Plants and algae are the main sources of natural bioactive compounds used in the food and pharmaceutical industries. It is very important to achieve an efficient and safe technique to recover bioactive compounds while maintaining their quality and properties. Subcritical water extraction is the most promising engineering approach that offers an environmentally friendly technique for extracting various compounds from plants and algae. Application of pressurized water and high temperature in subcritical phase is able to modify the dielectric constant and polarity of the solvent which then contributes to a better extraction process. The technique improves the mass transfer rate and preserves the biological potency of the extracts. This article reviews current studies on the extraction of bioactive compounds from various species of plants and algae using the subcritical water technique and discusses its effects and benefits for the food and pharmaceutical industries.

The lack of water on a global level has a direct impact on the development of agriculture and food industry, which is directly reflected in the in the increase of food production. The fact that water is a limiting factor in the production of food and the knowledge that a large number of people dying of starvation, indicating the importance of water in food industry. In addition to the food industry, pharmaceutical industry is also directly related to human health. Both of these industries not only consume large amounts of water but also have specific requirements in terms of the quality and water conditioning. Due to the high level of quality, these waters are subject to special statutory supervision, in which chemicals are without certificates FDA (Food and Drug Administration) should not be added to the water, whether it is a water treatment or conditioning. Requests of this kind often cause problems and limit the development of the food and pharmaceutical industries.