This study reports the possibility of obtaining the WPI-based meringues with the small sucrose content (0–15%). The whey protein isolate (WPI) solution (20%, w/v) was whipped and sucrose was added to foam at the concentrations of 5, 10 and 15%. The surface tension, viscosity, zeta potential of the pre-foam solutions, foam overrun, foam stability and their rheological properties (G′, G″ and tan (δ)) were evaluated. To produce meringues, liquid foams were solidified at 130 °C for 2 h. The surface properties (roughness, contact angles, apparent free surface energy) as well as microstructural ones were determined for the solid foams (meringues). The 15% sugar concentration was detrimental for overrun, stability and rheological properties of liquid foams. The meringue production without sugar was infeasible. The addition of the smallest amount of sucrose (5%) enabled preservation of the aerated structure of the liquid foam during solidification. The 10% sugar concentration increased the stability of liquid foam, its rheology and it was the most effective for air bubbles stabilization during the foam solidification, however, its largest addition (15%) resulted in an increase in the final meringue volume. Larger sucrose concentrations produced a smoothing effect on the meringue surfaces.
The aim of the paper was to investigate the effects of the addition of whey protein isolate (WPI) and whey protein concentrate (WPC80) on physicochemical properties of high‐protein yoghurts. Changes in storage, loss moduli, phase angle values, flow behaviour and textural parameters were determined. Surface properties (roughness, contact angles) were also estimated. The properties of yoghurts depended on the preparation type and their concentration. The application of WPI resulted in accelerated gel formation in comparison with the yoghurts produced with WPC80. This technology is addressed to particular consumers who search for new foods to meet their daily protein requirements.
The aim of this paper was to investigate the effect of whey protein isolate (WPI) and polymerised whey protein isolate (WPP) addition on physicochemical properties of processed cheese with partial fat replacement. Surface properties were determined by advancing (h a ) and receding (h r ) contact angles, apparent free surface energy (c s ). Roughness measurements, cheese meltability and Turbiscan Stability Index (TSI) were evaluated by Turbiscan. Higher WPP concentrations produced the more hydrophobic surfaces of the samples. Conversely, increase in WPI addition promoted the hydrophilic cheese surfaces. The effect of roughness was much larger for samples containing WPI. The increase in protein addition caused a decrease in meltability and an increase in stability of cheeses. The optical and confocal images have proved that cheeses with WPP demonstrated more packed and denser structure in comparison to samples with WPI.Surface properties of processed cheese M. Nastaj et al.
This paper reports the potential use of fermented curly kale juice in Feta-type cheese production. The rheological study and Turbiscan assay demonstrated that fermented curly kale juice coupled with rennet accelerated curd formation resulted in a stronger curd compared to the sample containing rennet alone. Laboratory-scale cheese was manufactured from cow’s milk with the use of fermented curly kale juice. Several parameters that affect the quality of cheese were investigated, including physicochemical, textural and microstructure characteristics. The content of amino acids and fatty acids was determined, surface properties were assessed and microbial enumeration of the experimental cheese was carried out before and after ripening. The values of pH and the content of lactose and protein significantly decreased as a result of maturation. In turn, an increase in LAB growth as well as saturated and unsaturated fatty acids was observed. The use of the fermented curly kale juice improved the textural characteristics and changed the microstructure of the obtained cheese. Finally, the ripening process enhanced the amino acid profile of the Feta-type cheese. These findings indicate that the fermented curly kale juice can be used for manufacture of cheese with improved characteristics and functional properties.
WPŁYW CHLORKU SODU NA WŁAŚCIWOŚCI REOLOGICZNE PIAN OTRZYMANYCH Z ALBUMINY WYSOKO PIENISTEJS t r e s z c z e n i e Celem pracy było określenie wpływu dodatku chlorku sodu na właściwości reologiczne pian otrzymanych ze sproszkowanej albuminy wysoko pienistej. Z preparatu białkowego użytego do badań przygotowano roztwory o stężeniu białka: 2, 6 i 10 % (m/v). Zastosowano następujące stężenia molowe roztworów soli [mM]: 60, 120, 240 i 480. Piany wytwarzano przez ubijanie 50 ml roztworu w zlewkach wysokościennych o pojemności 600 ml przy użyciu miksera Philips Essence. Czas ubijania każdej próbki roztworu wynosił 2 min.Właściwości reologiczne pian badano przy użyciu reometru oscylacyjnego HAAKE RS 300 (ThermoHaake, Karlsruhe, Niemcy). Pomiary granicy płynięcia (τ o ) wykonywano przy stałej prędkości ścinania wynoszącej 0,01 s -1 zastosowaniem modułu pomiarowego vane oraz układu dwóch płytek równoległych. W teście oscylacyjnym określono liniowy zakres lepkosprężystości badanych pian przy częstotliwości 1 Hz i zakresie odkształcenia 0,002 -0,05 %. Określono również wartości modułów zachowawczego (G') i stratności (G") oraz wielkość kąta przesunięcia fazowego (δ) przy zakresie częstotliwości drgań 0,1 -10,00 Hz i przy odkształceniu wynoszącym 0,003 %. Pomiary wykonywano w trzech powtórzeniach. Wyznaczono także wydajność pienienia roztworów badanych preparatów.Właściwości reologiczne otrzymanych pian były zależne od stężenia zastosowanego preparatu i stęże-nia NaCl. Piany otrzymane z roztworów o największym stężeniu białka cechowały się najlepszymi wła-ściwościami reologicznymi. Wzrost stężenia molowego NaCl do wartości 120 mM w badanych roztworach białek prowadził do systematycznego zwiększania się granicy płynięcia i wydajności pienienia. Z kolei dalsze zwiększanie stężenia soli prowadziło do zmniejszenia wartości wyżej wymienionych parametrów, co świadczy o pogorszeniu się właściwości reologicznych badanych pian.Słowa kluczowe: albumina, NaCl, piany, właściwości reologiczne
WprowadzeniePienienie się jest zjawiskiem, które umożliwia wytwarzanie unikalnej struktury i tekstury żywności w procesach technologicznych. Głównie białkom, jak albumina jaja kurzego i preparaty białek serwatkowych, przypisuje się zdolność do tworzenia Dr inż. M. Nastaj,
Due to the lack of studies on the influence of the whipping process on the protein aggregation in prefoam solutions, resulting foams and drainage serum, the influence of pH on foaming properties of whey protein isolates (WPIs) and whey protein concentrates (WPCs; WPC 80 and WPC 65)was investigated in this study. The WPI foams were superior to the WPC ones. The optimal pH values for foaming of all whey protein preparations were 5.0 and 9.0, while the foamability deteriorates at pH 3.0. There was a logarithmic correlation between yield stress and phase angle for WPI foams. Protein aggregates at pH 9.0, especially in the prefoam WPI solutions.
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