{"id":142300,"date":"2024-04-18T07:20:00","date_gmt":"2024-04-18T05:20:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=142300"},"modified":"2024-04-15T14:55:03","modified_gmt":"2024-04-15T12:55:03","slug":"avocado-tree-waste-used-to-make-sustainable-food-packaging","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/avocado-tree-waste-used-to-make-sustainable-food-packaging\/","title":{"rendered":"Avocado tree waste used to make sustainable food packaging"},"content":{"rendered":"\n\n\n

Although plastic has allowed for convenient, hygienic food packaging, plastic waste<\/a> continues to be a major problem for the environment<\/a>. To make food packaging more sustainable, researchers at the University of C\u00f3rdoba and the University of Girona in Spain turned to avocado pruning residue<\/a> \u2014 the branches and leaves removed from avocado trees annually.<\/p>\n\n\n

\n
\"\"
\u00a9 Robin Kutesa\u00a0on Unsplash<\/figcaption><\/figure><\/div>\n\n\n

This residue is a source of biomass<\/a>, the term given to plant-based materials not consumed as food. Spain\u2019s southern region of Andaluc\u00eda is ripe with fruit trees, particularly avocado.<\/p>\n\n\n\n

\u201cCompared to other avocado byproducts, like pulp and seed, avocado pruning residue has a high cellulose content, similar to other agricultural tree species,\u201d said Eduardo Espinosa, assistant professor at the Chemical Institute for Energy and the Environment at the University of C\u00f3rdoba, and one of the material\u2019s developers.<\/p>\n\n\n\n

Cellulose<\/a>, a biopolymer found in plants<\/a>, can be processed into fibers for the reinforcement of synthetic materials, like polyethylene, a nontoxic, inexpensive plastic that has been essential to keeping foods fresh and contamination free<\/a>. <\/p>\n\n\n\n

However, polyethylene is normally derived from fossil fuels<\/a> and is non-biodegradable, making it unsustainable. Polyethylene produced from bioethanol, a fuel derived from plant-based sources, is a better alternative. <\/p>\n\n\n\n

Reinforcing polyethylene <\/strong><\/h3>\n\n\n\n

Espinosa and his colleagues aimed to make an environmentally friendly food packaging material by partially substituting bio-polyethylene with fibers extracted from avocado pruning residue.  <\/p>\n\n\n\n

To produce the lignocellulosic fibers, they concentrated the avocado pruning residue into a pulp and separated the fibers through a fractionation process that preserved some of the lignin \u2014 another major component of lignocellulosic biomass.<\/p>\n\n\n\n

\u201cThis retains interesting properties because the residual lignin content allows us to leverage the advantages of cellulose fibers along with the reactivity and properties provided by lignin,\u201d Espinosa explained.<\/p>\n\n\n\n

The researchers then prepared a composite from the bio-polyethylene and lignocellulosic fiber using a high-speed mixer. \u201cThe friction generated by the rotation melts the bioplastic and disperses the fibers in the matrix, creating the composite material,\u201d Espinosa stated. <\/p>\n\n\n\n

But an additive is needed to strengthen the interaction between the two materials, which are naturally incompatible owing to their different chemical structures \u2014 polyethylene is hydrophobic (water-hating) and the fiber is hydrophilic (water-loving). A compound called maleic anhydride, a common additive in plastic manufacturing, is the key to enhancing their compatibility. <\/p>\n\n\n\n

\u201cWhen maleic anhydride is added to the mixture, it positions itself between the fiber and the plastic, reducing the interfacial tension and bonding the two phases together,\u201d Espinosa said. This results in maleic-anhydride-grafted polyethylene.<\/p>\n\n\n\n

On a molecular level, the improved bonding interaction arises from the formation of carbon\u2013oxygen bonds between the maleic anhydride molecule and the surface of the lignocellulose fibers. Maleic anhydride also improves the load-bearing capacity of the composite at the interface between the fiber and polymer, which is usually the weakest phase of a composite material.<\/p>\n\n\n\n

Advantages of the biocomposite <\/strong><\/h3>\n\n\n\n

The composite is not only more biodegradable than bio-polyethylene but also stronger, partially due to the role of maleic anhydride and partially due to the inherent strength of natural fibers.<\/p>\n\n\n\n

\u201cNatural fibers possess strong mechanical properties. When these fibers are combined with a thermoplastic matrix like bio-polyethylene, they are dispersed and embedded within the plastic matrix, aiding in the transfer of loads when the material is subjected to mechanical stress,\u201d Espinosa explained.  <\/p>\n\n\n\n

\u201cUtilizing agricultural waste for biocomposite production adds value to what would otherwise be considered waste, promoting a circular economy and local resource utilization,\u201d he added.<\/p>\n\n\n\n

Espinosa also pointed out that their study focused on improving the mechanical properties, specifically the tensile strength, of bio-polyethylene. In reality, food packaging undergoes other types of mechanical stress<\/a>, such as flexural stress.<\/p>\n\n\n\n

\u201cAdditionally, the mechanical properties were measured at a temperature of 25\u00b0C and a relative humidity of 50%, which may not always reflect the conditions experienced by these materials during the food preservation period,\u201d he said.<\/p>\n\n\n\n

We also asked Espinosa if a food packaging material made entirely of lignocellulosic fibers would be practical. \u201cCreating food packaging entirely from the lignocellulosic fibers presents challenges,\u201d he responded. <\/p>\n\n\n\n

\u201cFood packaging demands various properties, especially mechanical strength and barrier properties,\u201d he continued. \u201cSince cellulose fibers are highly hygroscopic [they absorb moisture from the air], treating these fibers chemically, and\/or with other materials is necessary to develop food packaging materials with high lignocellulosic fiber content.\u201d<\/p>\n\n\n\n

In the future, the researchers plan to investigate the environmental impact of their process and assess its economic feasibility. They also need to conduct a shelf-life study of a specific food product using the avocado waste\u2013derived packaging material.  <\/p>\n\n\n\n

\u201cIt would be interesting to test the fibers as a possible raw material for the development of other food packaging formats [in addition to rigid packaging],\u201d Espinosa shared. \u201cThese include food films and edible coatings for fruits, among others.\u201d<\/p>\n\n\n\n

Reference <\/h3>\n\n\n\n

Ram\u00f3n Morcillo-Mart\u00edn, et al.,\u00a0<\/em>Avocado Pruning Residues for the Formulation of Bio-Based Polyethylene\/Fiber-Based Biocomposites for Sustainable Food Packaging<\/strong><\/a>. Advanced Sustainable Systems (2024). <\/em>DOI: 10.1002\/adsu.202300600<\/p>\n","protected":false},"excerpt":{"rendered":"

Although plastic has allowed for convenient, hygienic food packaging, plastic waste continues to be a major problem for the environment. To make food packaging more sustainable, researchers at the University of C\u00f3rdoba and the University of Girona in Spain turned to avocado pruning residue \u2014 the branches and leaves removed from avocado trees annually. This residue is a source of biomass, […]<\/p>\n","protected":false},"author":59,"featured_media":142321,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"A material derived from avocado pruning waste and bio-polyethylene combines high strength with biodegradability","footnotes":""},"categories":[5572],"tags":[11270,5842,22586,6162,23812,7105],"supplier":[2851,19244],"class_list":["post-142300","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bio-based","tag-biodegradability","tag-biomass","tag-biopolyethylene","tag-cellulose","tag-cellulosefibers","tag-packaging","supplier-university-of-cordoba","supplier-university-of-girona"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/142300","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=142300"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/142300\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media\/142321"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=142300"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=142300"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=142300"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=142300"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}