Natural blue food colorants: Consumer acceptance, current alternatives, trends, challenges, and future strategies

The food industry seeks to expand the color palette with natural colorants. Nevertheless, in nature, the blue color is rare compared to other colors. Despite synthetic colorants' effects on human health, synthetic blue colorants are largely used by the food industry. In this way, consumers usually associate the blue color with artificial ingredients. However, whether blue colorants obtained from natural sources were used in food production, would consumers better accept these products? The current demand for manufacturing food products with natural ingredients has increased the market interest for natural blue colorants. Therefore, this review summarizes the current scenario of synthetic blue colorants' use and the possible sources of natural colorants that the industry can use to replace them. Also, the challenges, alternatives, and future strategies are discussed. Although a considerable effort has been dedicated to searching for new blue colorants, they present some limitations: physical and chemical instability, the unfamiliarity of the blue color compound, and high-production cost. Among the blue colorant options, the compound formed by the reaction between genipin and primary amines seems to have the highest potential for industrial application. However, its composition, toxicity, physical and chemical stability in adverse processing and storage conditions are still unknown. •Natural blue colorants and their application in food products were discussed.•Studies on natural blue colorants have increased in the last years.•Natural blue foods and their promising market were evaluated.•Primary sources, solubility, physical and chemical stability of natural colorants were examined.•Blue synthetic dyes were compared to natural blue pigments.