Citric Acid E330 is known as lemon salt. It appears as a colorless powder with a sour taste, easily soluble in water.
Spread
Citric acid is very common in nature, especially in lemon, orange, pineapple, raspberry, currants, grape juice, etc. It has also been identified in the animal body, for example, in milk and blood, etc.
- Obtaining and characterization/characteristics
Its chemical name is: 2-hydroxy-1,2,3-propanetricarboxylic acid, β-hydroxycitric acid, or monohydroxycitric acid.
It is found in two forms:
– The anhydrous form with the molecular formula C6H8O7 and a molecular weight of M=192.13.
– The monohydrate form with the molecular formula C6H8O7·H2O and a molecular weight of M=210.15.
The name of the citric acid comes from the Latin word citrus, referring to the citrus tree, whose fruit resembles a lemon. Citric acid was first isolated from lemon juice in 1784 by Carl Scheele, a Swedish chemist (1742–1786). Citric acid is an almost universal intermediate product of metabolism, and its traces can be found in nearly all plants and animals.
Commercial production of citric acid began in England around 1826 from imported Italian lemons. As its commercial importance grew, Italian lemon crops started to produce it, establishing a virtual monopoly for most of the 19th century. Lemon juice remained the commercial source of citric acid until 1919 when the first industrial process using Aspergillus Niger was initiated in Belgium.
Citric acid was synthesized from glycerol by Grimoux and Adams in 1880. Subsequently, several chemical synthesis methods were attempted, but they proved to be non-competitive compared to fermentation-based production, mainly due to the high cost of raw materials compared to the final product.
In 1893, Wehmer first showed that a “Citromyces” (now Penicillium) accumulated citric acid in a culture medium containing sugars and inorganic salts. Since then, it has been discovered that many other microorganisms accumulate citric acid, including strains of A. niger, A. awamori, A. nidulans, A. fonsecaeus, A. luchensis, A. phoenicus, A. wentii, A. saitoi, A. flavus, Absidia sp., Acremonium sp., Botrytis sp., Eupenicillium sp., Mucor piriformis, Penicillium janthinellum, P. restrictum, Talaromyces sp., Trichoderma viride, and Ustulina vulgaris.
Currie discovered in 1917 that some strains of A. niger grew abundantly in a nutrient medium with high sugar and mineral salt concentration and an initial pH of 2.5–3.5. As they grew, these strains excreted large amounts of citric acid. This established the basis for industrial citric acid production.
Although many microorganisms can be used to produce citric acid, A. niger remains the principal industrial producer.
- The necessity of using citric acid in the food industry
Citric acid is used in the food industry because it provides a pleasant acidic taste to products. It is highly soluble in water, making it suitable for use in juices, sweets, candies, jellies, and frozen fruits. The use of citric acid is necessary for the enzymatic clarification of juices and to prevent honey crystallization.
It can also be used in the production of alcoholic beverages such as wine, beer etc. In wine production, it serves as an acidulant (adjusting the wine’s pH) and prevents the formation of unwanted precipitates (iron complexes as soluble ferrocitric acid).
Approximately 50% of the world’s citric acid production is used as a flavor enhancer in beverages, and 20% in the food processing industry, where it functions as an acidulant, buffering agent, flavor enhancer, and has a synergistic effect in antioxidant blends.
In addition to giving an acidic flavor to food products, in the fruit and vegetable processing industry citric acid plays a protective role in preserving ascorbic acid (vitamin C) by complexing heavy metals.
Peeled fruits and vegetables, when treated with a citric acid solution, are protected against enzymatic browning.
In ice cream, it acts as an emulsifier. It can contribute to the inactivation of oxidative enzymes by lowering the pH of the food.
The use of the food additive E330 is essential to inhibit the rancidity of vegetable and animal oils and fats. It has an antioxidant action and works synergistically with antioxidants such as BHA (E320), BHT (E321), and propyl gallate (E310).
In the production of melted cheese, it is a component of melting salts.
Citric acid increases the efficiency of preservatives in food. By lowering the pH, the likelihood of microorganism growth and survival in processed foods is reduced, thus extending their shelf life.
Citric acid can also be used as a stabilizing agent in spices.
Monohydrated citric acid is a crystalline white powder. It can be used as a preservative and antioxidant. It is also employed as an acidulant and flavoring agent in fruit drinks, candies, cakes, cookies, preserves, fruits, jams, and jellies. It differs from other forms of citric acid by having a moisture content ranging from 7.5% to 9.0%.”
- Allowed doses in food products
The safety of citric acid was evaluated in 1990 by the Scientific Committee for Food, which set the acceptable daily intake as “unspecified.” The term “unspecified” is used when, based on available toxicological, biochemical, and clinical data, the total daily dose of the substance resulting from its natural occurrence and its current use in food at the levels necessary for achieving the desired technological effect does not pose a health risk.
Citric acid (E 330) is an approved food additive in a variety of foods in accordance with Annex II of Regulation (EC) No. 1333/2008.
