Wines ascorbic acid

Fig. 9.4. Evolution of oxidation-reduction potential of reduced wines, aerated after the addition of 100 mg of ascorbic acid per liter, compared with control wine (Rib6reau-Gayon et ah, 1977). (A) Red wine control. (B) Red wine + ascorbic acid. C) White wine control. (D) White wine + ascorbic acid...

The taste improvement due to ascorbic acid depends on several factors. The first is the type of wine. Ascorbic acid is of little interest in the case of wines made from certain varieties or very evolved wines—for example, barrel-aged wines oxidized white wines, botrytized sweet wine, and fine red wines. On the contrary, it improves the stability of fresh and fruity wines (generally young wines), having conserved their varietal aromas. 

In sparkling wines, ascorbic acid acts not only by its reducing properties but also by its capacity as an oxidation-reduction buffer. Their potential remains stable at 240 mV for several years. In the absence of ascorbic acid, it varies between 200 and 265 mV, according to the effectiveness of corking. This phenomenon clearly affects the organoleptical characters of wine (Makaga and Maujean, 1994). 

Other Food Uses. Jellies, jams, and preserves use malic acid to balance flavor and adjust pH for pectin set. Canned fmits and vegetables employ malic acid in combination with ascorbic acid to produce a synergistic effect that aids in the reduction of browning. Wine and cider producers use malic acid in malolactic fermentation to provide bouquet and for pH adjustment. 

Alpha hydroxy acids (AHAs) are water-soluble substances and thereby penetrate the outermost epidermal skin layers. In contrast, beta hydroxy acids (BHAs) are lipid (fat) soluble and are capable of penetrating to the underlying layers of skin (the dermis) located 1-5 mm below the surface of the skinJ2 Most AHAs are derived from plant materials and marine sources. Commonly used AHAs include malic acid (found in apples), ascorbic acid (a common ingredient in numerous fruits), glycolic acid (a constituent of sugar cane), lactic acid (a component of milk), citric acid (naturally abundant in citrus fruits), and tartatic acid (found in red wine). A common BHA is salicylic acid (an ingredient in aspirin). 

Electrocatalysis in oxidation has apparently first been shown for ascorbic acid oxidation by Prussian blue [60] and later by nickel hexacyanoferrate [61]. More valuable for analytical applications was the discovery in the early 1990s of the oxidation of sulfite [62] and thiosulfate [18, 63] at nickel [62, 63] and also ferric, indium, and cobalt [18] hexacyanoferrates. More recently electrocatalytic activity in thiosulfate oxidation was shown also for zinc [23] hexacyanoferrate. Prussian blue-modified electrodes allowed sulfite determination in wine products [64], which is important for the wine industry. 

Phytochemicals present in fruits and vegetables are very diverse, such as ascorbic acid, carotenoids, and phenolic compounds (Liu 2004 Percival and others 2006 Syngletary and others 2005 Yahia and others 2001a, 2001b). Plant polyphenols are ubiquitous in the diet, with rich sources being tea, wine, fruits, and vegetables they demonstrate considerable antioxidative activity in vitro, which can have important implications for health (Duthie and others 2000). 

Bradshaw MP, Prenzler PD and Scollary GR. 2001. Ascorbic acid-induced browning of (-l-)-catechin in a model wine system. J Agric Food Chem 49(2) 934—939. 

Ascorbic acid/tartaric acid rn 5,(bipyridyl)ruthenium(II)-Ce(IV) 0.05-1.7/1.4-140 4.8/1.7 The method was applied to wine samples 66... 

Figure 19 Antioxidative qualities of wines (white rectangles) in comparison to watery extracts from solid grape constituents skins (gray rectangles) and pips (black rectangles) in equivalent concentrations of ascorbic acid (mmol/L, mmol/g).

Small amounts of organic radicals are formed continually in the skin during photolysis (in a process with rate constant k( )). The radicals are consumed immediately by natural substances in the skin, termed antioxidants (in a different process with rate constant k(2)). Vitamin C (L-(+)-ascorbic acid, IV) is one of the best naturally occurring antioxidants. Red wine and tea also contain efficient antioxidants. 

There is increasing interest in the use of specific sensor or biosensor detection systems with the FIA technique (Galensa, 1998). Tsafack et al. (2000) described an electrochemiluminescence-based fibre optic biosensor for choline with flow-injection analysis and Su et al. (1998) reported a flow-injection determination of sulphite in wines and fruit juices using a bulk acoustic wave impedance sensor coupled to a membrane separation technique. Prodromidis et al. (1997) also coupled a biosensor with an FIA system for analysis of citric acid in juices, fruits and sports beverages and Okawa et al. (1998) reported a procedure for the simultaneous determination of ascorbic acid and glucose in soft drinks with an electrochemical filter/biosensor FIA system. 

Bradshaw, M.P. et al., Defining the ascorbic acid crossover from anti-oxidant to pro-oxidant in a model wine matrix containing (-l-)-catechin. J. Agric. Food Chem. 51, 4126, 2003. 

