The vast and ever-growing amount of agricultural and food wastes has become a major concern throughout the whole world. Therefore, strategies for their processing and value-added reuse are needed to enable a sustainable utilization of feedstocks and reduce the environmental burden. By-products of potato, tomato, cereals and olive arise in significant amounts in European countries and are consequently of high relevance. Due to their composition with various beneficial ingredients, the waste products can be valorized by different techniques leading to economic and environmental advantages. This paper focuses on the waste generation during industrial processing of potato, tomato, cereals and olives within the European Union and reviews state-of-the-art technologies for their valorization. Furthermore, current applications, future perspectives and challenges are discussed.

There is increasing research towards the substitution of petrochemicals by sustainable components. Biopolymers such as proteins, polysaccharides, and lipids derive from a variety of crop sources and most promisingly from waste streams generated during their processing by the agro food industry. Among those, proteins of different types such as whey, casein, gelatin, wheat gluten, soy protein or zein present a potential beyond the food and feed industry for the application in packaging. The general protein hydrophilicity promotes a good compatibility to polar surfaces, such as paper, and a good barrier to apolar gases, such as oxygen and carbon dioxide. The present review deals with the development of protein-based coatings and films. It includes relevant discussion for application in paper or board products, as well as an outlook on its future industrial potential. Proteins with suitable functionalities as food packaging materials are described as well as the different technologies for processing the coatings and the current state of the art about the coating formulations for selectively modulating barrier, mechanical, surface and end of life properties. Some insights onto regulations about packaging use, end of life and perspectives of such natural coating for decreasing the environmental impact of packages are given.

The thermal, mechanical, and rheological properties of biocomposites of poly(lactic acid) (PLA) with potato pulp powder were investigated in order to (1) quantify how the addition of this filler modifies the structure of the polymeric material and (2) to obtain information on the possible miscibility and compatibility between PLA and the potato pulp. The potato pulp powder utilized is a residue of the processing for the production and extraction of starch. The study was conducted by analyzing the effect of the potato pulp concentration on the thermal, mechanical, and rheological properties of the biocomposites. The results showed that the potato pulp powder does not act as reinforcement but as filler for the PLA polymeric matrix. A progressive decrease in elastic modulus, tensile strength, and elongation at break was observed with increasing the potato pulp percentage. This moderate loss of mechanical properties, however, still meets the technical requirements indicated for the production of rigid packaging items. The incorporation of potato pulp powder to PLA offers the possibility to reduce the cost of the final products and promotes a circular economy approach for the valorization of agro-food waste biomass.

The development of new bio-based coating materials to be applied on cellulosic and plastic based substrates, with improved performances compared to currently available products and at the same time with improved sustainable end of life options, is a challenge of our times. Enabling cellulose or bioplastics with proper functional coatings, based on biopolymer and functional materials deriving from agro-food waste streams, will improve their performance, allowing them to effectively replace fossil products in the personal care, tableware and food packaging sectors. To achieve these challenging objectives some molecules can be used in wet or solid coating formulations, e.g., cutin as a hydrophobic water- and grease-repellent coating, polysaccharides such as chitosan-chitin as an antimicrobial coating, and proteins as a gas barrier. This review collects the available knowledge on functional coatings with a focus on the raw materials used and methods of dispersion/application. It considers, in addition, the correlation with the desired final properties of the applied coatings, thus discussing their potential.

The thermal and mechanical properties of biocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 5 wt % of valerate units, with 20 wt % of potato pulp powder were investigated in order (i) to obtain information on possible miscibility/compatibility between the biopolymers and the potato pulp, and (ii) to quantify how the addition of this filler modifies the properties of the polymeric material. The potato pulp powder utilized is a residue of processing for the production and extraction of starch. The final aim of this study is the preparation of PHBV based materials with reduced cost, thanks to biomass valorization, in agreement with the circular economy policy, as result of the incorporation of agricultural organic waste. The results showed that the potato pulp powder does not act as reinforcement, but rather as filler for the PHBV polymeric matrix. A moderate loss in mechanical properties is detected (decrease in elastic modulus, tensile strength and elongation at break), which regardless still meets the technical requirements indicated for rigid packaging production. In order to improve the mechanical response of the PHBV/potato pulp powder biocomposites, surface treatment of the potato pulp powder with bio-based and petroleum-based waxes was investigated. Good enhancement of the mechanical properties was achieved with the natural carnauba and bee waxes.