In this study, the stabilising property of various concentrations of gum tragacanth in nonfat doogh, an Iranian fermented milk drink, was investigated by measuring phase separation, particle size, flow behaviour and viscoelastic properties. Moreover, light microscopy was used to get more insight into morphological characteristic of protein–polysaccharide complexes in doogh samples. The addition of gum tragacanth improved stabilisation of doogh samples which was associated with an increase in apparent viscosity and storage modulus. Furthermore, the particle size distribution showed an increase in polydispersity and a pronounced reduction in median diameter of protein–polysaccharide complexes which was accompanied by no phase separation at 0.3% concentration of gum tragacanth.
Beta-lactoglobulin (BLG) and bovine
serum albumin (BSA) coacervate
formation with sodium alginate (ALG) was investigated by turbidimetric
analysis, zeta potential, particle size, viscosity, transmission electron
microscopy (TEM) and isothermal titration calorimetric (ITC) measurements
as a function of pH (1.0–7.0) and protein/alginate mixing ratio
(1:1, 1.5:1, 2:1, 1:0, and 0:1 wt.). Critical pH values of phase transitions
for BSA–ALG complexes (pHC, pHφ1, and pHφφ2) representing the formation of
soluble and insoluble complexes of a protein–ALG mixture (2:1)
at pH 4.8, 4.2, and 1.8, respectively. In the case of BLG–ALG,
critical pH values (pHC, pHφ1, and pHφ2) were found to be 4.8, 4.2, and 1.6, respectively.
The pHopt values, expressed by the highest optical density,
were pH 2.8 for BSA–ALG and 2.4 for BLG–ALG. TEM and
zeta-potential results showed that maximum coacervate formation occurred
at pH 4.2 for both protein–polysaccharide solutions. The interaction
between BLG–ALG and BSA–ALG was spontaneously exothermic
at pH 4.2 according to ITC measurements. The findings of this study
provide insights to a thorough understanding about the nature of interactions
between milk proteins and ALG and formulate new applications for food,
pharmaceutical, nutraceutical, and cosmetics applications.
In this study, the physicochemical properties of a low-fat dried yogurt paste (kashk) were determined, and the effects of different concentrations (0, 0·1, 0·3 and 0·5% w/w) of gum tragacanth exudates from Astragalus gossypinus on the stability and texture of the samples were investigated by measuring amount of syneresis, turbidity, particle size distribution (PSD), flow behaviour and viscoelastic properties. The flow behaviour index was not very sensitive to the concentration of gum, while a remarkable concentration dependency of the power-law consistency coefficient and Herschel-Bulkley yield stress was observed. The initial increase in the gum concentration at 0·1 and 0·3% levels led to a higher degree of syneresis, which was related to the depletion flocculation mechanism. However, the reduced amount of syneresis in samples containing 0·5% gum tragacanth was attributed to the significant increase in viscosity of the continuous phase, which is also accompanied by trapping of the aggregated casein particles. The presence of 3% salt in the samples may have led to the neutralization of charges on the surface of gum tragacanth; consequently, the non-adsorbing behaviour of high-ionic-strength polysaccharides inhibited the formation of electrostatic protein-polysaccharide complexes. Furthermore, maximum values of polydispersity, syneresis and tan δ at high frequencies were found in samples containing 0·1% gum tragacanth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.