Textural properties of legume protein isolate and polysaccharide gels

The influence of legume proteins from lupin, pea and fababean on the formation of gels prepared by heat treatment in the absence or presence of xanthan gum, locust bean gum and NaCl was investigated. The resulting fracture and texture properties of gels not only are associated with the heating process used to form the gel but also depend on the conformational aspects of xanthan–locust bean gum in admixture with legume proteins, which after 10 days of aging reinforce the system. The fracture and textural properties are explained in terms of the effect of the protein–polysaccharide molecular structure and physicochemical conditions applied in the gel system during the gel preparation and measurements. Copyright © 2006 Society of Chemical Industry     

Influence of preparation methods on physicochemical and gelation properties of chickpea protein isolates

Two protein isolates were prepared from defatted chickpea seed flour by applying alkaline extraction followed by isoelectric precipitation or ultrafiltration (TpI and TUF, respectively), while another one (TF) was obtained by a combination of protein extraction at a mildly acidic environment and ultrafiltration processes. The isolates differed in composition, with the TpI and TF containing mainly the chickpea globulins and the albumins, respectively, whereas the TUF isolate consisted of both types of proteins with the globulin fraction dominating over the albumins. The differences in protein composition between the isolates as well as the impact of extraction conditions were reflected in their protein solubility, surface hydrophobicity, sulfhydryl group content, thermal properties and the onset of gelation during heating. On the other hand, the protein isolate gelling behavior depended mainly on the method applied for their preparation rather than the protein composition, with the isolates obtained by ultrafiltration exhibiting lower gelling concentrations and gel networks of higher elasticity at protein contents below 12% (w/v).     

Technological properties and non-enzymatic browning of white lupin protein enriched spaghetti

Spaghetti was prepared by replacing semolina with different amounts of lupin protein, in order to increase the protein content. A detailed investigation of the rheological properties of the dough and the cooking quality of pasta was performed in comparison to standard semolina spaghetti. Moreover, the effect of the addition of lupin protein on non-enzymatic browning was evaluated by measuring ε-furoylmethyllysine (furosine) and 5-hydroxymethyl-2-furancarboxaldehyde (HMF), which are considered useful indices of semolina quality and pasta processing conditions. Dried spaghetti fortified with 5% of lupin protein isolate has a colour and rheological features comparable with the semolina sample and also the behaviour during cooking results to be satisfactory. As far as the thermal damage is concerned, the furosine values of fortified spaghetti differ only marginally from standard pasta and the percentage lysine loss is quite small (ranging from 12.1% to 15.7%).     

Analytical rheology as a tool for the structural investigation of citrus pectin

Rheological analysis of citrus pectin at pH 3 and 7 elucidates its structural dynamics, revealing distinct behaviors influenced by pH. At pH 3, pectin exhibits shear-thinning, with solvent-independent unified rheological profiles identifying three concentration regimes: 0.5%–1.5%, 2%–3%, and 3.5%–4%. These regimes, alongside Cox–Merz superpositions, outline the semi-dilute (c*) and concentrated (c**) transitions at 1.5%–2% and 3%–3.5%, respectively. Moreover, a Morris equation exponent of 0.65 indicates flexible, mobility-restricted macromolecules. Conversely, at pH 7, increased viscosities and Morris plot linearity for p = .1 suggest rigid chain behavior due to electrostatic repulsion among ionized acidic groups. This rigidity leads to concentration-dependent self-assembly structures that diverge from expected unified rheological profiles, a deviation amplified by heating–cooling cycles. This study clarifies the impact of pH on citrus pectin's rheology and emphasizes the intricate relationship between polymeric chain rigidity, self-assembly, and viscosity. By providing a refined understanding of these mechanisms, our findings contribute to the broader field of polysaccharide research, offering insights critical for developing and optimizing pectin-based applications in various industries.     

Chickpea protein isolates obtained by wet extraction as emulsifying agents

BACKGROUND: Wet extraction of protein from defatted chickpea (variety Thiva (T), Greece) flour, at alkaline or slightly acidic pH, followed by isoelectric precipitation (pI) or ultrafiltration (UF) to recover the protein, was employed to obtain a number of chickpea protein isolates, enriched either in protein constituents belonging to the globulin (TpI, TUF, TUFG) or to the albumin fraction (TUFA). RESULTS: The interfacial activity and film‐forming ability of the isolate protein constituents as well as their emulsifying properties were evaluated. The method applied for chickpea protein isolate preparation influenced to an appreciable extent their composition, adsorption behaviour to oil–water interfaces and emulsion formation and stabilization characteristics, especially with respect to oil droplet flocculation and coalescence. The isolates also differed in their ability to stabilize emulsions subjected to thermal processing or following storage under freezing conditions. The results are discussed in terms of compositional and, possibly, structural differences existing between the protein constituents of the chickpea isolates that may influence their functional behaviour in emulsion systems. CONCLUSION: The method applied for isolate preparation influenced to an appreciable extent the ability of proteins to adsorb to the oil–water interface and stabilize emulsions during long‐time ageing or following heat treatment or freezing. Copyright © 2009 Society of Chemical Industry     

Model salad dressing emulsion stability as affected by the type of the lupin seed protein isolate

Model salad dressing emulsions of an oil volume fraction of 0.50 were prepared using two types of lupin seed protein isolate (LSPI) differing in the method applied for their isolation and their protein composition. The dressing stability against creaming and droplet coalescence were studied and correlated with data on oil droplet size, rheological characteristics and the amount of protein adsorption at the droplet surfaces. Model salad dressing emulsions containing the isolate, mainly composed of lupin globulins, exhibited higher stability and more pronounced rheological characteristics compared to those prepared with the isolate enriched in albumins or with the mixture of the two isolates. The lupin albumins appeared to displace the globulins from the droplet surfaces, following competitive adsorption from mixtures of the two types of the lupin isolates. The results are discussed in terms of droplet interaction and rearrangement as they are influenced by the presence of the adsorbed protein molecules and aggregates which appear to determine long‐term stability of the emulsion systems. Copyright © 2006 Society of Chemical Industry     

Effect of medium molecular weight xanthan gum in rheology and stability of oil‐in‐water emulsion stabilized with legume proteins

Xanthan gum is a water‐soluble extracellular polysaccharide that has gained widespread commercial use because of its strong pseudoplasticity and tolerance to high ionic strength, which bring unique rheological properties to solutions. This study compares and evaluates the emulsifying properties of oil‐in‐water (30:70 v/v) emulsions stabilized with lupin and soya protein isolates and medium molecular weight xanthan gum. The protein was obtained by an isoelectric precipitation method and the polysaccharide was produced by Xanthomonas campestris ATCC 1395 in batch culture in a laboratory fermenter (LBG medium) without pH control. The addition of xanthan gum in the emulsion formulation enhances emulsion stability through the phenomenon of thermodynamic incompatibility with the legume protein, resulting in an increase of the adsorbed protein at the interface. The emulsion stability is also enhanced by a network structure built by the polysaccharide in the bulk phase. Copyright © 2005 Society of Chemical Industry