Avocado Peels and Seeds: Processing Strategies for the Development of Highly Antioxidant Bioplastic Films

Abstract

The industrial processing of avocados annually generates more than 1.2 million tons of avocado peels (APs) and avocado seeds (ASs) that have great potential in the production of active bioplastics, although they have never been considered for this aim until now. Separately, the APs and ASs, as well as a combination of avocado peels and seeds (APSs), were evaluated here for the first time for the preparation of antioxidant films, with application in food packaging. Films were prepared by casting, after their processing by three different methods: (1) hydrolysis in acid media, (2) hydrolysis followed by plasticization, and (3) hydrolysis and plasticization followed by blending with pectin polymers in different proportions (25 and 50 wt %). The results indicate that the combination of hydrolysis, plasticization, and pectin blending is essential to obtain materials with competitive mechanical properties, optical clarity, excellent oxygen barrier properties, high antioxidant activity, biodegradability, and migration of components in TENAX suitable for food contact applications. In addition, the materials prepared with APSs are advantageous from the point of view of the industrial waste valorization, since the entire avocado wastes are used for the production of bioplastics, avoiding further separation processes for their valorization.

Food and cosmetic applications of the avocado seed: a review

“…Employing acid hydrolysis, plasticizer, and pectin crosslinking, biodegradable and active food packaging was developed. 24 The elongation at break of their environmentally friendly avocado seed bioplastic exceeded that of previous studies. 24 Their avocado seed bioplastic achieved tensile strength of 18.5 ± 1.3 and elongation at break percentage of 13.8 ± 2.4.…”

“…24 Their avocado seed bioplastic achieved tensile strength of 18.5 ± 1.3 and elongation at break percentage of 13.8 ± 2.4. 24 This bioplastic also demonstrated significant antioxidant activity, contributing to its oxygen barrier properties. 24 Although these studies show the potential of avocado seed application in bioplastic production, there are still many problems that need to be addressed.…”

A second life for fruit and vegetable waste: a review on bioplastic films and coatings for potential food protection applications

“…106 Besides, when the fiber content is high, the biocomposites can be blended with other amorphous polymers acting as binding agents. 66…”

“…Bioplastic films, intended for various applications among which also food packaging, are then obtained mainly through techniques such as blending, solution casting, [66][67][68] chemical synthesis starting from the monomers, 69,70 to obtain biopolymers that can be processed by thermomechanical processes like extrusion. [71][72][73] Concerning bioplastic coatings, liquid solutions containing biopolymers and active phytochemicals can be applied onto substrates, i.e.…”

“…133 Furthermore, lignocellulosic biomass was also reported to provide antioxidant properties to bioplastics. For instance, antioxidant bioplastics were reported for thermoplastic corn starch composites prepared upon melt blending and compression molding with rice and coffee husks, 110 and for pectin composites films obtained by casting with avocado peels, 66 measured this property in all cases against the DPPH radical.…”