Stability of aqueous food grade fibrillar systems against pH change

Abstract

We report that the stability of an aqueous food grade fibril system upon pH change is affected by the presence of peptides that are formed during the process of fibril formation. We discuss several other relationships between food relevant properties and nano-scale characteristics, and compare these relationships for aqueous fibril systems to those of oil based fibril systems. In such fibril systems, dynamics, self-organisation, and sensitivity to external conditions, play an important role. These aspects are common to complex systems in general and define the future challenge in relating functional properties of food to molecular scale properties of their ingredients.

Characterisation and use of β-lactoglobulin fibrils for microencapsulation of lipophilic ingredients and oxidative stability thereof

“…In contrast to these findings fibrils maintain their structure at pH's up to 8.0 when pH is increased after fibrillation. However, in a critical pH region (5-6), the fibrils aggregate and collapse (Jung and Mezzenga, 2009;Kroes-Nijboer et al, 2012a).…”

“…The authors identified the fraction of non-aggregated peptides in fibril solutions as being mainly responsible for the turbidity observed when pH is increased to pH 5.0 which is the isoelectric point of b-lactoglobulin. The potential of fibrils to solidify oil phases as alternative to triglycerides and plant sterols in food was also discussed by the same authors (Kroes-Nijboer et al, 2012a Fibrils were shown to exert a highly elastic behaviour at o/winterfaces during interfacial shear rheology analyses . Quite recently, Rühs et al (2013) showed distinct differences in shear and dilatational rheology properties of the different fractions present in fibrillar solutions, i.e.…”

“…Thermodynamic phase diagrams of b-lactoglobulin fibrils that have initially been prepared at pH 2.0 in dependence of concentration and pH values (2.0-7.5) were published by Jung and Mezzenga (2009). The stability of aqueous food grade fibrillar systems as a function of pH increase for future use in food was recently addressed by Kroes-Nijboer et al (2012a). The authors identified the fraction of non-aggregated peptides in fibril solutions as being mainly responsible for the turbidity observed when pH is increased to pH 5.0 which is the isoelectric point of b-lactoglobulin.…”

Cold-set hydrogels made of whey protein nanofibrils with different divalent cations

“…The acidic hydrolysis of proteins including ␤-lactoglobulin during the fibrillation process [15] is also noteworthy when assessing gelation. We argue that since not all of the acid-generated peptides are converted to fibrillar structures [14] and so remain as individual entities within the fibrillation-underwent solution, can impact the gelation behavior and gel characteristics of fibril solution. Non-fibrillated peptides possess much more negatively-charged carboxyl groups than parent protein molecules at identical mass concentrations, thus could be cross-linked ionically in a more efficient way than protein counterparts.…”

“…Veerman et al [2] also obtained calcium-induced cold-set hydrogels from fibrillated ␤-lactoglobulin solution at a lower protein concentration in comparison with heat-denatured solution. Fibrillar structures can form a space filling network at low volume fractions because of significant contour length, high aspect ratio and their random orientation [14]. The acidic hydrolysis of proteins including ␤-lactoglobulin during the fibrillation process [15] is also noteworthy when assessing gelation.…”