Effect of different vegetable oils on extruded plant-based meat analogs: Evaluation of oxidative degradation, textural, rheological, tribological and sensory properties

Vegetable oils are often added during high moisture extrusion of plant-based meat analogs to improve their textural and sensory quality. However, the impact of extrusion processing on lipid degradation often receives minimal attention, despite its potential to reduce the nutritional and sensory quality of the product. Therefore, in this study the influence of four different oil types (MCT, coconut, olive and grapeseed oil) at different oil concentrations (0, 3, 6%) on the extrusion process and relevant quality characteristics of wheat gluten-based meat analogs was evaluated. The vegetable oils were added as emulsions, and the die pressure measured during processing, as well as the rheological, textural, tribological and sensory properties of the extrudates were characterized as a function of oil concentration and oil type. Extrudates without oil showed significantly higher storage moduli, which correlated with higher firmness and chewiness as measured by texture profile analysis. With increasing oil concentration, storage modulus, firmness and chewiness decreased significantly for all oil types, which was reflected in a higher perception of tenderness during sensory evaluation. Determination of polar compounds of the oils before and after extrusion processing showed that oils with a high degree of unsaturation, i.e., olive oil and grapeseed oil, are more susceptible to lipid oxidation caused by high moisture extrusion. However, sensory evaluation did not reveal any rancid off-flavors associated with lipid oxidation in any of the extrudates, irrespective of oil type. Future studies could involve the evolution of oxidative degradation during shelf-life, and its implications on sensory properties.