Acid sorbic

Sorbic acid is prepared by the condensation of crotonaldehj de with malonic acid ill the presence of pyridine at 100° (Doebner reaction)  

CH3CH=CHCHO-1-HjC(COjH)2 CH3CH=CHCH=CHCOjH-1-COj-1-HjO 

This unsaturated hydrocarbon is easily prepared by the action of sodium upon allyl iodide or bromide  

Place 56 g. of clean sodium, cut into small pieces, in a 500 ml. round-bottomed flask fitted with two 25 or 30 cm. double surface condensers in series. Weigh out 136 g. (72 ml.) of freshly distilled allyl iodide, b.p. 99-101° (Section 111,39). Introduce about one quarter of the aUyl iodide through the condensers. Warm the flask gently until the sodium commences to melt and immediately remove the flame. A vigorous reaction sets in and a liquid refluxes in the condensers. Add 

CH3CH=CHCHO+H2C(COjH)j CH3CH=CHCH=CHC02H+C0,+H20 

Sorbic acid is preferred to other organic acids because of its physiological harmlessness and organoleptic neutrality. In the United States, sorbic acid is a GRAS substance and its use is permitted in any food product to which preservatives may be added (Banerjee and Sarkar, 2004). Sorbic 

Sorbic acid has a pK, value of 4.76 and in a pH 4.2 solution about 75% will be in its undissociated form. At pH 7 1% will be undissociated. Although acetic acid has the same pK, value as sorbic acid, a tenfold higher concentration of acetic acid is required to produce the same extent of growth inhibition as sorbic acid (Papadimitriou et al., 2007). 

Until recently, the use of sorbic acid was a standard approach for preservation in the food industry. However, much attention has now focused on the development of resistance against this weak organic acid preservative (Brul et al., 2002). 

CH3CH=CHCH0-(-HssC(C02H)2 - 4. CH3CH=CHCH=CHC02H-1-C0,-(-H20 

2CH3=CHCHr3l -1- 2Na — CH3=CHCHjCH3CH=CHj + 2NaI AUyl iodide Diallyl 

Sorbic acid is a short-chained (a-p-unsaturated fatty acid) which is widely used in food industries as a fungistatic agent. In the wine industry, it finds application at bottling in the prevention of refermentation in sweetened wines by Saccharomyces cerevisiae. 

The BATF limit for sorbic acid in table wines is 300 mg/L, whereas OIV places a limit of 200 mg/L. In the case of wine coolers, the level is much higher, 1000 mg/L, or when used with benzoic acid, their combined concentrations are 1000 mg/L. In table wines, depending on alcohol, pH, SO2, and yeast titer, 100-200 mg/L are typically used. 

The inhibitory action of sorbic acid is thought reside in its lipophilic properties disrupting cell membrane function. 

As sorbic acid is relatively insoluble, it is usually sold as the salt potassium sorbate. In this case, it is necessary to consider the differences in molecular weights in the calculation of the amount needed  

The required weight of potassium sorbate should be hydrated in wine or water before mixing into the volume of wine. 

BP Sorbic acid PhEur Acidum sorbicum USPNF Sorbic acid 

E200 (2-butenylidene) acetic acid crotylidene acetic acid hexadienic acid hexadienoic acid 2,4-hexadienoic acid 1,3-pentadiene-l-carboxylic acid 2-propenylacrylic acid ( , )-sorbic acid Sorbistat K. 

Antimicrobial activity sorbic acid is primarily used as an antifungal agent, although it also possesses antibacterial properties. The optimum antibacterial activity is obtained at pH 4.5 and practically no activity is observed above pH The efficacy of sorbic acid is enhanced when it is used in combination with other antimicrobial preservatives or glycols since synergistic effects occur. Reported minimum inhibitory concentrations (MICs) at pH 6 are shown in Table 

Sorbic acid is an antimicrobial preservative with antibacterial and antifungal properties used in pharmaceuticals, foods, enteral preparations, and cosmetics. Generally, it is used at concentrations of 0.05-0.2% in oral and topical pharmaceutical formulations, especially those containing nonionic surfactants. Sorbic acid is also used with proteins, enzymes, gelatin, and vegetable gums. It has been shown to be an effective preservative for promethazine hydrochloride solutions in a concentration of 1 g/L.  

Sorbic acid has limited stability and activity against bacteria and is thus frequently used in combination with other antimicrobial preservatives or glycols, when synergistic effects appear to occur see Section 10. 

Bacteria are not affected by sorbic acid, and, in fact, several species can metabolize the acid to eventually yield 2-ethoxyhexa-3,5-diene, a compound that imparts a distinctive geranium odor/tone to wines (Section 11.3.5). Other odor/flavor-active compounds detected in spoiled wines treated with sorbic acid include l-ethoxyhexa-2,4-diene and ethyl sorbate (Chisholm and Samuels, 1992), the latter of which has been associated with off-flavors in sparkling wines (De Rosa et al., 1983). Whereas Chisholm and Samuels (1992) described ethyl sorbate as possessing a honey or apple aroma, De Rosa et al. (1983) thought the compound imparted a very unpleasant pineapple-celery odor upon short-term (6 month) storage. Based on this observation, De Rosa et al. (1983) recommended that sorbates should not be used in sparkling wine production. 

