Hydrophobic Polymers from Food Waste: Resources and Synthesis

Ionic Liquids for the Chemical Recycling of Polymeric Materials and Control of Their Solubility

Plastics are wonderful materials that have modernized our daily life; however, importance of effective recycling of plastics is gradually recognized widely. In this account, we describe our discovery of new and efficient methods for the chemical recycling of plastics using ionic liquids (ILs). Since the chemical recycling usually requires high temperature conditions to breakdown chemical bonds in polymeric materials, we thought that less-flammability and non-volatility of ionic liquids are the most suitable physical properties for this purpose. Ionic liquids successfully depolymerized polyamides and unsaturated polyesters smoothly and corresponding monomeric materials were obtained in good yields. To the best of our knowledge, this was the first use of Ionic liquids for such reactions. However, we encountered another difficult problem-separation. To solve the problem, we developed solubility-switchable ionic liquids, a new type of ionic liquids in which solubility is readily changed using the chemistry of protective groups. Conversion between hydrophilic and lipophilic forms was readily achieved using a simple chemical treatment under mild conditions, and the complete separation of products was achieved by liquid-liquid-extraction. The robustness of either form unlocks their wide use as reaction solvents.

Value Addition Employing Waste Bio-Materials in Environmental Remedies and Food Sector

Overall, combating food waste necessitates a multifaceted approach that includes education, infrastructure, and policy change. By working together to implement these strategies, we can help reduce the negative impacts of food waste and create a more sustainable and equitable food system. The sustained supply of nutrient-rich agrifood commodities is seriously threatened by inefficiencies caused by agricultural losses, which must be addressed. As per the statistical data given by the Food and Agriculture Organisation (FAO) of the United Nations, nearly 33.33% of the food that is produced for utilization is wasted and frittered away on a global level, which can be estimated as a loss of 1.3 billion metric tons per annum, which includes 30% cereals, 20% dairy products 35% seafood and fish, 45% fruits and vegetables, and 20% of meat. This review summarizes the various types of waste originating from various segments of the food industry, such as fruits and vegetables, dairy, marine, and brewery, also focusing on their potential for developing commercially available value-added products such as bioplastics, bio-fertilizers, food additives, antioxidants, antibiotics, biochar, organic acids, and enzymes. The paramount highlights include food waste valorization, which is a sustainable yet profitable alternative to waste management, and harnessing Machine Learning and Artificial Intelligence technology to minimize food waste. Detail of sustainability and feasibility of food waste-derived metabolic chemical compounds, along with the market outlook and recycling of food wastes, have been elucidated in this review.

Production of biopolymers from food waste: Constrains and perspectives

Food is an essential commodity for the survival of any form of life on earth. Yet generation of plethora of food waste has significantly elevated the global concern for food scarcity, human and environment deterioration. Also, increasing use of polymers derived from petroleum hydrocarbons has elevated the concerns towards the depletion of this non-renewable resource. In this review, the use of waste food for the production of bio-polymers and their associated challenges has been thoroughly investigated using scientometric analysis. Various categories of food waste including fruit, vegetable, and oily waste can be employed for the production of different biopolymers including polyhydroxyalkanoates, starch, cellulose, collagen and others. The advances in the production of biopolymers through chemical, microbial or enzymatic process that increases the acceptability of these biopolymers has been reviewed. The comprehensive compiled information may assist researchers for addressing and solving the issues pertaining to food wastage and fossil fuel depletion.

Critical challenges and technological breakthroughs in food waste hydrolysis and detoxification for fuels and chemicals production

Organic waste has increased as the global population and economy have grown exponentially. Food waste (FW) is posing a severe environmental issue because of mismanaged disposal techniques, which frequently result in the squandering of carbohydrate-rich feedstocks. In an advanced valorization strategy, organic material in FW can be used as a viable carbon source for microbial digestion and hence for the generation of value-added compounds. In comparison to traditional feedstocks, a modest pretreatment of the FW stream utilizing chemical, biochemical, or thermochemical techniques can extract bulk of sugars for microbial digestion. Pretreatment produces a large number of toxins and inhibitors that affect bacterial fuel and chemical conversion processes. Thus, the current review scrutinizes the FW structure, pretreatment methods (e.g., physical, chemical, physicochemical, and biological), and various strategies for detoxification before microbial fermentation into renewable chemical production. Technological and commercial challenges and future perspectives for FW integrated biorefineries have also been outlined.

