A.J. van der Goot

The science of food structuring

Food structuring is discussed from the viewpoints of soft matter physics and molecular gastronomy. Food is one of the most complex types of soft matter, with multiple dispersed phases and even hierarchical structure. Food structuring seems to be a kind of art, comprising a careful balance between forces driving the system towards equilibrium and arresting forces. A more scientific approach to this complex matter is desirable, using (1) concepts from soft matter physics, e.g. free energy and jamming, and (2) complex disperse system (CDS) notation as developed for molecular gastronomy. Combining CDS with state diagrams renders a new tool for the qualitative description of the complex process of making structured foods.

A new method to study simple shear processing of wheat gluten-starch mixtures

ABSTRACT This article introduces a new method that uses a shearing device to study the effect of simple shear on the overall properties of pasta-like products made from commercial wheat gluten-starch (GS) blends. The shear-processed GS samples had a lower cooking loss (CL) and a higher swelling index (SI) than unprocessed materials, suggesting the presence of a gluten phase surrounding starch granules. Pictures of dough micro-structure by confocal scanning laser microscopy (CSLM) showed the distribution of proteins in the shear-processed samples. This study revealed that simple shear processing could result in a product with relevant cooking properties as compared with those of commercial pasta. Increasing gluten content in GS mixtures led to a decrease in CL and an increase in maximum cutting stress of processed samples, whereas no clear correlation was found for SI values of sheared products. It was concluded that the new shearing device is unique in its capability to study the effect of pure shear defo...

The potential of aqueous fractionation of lupin seeds for high-protein foods

Aqueous fractionation of protein from lupin seeds was investigated as an alternative to the conventional wet fractionation processes, which make use of organic solvents. The effect of extraction temperature was studied and the consequences for downstream processing were analysed. Omitting the extraction of oil with organic solvents resulted in a protein isolate that contained 0.02-0.07 g oil g(-1) protein isolate, depending on the exact extraction conditions. Nevertheless, the protein functionality of the aqueous fractionated lupin protein isolate was similar to the conventional lupin protein isolate. The protein isolate suspension could be concentrated to 0.25 g mL(-1) using ultrafiltration, which provides a relevant concentration for a range of high-protein products. Based on the results, we conclude that aqueous fractionation can be a method to lower the environmental impact of the extraction of proteins from legumes that contain water- and dilute salt-soluble proteins.

Production of Glucose Syrups in Highly Concentrated Systems

We have investigated the hydrolysis of maltodextrins in a high concentration (up to 70%), by means of enzymatic and acid catalysis. The study revealed that the equilibrium compositions of the catalyzed reactions were kinetically determined by the selectivity of the catalyst, the substrate concentration and the reaction time. A model comprising a set of two kinetic equations was used to describe the hydrolysis and condensation reactions of glucoamylase‐catalyzed reactions, even to highly concentrated systems. Increased substrate concentration resulted in the formation of more condensation products. The enzyme inhibition was low and was found to be independent of the substrate concentration.

Factors Impeding Enzymatic Wheat Gluten Hydrolysis at High Solid Concentrations

Enzymatic wheat gluten hydrolysis at high solid concentrations is advantageous from an environmental and economic point of view. However, increased wheat gluten concentrations result in a concentration effect with a decreased hydrolysis rate at constant enzyme‐to‐substrate ratios and a decreased maximum attainable degree of hydrolysis (DH%). We here identified the underlying factors causing the concentration effect. Wheat gluten was hydrolyzed at solid concentrations from 4.4% to 70%. The decreased hydrolysis rate was present at all solid concentrations and at any time of the reaction. Mass transfer limitations, enzyme inhibition and water activity were shown to not cause this hydrolysis rate limitation up to 50% solids. However, the hydrolysis rate limitation can be, at least partly, explained by a second‐order enzyme inactivation process. Furthermore, mass transfer impeded the hydrolysis above 60% solids. Addition of enzyme after 24 h at high solid concentrations scarcely increased the DH%, suggesting that the maximum attainable DH% decreases at high solid concentrations. Reduced enzyme activities caused by low water activities can explain this DH% limitation. Finally, a possible influence of the plastein reaction on the DH% limitation is discussed. Biotechnol. Bioeng. 2014;111: 1304–1312.

Applicability of product-driven process synthesis to separation processes in food

The demand for more sustainable processing in the food industry is rising but requires structured methodologies to support the fast implementation of new economic and sustainable processes. Product-driven process synthesis (PDPS) is a recently established methodology facilitating the rapid development of feasible process alternatives for structured products, such as in mayonnaise, ice-cream, or margarine. Here, we present the application of the PDPS methodology to valorize okara, which is a by-product from soy milk production. It is produced in large amounts, but its use as food or feed is not fully exploited. Besides fibers, protein, and fat, it contains substantial amounts of isoflavones, which are high value components. This paper evaluates the PDPS-methodology for the design of an economic and sustainable process for the production of isoflavones from okara. The main challenge is to adapt the method in such a way that it is able to deal with a complex matrix as starting material. Therefore, the PDPS methodology may require extension. Nevertheless, it promises to be a useful tool also for fractionation of food materials.

Gluten protein composition in several fractions obtained by shear induced separation of wheat flour.

Recently, it was found that applying curvilinear shear flow in a cone-cone shearing device to wheat flour dough induces separation, resulting in a gluten-enriched fraction in the apex of the cone and gluten-depleted fraction at the outer part. This article describes whether fractionation of the various proteineous components occurs during and after separation of Soissons wheat flour. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size-exclusion high performance liquid chromatography (SE-HPLC) were found to be suitable techniques for this. It is concluded that all protein fractions migrate to the center of the cone as a result of which the composition of the gluten-enriched fraction remains rather similar to that in the original flour. However, the larger glutenin polymer fraction migrated faster, as a result of which the concentration of large polymers was increased with a factor 2.4 compared to that of Soissons flour. The concentration of monomers in the gluten-enriched fraction was decreased to 70% of the original concentration in the original wheat flour.