Ascorbic acid retention

Food process optimi2ation measurements may link a single chemical such as a vitamin, or a physical change such as viscosity, to process conditions and to consumer acceptance. Retention levels of ascorbic acid [50-81-7] C HgO, or thiamine can often be used as an indicator of process conditions (see... 

Fig. 10. Suggested pathway for the biosynthesis of L-ascorbic acid (with retention of configuration) in higher plants based on D-glucose-l- C...

Choi, M.H., Kim, G.H., and Lee, H.S., Effects of ascorbic acid retention on juice color and pigment stability in blood orange Citrus sinensis) juice during refrigerated storage, Food Res. Int, 35, 753, 2002. 

Camire (2002) showed that texturization does not seem to have a great effect on mineral retention and bioavailability. Others have reported increased retention of ascorbic acid in rice- and maize-based snacks (Hazell and Johnson, 1989 Plunkett and Ainsworth, 2007), increased iron diffusibility and absorption of iron-complexed protein (Poltronieri et al, 2000 Watzke, 1998), and no difference in iron and zinc absorption in human subjects fed textured bran-flour (Fairweather-Tait et al, 1989). 

Plunkett, A. and Ainsworth, P. (2007). The influence of barrel temperature and screw speed on the retention of L-ascorbic acid in an extruded rice based snack product. /. Food Eng. 78,1127-1133. 

Ascorbic acid retention in some fresh-cut produce is affected by the nature of the slicing method used (Lee and Kader 2000). Higher levels of ascorbic acid were retained in samples that had been prepared by manually tearing the lettuce into strips. Lettuce shredded using a sharp knife initially retained 18% less ascorbic acid than the torn samples. The retention of ascorbic acid in the products sliced by machine was 25-63% lower than that in lettuce shredded by manual tearing. Using a blunt machine blade resulted in 10% lower ascorbic acid levels than when a sharp blade was used (Barry-Ryan and O Beirne 1999). Losses in ascorbic acid occur when vegetables are severely cut or shredded (Lee and Kader 2000). 

Ascorbic acid is probably the most labile bioactive compound in fruit juices and fruit and vegetable pieces, as we described in the first part of this chapter. Retention of this phytochemical after the nonthermal treatments ranged from 47% to 100%, depending on the intensity of the applied treatment and the product. For example, the greatest losses of vitamin C were found in fresh-cut red lettuce and melon treated with IR and HHP (Fan and others 2008 Wolbang and others 2008), respectively. However, the use of gamma radiation in various vegetables retained 100% of their total ascorbic acid content (Fan and others 2008). 

It may be concluded that PEF, HHP, and IR are adequate techniques for the retention of bioactive compounds in fruit and vegetable products and may even enhance bioactivity of juices, purees, and fresh-cut produce. A greater degradation of ascorbic acid in comparison with phenolics and carotenoids is usually observed. 

Barry-Ryan C and O Beime D. 1999. Ascorbic acid retention in shredded iceberg lettuce as affected by minimal processing. J Food Sci 64(3) 498—500. 

Howard LA, Wong AD, Perry AK and Klein. 1999. fi-Carotene and ascorbic acid retention in fresh and processed vegetables. J Food Sci 64(5) 929-936. 

The action of ascorbic acid in the dough is to strengthen the gluten, which improves gas retention and hence the volume of loaves is improved. Ascorbic acid is faster acting than potassium bromate, which why ascorbic acid has always been associated with rapid processes. 

Water-soluble vitamins in formulations have been determined by use of ion-pair chromatography. The vitamins include several B vitamins as well as niacin, folic acid, and ascorbic acid (565). Vitamins D and Da were rapidly separated on reverse phase columns (247) as are vitamins A, D, and E in multivitamin tablets (564). Addition of silver ions to the mobile phase has been shown to increase the flexibility inherent in RPC by complexing with the unsaturated bonds and thereby decreasing the retention factor. This effect is also observed with other unsaturated drug molecules including steroids (247). Vitamin A and related compounds have... 

Berkessel and Sklorz screened a variety of potential co-ligands for the Mn-tmtacn/H202 catalyzed epoxidation reaction and found that ascorbic acid was the most efficient one. With this activator the authors could oxidize the terminal olefins 1-octene and methyl acrylate with full conversion and yields of 83% and 97%, respectively, employing less than 0.1% of the metal complex (Scheme 86). Furthermore, with E- and Z-l-deuterio-1-octene as substrates, it was shown that the oxygen transfer proceeded stereoselectively with almost complete retention of configuration (94 2%). Besides the epoxidation, also the oxidation of alcohols to carbonyl compounds could be catalyzed by this catalytic system (see also Section in.C). 

Negi, P.S. and Roy, S.K. 2000. Effect of blanching and drying methods on p-carotene, ascorbic acid and chlorophyll retention on leafy vegetables. Lebensm.-Wiss. U.-Technol. 33 295-298. 

The loss of ascorbic acid during extraction, finishing, and blending is minimal. Based on the data of Sale (70) and Hayes et al. (71), the loss should be no greater than 2%. Hayes et al. (71) prepared orange juice concentrates having 50-60% solids and reported a mean retention of 96.6% of ascorbic acid. 

Bissett and Berry (76) reported on the ascorbic acid retention in orange juice as a function of container type. They stored FCOJ in fcil-lined cardboard, rectangular cartons and in polyethylene (PE)-lined fiber cylindrical cans for a year at -20.5°, -6.7°, and 1.1°C. At -20.5°C, the ascorbic acid retention was 93.5% in the foil-lined cartons and 91.5% in the PE-lined cans. Neither container proved effective above freezing due to microbial spoilage. The foil-lined carton was superior at 1.1°C, in that 89% of the ascorbic acid was retained after three months. In the PE-lined can, the retention was 44% after three months at 1.1°C. 

Figures 5 and 6 show the ascorbic acid retention in the 200-ml packages as a function of time. The data for the 6-oz. composite can are not shown because the ascorbic acid retention in these packages was similar to but just marginally poorer than was the retention in the 200-ml packages at -17.8°C. This marginal difference was attributed to the presence of some head-space oxygen in the 6-oz. cans which resulted in the loss of slightly more ascorbic acid.

Figure 5. Ascorbic acid retention in 54° Brix concentrated orange juice as a function of storage temperature ((O) —17.8°C (O 7.2°C (A) 23.9°C)...

The ascorbic acid retention in both the 45°Brix and 54°Brix concentrates stored at 7.2°C were very similar over 12 months. 

They concluded that the acceptable shelf life for these products was 20 days, at which time the ascorbic acid retention had decreased by about 39% to a level of 28mg/100ml of juice (49.6mg/ 177ml serving or 82.6% of the U.S. RDA). 

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