| Abstrakt: |
Yogurt is widely consumed as functional food because of the good taste and nutritional properties (rich in potassium, calcium, protein and vitamins), being an excellent vehicle to deliver probiotics to consumers. However, its enrichment with various physiologically active ingredients could provide specific health benefits beyond basic nutrition. The reason for incorporating the sea buckthorn powder (SBP) in yogurt was to enhance its functionality, considering the sea buckthorn content in non-digestible oligosaccharides which have the ability to improve the activity of health promoting bacteria found in the human digestive system. Also, sea buckthorn contains a large variety of substances which are possessing strong biological activity, such as vitamins and flavonoids. Therefore, this paper presents a study of the influence of different concentrations of SBP on the yogurt's sensory acceptance, rheological, textural and physicochemical properties. The rheological behavior of yogurts with different amounts of SBP was compared with the rheological behavior of the simple yogurt. The flow and viscosity curves were obtained from Modular Advanced Rheometer System Haake Mars, with a range of shear rate from 0.02 to 100 s-1 (rising curve) and 100 to 0.02 s-1 (descendent curve) at a total time of 20 minutes. Hysteresis was determined as the area between the curves and adjusted to the models of Bingham, Casson, Herschel-Bulkley and Ostwald-de-Waele. There were also carried out tests of thixotropy, by measuring the viscosity as a function of time at a constant rate of 100 s-1 for 10 minutes. The the structural compactness (|η*|, G', G") and the model of structural organisation (tan δ) were also studied. The Mark-10-ESM301 Texturometer was used for the texture profile analysis (TPA) of the samples. The color of different % SBP yogurts was measured with the Konica Minolta CR-400 Chroma Meter. The physicochemical properties (pH, titrable acidity, syneresis) and the sensory acceptance of the samples were evaluated, too. The results of the study lead to the determination of the optimum concentration of SBP in yogurt, with best sensory acceptance, rheological, textural and physicochemical properties. [ABSTRACT FROM AUTHOR] |
