Plant-Derived Citrulline: From Agricultural Sources to Functional Food Applications

Citrulline, a non-protein amino acid, has recently gained prominence as a valuable functional food bioactive due to its many physiological and nutritional advantages.Citrulline is predominantly found in cucurbit vegetables (like watermelon, or Citrullus lanatus) and is an active participant in, among other things, the metabolism of plants (primarily through nitrogen cycling) and stress tolerance in plants.In addition to its applications in plants, there has been a steady increase in recent years in the use of citrulline in food science, especially for functional foods and nutraceuticals.This review will provide an overview of citrulline, including its distribution in agricultural commodities, its biosynthesis in plants, and its physicochemical properties that may be important for use in food systems.The effect of different processing and storage conditions (both from a raw and finished product perspective) on the stability of citrulline is reviewed with an emphasis on the need for the development of improved methods to help maintain the bioactivity of citrulline in foods.Extraction, isolation, and quantification methods are summarized so that citrulline may be efficiently used in food formulations.A brief discussion of citrulline bioavailability, metabolic fate of citrulline in human beings, and the associated health benefits of citrulline (such as its role in nitric oxide production, cardiovascular support, and improved muscle metabolism) is also provided.This review examines the growing trend of utilizing citrulline in the development of new products using food technology.A wide range of viable methods for incorporating citrulline into food products is evaluated, as well as several new and innovative delivery methods.The review focuses on the use of sustainable methods to obtain citrulline, such as the use of agricultural byproducts, such as watermelon rinds, which are a particularly rich source of citrulline.Ultimately, this review shows that citrulline has considerable potential as a valuable bioactive compound that can improve food quality and enhance food production sustainability in an environmentally friendly manner.