Foods, volatile acids

Muratore, G., Nicolosi Asmundo, C., Lanza, C. M., Caggia, C., Licciardello, F., and Restuccia, C. (2007). Influence of Saccharomyces uvarum on volatile acidity, aromatic and sensory profile of Malvasia delle Lipari wine. Food Technol. Biotechnol. 45,101-106. 

Table VI summarizes the effect of heating medium on the loss of acids after 3 minutes of microwave heating. Loss of volatile acids varied widely dependent on the microwave medium. Acetic and caproic acids had losses ranging from 20-80% and 0-73%, respectively, depending on medium composition. The dielectric property, specific heat, or other physical/chemical properties of individual flavor compounds can provide valuable insight into the potential behavior of these compounds during the microwave process. The dielectric property of the total food system and the affinity of the flavor compound for the microwave medium, however, were primarily responsible for the behavior of these flavor compounds during microwave heating.

Vidal-Carou, M.C., Codony-Salcedo, R. Marine-Eont, A. (1990a). Histamine and tyramine in Spanish wines Relationships with total sulfur dioxide level, volatile acidity and malolactic fermentation intensity. Food Chem., 35, 217-227. 

Acetic acid is one of the main products of AAB metabolism and is found in many foods as the result of the presence and activity of these bacteria. Acetic acid is also a major volatile acid in wine but also one of the... 

DHS applications have been developed, for example, for the determination of aroma-active compounds in bamboo shoots (83), styrene in yoghurt (8- ) and volatile acids in tobacco, tea, and coffee (88), volatile compounds of strawberries (89) and odor-active compounds of hams (90). The applications of DTD-GC include, for example, in the determination of volatile components of Lavandula luisieri (85), in the analysis of volatile components of oak wood (87) and volatiles in various solid-food products such as spices and herbs (black pepper, oregano, basil, garlic), coffee, roasted peanuts, candy and mushrooms (82). 

Sinha, R. N., and Sinha, P. R. (1988). Volatile and non-volatile acids produced by Clostridium sporogenes isolated from processed cheese. J. Food Sci. Technol. 25, 101-102. 

The term volatile acids refer to steam-distillable acids. The primary volatile acid in foods is acetic acid, and volatile acidity is often expressed as acetic acid. Propionic, formic, and butyric acids are also volatile acids found in some foods. Lactic and succinic acids are slightly steam distillable and therefore may not be considered as a part of the volatile acids. 

Food contains one polysaccharide (starch) and three disaccharides (maltose, sucrose, and lactose). Salivary and pancreatic amylase digests starch to yield maltose and sucrose, and lactose to yield maltose and sucrose. Sucrose, maltose, and lactose are split by invertase, maltase, and lactase, respectively. The products of the disaccharidase reactions are fructose, glucose, and galactose. Whenever amylase or one of the disacchari-dases is absent from the intestinal content, the undigested sugars pass in the lower part of the intestinal tract and are fermented by the bacterial flora. As a result, lactic acid and volatile acids are formed and stimulate peristalsis and fluid secretion by the intestinal mucosa. Liquid foaming acid and foul-smelling feces are emitted. Amylase may be absent in pancreatic disease. Inborn errors characterized by the absence of intestinal lactase, maltase, and invertase have been described. 

One finds that pH influences both the taste and the aroma of a food. In terms of taste, hydrogen ion concentration is generally linked to the tartness of a food the lower the pH, the more tart the food tastes. While the effect of pH on taste is well recognized, pH also influences the release of some aroma chemicals, i.e., those that act as acids or bases. For example, one would expect the contribution of volatile acids to aroma to be enhanced in aqueous solution at lower pHs, i.e., those below the pKa of the acid. At low pHs, the acid would be in its protonated form (not ionized) and thus be less soluble in the aqueous phase. This would tend to drive the acid into the sample headspace, increasing its contribution to aroma. Basic odorants (e.g., amines or pyrazines) would behave in an opposite manner. These compounds would become more soluble in the aqueous phase below their pKa since they would be ionized and thus more soluble. This would decrease their contribution to aroma at low pHs. The effect of pH on aroma is obvious when one increases the pH of a traditional acidic food or tries to produce a good chocolate flavor in low pH foods (typically neutral or slightly basic). 

