Unconventional methods for food preservation and recovery of phytochemicals from plant wastes: towards a science for sustainable development

Plants are irreplaceable sources of food and bioactive phytochemicals. In this sense, this work has been focused on valorisation and processing of traditional plant foods, including medicinal plants (consumed in herbal beverages), leafy vegetables, and tomato farmers’ varieties, but also biowastes (source of biomolecules), using non-conventional and emerging technologies [1]. The preservation of dried medicinal plants (Tuberaria lignosa (Sweet) Samp. and Malva neglecta Wallr.) and fresh vegetables (Nasturtium officinale R. Br. and Rumex induratus Boiss. & Reut.) by using gamma irradiation treatments [2–4] and/or inert gas-enriched modified atmospheres [4,6] was investigated. The main goal was to ensure food safety and shelf-life extension without negatively affect quality parameters, and therefore reduce food waste. Argon was a suitable choice for preserving the overall postharvest quality of the selected vegetables during refrigerated storage. The adequacy of post-packaging irradiation treatments for shelf-life extension was also demonstrated. This extensive work also highlights the bioactive compounds of tomatoes as health promoters [7] and described for the 1st time the chemical and nutritional composition of four tomato farmers’ varieties in Northeastern Portugal homegardens [8,9]. The optimization of microwave- and high pressure-assisted extraction processes for recovery of valuable phytochemicals and production of antioxidant and nutrient-rich ingredients has been carried out using response surface methodology. Relevant independent variables and optimal processing condition for recovery of hydrophilic and lipophilic antioxidants [10] and phenolic compounds [11] from tomato wastes were determined. Green solvents have been used. The current research focuses on the optimization of high pressure-assisted extraction of phenolic compounds from N. officinale and in the effects of the treatment on antioxidant and antitumor properties of this fast growing cruciferous plant rich in glucosinolates. It is also intended to investigate the combined effects of modified atmosphere packaging and antioxidant coatings in the preservation of plant foods.PRODER - Project AROMAP for financial support of the work; FCT (Portugal) for financial support to CIMO (UID/AGR/00690/2013), REQUIMTE (UID/ QUI/50006/2013 - POCI/01/0145/FERDER/007265) and J. Pinela (SFRH/BD/92994/2013); L. Barros for the expertise in chromatographic techniques; A.L. Antonio and S. Cabo Verde for the ionizing radiation treatments; M.A. Prieto for the optimization statistics tools; J.C.M. Barreira for the statistical analysis; M.F. Barreiro for the microwave equipment; and J.A. Saraiva for the ongoing work on high hydrostatic pressure.