Waste biomass from the food supply chain (i. e., agricultural residues such as wheat straw, rice husks, waste cooking oil or food manufacturing waste such as tomato peels) are an ideal renewable material as they do not compete with the food and feed industries for land. An FAO report issued in 2011, estimates that ‘one-third of food produced for human consumption is lost or wasted globally, which amounts to about 1.3 billion tons per year’ (Gustavsson et al, 2011). It is important to note the difference between food waste and food loss, the latter being food lost due to the use of poor technological means or diseases affecting crops, for example (Parfitt et al., 2010).

The agro-food supply chain includes a broad variety of manufacturing processes producing consequent cumulative quantities of different wastes, especially organic residues at every step of the supply chain (Gomez et al., 2010; Laufenberg et al., 2003). The increasing demand for chemicals and fuel together with other drivers are encouraging the re-use and valorization of organic waste from the food supply chain for the production of novel added-value bio-derived sustainable products. A description of a food supply chain is given in Fig. 1.6.

Food waste encompasses domestic waste produced by individuals in their homes. This represents a logistical problem as it would be difficult to collect and concentrate in one place, except in large housing complexes. On the other hand, it might be argued that if the waste produced by the agricultural and processing sectors before it reaches the consumer is generated in a more concentrate manner, it would be easier to collect and valorize. The problems associated with these wastes are:

• severe pollution problems due to high associated chemical and biological oxygen demand (COD and BOD) (Kroyer, 1995)

• varying pH (Kroyer, 1995)

• material prone to bacterial contamination (Schieber et al., 2001) (e. g., fruit and vegetable by-products)

• high accumulation rate leading to disposal management problems (Zaror, 1992)

• variations in chemical content due to different varieties and seasonal variations.

Current practices for the management of food waste include:

• incineration (GHG and toxic chemical emissions)

• landfilling (polluting, GHG emissions)

• conversion to cattle feed (uneconomical process, high moisture content)

•
composting

• anaerobic digestion (loses much of the chemical value and low carbon efficiency).

Composting is a popular re-use practice as it lowers waste management costs, diverts waste from landfill and reduces waste disposal costs (Schaub and Leonard, 1996), but composting is also ‘time consuming, location dependent and subject to contamination’ (Davis, 2008).

While progress is being made in using anaerobic digestion to both treat food waste and provide some energy value, the chemical and material potential of food supply chain waste is such that we should also quickly move to realizing that potential through the use of other green chemical technol­ogies. There are five reasons to develop the valorization of residues and by-products of food waste: they are a rich source of functionalized molecules (i. e., biopolymers, protein, carbohydrates), abundant, readily available, under-utilized and renewable. Many waste streams even contain compounds
such as antioxidants which could be recovered, concentrated and re-used in functional food and lubricant additives (Peschel et al., 2006). Such applica­tions solve both a resource problem and waste management problem as the issues associated with agro-food waste are important. Other than decreasing landfill options, when landfilled, waste is a source of pollution: municipal solid waste for example can produce uncontrolled GHG emissions and contaminate water supplies through leaching of inorganic matter (Cheng and Hu, 2010). Incineration is energy intensive, emits CO2 and toxins and is sensitive to the waste’s moisture content. The scale at which waste from the food supply chain is generated is significant. In the United States, USDA calculated that US$ 50 million could be saved annually if 5% of the waste generated by the processing, retail and service sectors together with con­sumer food losses were recovered (Laufenberg et al., 2003).

This type of waste represents a valuable and sustainable source of useful products that could be used by other industries, especially the chemical industry, as shown in Fig. 1.7. Novel strategies and technologies for waste valorization can potentially have a global impact on the chemical and biotechnological industries and waste management regulations in the years to come. However, despite the clear benefits, the utilization of food waste represents a challenge. A regular and consistent supply chain is important for the successful realization of a biorefinery. But high cumulative volumes of waste are often generated intermittently, over a period of a couple of months in a year, affecting the year-round availability of chemicals and materials produced from food supply chain by-products and residues. The large volumes of food supply chain by-products available are illustrated in Table 1.4.

Table 1.4 Examples of food supply chain by-products and corresponding volumes available

Nature of the food supply chain Estimated volume/year

by-product

Citrus waste produced post-juicing

Used cooking oil

Palm oil residues

Olive mill residue

Cocoa pods

Rice husks

Bagasse

Starchy wastes

Wheat straw surplus

Tomato pomace

Grape pomace

5.0. 000 T in Florida, USA 0.7-1 million T in Europe

15.800.0 T in Indonesia

30.0. 000 T in the Mediterranean basin 20 million T in Ivory Coast

110 million T worldwide

194.692.0 T in Brazil 8 million T in Europe 5.7 million T in Europe 4 million T in Europe 15 million T in the USA

7.7 Components of food supply chain waste useful in bio-derived daily consumer products.

Although the availability of some food supply chain by-products is clearly an advantage regarding security of supply, several limitations exist and need to be taken into account as part of the logistics needed to valorize this resource. Food supply chain waste can be/can have:

• a heterogeneous variable composition (lipids, carbohydrates, proteins) (Litchfield, 1987)

• fluctuating in volumes available across the year (Litchfield, 1987)

• a high water content (Laufenberg et al., 2003) and

• a low calorific value (Laufenberg et al., 2003).

At a European level, research is being promoted via the Framework VII KBBE (Knowledge-Based Bio-economy) theme. In the UK, a number of food supply chain waste related research projects are being carried out in collaboration with industry on, for example, the use of supercritical carbon dioxide to extract chemicals from cereal straws and also the use of starch- rich wastes to make adhesives for carpet tiles and other consumer goods. In the Review of Waste Policy issued by DEFRA in June 2011, launching a zero waste economy plan, the UK Government announced it will work with industry to drive innovation in reuse and recycling for materials, such as metals, textiles and all biodegradable waste (DEFRA, 2011). The EU issued new FP7 funding calls for 2012 mentioning that ‘research is needed to develop innovative concepts and practical approaches that would add value to and find markets for food waste of plant and dairy origin’ (CORDIS, 2011).

In France, work on the valorization of oil crop by-products is now being supported by the French government-funded ‘project PIVERT’. In Spain, a research team in Barcelona is studying the use of amino acids derived from food supply chain residues for the synthesis of amino-acid derived surfactants such as ethyl-N-lauroyl-L-arginate HCl or LAE, which have been successfully commercialized (Infante et al., 1992). Waste cooking oil and citrus waste produced from the juicing industry are also being studied in Spain as raw materials for the production of bio-diesel and bio-ethanol/ D-limonene extraction, respectively (Kulkarni and Dalai, 2006; Sunde et al., 2011). In Greece, whey is being explored as feedstock for microbial oil production that could be used for oleochemical synthesis (Vamvakaki et al., 2010).

The topic is gaining increased attention worldwide: the NAMASTE project (EU-India) is directed at the valorization of selected by-products, such as fruit and cereal processing residues, for the global food and drink industry. In the United States, the Center for Crop Utilization Research at Iowa State University is focusing on adding value to Midwest crop (i. e., soy, corn) by-products to increase the value of the food supply chain. Scientists at the American company Cardolite have succeeded in producing thermosetting binder resins for use in the transportation and brake industries from cashew nutshell liquid (highly thermostable, impermeable and durable) (Cardolite, n. d.).