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Food preservation

As millions of people continue to go hungry around the globe, a vast amount of the world’s food is wasted – due to overproduction, environmental conditions, or a lack of adequate post-harvest storage solutions. More efficient food preservation and distribution is therefore crucial for balancing global inequalities in supply and demand.

Access to food around the world is affected by a number of factors, including uneven distribution of access to food, the increasing urbanisation of worldwide populations (meaning that food has to travel further to reach consumers), food waste, climate change(leading to uneven, unpredictable yields) and the associated rise in extreme weather events.

Extreme weather events such as droughts and floods can have devastating effects on farming. In developing countries, for instance, more than 80% of the damage caused by drought affects the agricultural sector – creating a reduction in the overall amount of food available for consumption, as well as limiting potential for dietary diversity. As a result, children born in Zambia under drought conditions are up to 12% more likely to have below-average height and weight than children born in non-crisis years, while children born in Niger during a drought are more than twice as likely to be malnourished between the ages of one and two years old.

Conversely, good weather conditions can often result in the overproduction of food – which, without appropriate processing, packaging, and storage solutions, often goes to waste.

The problem of food wastage

While over 800 million people around the world go to bed hungry every night, an alarmingly large proportion of the world’s food resources continue to be either spoiled or squandered, with at least a third of all food produced globally never actually being eaten.

Food is lost or wasted throughout the entire supply chain, from field to household, due to a range of factors – including overproduction, the lack of facilities or infrastructure to adequately harvest, store, process and transport produce to market, or consumers simply buying more than they actually need, and subsequently throwing food away.

While consumer food waste is becoming a major issue in higher-income countries, pre-consumer food losses are more prevalent in developing countries. For example, Indian farmers complain that many of the bananas they harvest are spoiled before they can reach consumers, due to a lack of adequate cold storage facilities, or damage received in transit on bumpy rural roads. In such cases, a wider adoption of post-harvest technologies, more coordinated processing systems and even simple solutions – such as shock-absorbent packaging for transporting the produce – could greatly reduce waste.

Shifting populations

Not only is the global population growing at a rate that continues to threaten food security, but people are increasingly moving to urban areas – reducing the amount of land actually being farmed, while increasing the distance from field to fork.

Urbanisation is a complex phenomenon with multiple dimensions, including the expansion of the built environment, infrastructure, and change of lifestyles. It also deeply affects the food system in terms of supply, demand and distribution, necessitating better post-harvesting handling procedures, data management and supply chain logistics, as well as improved processing facilities.

Improved food preservation through technology

More effective food preservation systems, including technologies for processing and storage, are essential for balancing supply and demand, evening out the shocks of extreme weather events, balancing under/overproduction cycles, and improving market delivery. New technologies also extend the shelf life of food – guaranteeing safety without affecting taste, appearance or nutritional properties. Most of these solutions rely on metals and minerals for their key components.

  • Heating

    Heating technologies can be divided into thermal (microwave or ohmic heating) and non-thermal: primarily High Pressure Processing (HPP) or Pulsed Electric Field (PEF). The first HPP equipment – introduced in 1899 to pasteurise raw milk – comprised tubular containers made of tin, lead and steel, pressured using a steel piston. Without these metals, this machine could not be built – even today, where HPP is used to inactivate spoilage microorganisms in packaged foods, extending shelf life. HPP also preserves solid foods, and can be used for other processing procedures, such as removing meat from shellfish. Its usage continues to grow, mainly due to health-conscious consumers demanding organic or naturally-treated convenience food. A PEF system, meanwhile, comprises three basic components: a high voltage pulse generator, a treatment chamber and a control system for monitoring the process parameters. The treatment chamber, which is the heart of the machine, usually consists of two electrodes – built from stainless steel, carbon, gold, platinum and metal oxides.

  • Irradiation

    During the irradiation process, food is exposed to a carefully measured amount of ionising radiation. This improves food safety and extends shelf life by reducing or eliminating microorganisms and insects, preventing the germination or sprouting of vegetables, as well as slowing down the ripening and ageing of fruit. Currently, there are around 200 large-scale irradiators in 40 countries around the world, including developing countries such as Ghana and Bangladesh. At an irradiation facility, the radiation source is contained in a stainless steel casing. The casings are in turn contained in a lead-lined chamber. Packaged food travels on a conveyor belt between concrete walls, into and through a chamber, where it is exposed to radiation. This process would not be possible without metals and minerals, including cobalt, iron, chromium, lead, and lime.

  • Cooling

    Freezing and refrigeration are key methods of preservation throughout the food chain, from producers and freight companies to consumers. However, its usage is highly related to any area’s level of economic development, including reliable energy access. While 99% of households in developed countries own a fridge, in India it is only one in four. Refrigeration systems are either closed mechanical systems or open cryogenic systems. The main elements of the former are a condenser, compressor, evaporator and expansion valve, as well as refrigerants circulated within this system, most commonly hydrochlorofluorocarbon (HCFC) and ammonia. A cryogenic system comprises two major components: the compressor package, which compresses refrigerant and removes heat from the system, and the cold head, which takes refrigerant to cool it down to cryogenic temperatures. In general, a refrigerator is built from a variety of metals and minerals, including hematite, chromite (stainless steel), galena, copper, cinnabar, and pentlandite.

  • Silo storage

    Hi-tech solutions are not always needed to reduce hunger. In Bangladesh, for example, the World Bank financed simple silos which can store grain for up to three years. The silos are flat-bottomed constructions which can be erected quickly and easily moved to different places. Another advantage is that they occupy much less space than conventional concrete warehousing. The silos are equipped with computerised humidity and temperature controls, helping retain the nutritional quality of food. The project is particularly important in increasing the grain reserve available to households to meet post-disaster needs. The silos in question are completely waterproof, weather-resistant, and have a long life thanks to the resilience of their construction materials, primarily stainless steel and aluminium.

  • Packaging

    Effective packaging of food is particularly important where a reliable power supply for freezing is not available, which is often the case in lower-income countries. Packaging can be made from multiple materials, including glass, plastics, wood, paper, or metal (aluminium or steel). The global market for metal packaging is projected to reach 135.69bn USD by 2020, with an annual growth rate of 3.0% from 2015 to 2020. With regards to sustainability, metals are called permanent materials, recycled again and again without changing their physical properties. Moreover, metal packaging can be used in a variety of sizes, from a small tomato can to a steel drum for bulk tomato transport. Metal elements also complement other kinds of packaging (eg a metal vacuum closure for a glass jar), while packaging machinery is mostly made from metals. Minerals are also crucial to the packaging industry; for example, silica – a compound of several minerals – is indispensable for glass production.