Functional bioplastics from food residual: Potentiality and safety issues

Plastic pollution and food waste are two global issues with much in common. Plastic containers were introduced as a practical and easy remedy to improve food preservation and reduce the risk of creating waste, but ironically, to address one problem, another has been made worse. The spread of single-use containers has dramatically increased the amount of plastic that has to be discarded, and the most urgent task is now to find a solution to what has become part of the problem. An innovative way around it consists of promoting the valorization of food residues by turning them into novel materials for packaging. Although the results are promising, the aim of completely replacing plastics with biodegradable materials still seems far from being achieved. This review illustrates the main strategies adopted thus far to produce new bioplastic materials and composites from waste resources and focuses on the pros and cons of the food recovery process to look for the aspects that represent an obstacle to the development of the circular food economy on an industrial scale.

Progress in valorisation of agriculture, aquaculture and shellfish biomass into biochemicals and biomaterials towards sustainable bioeconomy

The recurrent environmental and economic issues associated with the diminution of fossil fuels are the main impetus towards the conversion of agriculture, aquaculture and shellfish biomass and the wastes into alternative commodities in a sustainable approach. In this review, the recent progress on recovering and processing these biomass and waste feedstocks to produce a variety of value-added products via various valorisation technologies, including hydrolysis, extraction, pyrolysis, and chemical modifications are presented, analysed, and discussed. These technologies have gained widespread attention among researchers, industrialists and decision makers alike to provide markets with bio-based chemicals and materials at viable prices, leading to less emissions of CO₂ and sustainable management of these resources. In order to echo the thriving research, development and innovation, bioresources and biomass from various origins were reviewed including agro-industrial, herbaceous, aquaculture, shellfish bioresources and microorganisms that possess a high content of starch, cellulose, lignin, lipid and chitin. Additionally, a variety of technologies and processes enabling the conversion of such highly available bioresources is thoroughly analysed, with a special focus on recent studies on designing, optimising and even innovating new processes to produce biochemicals and biomaterials. Despite all these efforts, there is still a need to determine the more cost-effective and efficient technologies to produce bio-based commodities.

Synthesis of α-Hydroxy Fatty Acids from Fatty Acids by Intermediate α-Chlorination with TCCA under Solvent-Free Conditions: A Way to Valorization of Waste Fat Biomasses

Within food wastes, including edible and inedible parts, fat biomasses represent a significant portion, often uneconomically used or improperly disposed causing pollution issues. Interesting perspectives for their management and valorization could be opened by conversion of fatty acids (FAs), which are their main constituents, into α-hydroxy FAs (α-HFAs), fine chemicals of great, but largely untapped potential, possibly due to current poor availability. Here, a simple and efficient procedure is reported to α-chlorinate FAs with trichloroisocyanuric acid (TCCA), a green halogenating agent, under solvent-free conditions and to directly convert the resultant α-chloro FAs, without previous purification, into α-HFAs. The procedure was applied to stearic, palmitic, and myristic acid and, with analogous success, to their mixture, ad hoc created to simulate a FAs mixture obtainable from a fat biomass.

A State-of-the-Art Review on Biowaste Derived Chitosan Biomaterials for Biosorption of Organic Dyes: Parameter Studies, Kinetics, Isotherms and Thermodynamics

Chitosan is a second-most abundant biopolymer on earth after cellulose. Its unique properties have recently received particular attention from researchers to be used as a potential biosorbent for the removal of organic dyes. However, pure chitosan has some limitations that exhibit lower biosorption capacity, surface area and thermal stability than chitosan composites. The reinforcement materials used for the synthesis of chitosan composites were carbon-based materials, metal oxides and other biopolymers. This paper reviews the effects of several factors such as pH, biosorbent dosage, initial dye concentration, contact time and temperature when utilizing chitosan-based materials as biosorbent for removing of organic dyes from contaminated water. The behaviour of the biosorption process for various chitosan composites was compared and analysed through the kinetic models, isotherm models and thermodynamic parameters. The findings revealed that pseudo-second-order (PSO) and Langmuir isotherm models were best suited for describing most of the biosorption processes or organic dyes. This indicated that monolayer chemisorption of organic dyes occurred on the surface of chitosan composites. Most of the biosorption processes were endothermic, feasible and spontaneous at the low temperature range between 288 K and 320 K. Therefore, chitosan composites were proven to be a promising biosorbent for the removal of organic dyes.