If used to stabilize a sweet wine, sorbic acid should be added just prior to bottling. Additions should be carried out in stainless steel or other containers that can be cleaned and sanitized. Use of wood tanks for pre-botding mixing and storage should be avoided. Here, residual sorbic acid trapped in the wood may be utilized by resident lactic acid bacteria in the production of geranium-tone, which can continually leech into wines subsequently processed through that tank. 

The amount of ethanol presentwill also dictate the appropriate amounts of sorbic acid to add. Although Ough and Ingraham (1960) recommended adding 150 mg/L to a wine with 10% to 11% v/v ethanol, that concentration decreased at alcohol concentrations of 12% (100mg/L) or 14% v/v (50 mg/L). 

German Sorbinsaure, French Acide sorbique, Spanish Acido sorbico. 

Potassium (E,E)-sorbate Sorbic acid, potassium salt Potassium (E,E)-hexa-2,4-dienoate Potassium sorbate Vinosorb E 202. 

Caldum (E,E)-sorbate Sorbic acid-calcium Calcium sorbate E 203. 

Sorbic acid - sodium salt. Although the sodium salt of sorbic acid is mentioned in different food regulations it was never used to such an extend as its potassium or caldum salt. Because of its instability it caimot be stored for longer periods. This is the main reason that it is not produced on industrial scale (Lueck et al., 1998). 

The LD50 for rats after oral administration is 7.4 10.5 g/kg body weight (Deul et al., 1954 Sado, 1973). 

The antimycotic effect of straight chain carboxylic acids has long been known. In particular the unsaturated acids, for example crotonic acid and its homologues, are very active. Sorbic acid (2-trans, 4-trans-hexadienoic acid pK = 4.76) has the advantage that it is odorless and tasteless at the levels of use (0.3% or less). The acid is obtained by several syntheses  

Unlike benzoic acid, the esters can be used over 3 CH3CH0 a wide pH range since their activity is almost independent of pH (cf. Fig. 8.12). As additives, pH i2.5 they are applied at 0.3-0.06% as aqueous alkali Ag/Oz/aox solutions or as ethanol or propylene glycol solutions in fillings for baked goods, fruit juices, marmalades, syrups, preserves, olives and pick-led sour vegetables. 

From crotonaldehyde obtained from ethanal (cf. Reaction 8.29). 

The microbial activity of sorbic acid is primarily against fungi and yeasts, less so against bacteria. The activity is pH dependent (Fig. 8.12). Its utilization is possible up to pH 6.5, the proportion of undissociated acid being still 1.8%. 

The LD50 (rats) of sorbic acid is ca. 10 g/kg body weight. Feeding experiments with rats for more than 90 days, with 1-8% sorbic acid in the diet, had no effect, while only 60% of the animals survive an 8% level of benzoic acid. 

See Genetic ENGINEERING, animals Growih regulators Hormones, human growih hormone. 

The soibic acid crystal has a weU-oideied morphology as a result of its hydrogen bonding and trans,trans stmcture (1). 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

The chemical reactivity of sorbic acid is determined by the conjugated double bonds and the carboxyl group. 

Conjugated Double Bonds. Sorbic acid is brominated faster than other olefinic acids (7). Reaction with hydrogen chloride gives predominately 5-chloro-3-hexenoic acid (8). 

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The reaction is readily illustrated by the formation of crystalline sorbic acid by the condensation of crotonaldehyde and malonic acid in hot pyridine solution ... 

Add 4 g. of malonic acid to 4 ml. of pyridine, and then add 3 1 ml. of crotonaldehyde. Boil the mixture gently under reflux over an asbestos-covered gauze, using a small Bunsen flame, for 40 minutes and then cool it in ice-water. Meanwhile add 2 ml. of concentrated sulphuric acid carefully with shaking to 4 ml. of water, cool the diluted acid, and add it with shaking to the chilled reaction-mixture. Sorbic acid readily crystallises from the solution. Filter the sorbic acid at the pump, wash it with a small quantity of cold water and then recrystallise it from water (ca, 25 ml.). The colourless crystals, m.p. 132-133°, weigh ro-i-2 g. 

Sorbic acid could theoretically, by virtue of the two olefine linkages, exi.st in four geometrical I y-isomeric forms. The above synthesis gives only one form, which is undoubtedly the trans-trans form, analogous to the acu-diphenylpolyenes (p. 238) which are also normally produced solely in one form. 

Examples of the Knoevenagel reaction with aldehydes are given under crotonic acid (111,145), P-n-hexylacrylic acid (111,144), sorbic acid (111,145) and furylacryUc acid (V,10). 

ANTTBIOTTCS - BETA-LACTAMS - BETA-LACTAMASE INHIBITORS] (Vol 3) -inhibited by sorbates [SORBIC ACID] ( 7ol22)... 

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