15%) of protein isolate to wheat flour for bread production were determined. Water absorption, development time, stability, softening amount, and farinograph quality number properties of the dough were determined with the addition of protein isolate. Water absorption, development time, stability, and farinograph quality number increased and statistical differences were observed between the results. Moisture, weight, specific volume, protein, fat, and ash values of the bread made by adding 5%, 10%, and 15% protein isolate to wheat flour were determined and compared with the control bread made from wheat flour. The volume, specific volume, protein, ash, and fat values of the bread increased with the addition of protein isolate to wheat flour. It was determined that the brightness and yellowness values of the bread interior and crust decreased and redness values increased with the addition of protein isolate. Bread samples were evaluated by panelists for pore and homogeneity structure, taste, odor, bread stickiness, and chewiness. According to the results of the sensory analysis, it was determined that the bread with the addition of protein isolate was more liked than the control bread.