Creating Novel Structures in Food Materials: The Role of Well-Defined Shear Flow

Abstract

Structure formation in food materials is influenced by the ingredient properties and processing conditions. Until now, small structural elements, such as fibrils and crystals, have been formed using self-assembly, while processing was applied to create relatively large structures. The effect of self-assembly under flow is rarely studied for food materials, but it is widely studied for non-food systems. The use of well-defined flow, often simple shear, turned out to be essential to study and control the structure formation process in foods as well. This observation encouraged us to develop a number of different shearing devices that allowed processing of biopolymer systems under simple shear flow. This paper reviews our main findings. In the case of protein fibrillization, the shear rate was found to control the growth rate as well as the properties of the fibrils formed. In the case of dough processing, simple shear flow made the product more process tolerant and induced gluten migration. The use of shear flow for dense caseinate dispersions led to hierarchically structured and fibrous material. Based on the presented results, we conclude that introducing simple shear flow in food structuring processes can lead to a much broader range of structures, thereby better utilizing the full potential of food ingredients.

Microstructure of hydrated gluten network

“…A fibrous network would imply that fibers would have high degree of molecular orientation and linked by intramolecular bonds such as in collagen or cellulose (Gupta & Kothari, 1997). We now know that to produce fibers from gluten proteins requires chemical modification and special processing conditions (Athamneh & Barone, 2009;Reddy & Yang, 2007;Van Der Goot, Peighambardoust, Akkermans, & Van Oosten-Manski, 2008). Although some fiber-like structures may appear in micrographs of this early work they should be attributed mostly to shear forces that have been exerted to the samples during sample preparation prior to imaging.…”

Chitosan Nanoparticles as a Promising Nanomaterial for Encapsulation of Pomegranate (Punica granatum L.) Peel Extract as a Natural Source of Antioxidants

“…ImageJ (an open-source imaging freeware developed by the National Institutes of Health, MD, USA) was used to quantify particle size diameter and distribution [59,60]. After setting the scale of SEM images to the measured scale-bar value (500 nm), a manual mode of measuring particle diameter (length) was applied on the particles specified in Figure 3a2,b2 [61,62]. The results of particle number count, minimum, maximum and mean diameters, and standard deviations extracted from SEM images are shown in Table 4.…”

Viscoelastic phase separation in soft matter and foods

“…94 Unlike the formation of a rather narrow domain size distribution in simple shear, shear induced migration may lead to macroscopic phase separation under shear gradient or curve linear flow. 157 Such migration phenomena may also been described in terms of the two fluid model similar to the viscoelastic model 158 by considering effects of normal stress differences. 159 Furthermore, flow can generate anisotropic structures such as layered structures and fibrous structures, which provide anisotropic mechanical properties sometimes useful for food products known as anisotropic protein-rich foods.…”