A comprehensive review and recent advances of vitamin C: Overview, functions, sources, applications, market survey and processes

Vitamin C is widely applied in different industries such as cosmetics, feedstocks, food, and beverages which contribute greatly to the growth of the market and demand for pure vitamin C shown in the increasing market trends. This resulted in the advent of various simpler process technologies to address the limitations of previous technologies. The process technologies include conventional Reichstein, conventional two-step fermentation, new two-step fermentation, and the latest one-step fermentation process that is yet to be industrially scaled due to hardships in stability developments. However, the focus is generally given to the upstream processes meanwhile the downstream that covers the purification and recovery of vitamin C has been given limited focus and research. Moreover, this review paper also provides insights into various aspects of vitamin C including the functions, applications, and daily dosage required by different individuals to ensure vitamin C deficiency is avoided, which studies have shown that not only low- or middle-income countries covering Asia and Africa but also approximately 40% of the United States population experience vitamin C deficiency. Moreover, the paper also focuses on the stability and novel drug delivery system for vitamin C to provide a more holistic understanding of vitamin C.