Fragrant rapeseed oils: A review in production, volatile flavor formation and regulation

Rapeseed oil is one of the most famous edible oils with high affordability and versatility. The fragrant rapeseed oil (FRO) is becoming the most consumed cooking oils in China due to its attractive color, unique flavor and rich nutrition. Presently, at least three types of commercial rapeseed oils, classified as strong, mellow, and light fragrant rapeseed oils (SFRO, MFRO, and LFRO), are produced and consumed, based on odor attributes and appearance originated from roasting, pressing, and refining steps. On this basis, the increasing efforts have been made to identify the compositions of volatile flavors of fragrant rapeseed oils, find the relationship between volatile flavor formation with production processes, and elucidate the forming pathways of characteristic volatile flavors in fragrant rapeseed oils. Herein, we provide a comprehensive overview of typical physical/chemical/nutritional/volatile difference of strong, mellow, and light fragrant rapeseed oils, outline the production processes to result in their difference, and summarize the strategies including optimizing the roasting, pressing, and refining conditions, and increasing the substrate supply to enhance the volatile flavors of fragrant rapeseed oils. Some remaining unanswered questions in improving the quality, retaining the nutrients and controlling formation of the hazards such as benzopyrene were also pointed out. The review hopefully presents a reasonable full picture of production, volatile flavor formation and regulation of fragrant rapeseed oils and benefits for providing the flavor-attractive, nutritional, healthy, and safe fragrant rapeseed oils in the near future.