Expanding Policy for Biodegradable Plastic Products and Market Dynamics of Bio-Based Plastics: Challenges and Opportunities

Bio-plastics are rapidly growing in popularity, and many new techniques and approaches are emerging as a result of intensive research and development (R&D) activities. Many industries worldwide are installing their new production capability. Bio-plastics have attracted political leaders’ interest, especially in light of the evolving bio-economic orientation, through their use of renewable resources and their effects on sustainable growth. Related market determinants are defined, classified, and used as a base for their own estimates. The evolution of global production capacity is modeled annually for the timeframe up to 2030 by applying a system dynamics strategy. For a long-term forecast to catch the inherent volatility, various scenarios are identified and added to the model to represent different trends in the price of gross domestic product (GDP), oil, and bioplastic feedstock. Thus, our findings show the sensitivity in the macro-economic climate of the bioplastics sector. The simulations are completed by a debate on the regulatory environment and its future effect on industry development at the European level. The findings show considerable potential for development but are vulnerable to political and economic impacts.

Coffee Silverskin as a Multifunctional Waste Filler for High-Density Polyethylene Green Composites

This work aims to describe the coffee silverskin effect as a lignocellulosic waste filler for high-density polyethylene (HDPE) composites development. The main task was to determine various modification effects resulting from the complex chemical composition of coffee silverskin containing compounds with potential antioxidative properties, including caffeine, polyphenols, tannins, or melanoidins. The processing, thermal, physicochemical, and thermomechanical properties of the HDPE-based composites with different filler content (1–20 wt%) were evaluated. Comprehensively realized thermomechanical analysis revealed the filler’s reinforcing effects on the HDPE matrix while defining problems with obtaining adequate adhesion in the interfacial area. At the same time, studies have shown a very beneficial effect of the silverskin addition on the thermal properties of composites, that even the smallest addition allows for a significant increase in the thermooxidative resistance of HDPE composites assessed using the oxidation induction time from 20 min for HDPE up to 140 min for the composites with 20 wt% of the filler. The obtained research results allow classifying the coffee silverskin waste filler, not only as a filler intended for the production of composites with a high degree of filling but also as an additive that significantly changes the properties of polyethylene in the case of using low concentrations. This can have a very beneficial impact on the development of novel wood polymer (WPC) and natural fiber composites (NFC).

Tissue-specific proteome characterization of avocado seed during postharvest shelf life

Avocado is a nutritious and economically important fruit, generating significant income for exporter countries. Recently, by-products of this fruit such as seeds and peels, have raised interest in different industries. However, the biochemical features of the nutraceutical value of these tissues have not been analyzed using molecular approaches during the postharvest shelf life (PSL). We carried out comparative proteomics using tandem mass tagging (TMT) and synchronous-precursor selection (SPS)-MS³. We analyzed testa, cotyledon, and embryo axes from avocado seeds at detachment from the tree (unripe), and after five (breaker) and ten days (ripe) of PSL. We identified 1968 proteins, from which 933 were specific to the testa, 167 to the embryo axis, and 23 to the cotyledon. The testa had a more dynamic proteome than the other tissues, resembling similar stress responses to those observed in peel tissues, such as down-accumulation of translational machinery, cell wall catabolism and synthesis of secondary metabolites. In contrast, the up-accumulation of the biosynthesis of l-glutamine, L-isoleucine, and l-serine was observed in all tissues. Our study provides the basic biochemical and physiological features of avocado seed during PSL and demonstrates that avocado seed tissues could potentially be used as a costless source of high-value compounds. SIGNIFICANCE: Avocado seed as a fruit by-product is a source of different valuable molecules, including those with nutraceutical properties. During PSL, several biochemical and physiological modifications occur in this dispersal unit, which also includes the alteration of several key metabolites' content. However, the proteome profile associated with different metabolic pathways that regulate the inner content of seed metabolites has not been previously studied. Our tissue-specific proteomics TMT-SPS-MS³-based provides the first evidence of molecular and physiological changes in avocado tissues during PSL delivering fundamental knowledge of this organ. In this vein, the modulation of secondary metabolites, amino acid, and sugar metabolism of avocado tissues during PLS can encourage these by-products exploitation in multiple industries.

