Pectin-based Films for Applications in the Horticultural Sector: a Preliminary Characterization

Abstract

Plastic containers in the horticulture sector largely rely on plastics of fossil origin. Although these plastics have excellent mechanical properties, resilience towards chemical/microbiological degradation, durability, and affordable price, they have a high environmental impact due to their inherent non-biodegradability. In line with the most recent EU strategies on a trans-sectorial transition to sustainable systems, the horticultural sector is seeking for new materials to produce plant nursery plugs as an alternative to conventional plastics. The present work is a part of the project "BBPlug”, which aims to add value to agri-food industry wastes, reducing plastics and fertilizers in horticulture. Here, we propose a new material made of pectin extracted from citrus peel as a green and biodegradable substrate to produce plant nursery plugs. To this purpose, pectin-based films were fabricated by solvent-casting from film-forming solutions with increasing amounts of glycerol as plasticizer (6.7 – 33.3 gGlycerol/gPectin), microfibrillated cellulose (MFC) as reinforcing agent (2.7 – 8.1 mgMFC/gPectin), and at two different pH values (3.5 and 7.0). Puncture resistance, water solubility, and oxygen-barrier properties of the films were then investigated. Films from formulations at pH = 3.5 exhibited an overall better mechanical behavior over their counterpart at pH = 7. The best puncture resistance and water solubility were displayed by films from the least glycerol-loaded formulations. The addition of MFC to the film-forming solution improved the oxygen-barrier properties of the films but led to a reduction in their water solubility. In other tests, a selection of different plant growth-promoting (PGP) bacteria was demonstrated to have a boosting effect on the development of a model vegetable (i.e., lettuce), thus offering creative opportunities for the advancement of the “BBPlug” project.