A systematic comparison of the intrinsic properties of wheat and oat bran fractions and their effects on dough and bread properties : Elucidation of chemical mechanisms, water binding, and steric hindrance

This study aimed at elucidating the contribution of chemical interactions, water binding, and steric hindrance on the effect of wheat and oat brans and of their fractions, i.e., soluble and insoluble, on dough and bread properties. For such purpose, an inert filler, i.e., glass beads of comparable particle size and with no water binding capacity and moisture sorption properties, was also studied. The glass beads provided breads most similar to the control, indicating the limited role of steric hindrance. Brans and bran fractions showed distinct compositional and physical properties. The soluble fraction from oat bran, rich in β-glucan, was less hygroscopic than the wheat counterpart and could bind more water, resulting in larger detrimental effects on bread quality. The β-glucan content showed a prevalent role in affecting gluten development, the thermo-setting behaviour of the dough, and crumb texture, i.e., cohesiveness and resilience. Overall, the comparison between the two brans and their fractions indicated that the interplay between water binding, mainly provided by the insoluble fraction, and the plasticizing properties of the soluble bran fraction controlled the effects on bread volume and texture. From a compositional standpoint, β-glucan content was a determining factor that discriminated the effects of wheat and oat brans

Valorisation of proteins from palm kernel meal

A process to extract proteins from palm kernel meal was investigated. A sequence of unit operations was implemented and optimized in order to ensure an optimal process efficacy. It has been determined that among all the enzymes that were tested, Alcalase had the highest capacity to hydrolyse proteins and solubilize them in solution, especially after using 5% dry matter of PKM as a starting material. Thus, 80% of the proteins were solubilized in the supernatant after Alcalase treatment, but only 60% of the proteins were recovered in the permeate after applying ultrafiltration (300 kDa), with a purity of 60%. Functionality tests revealed that the protein fraction obtained had a very high solubility and a mild foaming and emulsification capacity

The impact of heating and freeze or spray drying on the interface and foam stabilising properties of pea protein extracts : Explained by aggregation and protein composition

The processing of plant protein extracts can affect the protein structure, leading to altered functional properties. In this work, we evaluated the impact of two common processes in pea protein extraction: heating and drying. Non-heated and heated (5 min at 95 °C) samples were compared, which were either freeze- or spray-dried. These processes led to alterations of the proteins, and resulted in changes of their interface and foam-stabilising properties. A mild protein extraction method was used to preserve the native protein structure during aqueous extraction, allowing the extraction of both albumin and globulin proteins. Spray-drying of these fractions led to higher surface hydrophobicity, which resulted in increased surface activity and stiffer interfacial layers at pH 3.8 and 7.0. The heating step induced aggregation of the globulins, while albumins remained soluble. Here, we demonstrated that the albumins had a dominant effect on the interfacial (rheology and ellipsometry) and foaming properties after heating, as the globulin aggregates were too large for effective interface stabilisation. A similar mechanism was also shown at pH 3.8, where the globulins precipitated, as the pH was close to their pI, while albumins remained soluble. Again, the albumins dictated the interfacial properties, leading to highly stable foams after removing the insoluble globulins. We have shown marginal differences in protein functionality after freeze- or spray-drying. More importantly, the changes in soluble protein composition dictate the protein functionality after heating or pH shifts