It is often said that the food industry is among those that grows continuously, because people have to eat in order to survive and work, no matter what other hardships they have to endure – hence it is described as non-cyclical.

Observation has confirmed that when people gain an increase in disposable income, their expenditure on food always increases.

Several developing countries including China, India, Brazil and Vietnam have overcome whatever economic constraints they previously experienced and are achieving unprecedented economic growth. Many African countries are also demonstrating greater economic stability and growth.

Millions of people are migrating to cities and industrial centres to earn their way to a better lifestyle – and this massive influx of consumers is driving explosive demand for basic food commodities and inflating food prices around the world.

Recent research to analyse the market demand for industrial gases in South Africa confirmed that one of the most buoyant industries in that country during the 2008/2009 world recession was food and beverage manufacturing, and this trend is echoed in the result statements of gas companies in most countries.

Nitrogen and carbon dioxide are the industrial gases required in the majority of food processing, manufacturing and packaging applications, but fairly small requirements for argon and oxygen are also involved.

Processing, bottling and canning of beverages
Carbon dioxide is the industrial gas required in the greatest volumes for the production of beverages including drinking water.

Potable water is even more vital to sustaining human and animal life than food and here, carbon dioxide is increasingly used for conditioning and PH adjustment. Natural water supplies can be obtained from a wide range of sources and most of these contain dissolved minerals and salts that determine the broad characteristics of the water source, such as hard or soft, brackish or sweet.

Many countries in drier parts of the world like the Middle East and North Africa have little choice than to produce potable water supplies by desalinating sea water.

Apart from disinfection and the adjustment of mineral content, to improve the taste of water it is often necessary to lower the PH; firstly to facilitate chemical processing and also to prevent the rapid decay of transmission pipelines, valves, pumps and other capital equipment.

Carbon dioxide has proved a very convenient agent for PH manipulation and its good solubility in water produces stable results. Companies and public utilities responsible for the provision of water supplies depend critically on continual supplies of pure carbon dioxide in many parts of the world.

The beverage bottling and canning industry forms a major constituent of the demand for carbon dioxide, especially in warm climates that also display strong seasonal fluctuations.

In most markets the mainstream suppliers of carbon dioxide can claim that their product is carbon neutral, because it is extracted from the waste gas emissions of existing energy intensive industries. Supply problems have persisted in many countries, where raw carbon dioxide is sourced from plants producing the ammonia that is required for agricultural fertiliser.

The reason for this is that the demand cycle for fertiliser runs out of phase with the demand cycle for carbonated drinks and the supply of the by-product carbon dioxide is often compromised when ammonia plants shutdown for maintenance.

In a global environment already awash with excessive emissions of carbon dioxide, it would seem absurd to deliberately produce more, merely to satisfy the demand of this industry. However in response to supply crises and despite severe cost penalties, such plants have been constructed that produce raw carbon dioxide by combusting petroleum gas or diesel and purifying it for food industry applications.

Freezing, chilling and preservation
The other major industrial gas requirement by the food industry is for nitrogen that is used in a wide range of applications.

Liquid nitrogen is widely supplied for use as a refrigerant in devices that are designed to chill or freeze either fresh or prepared food products. In the case of exotic or high value foods like shrimp and lobster, more expensive liquid nitrogen freezing is preferred for quality reasons over conventional mechanical freezing. An exception to this is the freezing of hamburger patties, for which nitrogen freezing is preferred in order to cope with very large production volumes and also to achieve the longest possible shelf-life.

The extremely low temperature of -196°C enables food products to be frozen very rapidly when either sprayed or immersed in liquid nitrogen. Typically, freezing time is reduced from hours to minutes and this has the useful benefit that discrete pieces remain separate instead of freezing together; the term Individually Quick Frozen (IQF) was coined to describe this.

Rapid freezing results in the formation of far smaller ice crystals, greater moisture retention, reduced drip-loss and less freezer-burn than slower conventional freezing methods.

Liquid nitrogen freezers also find application in situations where limited finance prevents the investment in a conventional freezing system that promises lower operating costs in the long-term, but electric power tariffs also influence this evaluation. Seasonal demand peaks requiring additional production of a food product can be accommodated by using liquid nitrogen freezing for only a part of the year.

Liquid nitrogen is produced commercially by separating air in a cryogenic air separation unit (ASU) and cannot be obtained from non-cryogenic separation plants. Maximum cooling efficiency is available when the freezing plant is located close to the ASU, because the cryogenic liquid gradually absorbs heat from the environment while in storage or transport – causing pressure build-up and wastage.

Industrial gases and food safety
The purity of gases supplied to the food industry is of primary importance to both the industrial gases industry and the food processing industry.

Historically there have been remarkably few incidents where gas quality has been shown to cause food contamination.

Various systems of quality assurance have been developed to manage this risk; the most widely recognised being known as Hazard Analysis Critical Control Point (HACCP) which is a systematic preventive approach to food and pharmaceutical safety that addresses physical, chemical and biological hazards as a means of prevention rather than finished product inspection.