Calcium lactate is a white crystalline salt with formula C 6H 10CaO 6, consisting of two lactateanionsH 3C(CHOH)CO− 2 for each calciumcationCa2+ . It forms several hydrates, the most common being the pentahydrate C 6H 10CaO 6·5H 2O.
The lactate ion is chiral, with two enantiomers, D (−,R) and L (+,S). The L isomer is the one normally synthesized and metabolized by living organisms, but some bacteria can produce the D form or convert the L to D. Thus calcium lactate also has D and L isomers, where all anions are of the same type.[5]
Some synthesis processes yield a mixture of the two in equal parts, resulting in the DL (racemic) salt. Both the L and the DL forms occur as crystals on the surface of aging Cheddar cheese.[5]
The solubility of calcium L-lactate in water increases significantly in presence of d-gluconate ions, from 6.7 g/dl) at 25 °C to 9.74 g/dl or more.[1][2] Paradoxically, while the solubility of calcium L-lactate increases with temperature from 10 °C (4.8 g/dl) to 30 °C (8.5 g/dl), the concentration of free Ca2+ ions decreases by almost one half. This is explained as the lactate and calcium ions becoming less hydrated and forming a complex C 3H 5O 3Ca+ .[2]
The DL (racemic) form of the salt is much less soluble in water than the pure L or D isomers, so that a solution that contains as little as 25% of the D form will deposit racemic DL-lactate crystals instead of L-lactate.[6]
The pentahydrate loses water in a dry atmosphere between 35 and 135 °C, being reduced to the anhydrous form and losing its crystalline character. The process is reversed at 25 °C and 75% relative humidity.[7]
Since the 19th century, the salt has been obtained industrially by fermentation of carbohydrates in the presence of calcium mineral sources such as calcium carbonate or calcium hydroxide.[8]: p200 [9][10] Fermentation may produce either D or L lactate, or a racemic mixture of both, depending on the type of organism used.[11]
Calcium lactate is used in medicine as an antacid.[12]
It is also used to treat hypocalcaemia (calcium deficiencies). It can be absorbed at various pHs, thus it does not need to be taken with food. However, in this use it has been found to be less convenient than calcium citrate. Calcium lactate contains 13% elemental calcium.[13]
In the early 20th century, oral administration of calcium lactate dissolved in water (but not in milk or tablets) was found to be effective in prevention of tetany in humans and dogs with parathyroid insufficiency or who underwent parathyroidectomy.[14][15]
The compound is also found in some mouth washes and toothpaste as an anti-tartar agent.[12]
Calcium lactate (or other calcium salts) is an antidote for soluble fluoride ingestion[16]: p165 and hydrofluoric acid.
Calcium lactate is also known as cheese lactate because it coagulates milk, making the chhena used in the production of paneer cheese.[12] Chhena is also used to make various sweets and other milk proteins.
The compound is also added to fresh-cut fruits, such as cantaloupes, to keep them firm and extend their shelf life, without the bitter taste caused by calcium chloride, which can also be used for this purpose.[20]
Calcium lactate may be added to animal rations as a source of calcium.[21]
Chemistry
The compound was formerly an intermediate in the preparation of lactic acid for food and medical uses. The impure acid from various sources was converted to calcium lactate, purified by crystallization, and then converted back to acid by treatment with sulfuric acid, which precipitated the calcium as calcium sulfate. This method yielded a purer product than would be obtained by distillation of the original acid.[8]: p180 Recently ammonium lactate has been used as an alternative to calcium in this process.[10]
Water treatment
Calcium lactate has been considered as a coagulant for removing suspended solids from water, as a renewable, non-toxic, and biodegradable alternative to aluminum chlorideAlCl 3.[22]
