Optimization of Optical Properties of Plant-Based Foods

Plant-based foods are considered to be more sustainable food source than animal-based foods due to their lower environmental impact. However, there is a challenge in producing plant-based foods with similar taste, texture, and appearance to animal-based products to meet consumers expectations. The appearance, which includes color, is the first sensory attribute consumers experience of foods, and so it influences consumers’ buying decisions. Food colorants are added to match the color of plant-based foods with animal-based ones. The food colorant choice is shifting toward natural colorants due to their perceived health benefits and clean-label aspects. Therefore, this study aimed to optimize the optical properties of plant-based foods using natural food colorants. Initially, the impact of natural pigments that selectively absorb light (turmeric, red beet, and butterfly pea flower) and colloidal particles that selectively scatter light (oil droplets) on the optical properties of model plant-based oil-in-water emulsions was investigated. It was found the pigment and oil droplet characteristics, including pigment type and concentration, and droplet size and concentration, could be adjusted to modulate the chromaticness or lightness of emulsions by altering light absorption and scattering effects. This knowledge is useful to optimizing the appearance of plant-based foods by adjusting these parameters. Then, natural pigments with three primary colors (yellow, red, and blue) were blended to mimic the color of animal-based products (raw meat, cooked meats, egg, and cheese). A color matching model developed from Kubelka-Munk and color theories was then used to determine the optimum ratio of each colorant needed to match the spectral reflectance of animal-based products. The methodology developed was able to optimize the color of model plant-based emulsions to that of different food matrices. The improved understanding of the optical properties of natural pigments and color matching theory developed in this study should help to formulate plant-based foods with more similar appearances to animal-based products, thereby increasing consumers’ acceptance of plant-based foods