Biodegradable Plastics: Standards, Policies, and Impacts

Plastics are ubiquitous in our society. They are in our phones, clothes, bottles, and cars. Yet having improved our lives considerably, they now threaten our environment and our health. The associated carbon emissions and persistency of plastics challenge the fragile balance of many ecosystems. One solution is using biodegradable plastics. Ideally, such plastics are easily assimilated by microorganisms and disappear from our environment. This can help reduce the problems of climate change, microplastics, and littering. However, biodegradable plastics are still only a tiny portion of the global plastics market and require further efforts in research and commercialization. Here, a critical overview of the state of the art of biodegradable plastics is given. Using a material flow analysis, the challenges of the plastic market are highlighted, and with it the large market potential of biodegradable plastics. The environmental and socio-economic impact of plastics, government policies, standards and certifications, physico-chemical properties, and analytical techniques are covered. The Review concludes with a personal outlook on the future of bioplastics, based on our own experience with their development and commercialization.

Utilization of food waste streams for the production of biopolymers

Uncontrolled decomposition of agro-industrial waste leads to extensive contamination of water, land, and air. There is a tremendous amount of waste from various sources which causes serious environmental problems. The concern in the disposal problems has stimulated research interest in the valorization of waste streams. Valorization of the wastes not only reduces the volume of waste but also reduces the contamination to the environment. Waste from food industries has great potential as primary or secondary feedstocks for biopolymer production by extraction or fermentation with pre-treatment or without pre-treatment by solid-state fermentation to obtain fermentable sugars. Various types of waste can be used as substrates for the production of biomaterials but recently more focus has been observed on the agro-industrial wastes which have a high rate of production worldwide. This review collates in detail the different food wastes used for biopolymer, technologies for the production and characterization of the biopolymers, and their economic/technical viability.

Potential of residual fungal biomass: a review

In this study, it was evaluated and documented the potential uses of the residual fungal biomass from fermentation. The chemical composition of the biomass was determined by instrumental analysis techniques for its characterization and its possible application. It was found that this biomaterial is generally composed of sugars, proteins, and lipids, which provide it certain properties and applications that must be characterized morphologically, chemically, and mechanically. The residual fungal biomass could be used for two processes: the extraction of biopolymers, with several applications in the food industry, cosmetics, and pharmaceutical, among others; and the removal of contaminants by mechanisms of adsorption with biopolymers, known also as biosorption, in tertiary treatments of wastewater.

Optimizing Food Waste Composting Parameters and Evaluating Heat Generation

The optimal initial moisture content and seeding proportion with mature compost (microbial inoculant) during food waste composting were investigated. This involved six different moisture contents (42%, 55%, 61%, 66%, 70%, and 78%) and four different mature compost seeding amounts (0%, 10%, 20%, and 30% w/w). The temperature variation of these different setups during the first four days of composting was used to determine the most effective one. Our findings showed that the initial moisture contents of 55–70% and the 20% w/w of mature compost were optimal for effective food waste composting. A 400 kg compost pile with the optimal compost mixture ratio was then used to study the evolution and spatial distribution of the temperature during a 30-day composting period. Finally, the heat produced during the 30-day composting process was estimated to be 2.99 MJ/kg. Further investigations, including a cost–benefit analysis from a pilot facility, would be required to comprehensively conclude the feasibility of food waste composting as a bioenergy source.

