Developed countries, generates annually million tonnes of by-products such as potato cull, barley straws, hull … These products have valuable components (cellulose, sugars, starch) which can be used as stabilized, bioethanol, sweetener etc. Thanks to subcritical and supercritical processes, it is possible to extract and keep the valuable components. For example, using subcritical water technology, laboratories have hydrolysed straws to generate nano cellulose and phenolic. Department of agricultural food and nutritional science of the university of Alberta Canada, studies showed that at optimized conditions, hemi cellulosic sugars recovery in the extract was found to be more than 72% and antioxidant activity of extracts obtained related to total phenolic content. According to scientist Marleny Saldana, bioactive films prolong ham shelf-life to 25 days (instead of 7 days). Therefore, Sub and supercritical processes are suitable technologies.