Recent Publications

Upcycling Orange Peel Agricultural Waste for the Preparation of Green Hydrogels as Active Soil Conditioners. Danila Merino et al. 2023.

Abstract: In this work, agar (Aa)-based hydrogels were developed incorporating different concentrations of orange peel (OP) particles, pretreated using three different methods (hydrolysis, ultrasonication, or simple suspension in hot water), and 1.5 wt % limonene (LMN), to be tested as active soil conditioners for agriculture. The results of swelling of these hydrogels in distilled and tap water showed that acid hydrolysis or ultrasonication pretreatments of OP are counterproductive and that the simplest and lowest-energy method of OP pretreatment resulted in the most efficient hydrogels in terms of swelling. The incorporation of LMN into the Aa-based hydrogels increased their swelling capacity in tap water, while the incorporation of OP particles in the Aa+LMN hydrogels increased the number and decreased the size of their pores but did not significantly influence their swelling capacity, which ranged from 650 to 700% after 4 h of immersion. The hydrogels developed here were prepared with up to 50 wt % OP particles due to the increased water solubility for higher concentrations. The biopesticide activity of the hydrogels was investigated against the bacterium Pseudomonas syringe pv tomato DC3000 (Psy) and the necrotrophic fungus Fusarium solani f. sp. eumartii (F. eumartii), while the ability of the hydrogels as soil conditioners to retain soil moisture under simulated drought conditions was exploratorily investigated in tomato plants. The results demonstrate that even if the hydrogels did not show biopesticide activity against the studied microorganisms, the addition of 2.5 wt % hydrogel to the substrate significantly increased the moisture content of the soil and consequently improved the relative water content of tomato leaves under drought stress.

Chapter 3 - From waste to resource: Methods for vegetable waste transformation into sustainable plant-based bioplastics. Ana Isabel Quilez-Molina & Danila Merino. 2023.

Abstract: Plant biomass is the most abundant renewable resource on Earth and the most promising substitute for petroleum feedstock. It is the source of polymers such as cellulose, starch, pectin, and other active compounds with antioxidant and antimicrobial properties. Although plant-biomass-derived polymers have been used to prepare bioplastics for more than a century, forefront methods for biomass deconstruction and reassembling into biocomposites have recently been proposed. These methods are expected to significantly impact the future since their use in new value-added products complies with the zero waste and circular economy principles. This chapter offers an updated overview of the traditional and emerging methods used to convert vegetable wastes into sustainable plant-based bioplastics. In addition, we outline some challenges and future research directions needed to explore their full potential.