Characterization of the mechanical properties of high-moisture meat analogues using low-intensity ultrasound: Linking mechanical properties to textural and nutritional quality attributes.

Plant-based meat analogues offer possible alternatives to meat consumption. However, many challenges remain to produce a palatable meat analogue as well as to understand the roles of different processing steps and ingredients on both the texture and nutritional properties of the final product. The goal of this paper is to help with addressing these challenges by using a low-intensity ultrasonic transmission technique, both online and 24 h after production, to investigate high-moisture meat analogues made from a blend of soy and wheat proteins. To understand the ultrasonic data in the context of traditional characterization methods, physical properties (meat analogue thickness, density, peak cutting force) and protein nutritional quality attributes of the meat analogues were also characterized separately. The ultrasonic velocity was found to decrease with the feed moisture content and to be strongly correlated (r = 0.97) with peak cutting force. This strong correlation extends over a wide range of moisture contents from 58% to 70%, with the velocity decreasing from about 1730 m/s to 1660 m/s over this range. The protein quality was high for all moistures, with the highest amino acid score and in vitro protein digestibility being observed for the highest moisture content treatment. The accuracy of the ultrasonic measurements was enhanced by the development of an innovative non-contact method, suitable for materials exhibiting low ultrasonic attenuation, to measure the meat analogue thickness ultrasonically and in a sanitary fashion - an advance that is potentially useful for online monitoring of production problems (e.g., extruder barrel-fill and cooling-die temperature issues). This study demonstrates, for the first time, the feasibility of using ultrasonic transmission techniques to measure both velocity and sample thickness simultaneously and provide information in real time during production that is well correlated with some textural and nutritional attributes of meat analogues.

X-Ray microtomography imaging of red lentil puffed snacks: Processing conditions, microstructure and texture.

Red lentils have a great potential to be used as healthy ingredients in puffed snacks due to their excellent nutritional qualities. However, these types of ingredients with relatively higher protein and fiber content when compared to ingredients that are typically used for the manufacture of puffed foods (e.g., refined cereal flours/starches) result in inferior textural quality. Extrusion processing parameters such as screw speed, moisture content and injection pressure of a blowing agent can be manipulated to optimize the microstructure of an extrudate, and as a consequence the texture of the final puffed product. In this study, X-Ray microtomography imaging is used to characterize and quantify the detailed microstructure of red lentil extrudates. The results indicate that an increase in the injected pressure of the physical blowing agent could be correlated with a decrease in mean cell size and wall thickness, as well as an increase in the number of cells. Evidence of wall rupture with an increased screw speed is also visible, and that effect can be counterbalanced by a higher moisture content during processing. A large variation of the cell wall thickness inside an extrudate (which can induce a weaker cellular structure) as well as a larger cell size and higher amount of wall rupture, significantly reduce the hardness of extrudates. This novel effort to quantitatively characterize the microstructure of red lentil extrudates using X-Ray microtomography establishes that an optimal product texture could, in principle, be achieved by manipulating extrusion parameters to achieve the perfect snack texture.

Bubbles in noodle dough: Characterization by X-ray microtomography.

Bubbles, found in a huge variety of food products, are known to afford desirable quality attributes, especially those related to texture, mouthfeel and taste. However, the presence of bubbles and their effects on wheat flour noodles is an aspect that has been, until now, largely overlooked, despite the positive and negative connotations of bubbly inclusions on Asian noodle quality. X-rays from a synchrotron source (Biomedical Imaging and Therapy facility at the Canadian Light Source) were used to rapidly and non-destructively acquire tomographic images of noodle dough. Appropriate image analysis protocols were used to determine the bubble size distribution, the orientation of bubbles, and their position within the dough sheet. The effect of processing (one or multiple lamination steps) on bubble properties in the dough that was subsequently sheeted (gradual elongation and reduction in thickness) was investigated. Bubble size distributions, well captured by lognormal distribution function, showed that the lamination process induced bubble entrapment and reduction in bubble size. Bubbles were found to be flat, elongated and oriented in the sheeting direction, this effect being less for doughs laminated ten times (90° rotations between lamination steps). Interestingly, a gradient in concentration of bubbles within the dough sheet was found from the noodle core to the sheet edges. Aging effects were also apparent. This first non-destructive study of bubbles in wheat-flour noodle dough provides a more complete knowledge of the dough sheet's internal structure, and how it originates via processing, and this has repercussions on the overall quality of Asian noodles.