Production of bioplastic through food waste valorization

The tremendous amount of food waste from diverse sources is an environmental burden if disposed of inappropriately. Thus, implementation of a biorefinery platform for food waste is an ideal option to pursue (e.g., production of value-added products while reducing the volume of waste). The adoption of such a process is expected to reduce the production cost of biodegradable plastics (e.g., compared to conventional routes of production using overpriced pure substrates (e.g., glucose)). This review focuses on current technologies for the production of polyhydroxyalkanoates (PHA) from food waste. Technical details were also described to offer clear insights into diverse pretreatments for preparation of raw materials for the actual production of bioplastic (from food wastes). In this respect, particular attention was paid to fermentation technologies based on pure and mixed cultures. A clear description on the chemical modification of starch, cellulose, chitin, and caprolactone is also provided with a number of case studies (covering PHA-based products) along with a discussion on the prospects of food waste valorization approaches and their economic/technical viability.

Aminopolyols from Carbohydrates: Amination of Sugars and Sugar-Derived Tetrahydrofurans with Transaminases

Carbohydrates are the major component of biomass and have unique potential as a sustainable source of building blocks for chemicals, materials, and biofuels because of their low cost, ready availability, and stereochemical diversity. With a view to upgrading carbohydrates to access valuable nitrogen-containing sugar-like compounds such as aminopolyols, biocatalytic aminations using transaminase enzymes (TAms) have been investigated as a sustainable alternative to traditional synthetic strategies. Demonstrated here is the reaction of TAms with sugar-derived tetrahydrofuran (THF) aldehydes, obtained from the regioselective dehydration of biomass-derived sugars, to provide access to cyclic aminodiols in high yields. In a preliminary study we have also established the direct transamination of sugars to give acyclic aminopolyols. Notably, the reaction of the ketose d-fructose proceeds with complete stereoselectivity to yield valuable aminosugars in high purity.

Development of a microwave-assisted sustainable conversion of furfural hydrazones to functionalised phthalimides in ionic liquids

A sustainable synthetic procedure to convert furfural hydrazones into functionalised phthalimides was developed. The reaction was performed in a microwave using a hydrophilic ionic liquid, [bmim][Cl], as the solvent which could be readily recovered by a simple extraction. The ionic liquid was successfully recycled with no significant loss in product yields.

Autoclave foaming of chemically modified polylactide

Polylactide has emerged as one of the most promising biopolymers due to its good mechanical properties, as reflected by the continual increase in its production volume per year. However, one of the main drawbacks of polylactide is its low melt strength, which is disadvantageous in terms of foaming. To overcome this issue, in this study, several chemical modifiers that induce crosslinking, chain extension or grafting were incorporated by reactive extrusion, which greatly affected the foaming process by increasing the molecular weight and thereby the melt properties of polylactide. By means of gel permeation chromatography, an increase in the molecular weight was observed in the modified polylactides. Elongational viscosity measurements indicate a dramatic viscosity increase for polylactide modified with a multifunctional epoxide and an organic peroxide. With pressure-induced batch foaming, almost all modifications, with the exception of styrene maleic anhydride, led to a decrease in foam density compared to the neat polylactide.

Advances in the synthesis of bio-based aromatic polyesters: novel copolymers derived from vanillic acid and ε-caprolactone

A new and sustainable pathway for the synthesis of polyesters and copolyesters derived from vanillic acid is reported. The one-pot procedure does not require either solvents or purification steps. New bio-based crystalline copolymers with tunable thermal properties are obtained.

Sustainable Synthesis of Chiral Tetrahydrofurans through the Selective Dehydration of Pentoses

L-Arabinose is an abundant resource available as a waste product of the sugar beet industry. Through use of a hydrazone-based strategy, L-arabinose was selectively dehydrated to form a chiral tetrahydrofuran on a multi-gram scale without the need for protecting groups. This approach was extended to other biomass-derived reducing sugars and the mechanism of the key cyclization investigated. This methodology was applied to the synthesis of a range of functionalized chiral tetrahydrofurans, as well as a formal synthesis of 3R-3-hydroxymuscarine.

The selective conversion of d-limonene to p,α-dimethylstyrene

The conversion of d-limonene selectively to p,α-dimethylstyrene (DMS) only has been achieved via a palladium acetate-catalysed dehydrogenation.