Labrador et al. (2009) developed a technique based on pulse voltammetry, used to predict concentrations of bisulfites, ascorbic acid, and histamine in wine samples, by means of PLS models evaluated via cross-validation. The best prediction results have been obtained for bisulfites. 

Peng, Z., Duncan, B., Pocock, K. F., and Sefton, M. A. (1998). The effect of ascorbic acid on oxidative browning of white wines and model wines. Aust. ]. Grape Wine Res. 4,127-135. 

Alcohol is justifiedly considered a nutrient because Nigerian palm wine is reported to contain 145 milligrams of ascorbic acid and 100 grams of vitamin C per serving. (Oshodin 1995,213)... 

Removal of trace levels of oxygen. Traces of oxygen in wines and fruit juices cause discolouration and/or oxidation of ascorbic acid. Chemical... 

Campanella et al. [1] Superoxide radical polyphenols Sulfite Ascorbic acid Wine Superoxide dismutase (SOD), or tyrosinase, or sulfite oxidase, or ascorbate axidase/in a gel-like kappa-carrageenan membrane sandwiched between a cellulose acetate membrane and a dialysis membrane Amperometric Pt electrode for hydrogen peroxide (for superaxide determination)/ +650 mV vs. Ag/AgCl/ Amperometric oxygen electrode (for the rest)/-650 mV vs. Ag/AgCl... 

For phenol 1-37 pM For H2O2 30-130 pM For lecithin 2.0-48.7 mg L"1 Superoxide radical 0.02-2.0 mM <5% Working media ft-hexane for tyrosinase electrode chloroform for catalase electrode chloroform/hexane (50% v/v) containing 1% by volume of methanol for lecithin electrode. Antioxidant capacity of wines was evaluated in terms of polyphenol content, sulfite and ascorbic acid, and compared to superoxide radical scavenging... 

Another important field of application concerns food and beverages, especially wine, juices, and tea (A2, A11, A17, B4, K12, V7, Yl). The antioxidant components of food include vitamin E (a-tocopherol), vitamin A (retinoids), vitamin C (ascorbic acid), and also fi-carotene (provitamin A), other carotenoids (of which more than 600 compounds have been identified), flavonoids, simple phenols, and glucobrasicins (H3). Unfortunately, the TAC value of a food is not informative on the bioavailability of its antioxidants. It has been estimated that polyphenols are normally present in blood plasma at concentrations of 0.2-2 //M (PI). However, it has been demonstrated that feeding rats a quercetin-augmented diet can increase their plasma levels of quercetin and its metabolites up to 10-100 //M (M27), and transient increases in the concentration of plant-derived phenolic compounds can take place after ingestion of food and beverages, which may affect blood plasma TAC (see later). 

Many researchers succeeded in demonstrating discernible transient effects of meals on TAC of blood plasma. Consumption of 500 ml of cranberry juice (but not blueberry juice) induced an increase in blood plasma TAC, attaining a maximum after 60-120 min (P5). TAC of elderly women was also increased 0 1 hr after consumption of 240 g of strawberries, 1250 mg of ascorbic acid, or 240 g of raw spinach or drinking 300 ml of red wine. TAC of urine collected over 24 hr was also increased after consumption of vitamin C (by 45%), spinach (by 28%), and strawberries (by 10%) (C13). 

The amount of S02 added to foods is self-limiting because at levels from 200 to 500 ppm the product may develop an unpleasant off-flavor. The acceptable daily intake (ADI) is set at 1.5 mg/kg body weight. Because large intakes can result from consumption of wine, there have been many studies on reducing the use of S02 in wine making. Although some other compounds (such as sorbic acid and ascorbic acid) may partially replace S02, there is no satisfactory replacement for S02 in wine making. 

DeBolt, S., Hardie, J., Tyerman, S., and Ford, C.M., 2004, Comparison and synthesis of raphide crystals and druse crystals in berries of Vitis vinifera L. cv. Cabernet Sauvignon Ascorbic acid as precursor for both oxalic and tartaric acids as revealed by radiolabelling studies. Aust. J. Grape Wine Res. 10 134—142. 

Various aldehydes are encountered in wine. The most abundant is acetaldehyde which is both a product of yeast metabolism and an oxidation product of ethanol. Glyoxylic acid, resulting from oxidation of tartaric acid, especially catalyzed by metal ions (Fe, Cu) or ascorbic acid, can also be present. Other aldehydes reported to participate in these reactions include furfural and 5-hydroxymethylfurfural that are degradation products of sugar and can be extracted from barrels (Es-Safi et al. 2000), vanillin which also results from oak toasting, isovaleraldehyde, benzaldehyde, pro-pionaldehyde, isobutyraldehyde, formaldehyde and 2-methylbutyraldehyde which are present in the spirits used to produce fortified wines (Pissara et al. 2003). 

---