Influence of protein and solid fat content on mechanical properties and comminution behavior of structured plant-based lipids.

Recently an approach has been developed to structure plant-based lipids with the intention to mimic animal fat tissue in processed meat products or analogues. This study investigated the comminution behavior in a bowl chopper of such structured lipids with varying mechanical properties. For products like salami-type sausages these systems need to withstand comminution to yield particles for inclusion in product matrices. Therefore, samples were prepared from protein suspensions with 6%, 8%, 10%, and 12% soy protein isolate (SPI) and 70% (w/w) total fat with varying solid fat contents (0-30%, w/w). The hardness of samples prepared with 6% and 8% SPI varied between 4.5 and 35.9 N. When comminuted in a bowl chopper, these structures had insufficient mechanical strengths to facilitate the formation of small particles and yielded a coarse paste. Higher concentrations of protein increased hardness (15.9-76.2 N and 15.6-96.1 N, for 10% and 12% SPI, respectively). These samples retained their structural integrity upon comminution yielding individual intact particles. The size of these particles increased with sample firmness, i.e. with increasing amount of protein. The shape of the particles was more elongated the higher the solid fat content as indicated by a higher aspect ratio. Taken together, results show that structural characteristics of the gelled emulsions can be tuned to yield desired fat particles after comminution.

Formation and characterization of plant-based emulsified and crosslinked fat crystal networks to mimic animal fat tissue.

Animal fat tissue (that is, pork or beef fat) is composed of liquid and solid fat incorporated in a network of connective tissue. Hence, their rheological and thermal properties may differ significantly from plant-derived fats. Specifically, animal fats have elastic and melting properties that give rise to not only a certain comminution behavior during processing, but also provide meat products such as sausages with certain organoleptic properties. To mimic key properties of animal fat tissue with plant-derived materials, a new structuring approach was used. Canola oil was mixed with <30% (w/w) of fully hydrogenated canola oil at 65 °C, hot-emulsified with a soy protein suspension (8%, w/w) at a lipid content of 70% (w/w) using a high-shear disperser, and cooled to 37 °C. The concentrated, emulsified fat crystal networks were then incubated with transglutaminase for 1 hr to induce protein crosslinking. Microscopy images showed that samples were composed of tightly packed lipid particles with regions of coalesced or unemulsified lipids appearing at higher solid fat concentrations. Texture analysis and rheological measurements showed that crosslinked samples possessed elasticities that decreased with increasing solid fat concentration. Above 30% solid fat, matrices reverted back to exhibiting a mainly plastic behavior. Results were attributed to the formation of either a droplet-filled protein network, a particulate fat crystal network, or a mixture thereof. Taken together, results show that plant-based crosslinked emulsified fat crystal networks are able to mimic mechanical properties of animal fat provided that not too much solid fat (<30% in this study) is used. This makes them useful for the manufacture of meat products or analogues. PRACTICAL APPLICATION: This study introduced a new structuring approach to mimic properties of animal fat tissue with only plant-derived materials. The structured lipids can, for example, be used for the manufacture of processed meat analogues.

Modulation of the bitterness of pea and potato proteins by a complex coacervation method.

The incorporation of novel plant-based proteins into foods is often challenging due to an unacceptable bitter sensation. Typically, a combination of electrostatic and hydrophobic forces contributes to the proteins' bitterness. The current study therefore focuses on the development of electrical properties on cationic plant proteins to reduce their overall bitterness in order to improve the perceived sensorial acceptance. As such, we utilized a simple mixing process to induce complex coacervation of oppositely charged biopolymers under acidic conditions. Pea and potato protein stock solutions were mixed with apple pectin (DE 71%) solutions at various biopolymer ratios to modulate the electrical, rheological, and sensorial properties of the complexes. Whey protein hydrolyzate was used as a control sample. Surface charge measurements revealed a transition from positive to negative values as the pectin concentration was increased regardless of the plant protein, whereas stable dispersions without sedimentation were observed above a critical pectin : protein ratio of 1. Low and intermediate biopolymer ratios (<1) promoted aggregation and led to rapid sedimentation. Sensory evaluation showed that bitterness scores depended on protein type and decreased from pea protein > potato protein > whey protein. Moreover, bitter off-notes were increasingly reduced with increasing pectin : protein ratios; however, high dispersion viscosities above 0.05 Pa s led to undesirable texture and mouthfeel of the biopolymer dispersions. Our results might have important implications for the utilization of novel plant proteins in food and beverage applications.