Porter W L, Buch M L, Willits C O 1951 Maple syrup. III. Preliminary study of the non-volatile acid fraction. Food Res 16 338-341... 

Aldehydes, alcohols, carboxylic acids, their esters and other transformation products of amino acid are important food volatiles. Aldehydes and fusel oil alcohols formed during alcoholic fermentation are important flavour-active compounds of alcoholic beverages. Esters of carboxylic acids are important flavour constituents of many foods, especially fruits, alcoholic beverages and dairy products. Aldehydes are also formed in the Maillard reaction during cooking, baking, frying and other thermal operations. 

Acetic acid is one of the most important aliphatic carboxylic acids, being the principal acid constituent of vinegars (5% w/v) and volatile acidity in wines. The food industry uses vinegar to preserve and season food at the same time. Determination of acidity by SIA is invariably based on titration with a base solution while the titration reaction is monitored by UV/Vis spectroscopy or potentiometry. 

Hollingworth, T. A., J. M. Hungerford, J. D. Barnett, and M. M. Wekell. 1994. Total volatile acids Temperature dependent decomposition indicator in halibut determined by flow injection analysis. J. Food Protect. 57(6) 505-508. 

Iodized Salt. Iodized table salt has been used to provide supplemental iodine to the U.S. population since 1924, when producers, in cooperation with the Michigan State Medical Society (24), began a voluntary program of salt iodization in Michigan that ultimately led to the elimination of iodine deficiency in the United States. More than 50% of the table salt sold in the United States is iodized. Potassium iodide in table salt at levels of 0.006% to 0.01% KI is one of two sources of iodine for food-grade salt approved by the U.S. Food and Dmg Administration. The other, cuprous iodide, is not used by U.S. salt producers. Iodine may be added to a food so that the daily intake does not exceed 225 p.g for adults and children over four years of age. Potassium iodide is unstable under conditions of extreme moisture and temperature, particularly in an acid environment. Sodium carbonate or sodium bicarbonate is added to increase alkalinity, and sodium thiosulfate or dextrose is added to stabilize potassium iodide. Without a stabilizer, potassium iodide is oxidized to iodine and lost by volatilization from the product. Potassium iodate, far more stable than potassium iodide, is widely used in other parts of the world, but is not approved for use in the United States. 

Diesters. Many of the diester derivatives are commercially important. The diesters are important plasticizers, polymer intermediates, and synthetic lubricants. The diesters of azelaic and sebacic acids are useflil as monomeric plasticizing agents these perform weU at low temperatures and are less water-soluble and less volatile than are diesters of adipic acid. Azelate diesters, eg, di- -hexyl, di(2-ethylhexyl), and dibutyl, are useflil plasticizing agents for poly(vinyl chloride), synthetic mbbers, nitroceUulose, and other derivatized ceUuloses (104). The di-hexyl azelates and dibutyl sebacate are sanctioned by the U.S. Food and Dmg Administration for use in poly(vinyl chloride) films and in other plastics with direct contact to food. The di(2-ethylhexyl) and dibenzyl sebacates are also valuable plasticizers. Monomeric plasticizers have also been prepared from other diacids, notably dodecanedioic, brassyflc, and 8-eth5lhexadecanedioic (88), but these have not enjoyed the commercialization of the sebacic and azelaic diesters. 

Foods such as meat, fish, and some vegetables contain sulfur-bearing amino acids that form volatile sulfur compounds during processing and storage. When these compounds react with iron, a black precipitate forms on the container and in most instances darkens the food. A small piece of aluminum welded to the tinplate can has been used to prevent container corrosion and sulfide staining in commercially canned hams. In this case, the aluminum acts as a sacrificial anode and stops the reaction with tin and iron that otherwise could occur at the small exposed tinplate areas (14). 

---