Food and Beverage Gases Information
Food and beverage gases are a category of industrial gases explicitly implemented in the manufacture, processing, handling, storage, and/or sterilization of foodstuffs. Since the final products are intended for consumption and nutrition, food and beverage gases face unique scrutiny.
This guide does not reference gases sold in oxygen bars or those used for water purification applications.
Food and Beverage Gases Operations
A select number of gases are used in the food and beverage industries. These gases are tightly regulated by government agencies to ensure that gas quality and consumer health are not compromised by the introduction of gaseous elements and compounds. Inclusion of gases in the creation and handling of food is limited to the following roles:
- As an additive within the food to enhance taste or texture
- As a controlled or modified atmosphere, to ease processing constraints and/or for preservation during storage
For the sterilization of food items without the use of solvents
As a propellant to dispense a food or beverage from its vessel
Image credit: Micromatic
The most prominent example of gas as a food additive would be in the carbonation of soft drinks and beers. In the instance of soft drinks and seltzer water, manufacturers dissolve gaseous CO2 within water at high pressure. A low concentration of carbonic acid is created, and a pH between 3 and 4 results in an acid-like taste which can be moderated with sodium bicarbonate. The infusion of CO2 into beverages provides a 'fizz' on the tongue, and this taste is largely-regarded as pleasant. A carbon-infused beverage must be kept under pressure to maintain the CO2within the drink. In bars and restaurants, carbonated water is created on-site by the use of a carbonator, and a concentrated soft drink mixture is then added for flavoring. Beers and carbonated spring waters are naturally carbonated by their means of production. In the case of the former, CO2 is a byproduct of the fermentation process as yeast digests the sugar in the beer. While most of the carbonation escapes, a detectable amount remains. Spring waters absorb CO2 as it is filtered in underground streams.
Also common is the use of hydrogen in vegetable oil processing to remove carbon-carbon double bonds, resulting in a solid or semi-solid fat. Hydrogenation results in a longer shelf life with more culinary flexibility.
Image credit: Air Liquide
Utilizing gases within a manufacturing or packaging environment is beneficial to many food products. It is common to introduce an inert gas, such as carbon dioxide or nitrogen, into containment vessels to prevent food products from moisture degradation or oxidation. Oxygen levels, it at all present, are tightly regulated. In the instance of fruit storage, operators will introduce ethylene to the products to initiate ripening, as ethylene is an important plant hormone. Modified atmospheres are used in product packaging to purge oxygen within the package in favor of a gas which inhibits product spoilage. N2 and CO2, alone or as a mixture, are used in this process for most food products, but CO is frequently chosen for meat storage as it helps maintain the color of the beef, pork, or fish (this process is banned in some jurisdictions). Grains, oats, flour, rice, and tobacco are all held in a carbon dioxide or nitrogen environment for four days upon harvest to eliminate insects which may have infested agricultural products. Beverage vessels may introduce an inert gas to prevent regular air or a vacuum inside the vessel as it's drained.
For the preservation of frozen food items, gases are liquefied to promote a cryonic state that offers several chilling advantages: quicker freeze rate and improved efficiency over mechanical freezers; increased production; reduced product dehydration; reduced bacterial activity; and increased shelf life. Nitrogen is most frequently liquefied for this purpose. Carbon dioxide may be solidified into dry ice as well.
Also notable is the use of sulfur dioxide as a winemaking preservative. As an antibiotic and antioxidant, SO2 prevents product spoilage and changes in acidity. Even wines marketed as 'unsulfurated' contain amounts of SO2 at up to 10 mg/L.
