Environmental Engineering Reference
In-Depth Information
The development of such valorisation routes may address the main weakness of
the food processing industry and aim to develop a more sustainable supply chain
and waste management system. Such routes can solve both resource and waste
management problems. The important issues associated with agro-food waste
include:
1. decreasing landfill options;
2. uncontrolled greenhouse gas emissions;
3. contamination of water supplies through leaching of inorganic matter; and
4. low efficiency of conventional waste management methods, notably incinera-
tion and composting.
Up-to-date and accurate data on the production of food waste (FW) at every
stage of the food supply chain are difficult to obtain, but food waste is being
mapped in Europe as part of the new COST (European Cooperation in Science
and Technology) Action TD1203. There are strong drivers for stakeholders and
public organisations in food processing and other sectors to reduce costs and
develop suitable strategies for the conversion and valorisation of side streams. The
development of knowledge-based strategies to realise the potential of food waste
should also help to satisfy an increasing demand for bio-derived chemicals, fuels
and materials, and probably affect waste management regulations over the years
to come. The valorisation of FSCW is necessary in order to improve the sustain-
ability and cost-effectiveness of food supply and the manufacture of chemicals.
Together with the associated ethical and environmental issues and the drivers for
utilising waste, the pressures for such changes are becoming huge.
1.3.3
Case Study: Citrus Waste
Citrus fruits are grown in many regions of the earth, including Latin and Central
America and the southern USA, southern Europe, northern and southern Africa,
China and India. Of the various fruit types orange is the largest in volume, repre-
senting about 95 million tonnes (Mt) annually. Major producers include Brazil,
USA, China, India and southern Europe, particularly Italy and Spain. After extrac-
tion of the juice, the residual peel accounts for 50 wt% of fruit that is costly to treat
and is highly regulated. However, with the high volumes of citrus production and
processing, there is a real opportunity to better utilise this resource for animal feed
(although it has low protein content) and essential oil extraction. Simple calcula-
tions show that the amount of organic carbon available in the peel and other resi-
dues from juicing corresponds to over 5 Mt, similar in weight to the total amount
of (mostly non-renewable, typically oil-derived) carbon used by the UK for the
manufacture of all of its chemicals [20].
Major components of wet orange peel are water (80% by weight), soluble sug-
ars cellulose and hemicellulose, pectin and d-limonene. The demand for pectin (a
valuable food thickener and cosmetic ingredient) and limonene (a flavour and