^ abMartina Vavrusova, Merete Bøgelund Munk, and Leif H. Skibsted (2013): "Aqueous Solubility of Calcium l-Lactate, Calcium d-Gluconate, and Calcium d-Lactobionate: Importance of Complex Formation for Solubility Increase by Hydroxycarboxylate Mixtures". Journal of Agriculture and Food Chemistry, volume 61 issue 34, pages 8207–8214. doi:10.1021/jf402124n
^ abcMartina Vavrusova, Ran Liang, and Leif H. Skibsted (2014): "Thermodynamics of Dissolution of Calcium Hydroxycarboxylates in Water". Journal of Agriculture and Food Chemistry, volume 62, issue 24, pages 5675–5681. doi:10.1021/jf501453c
^ abG.F. Tansman, P.S. Kindstedt, J.M. Hughes (2014): "Powder X-ray diffraction can differentiate between enantiomeric variants of calcium lactate pentahydrate crystal in cheese". Journal of Dairy Science, volume 97, issue 12, pages 7354–7362. doi:10.3168/jds.2014-8277
^Gil Fils Tansman (2014): Exploring the nature of crystals in cheese through X-ray diffraction Masters Dissertation, University of Vermont
^Yukoh Sakata, Sumihiro Shiraishi, Makoto Otsuka (2005): "Characterization of dehydration and hydration behavior of calcium lactate pentahydrate and its anhydrate". Colloids and Surfaces B: Biointerfaces, volume 46, issue 3, pages 135–141. doi:10.1016/j.colsurfb.2005.10.004
^ abH. Benninga (1990): "A History of Lactic Acid Making: A Chapter in the History of Biotechnology". Volume 11 of Chemists and Chemistry. Springer, ISBN9780792306252
^Kook Hwa Choi, Yong Keun Chang, and Jin-Hyun Kim (2011) "Optimization of Precipitation Process for the Recovery of Lactic Acid". KSBB Journal, volume 26, pages 13-18. (AbstractArchived 2017-04-16 at the Wayback Machine)
^ ab"A gypsum-free, energy-saving route to lactic acid" Chemical Engineering, July 1, 2009.
^Rojan P. John, K. Madhavan Nampoothiri, Ashok Pandey (2007): "Fermentative production of lactic acid from biomass: an overview on process developments and future perspectives" Applied Microbiology and Biotechnology, volume 74, issue 3, pages 524–534 doi:10.1007/s00253-006-0779-6
^Straub DA (June 2007). "Calcium supplementation in clinical practice: a review of forms, doses, and indications". Nutr Clin Pract. 22 (3): 286–96. doi:10.1177/0115426507022003286. PMID17507729.
^Sloan J. Wilson (1938): "Postoperative Parathyroid Insufficiency and Calcium Lactate". Archives of Surgery, volume 37, issue 3, pages 490-497. doi:10.1001/archsurg.1938.01200030139008
^A.B. Luckhardt and B. Goldberg (1923): "Preservation of the Life of Completely Parathyroidectomized Dogs by Means of the Oral Administration of Calcium Lactate." Journal of the American Medical Association, volume 80, issue 2, pages 79-80. doi:10.1001/jama.1923.02640290009002
^Carolyn A. Tylenda (2011): "Toxicological Profile for Fluorides, Hydrogen Fluoride, and Fluorine (Update)". DIANE Publishing. ISBN9781437930771
^E.J. Pyler (1988), Baking Science and Technology, Sosland Publishing
^Sudaa, R.; T. Suzukia; R. Takiguchib; K. Egawab; T. Sanob; K. Hasegawa (2006). "The Effect of Adding Calcium Lactate to Xylitol Chewing Gum on remineralization of Enamel Lesions". Caries Research. 40 (1): 43–46. doi:10.1159/000088905. PMID16352880. S2CID45316316.
^Luna-Guzman, Irene; Diane M. Barrett (2000). "Comparison of calcium chloride and calcium lactate effectiveness in maintaining shelf stability and quality of fresh-cut cantaloupes". Postharvest Biology and Technology. 19: 16–72. doi:10.1016/S0925-5214(00)00079-X.
^B.N. Paul, S. Sarkar, S. S. Giri, S. N Mohanty, P. K. Mukhopadhyay (2006): "Dietary calcium and phosphorus requirements of rohu Labeo rohita fry". Animal Nutrition and Feed Technology, volume 6, issue 2, pages 257-263
^R. Devesa-Rey, G. Bustos, J. M. Cruz, A. B. Moldes (2012): "Evaluation of Non-Conventional Coagulants to Remove Turbidity from Water". Water, Air, & Soil Pollution, volume 223, issue 2, pages 591–598. doi:10.1007/s11270-011-0884-8
^J.M. Irwan, L.H. Anneza, N. Othman, A. Faisal Alshalif (2016): "Compressive Strength and Water Penetration of Concrete with Enterococcus faecalis and Calcium Lactate". Key Engineering Materials, volume 705, pages 345-349. doi:10.4028/www.scientific.net/KEM.705.345