polymers Review Biodegradable Packaging Materials from Animal Processing Co-Products and Wastes: An Overview Diako Khodaei, Carlos Álvarez and Anne Maria Mullen * Department of Food Quality and Sensory Science, Teagasc Food Research Centre, Ashtown, Dublin, Ireland; [email protected] (D.K.); [email protected] (C.Á.) * Correspondence: [email protected]; Tel.: +353-(1)-8059521 Abstract: Biodegradable polymers are non-toxic, environmentally friendly biopolymers with con- siderable mechanical and barrier properties that can be degraded in industrial or home composting conditions. These biopolymers can be generated from sustainable natural sources or from the agri- cultural and animal processing co-products and wastes. Animals processing co-products are low value, underutilized, non-meat components that are generally generated from meat processing or slaughterhouse such as hide, blood, some offal etc. These are often converted into low-value products such as animal feed or in some cases disposed of as waste. Collagen, gelatin, keratin, myofibrillar proteins, and chitosan are the major value-added biopolymers obtained from the processing of animal’s products. While these have many applications in food and pharmaceutical industries, a sig- nificant amount is underutilized and therefore hold potential for use in the generation of bioplastics. This review summarizes the research progress on the utilization of meat processing co-products to fabricate biodegradable polymers with the main focus on food industry applications. In addition, the factors affecting the application of biodegradable polymers in the packaging sector, their current industrial status, and regulations are also discussed. Citation: Khodaei, D.; Álvarez, C.; Mullen, A.M. Biodegradable Keywords: biodegradable polymers; packaging materials; meat co-products; animal by-products; Packaging Materials from Animal protein films Processing Co-Products and Wastes: An Overview. Polymers 2021, 13, 2561. https://doi.org/10.3390/ polym13152561 1. Introduction Plastics play an important role in our world and naturally occurring polymers such Academic Editor: Jean-Marie Raquez as rubber, waxes, resins, and horn have been used in for a variety of applications since ancient times. However, since the 19th century and with the development of petroleum- Received: 7 July 2021 based thermoplastics, a revolution in plastic industry has occurred [1]. Petroleum-based Accepted: 29 July 2021 Published: 31 July 2021 plastics, due to their light weights, low production costs, durability, resistance against corrosions, thermal, and electrical insolation, have gained interest for a wide variety Publisher’s Note: MDPI stays neutral of applications from technological advances to the packaging sector [2]. However, the with regard to jurisdictional claims in increasing generation and usage of petroleum-based materials in the recent decades, has published maps and institutional affil- put an immense stress on the environment through generation of plastic waste and their iations. accumulation in landfills [3] and oceans [4]. Nearly 50 percent of the plastics are employed in single-use applications, such as disposable consumer items and packaging, with food packaging accounting for the majority of plastic waste [5]. Many of these plastics are used in plastic bags or on food products, with a lifetime of mere minutes to hours, while the plastics stay in the environment for decades. It is estimated that the oceans are polluted Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. with approximately 100–200 million tons of plastic waste, with 8 million tons entering This article is an open access article the waters each year [6]. Micro-plastics generated from plastics breakdown are reaching distributed under the terms and alarming levels in the air, water, seafood, and table salt presenting a serious health issue for conditions of the Creative Commons marine wildlife and humans [7,8]. Although only a low percentage of the carbon footprint Attribution (CC BY) license (https:// is attributed to fossil-based plastic materials (4% of European greenhouse gas emissions creativecommons.org/licenses/by/ are from using plastics); looking for alternative packaging materials with a lower carbon 4.0/). footprint and less emission of greenhouse gases is environmentally and economically Polymers 2021, 13, 2561. https://doi.org/10.3390/polym13152561 https://www.mdpi.com/journal/polymers Polymers 2021, 13, 2561 2 of 30 print is attributed to fossil-based plastic materials (4% of European greenhouse gas emis- sions are from using plastics); looking for alternative packaging materials with a lower carbon footprint and less emission of greenhouse gases is environmentally and economi- cally interesting, and also helps the sustainability of the value chain as outlined in the Polymers 2021, 13, 2561 “European Strategy for Plastics in a Circular Economy” released in2 of2018. 