Propionic acid, or propanoic acid, is a colorless, corrosive, short-chain carboxylic acid with a pungent odor that is miscible in water and various common organic solvents. It has diverse industrial applications due to its molecule's ability to be converted into a series of secondary compounds, resulting in a wide variety of products.<\/p>\n
Propionic acid is a naturally occurring organic acid resulting from the fermentation process of bacteria of the genus Propionibacterium. It is found in various environments, being present in dairy products, in the stomachs of ruminant animals, and even in human metabolism. For example, bacteria of the genus Propionibacterium participate in the ripening process of Swiss cheese, converting lactic acid and lactates into propionic acid and carbon dioxide, the latter being responsible for the characteristic holes in the cheese.<\/p>\n
In cattle, bacteria of this genus participate in the digestion of cellulose contained in the diet and release propionic acid and acetic acid in the rumen, which are used as an energy source by the animals after undergoing extensive metabolic pathways. In humans, the acid is produced in small quantities by the breakdown of amino acids and oxidation of fatty acids in the intestine.<\/p>\n
Among its applications in industry, it is commonly used as a food preservative. food<\/em><\/strong> e feed<\/em><\/strong>, Propionic acid is an important chemical intermediate in the synthesis of cellulose fibers, herbicides, perfumes, cosmetics, dyes, artificial fruit flavors, esters used as solvents, plasticizers, rubber products, and pharmaceuticals. Below are some of the many industrial applications of propionic acid.<\/p>\n As mentioned earlier, propionic acid has several industrial applications. We will begin by describing its application in food preservation. food<\/em><\/strong>. According to the FAO and the WHO (Food and Agriculture Organization of the United Nations; World Health Organization), the use of propionic acid is permitted for the preservation of food (breads, cakes, cheeses, meats, fruits, vegetables and canned sausages) and beverages, at a maximum concentration of 3,000 mg\/kg-1. <\/p>\n In Brazil, propionic acid is a preservative approved by the National Health Surveillance Agency (ANVISA). Furthermore, it is listed among the products generally recognized as safe by the U.S. Food and Drug Administration (FDA), attesting that its addition to food does not pose health risks. It can be used as a preservative in the form of solutions of the pure acid or its sodium, calcium, and potassium salts. <\/p>\n But in Brazil, is there a limit to the use of preservatives in food? ANVISA, the responsible public agency, publishes and updates its resolutions for each food category. For example, regarding food additives authorized for use in meats and meat products, the most recent resolution, RDC No. 272, of March 14, 2019, establishes maximum limits and conditions of use of 0.5 g\/100 g, for both propionic acid and sodium propionate and potassium propionate.<\/p>\n Some foods, such as certain varieties of cheese, contain a small amount of propionic acid produced naturally during their maturation. However, the small amount produced is not sufficient for food preservation, making it necessary to add other solutions, such as calcium and sodium propionate. However, according to the aforementioned RDC (Resolution of the Collegiate Board), when two or more food additives with the same technological function are used and for which there are established maximum numerical limits, the sum of the quantities of these additives in the product ready for consumption cannot exceed the highest limit established for the additive permitted in the largest quantity. Therefore, it is worthwhile to check the legislation and stay informed about the use of additives for different food categories.<\/p>\n Access our\u00a0LinkedIn<\/a>\u00a0And stay tuned for updates!<\/p>\n For the preservation of animal feed, propionic acid or its derivatives, known as propionates or propanoates, are widely used because their preservative action shows good results over extended periods. However, the molecule chosen for use depends on the storage conditions. For example, in agriculture, the most commonly used form of propionic acid is ammonium propionate, as it is less corrosive to agricultural equipment. Propionate in solution can be applied to high-moisture grains stored in silos, such as oats, corn, or sorghum. Other uses are associated with the preservation of forages such as hay; and on the surfaces of silage and grain storage areas.<\/p>\n Its action is primarily directed at inhibiting the growth of molds which, when present in feed or roughage, produce mycotoxins responsible for causing animal productivity problems, whether gastric, infertility, or immunodeficiency, which are closely linked to the economic impact on farms. It also combats the growth of yeasts, bacteria, and insects such as weevils, which, depending on the level of infestation, can cause considerable losses in stored products. Application is by spraying onto the raw material or feed, and it is not considered an additive that requires a withdrawal period before consumption of animal products. Another common method of application is via water, as the acid prevents the growth of algae and other microorganisms, thus avoiding contamination.<\/p>\n Among the applications of propionic acid is its use in the pharmaceutical industry as an antimicrobial in drug formulations. It is also a common ingredient in creams, lotions, and solutions to prevent contamination by microorganisms during handling or storage of medications.\u00a0<\/p>\n Another example of its application refers to its use as a raw material for the production of acrylic acid, which is used in the manufacture of plastics, food packaging, as well as in adhesives, surfactants, paints, coatings, among others. The carboxylation of propionic acid is a critical step in this process. Propionic acid also finds applications in other branches of the chemical industry, such as in the production of ester-based solvents, the manufacture of herbicides, and the synthesis of other organic compounds.<\/p>\n Its industrial synthesis occurs through two main routes: chemically from petroleum-based raw materials; and via fermentation, which has become an attractive alternative for producing this acid using renewable resources.<\/p>\n Industrially, propionic acid is obtained from raw materials from the petrochemical industry with good results in terms of production volumes. However, raw materials derived from petroleum are not renewable resources, and they also suffer from high price volatility and limited availability in certain regions. Some of the production routes are explained by the Reppe and Oxo processes, and processes where propionic acid is a byproduct. <\/p>\n The Reppe process consists of an exothermic reaction of ethylene with carbon monoxide and water in the presence of a nickel tetracarbonyl catalyst; the Oxo process (hydroformylation of olefins) consists of a reaction of ethene and synthesis gas to form propanal, followed by oxidation of the aldehyde formed; the production of propionic acid as a byproduct of other processes is basically derived from the production of acetic acid by oxidation of hydrocarbons.<\/p>\n A large quantity of propionic acid can be obtained by direct oxidation of hydrocarbons. This process is mainly employed for the production of acetic acid, with propionic acid, formic acid, and a mixture of butyric acid isomers formed as byproducts. The proportion of propionic acid formed varies with the raw material used.<\/p>\n The production of propionic acid through biotechnological routes has the great advantage of allowing the use of renewable raw materials and the reuse of agro-industrial waste such as sugarcane bagasse, molasses, and glycerol from biodiesel production. However, the volume produced is still not economically competitive with petrochemical-based production. Long fermentation times, low productivity, low final acid concentration, low yield, and the formation of byproducts that hinder and increase the cost of propionic acid recovery and purification are the factors that impede the industrial implementation of the bioprocess.<\/p>\n Interested and want to know more? Enter Contact our technical consultants.<\/a> For applied solutions!<\/p>\nIndustrial Applications<\/strong><\/h2>\n
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Production and extraction routes for propionic acid.<\/strong><\/h2>\n