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Reactive gases are used to kill microorganisms that may be present on foods or in water; it is an essential part of food manufacture. Most of the microbial mechanisms within the following gases are also harmful to humans, so considerations include a food product's permeability and chemical compatibility, the work environment and application method of the sterilizing agent, and the decontamination cycles of the sterilized gas. When using any type of gas sterilizer, required components include air exchanges, gas monitors, and quality operator training. Some of the more common sterilizing gases include:
Ehtylene dioxide: Kills viruses, bacteria, fungi, and spores; easily permeates materials; falling out of favor due to flammability, toxicity, carcinogenic characteristics, and residues and byproducts which must also be chemically removed.
Ozone: Can sterilize liquids, gases, and surfaces; destroys a number of harmful pathogens without affecting food; can easily be turned back into oxygen when sterilization is complete; extremely reactive so it must be produced on-site, which could be impractical.
Formaldehyde: A gas at room temperature with the ability to kill many pathogens; weak penetrating power; long post-process decontamination times.
Chlorine dioxide: Dissolved in water where it turns into chlorite, which can be turned into the harmless chloride; effective for water treatment and the cleaning of food production lines; frequently used to sanitize berries; it is very volatile and dangerous in gas form.
Hydrogen peroxide: Oxidizing properties kill dangerous bacteria and viruses; extremely harmful to humans in gas form; it produces free radicals which disrupts the metabolism of microorganisms; byproducts are nontoxic, and the food products can be handled immediately after sterilization.
Notably, CO2 and N2 are used in restaurants and bars to pressurize draft beverage lines, such as in a keg. Pressurizing a beverage lines with CO2 or N2 allows the keg to be placed away from the service site without exposing the beverage to oxidation. Similarly, cream products sold in aerosol cans utilize nitrous oxide to pressurize the container.
Food and Beverage Gas Quality
In most countries, legislation has been enacted to protect food stocks from being contaminated by inferior manufacturing and storage processes. Similarly, each country appoints an agency to oversee consumer health issues, as well as what materials and processes are considered safe for food and beverage operations. In the United States it is represented by the Food and Drug Administration, and in Canada by the Food Inspection Agency. Regulations are not internationally uniform, even between affable neighbors such as the U.S. and Canada. As such, the Compressed Gas Association enlisted the help of individuals from the aforementioned nations to create the standards document: CGA M-10 (2012) Food Safety Management Systems and Good Manufacturing Practices for Food Gas Manufacturers. The document is to be used in conjunction with the federal, state, and provincial legal standards concerning food gas implementation. The following gases are uniformily believed to be safe to be used as an ingredient or food contact substance.
- Carbon dioxide: As an additive, pressurizing agent, aerating agent, or atmospheric preservative
- Nitrogen: As an aerating or pressurizing agent, or blanket preservative
- Oxygen: As an oxidizing agent
- Ozone: As a cleansing agent
- Nitrous oxide: As a pressure dispensing agent
- Propane: As an aerating agent or propellant
- Iso-butane / n-butane: As a propellant
- Ethylene: As a fumigant
- Chlorine: As a sanitizer
Other gases may be used, but have not been reviewed by the CGA's technical committee on food-grade gas stocks. The CGA has also released the Compressed Gas Handbook and a standard regarding impurities in CO2 of carbonated beverages. Admirably, the International Society for Beverage Technologist's CO2 Guidelines summarizes the best-practices for soft drink carbonation.
- SAA AS 5034 Using inert gases for beverage dispensing
- DIN 6653-2 Dispense systems for draught beverages
- BS PD CEN/TR 15623 MAP food processing machinery
- ASTM E460 Effect of packaging on food and beverages
- ASTM F1115 Measuring carbon dioxide loss of beverage containers
Gas Storage and Delivery
In most instances where food and beverage gases are needed, it is more efficient for the operator to generate the gas on-site due to the volumes and frequency with which the gas is processed. The most common use of a food-grade gas generator would be the implementation of the carbonator in bars and restaurants. Many industrial gas solutions experts can offer volumes of food-grade gases for limited production runs or prototyping, but these bulk deliveries are inefficient for sustained usage during manufacturing.
On-site carbonator. Image credit: Direct Industry