Plant-Derived Phytonutritional Ingredients for Food and Pet Food: Processing, Functionality, and Applications

Processing modifies the structure, nutritional characteristics, and technological properties of plant-derived food matrices, but findings from isolated ingredients and experimental models do not necessarily describe their performance in finished foods. This selective narrative review examines five processing-responsive matrix categories relevant to functional-food development: legume-derived protein–carbohydrate matrices, resistant and slowly digestible carbohydrates, plant-derived dietary fibers, prebiotic fibers and oligosaccharides, and fermented plant ingredients. Evidence from human-food research is synthesized to examine the effects of thermal, enzymatic, mechanical, pressure-based, extraction, and fermentation processes on matrix properties, digestibility, fermentability, and food applications. Physicochemical, in vitro, cellular, animal-model, and human-intervention findings are distinguished according to their experimental systems. Feeding studies in dogs and cats are considered separately as application-level evidence from formulated diets, with emphasis on nutrient digestibility, fecal characteristics, fermentation metabolites, microbiota responses, postprandial glycemic responses, and dietary acceptance. Reported outcomes differ with ingredient composition, processing conditions, inclusion level, and dietary formulation, while the heterogeneity and limited duration of many feeding studies restrict conclusions about longer-term physiological effects. Across the selected literature, matrix properties measured before food manufacture require separate evaluation after formulation, and experimental indicators of functionality should not be treated as demonstrated health benefits without appropriate evidence. The review provides a processing–matrix–function framework for interpreting plant-derived ingredients in finished foods while identifying limitations in the assessment of their physiological relevance.