36 Plastic packaging materials are one of the major challenges for waste management and the environment. For example, less than 30% of plastic waste generated in Europe is recovered for recycling interesting,and andthe alsomajority helps the is exported sustainability to ofthe the Southeast value chain Asia as outlined [9]. in the “European Strategy forBy Plastics acknowledging in a Circular Economy” the serious released environmental in 2018. Plastic and packaging health materials issues attributed to petro- are one of the major challenges for waste management and the environment. For example, less thanleum 30% plastics, of plastic and waste the generated inevitable in Europe demand is recovered for their for application recycling and in thevarious industries, re- majoritysearch is exported in the to development the Southeast Asia of environmental-friendly [9]. plastics has gained huge interest in Bythe acknowledging past decades the [10–12]. serious environmental Moreover, andthe health European issues attributedUnion Sustainable to petroleum Development Strat- plastics,egy and [13] the and inevitable the United demand Nations for their application2030 Sustainable in various Development industries, research Goals in [14], particularly in the development of environmental-friendly plastics has gained huge interest in the past the packaging supply chain, have accelerated the demand for shifting from petroleum- decades [10–12]. Moreover, the European Union Sustainable Development Strategy [13] and thebased United packaging Nations 2030 to the Sustainable bio-base Developmentd plastics that Goals are [14 ],more particularly effective, in the safer for human, and packagingmore supply eco-friendly chain, have [15]. accelerated Bioplastic the demand materials for shifting are fromcommonly petroleum-based categorized in two major packaginggroups: to the the bio-based first group plastics thatis recyclable are more effective, polymers, safer forwhich human, are and partially more eco- or completely made friendlyfrom [15]. biological Bioplastic materials and sustainable are commonly sources categorized such as in twograins, major starchy groups: root the first vegetables, sugar cane group is recyclable polymers, which are partially or completely made from biological and sustainableor vegetable sources such oils. as grains, The second starchy root group vegetables, is biodeg sugarradable cane or vegetable plastics oils. that The can be degraded by secondnatural group is microorganisms biodegradable plastics present that canin soil be degraded or water by into natural carbon microorganisms dioxide (CO2), methane (CH4), presentwater, in soil and or water inorganic into carbon compounds dioxide (CO [16].2), methane The life (CH cycle4), water, for biodegradable and inorganic packaging materi- compoundsals is [shown16]. The lifein Figure cycle for 1. biodegradable packaging materials is shown in Figure1. Proteins Natural biopolymers Polysaccharides Lipids Polyhydroxyalkanoate Microbial fermentation (PHA) Polylactic Acid (PLA) Biodegradable polymers Polymerized monomers Polyethylene Furanoate derived from biomasses (PF) Polybutylene Succinate (PS) FigureFigure 1. Biodegradable 1. Biodegradable polymers from polymers different from sources. different sources. 1.1. Biodegradable Packaging Materials Biodegradable1.1. Biodegradable packaging Packaging materials Materials are commonly generated from sustainable natural resources orBiodegradable from the by-products packaging of food and materials agricultural are products commonly and, based generated on the rawfrom sustainable natu- materialral used, resources can be categorizedor from the into by-products three main groups of food (Figure and2). agricultural These non-toxic products poly- and, based on the mers exhibit considerable mechanical and barrier properties, and can be biodegradable and compostableraw material making them used, excellent can be candidate categorized material into for th foodree andmain agricultural groups (Figure applica- 2). These non-toxic polymers exhibit considerable mechanical and barrier properties, and can be biodegrada- ble and compostable making them excellent candidate material for food and agricultural Polymers 2021, 13, 2561 3 of 30 applications [17]. Polylactic acid (PLA), an aliphatic polyester from lactic acid or lactide Polymers 2021, 13, 2561monomers, is one of the most studied and prevalent biodegradable polymers with3 of various 36 applications in the industrial packaging sector. PLA is manufactured by the controlled fermentation of carbohydrates