The influence of milk protein-based ingredients on the textural characteristics, sensory properties, and microstructure of probiotic yogurt during a refrigerated storage period of 28 d was studied. Milk was fortified with 2% (wt/vol) skim milk powder as control, 2% (wt/vol) sodium calcium caseinate (SCaCN), 2% (wt/vol) whey protein concentrate (WPC) or a blend of 1% (wt/vol) SCaCN and 1% (wt/vol) WPC. A commercial yogurt starter culture and Bifidobacterium lactis Bb12 as probiotic bacteria were used for the production. The fortification with SCaCN improved the firmness and adhesiveness. Higher values of viscosity were also obtained in probiotic yogurts with SCaCN during storage. However, WPC enhanced water-holding capacity more than the caseinate. Addition of SCaCN resulted in a coarse, smooth, and more compact protein network; however, WPC gave finer and bunched structures in the scanning electron microscopy micrographs. The use of SCaCN decreased texture scores in probiotic yogurt; probably due to the lower water-holding capacity and higher syneresis values in the caseinate-added yogurt sample. Therefore, the textural characteristics of probiotic yogurts improved depending on the ingredient variety.

Recently, the demand for goat and sheep cheese has increased mainly because of its nutritional and health benefits. As a result, an enormous amount of whey from various animal species is produced as a waste/by-product. The production of functional probiotic fermented beverages from different types of whey protein concentrates (WPC) could be a good way to valorize whey. Meanwhile, reduced environmental pollution and economic sustainability will be provided. In this study, probiotic beverages enriched with 1% kiwi powder were produced from goat, sheep, and cow WPC (15%). Moreover, Streptococcus salivarius subsp. thermophilus and the probiotic bacteria Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis were used for fermentation. The results showed that WPC significantly increased the protein content and acidity of beverages (p < 0.05). Production with WPC also improved the viability of probiotic bacteria and S. thermophilus, total phenolic compound (TPC), and antioxidant activity of beverages. The highest viability of probiotic bacteria (9.67 log CFU/mL for Bb-12 and, 9.35 log CFU/mL for L. acidophilus) was found in beverages produced from goat WPC. In addition, WPC increased the free amino acid content of beverages, and the highest essential amino acids and branched-chain amino acids were found in beverages produced from goat WPC as 146.19 mg/100 g and 70.31 mg/100 g, respectively (p < 0.05). Consequently, while production with goat, cow, and sheep WPC improved quality compared to the control, beverages produced from goat WPC excelled. The production of a functional probiotic beverage with goat WPC is promising for dairy technology.

There is an increasing interest in applying fruit-processing wastes as functional food ingredients. Hazelnut skin, an interesting and innovative ingredient has recently been evaluated as one of the richest edible sources of polyphenolic compounds. This study aimed to evaluate the use of hazelnut skin as a functional additive in yogurt and to determine the effect of various percentages (2%, 3%, and 4%) of hazelnut skin on the physicochemical, microbiological, rheological, biochemical, and sensorial properties of yogurt. The results showed that the addition of hazelnut skin significantly increased total solids from 16.5% to 17.7% and fat content from 3.45% to 4.60% and decreased titratable acidity by up to 36%. The enrichment with hazelnut skin also improved the viability of yogurt bacteria, water holding capacity (WHC), and antioxidant activity of yogurts. Better results for WHC and antioxidant values were found in yogurt enriched with 4% hazelnut skin. Total phenolic content and Fe²⁺ chelating activity of yogurts increased with the increasing hazelnut skin ratio. However, yogurts with hazelnut skin had low instrumental texture parameters and apparent viscosity values. On the other hand, acceptable sensorial properties similar to control yogurts increase the consumption potential of yogurts enriched with hazelnut skin.

The possibility of using a commercial vegetable fat blend in Kashar cheese was investigated. Kashar cheeses were manufactured by replacing the milk fat (MF) with a vegetable fat (VF) blend. Kashar cheeses from whole milk were also manufactured to compare textural, microstructural, meltability, color and sensory characteristics during a ripening period of 90 days. The use of vegetable fat decreased the meltability, hardness, cohesiveness, gumminess and chewiness of the cheese; while increasing adhesiveness where springiness was not affected. Differences became less notable toward the end of ripening. Scanning electron micrographs displayed VF cheese with a compact network with small and uniform fat globules embedded in the protein matrix. The MF cheese exhibited an open protein matrix containing milk fat globules of various sizes and forms. The color analysis demonstrated significant differences between cheeses. Finally, all sensory characteristics of the cheese were affecte d by the vegetable fat blend.La posibilidad de usar una mezcla de grasas vegetales comerciales en queso Kashar fue investigada. Los quesos Kashar fueron elaborados con una mezcla de grasas vegetales (VF) en lugar de grasa de leche (MF). Quesos Kashar con leche entera fueron también elaborados para comparar las características sensoriales, de color, de fusión, microestructurales y de textura durante el periodo de maduración de 90 días. El uso de grasas vegetales decreció la dureza y las propiedades de fusión, de cohesión, de gomosidad y de masticación e incremento la adhesividad mientras que la elasticidad no fue afectada. Las diferencias se hicieron menos notables hacia el final de la maduración. La micrografía electrónica de barrido de quesos VF mostro una red compacta con pequeños y uniformes glóbulos de grasa embebidos en la matriz de proteínas. Los quesos MF exhibieron una matriz de proteínas abierta conteniendo glóbulos de grasa de leche de varios tamaños y formas. El análisis del color demostró significativas diferencias entre los quesos. Finalmente, todas las características sensoriales del queso fueron afectadas por la mezcla de grasas vegetales

The Influence of Transglutaminase Treatment on Functional Properties of Strained Yoghurt

Kashar cheese was produced from whole milk (MF) or skim milk homogenized with a commercial vegetable fat blend (VF) by the traditional procedure. The resulting cheese was stored for 3 months at 5°C, and analyzed initially for its gross composition and cholesterol content. In addition, the proteolysis and lipolysis, organic acid content and fatty acid composition were studied during the ripening of the cheese. The replacement of milk fat with a vegetable fat blend mainly affected pH, total solids and cholesterol content in the initial composition of the cheese (P < 0.05). The acid degree value and tyrosine contents in both types of cheese increased throughout ripening and significant differences were found between the cheeses after only 30 days of ripening (P < 0.05). The organic acid concentrations of both cheeses changed during ripening (P < 0.05) except for citric and oxalic acids. MF cheese showed higher levels of citric, succinic and oxalic acids especially towards to the end of ripening. Palmitic acid was the dominant fatty acid in MF cheese while the most abundant fatty acids in VF cheese were palmitic and oleic acid. The higher unsaturated fatty acid composition of the VF cheese has attracted attention from the healthy food image point of view.