The table below shows the permitted doses of citric acid in various food products where it can be used.
| Nr. crt. | Product Category | Maximum Limit (restrictions/exceptions) |
| 1 | Unripened cheese, with the exception of products from category 16 (01.7.1) | quantum satis only for Mozarella |
| 2 | Fats and oils, and emulsions from fats and oils | quantum satis exception virgin oils and olive oils |
| 3 | Fruit nectars as defined by Directive 2001/112/EC, and vegetable nectars and similar products | ML = 5000 mg/l |
| 4 | Cereal-based processed foods and foods for infants and young children, as defined by Directive 2006/125/EC (13.1.3) | quantum satis only processed food based on cereals and food for children, only for adjusting the pH |
| 5 | Fruit juices, as defined by Directive 2001/112/EC, and vegetable juices (14.1.2) | quantum satis only grape juice |
| 6 | Fruit nectars, as defined by Directive 2001/112/EC, and vegetable nectars and similar products (14.1.3). | ML = 5000 mg/l |
| 7 | Meat products as defined by Regulation (EC) No. 853/2004 (8.2). | quantum satis only for minced meat, prepackaged food from fresh minched meat and meat products to which other ingredients other than additives or salt have been added |
| 8 | Potato gnocchi (06.4.4) | quantum satis only for gnocchi made from fresh refrigerated potatoes |
| 9 | Cacao și produse din ciocolată care sunt acoperitre de Directiva 2000/36/EC (5.1), (EC) No 0351/2020, aplicabila din 24/03/2020) | ML = 5000 mg/kg
ML = 10000 mg/kg , only milk chocolate |
| 10 | Peeled, cut and chopped fruits and vegetables (04.1.2) | quantum satis numai fructe și legume neprelucrate, refrigerate preambalate, gata de consum, cartofi neprelucrați și decojiți preambalați și legume albe preambalate destinate prelucrării ulterioare, inclusiv tratament termic, înainte de consum.”
|
Source: https://eur-lex.europa.eu/legal-content/RO/TXT/PDF/?uri=CELEX:02008R1333-20160525&from=FR
- The toxicity of citric acid
Citric Acid (E 330) in food (99,5%) does not pose any health risk or danger.
However, pure or concentrated citric acid (99-99.8%) poses a safety hazard and, therefore, should not be consumed.
Whether pure or concentrated, it is corrosive and irritating upon contact with the skin and mucous membranes of the eyes, nose, and throat. It can cause skin allergies and acute toxicity if ingested.
Inhaling pure citric acid dust can also affect the respiratory tract’s mucous membrane, potentially leading to breathing difficulties, allergies, sensitization of the respiratory mucosa, and even asthma.
Toxic effects on reproductive function have been reported. Citric acid can induce genetic defects by causing mutations in germ cells. It is considered hazardous or toxic to aquatic habitats, and in general, concentrated citric acid is corrosive to metals.
Some studies have shown that citric acid has low acute toxicity when orally administered to rats (LD50 = 3,000–12,000 mg/kg, with three different values) and mice (LD50 = 5,400 mg/kg). General effects included physiological disturbances (acidosis and calcium deficiency), while “high” doses had effects on the nervous system, as well as severe stomach mucosa damage.
Subcutaneous administration reported LD50 values of 5,500 mg/kg in rats and 2,700 mg/kg in mice. Injecting citric acid through various routes in rats, mice, and rabbits (doses not specified) caused effects on the nervous system, lungs, spleen, and liver, partially attributed to acidosis and calcium deficiency.
Other studies have shown that injecting large volumes of citrate into the bloodstream during transfusion can lead to hypocalcemia and changes in blood composition, with concurrent nausea, muscle weakness, breathing difficulties, and even cardiac arrest.
Bibliography
- Maria Papagianni, Research review paper Advances in citric acid fermentation by Aspergillus niger: Biochemical aspects, membrane transport and modeling, Biotechnology Advances, vol. 25, 2007, pages 244–263;
- Dallal Chergui, Soraya Akretche-Kelfat , Lynda Lamoudi , Mamoon Al-Rshaidat , Farida Boudjelal , Hamid Ait-Amar, Optimization of citric acid production by Aspergillus niger using two downgraded Algerian date varieties, Saudi Journal of Biological Sciences, Volume 28, Issue 12, December 2021, pages 7134-7141;
- Elena Oranescu, Aditivii alimentari-necesitate și risc, Editura SemnE, 2005, Bucuresți, page 146;
- Raluca Stan, Aditivii alimentari produsi naturali de de sinteză, Editura Printech, 2007, page 109;
- Regulation (EC) No 1333/2008 of the European Parliament and of the Council of 16 December 2008 on food additives;
- Commission Regulation (EU) 2020/351 of 28 February 2020 2020 amending Annex II to Regulation (EC) No 1333/2008 of the European Parliament and of the Council as regards the use of citric acid (E 330) ) in cocoa and chocolate products;
- OECD SIDS, Citric acid, https://hpvchemicals.oecd.org/ui/handler.axd?id=ff78c453-36c1-430d-9034-63e15899d24b#;
- Commission Regulation (EU) 2020/351 of 28 February 2020 amending Annex II to Regulation (EC) No 1333/2008 of the European Parliament and of the Council as regards the use of citric acid (E 330) in cocoa and chocolate products;
- Online Edition: “Combined Compendium of Food Additive Specifications”
- https://hpvchemicals.oecd.org/ui/handler.axd?id=ff78c453-36c1-430d-9034-63e15899d24b;
- https://www.fao.org/fileadmin/user_upload/jecfa_additives/docs/monograph16/additive-135-m16.pdf;
- https://topingrediente.com/acid-citric-5kg/;
- https://www.chemistryworld.com/podcasts/citric-acid/8736.article;
- https://ro.wikipedia.org/wiki/Acid_citric;
- http://www.chimopar.com/files/ACID%20CITRIC%20FTS_1.pdf;
Translated from Romanian by: Andra Nițu