Baktybala Kabdylzhar

This study investigated the valorization of chicken feet, an underutilized poultry by-product, through enzymatic hydrolysis to obtain a protein hydrolysate with improved functional properties. Enzymatic treatment was carried out using Enzy-Mix U100 and collagenase from Streptomyces lavendulae, with cheese whey applied as a process medium. The resulting protein hydrolysate contained 59.1% protein and was characterized by high levels of glycine (31.64 g/100 g protein), hydroxyproline (10.91 g/100 g protein), and alanine (10.58 g/100 g protein). The hydrolysate exhibited strong techno-functional performance, with a water-binding capacity of 580%, an emulsifying activity index of 166 m²/g, and an emulsion stability index of 31 min. Microstructural analysis revealed irregular porous particles typical of freeze-dried protein hydrolysates, reflecting structural modification of collagen during enzymatic treatment. Mineral analysis showed notable levels of sodium (463.1 mg/100 g) and magnesium (351.8 mg/100 g). Microbiological evaluation demonstrated high sanitary quality, with a total viable count of 100 CFU/g and absence of coliforms, Escherichia coli, yeasts, and molds in 1 g of product. The technological process reduced the characteristic odor of chicken feet while maintaining a light color and good dispersibility. These findings confirm the potential of enzymatic hydrolysis as a sustainable strategy for converting poultry by-products into safe, value-added functional protein ingredients for food applications.

The poultry industry generates large amounts of protein- and mineral-rich by-products that remain underutilized. This study investigated the use of chicken skin protein hydrolysate and chicken bone protein–mineral mass (PMM) as functional ingredients in emulsified poultry sausages. The hydrolysate was characterized by a high protein content (52.25%) and high water- and fat-binding capacity (142% and 125%, respectively), while the PMM served as a source of protein and minerals with stable physicochemical and rheological characteristics. These ingredients were incorporated into sausage formulations at different substitution levels. Partial replacement of poultry meat increased protein and mineral content and affected key technological properties, including water-binding capacity, emulsion stability, cooking loss, and shear force. Moderate inclusion levels were associated with a more cohesive protein matrix, lower cooking losses, and improved structural stability, whereas excessive substitution resulted in increased firmness and less favorable sensory characteristics. Among the tested formulations, the combination of 18% PMM and 4% protein hydrolysate showed the most balanced technological and sensory performance. The findings suggest that poultry by-products processed into functional ingredients may have potential for application in value-added sausage formulations.

This study evaluated the potential of chicken by-products (hearts, gizzards, and skin) as functional raw materials for protein–fat emulsions to partially replace animal fat in pâtés. Five variants of pâté (PV1–PV5) were prepared, including a control without emulsion and four samples with increasing emulsion levels. Emulsions were formulated from chicken by-product mixtures and vegetable oil with potato starch, sodium bicarbonate, and salt to improve solubility and viscosity. The chemical composition of by-product mixtures varied with organ ratio: heart-rich mixtures supplied higher protein, supporting emulsion stability, whereas skin-rich mixtures contributed more fat for texture. Emulsion composition ranged from 6.6–8.1% protein, 19.1–28.4% fat, and 56.7–66.9% moisture. Functional properties depended on formulation balance: water-holding (58–67%), fat retention (70–83%), emulsifying capacity (50–62%), and stability (47–55%). Variant 5 achieved the most favorable combination of composition, stability, and viscosity. In pâtés, emulsion addition reduced protein and fat but increased ash and carbohydrate contents (p < 0.05), improving hydration and stability. Fat retention rose up to 83% and emulsion stability up to 62%. Drip loss declined markedly from 9.2% in the control to 3.6% in Variant 5, while yield stress decreased by 25%, producing softer, more spreadable products. Sensory evaluation favored emulsion-containing samples, with PV-5 scoring highest in texture and appearance. TBARS values rose with the amount of emulsion due to higher PUFA, but acid numbers increased more slowly, indicating reduced hydrolytic rancidity. Overall, pâté with 25% of emulsion offered the best balance of technological performance, sensory quality, and lipid stability, highlighting chicken by-products as sustainable emulsifiers in pâté production.

This article presents the results of the study of the dependence of yield stress (YS) and water-binding capacity (WBC) on mechanical processing of meat and bone raw materials when changing the rotational speed and the gap between the rotary knives of the grinder. It is revealed that the parameters of YS and WBC also increase when the rotational speed increases. Thus, the highest values of YS (943.29 Pa) and WBC (66.98%) are observed when the rotary knives’ rotational speed is 4000 min⁻¹ and the clearance between knives is 0.16 mm, while the lowest values of YS (635.87 Pa) and WBC (63.83%) are observed when the knives’ rotational speed is 1000 min⁻¹ and the clearance is 0.38 mm. The power consumption of the electric motor of the unit increases as the rotation speed of the working bodies increases and the gap between the knives decreases.

The production technology of meat-bone paste and its effect on chemical, mineral and amino acid compositions of liver pâté were studied. The liver was replaced by meat-bone paste in the concentration of 5, 10, 15, 20, and 25% for the production of experimental samples. The compositional analysis of pâté manufactured with meat-bone paste showed that the reformulation did not influence the content of moisture (~56%), fat (~28%), or protein (~11%) while producing a significant increase of ash and a decrease of carbohydrates in comparison with control pâtés. The higher amounts of minerals of bone-meat paste, including calcium (3080 mg/100 g), magnesium (2120 mg/100 g), phosphorous (2564 mg/100 g), and iron (7.30 mg/100 g), explained the higher amount of both ash and these minerals in the reformulated samples compared to the control samples. The total caloric value (~300 kcal/100 g) was also unaffected by the addition of bone-meat paste. The content of both essential and non-essential amino acids decreased with the inclusion of meat-bone paste, although this decrease was lower in essential (6280 mg/100 g in control vs. 5756 mg/100 g in samples with 25% of meat-bone paste) than in non-essential amino acids (6080 mg/100 g in control vs. 3590 mg/100 g in samples with 25% of meat-bone paste). This fact is due to several essential amino acids not showing differences between control and reformulated samples, while in non-essential amino acids, these differences were greater. The results of this study showed that meat-bone paste addition is a good strategy to produce liver pâté enriched in minerals and with minimum influence on the content of the other important nutrients. Therefore, these results can be used for the design of new liver pâté with an increased nutritional significance by using meat industry by-products. According to the balance of minerals, the use of 15% of meat-bone paste to reformulate liver pâté is the best strategy used in the present research. However, additional studies on the stability (during storage), shelf-life, and sensory acceptability of these reformulated pâtés should be carried out.

Identifying patterns in the effect exerted by a cooling process and the fine grinding modes on the qualitative indicators of a meat and bone paste