Proteins from Agri-Food Industrial Biowastes or Co-Products and Their Applications as Green Materials

Abstract

A great amount of biowastes, comprising byproducts and biomass wastes, is originated yearly from the agri-food industry. These biowastes are commonly rich in proteins and polysaccharides and are mainly discarded or used for animal feeding. As regulations aim to shift from a fossil-based to a bio-based circular economy model, biowastes are also being employed for producing bio-based materials. This may involve their use in high-value applications and therefore a remarkable revalorization of those resources. The present review summarizes the main sources of protein from biowastes and co-products of the agri-food industry (i.e., wheat gluten, potato, zein, soy, rapeseed, sunflower, protein, casein, whey, blood, gelatin, collagen, keratin, and algae protein concentrates), assessing the bioplastic application (i.e., food packaging and coating, controlled release of active agents, absorbent and superabsorbent materials, agriculture, and scaffolds) for which they have been more extensively produced. The most common wet and dry processes to produce protein-based materials are also described (i.e., compression molding, injection molding, extrusion, 3D-printing, casting, and electrospinning), as well as the main characterization techniques (i.e., mechanical and rheological properties, tensile strength tests, rheological tests, thermal characterization, and optical properties). In this sense, the strategy of producing materials from biowastes to be used in agricultural applications, which converge with the zero-waste approach, seems to be remarkably attractive from a sustainability prospect (including environmental, economic, and social angles). This approach allows envisioning a reduction of some of the impacts along the product life cycle, contributing to tackling the transition toward a circular economy.

Comparison of Protein Content, Availability, and Different Properties of Plant Protein Sources with Their Application in Packaging

“…Different sources of proteins and proteins extracted from the waste by-products being a sustainable ecological burden are utilized in various packaging applications [60]. Biodegradable packages, edible films, edible cutlery, thermoforms, trays, and coatings are also used as wraps, casings, pouches, bags, and covers as an alternative to synthetic and atmospheric packaging [64][65][66][67][68][69][70][71].…”

“…Many studies predominantly involve the casting method for the preparation of complex films and cannot be developed on an industrial scale [58]. Rich plant protein sources with their total protein content and with the top global producer countries are listed in Tables 1 and 2 [59][60][61][62]. Specific data on cover crops in Canada are summarized in Table 3 [63].…”

Disposable Food Packaging and Serving Materials—Trends and Biodegradability

“…Zein is a prolamin predominantly present in the endosperm. Zein may be obtained from corn or corn byproduct from the production of ethanol, starch, or oil [ 158 ]. More than 50% of amino acids in zein are hydrophobic (leucine (20%), proline (10%), and alanine (10%)), while the main hydrophilic amino acid is glutamine, with 21–26% [ 159 ].…”

Recovery of Nitrogen from Low-Cost Plant Feedstocks Used for Bioenergy: A Review of Availability and Process Order

“…There are several reviews addressing utilization of N-rich lignocellulose biomass for biofuels through thermochemical and biochemical conversions − and N (protein) recovery and conversion into high-value-added compounds such as food, , bioplastics, , adhesives, pharmaceutical intermediates, hydrolysates, , bulk chemicals, and enzymes and bioactive compounds. , Previous studies on protein recovery have focused either on direct production of fuel or on protein extraction. A review with emphasis on the availability of low-cost feedstocks and N recovery before or after biofuel production, with the goal of commercialization of biofuel based on these feedstocks, is not still available.…”