Foodstuffs citric acid

Despite the popularity of citric acid as a food additive and preservative, its sharp and overwhelming acidic taste is, however, inclined to overpower the flavor of sweeteners or other flavorants that may be present in a foodstuff. Citric acid also presents a short-lived tartness flavor. Other disadvantages have also been noted when using citric acid as a food additive. For example, due to its hygroscopic nature, it tends to cake when used in dry powders such as soft drink or beverage mixes. It also has an uneven particle size and is not always free-flowing. However, despite these few drawbacks, citric acid is by far the most commonly used food acidulant. The initial sharpness associated with citric acid is preferable in some end products such as citrus-flavored drinks (Fowlds, 2002). 

Linalool has been used to prepare a mixture of terpenes useful for enhancing the aroma or taste of foodstuffs, chewing gums, and perfume compositions. Aqueous citric acid reaction at 100°C converts the linalool (3) to a complex mixture. A few of the components include a-terpineol (34%) (9), Bois de Rose oxide (5.1%) (64), ocimene quintoxide (0.5%) (65), linalool oxide (0.3%) (66), tij -ocimenol (3.28%) (67), and many other alcohols and hydrocarbons (131). 

A common form of EDTA used as a preservative is calcium disodium EDTA (CaNa2EDTA). What metals will this form of the sequestrant scavenge effectively The dissolution of the solid will yield calcium ions, sodium ions, and the EDTA anion. Any metal more effectively complexed than calcium will be readily scavenged, including all ions listed in Table 9.1 except silver (Ag+) and magnesium (Mg2+). (In the absence of the calcium counterion, as in the case of the acid form of EDTA, chelation of calcium in the body can occur. In fact, EDTA administered orally is an FDA-approved treatment for calcium deposits in the bloodstream that lead to cardiovascular disease.) Citric acid (Fig. 9.3.3) is another sequestrant of metal ions in foodstuffs. 

The hemoglobin-catalyzed oxidation of o-phenylenediamine to 2,3-diaminophenazine (100), in phosphate-citric acid buffer at pH 5.0, shown in equation 30, is the basis for a kinetic method for determination of H2O2, in a FIA system, measuring at 425 mn by the stopped-flow method. The LOD is 9.2 nM, with RSD 2.08% at 0.5 p,M and linearity in the 50 to 3500 nM range . This colorimetric method was proposed for development as a standard procedure in the Republic of China for determination of H2O2 in foodstuffs . ... 

In most living organisms, the citric acid cycle constitutes the final common pathway in the degradation of foodstuffs anil cell constituents to carbon dioxide and water. This cycle is described In the entry-on Carbohydrates. 

Figure 20-8 Perspective of the metabolic scheme whereby carbohydrates, fats, and proteins in foodstuffs are oxidized to C02, showing the link between glycolysis, the citric acid cycle, and oxidative phosphorylation...

Citric acid (melting point 153°C, density 1.665) is one of our most versatile organic acids and is used as an acidulant in carbonated beverages, jams, jellies, and other foodstuffs. Another large outlet is in the medicinal field, including the manufacture of citrates and effervescent salts. Industrially citric acid is used as an ion-sequestering agent buffer and in the form of acetyl tributyl citrate, as a plasticizer for vinyl resins. 

Acetyl-CoA is oxidized to C02 by the Krebs cycle, also called the tricarboxylic acid cycle or citric acid cycle. The origin of the acetyl-CoA may be pyruvate, fatty acids, amino acids, or the ketone bodies. The Krebs cycle may be considered the terminal oxidative pathway for all foodstuffs. It operates in the mitochondria, its enzymes being located in their matrices. Succinate dehydrogenase is located on the inner mitochondrial membrane and is part of the oxidative phosphorylation enzyme system as well (Chapter 17). The chemical reactions involved are summarized in Figure 18.7. The overall reaction from pyruvate can be represented by Equation (18.5) ... 

Finally, microorganisms also produce ingredients for foodstuffs, such as in citric acid fermentation in which citric acid is obtained from molasses using a mould. 

Increased effectiveness of organic acids may be achieved when used in lower concentrations, but in combination with additional inhibitors. For example, combining nisin with reduced organic acid concentrations may decrease potential flavor flaws in meat products (Samelis et al., 2005). Citric and ascorbic acids, in combination, are effective in inhibiting growth and toxin production of C. botulinum type B in vacuum-packed foodstuffs (Barbosa-Canovas et al., 2003 Samelis et al., 2005). In other studies, a combination of equal amounts of ascorbic acid and citric acid did not have additional benefits, compared with using ascorbic acid alone (Mancini et al., 2007). 

The answer is b. (Murray, pp 627—661. Scriver, pp 3897—3964. Sack, pp 121-138. Wilson, pp 287—320.) Pantothenic acid, also called coacetylase, is a component of coenzyme A (CoA). Acetyl CoA is the activated form of acetate employed in acetylation reactions, including the citric acid cycle and lipid and cholesterol metabolism. A deficiency of pantothenic acid would limit CoA and have deadly consequences in mammals. However, since it is common in foodstuffs, there is little evidence of pantothenic acid deficiency in humans. 

As Table 15.1 shows, many carboxylic acids occur in nature. Fatty acids can be isolated from a variety of sources including palm oil, coconut oil, butter, milk, lard, and tallow (beef fat). More complex carboxylic acids are also found in a variety of foodstuffs. For example, citric acid is found in citrus fruits and is often used to give the sharp taste to sour candies. It is also added to foods as a preservative and antioxidant. Adipic acid (hexanedioic acid) gives tartness to soft drinks and helps to retard spoilage. 

Use The racemate is used to impregnate packing materials for cheese and other foodstuffs (against mold fungi) and, in place of citric acid, as souring agent for bread and confectionery as well as beverages. The enantiomers find use in racemate separation. 

The world market for chemicals produced by fermentation methods is predicted to be about 44 billion by 2012, with more than half of that amount involving ethanol fermentation. A short list of economically important materials other than foodstuffe produced by fermentation methodologies includes bulk antibiotics, alcohols (ethanol, butanol, and so on), enzymes, organic acids (amino acids, citric acid, lactic acid, and others), vitamins, polymers, and biogums. 

Chlorinated hydrocarbons Chlorine oxides Chlorine, water and brine Chlorine, wet or dry Chloroacetic acid Chrome-plating solutions Chromic acid Citric acid Cleaning solutions Copper salts Ethyl sulfate Ethylene dibromide Fatty acids Ferric chloride Ferrous sulfate Foodstuffs Formaldehyde Formic acid Fruit products Flydriodic acid... 

The end products of catabolism are mainly CO2 and H2O. Carbon dioxide arises largely from decarboxylation in the citric acid cycle water originates from biologic oxidation in the respiratory chain. Since the breakdown products of the three main foodstuffs, carbohydrates, fats, and proteins, all enter these common terminal pathways, it is not surprising that these foodstuffs can replace each other as nutrients. 

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