Juice ascorbic acid retention

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. 

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. 

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)...

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). 

Paper cartons with an aluminum-foil barrier between the paper and plastic are used for the distribution of some chilled products. Because of the foil barrier, products in these cartons exhibit better ascorbic acid retention than do the plastic-lined cartons. As an example, grapefruit juice stored in such cartons retained 74% of its ascorbic acid over a 40-day storage period at 4.4°C. The rate of ascorbic acid loss was 0.7% per day. Grapefruit juice in a plastic-lined container lost 1.5% of its ascorbic acid per day when stored under similar conditions. 

Moore (84) reported that the ascorbic acid retention was 89.2% for bottled orange juice and 93.2% for canned orange juice stored at 4.4°C for 18 months. At 24.4°C, the ascorbic acid retentions after 18 months were 50.9% and 59.8% for bottled and canned orange juice, respectively. This effect of container type was further demonstrated in studies by Riester et al. (85), Curl (48), and by Moore et al. (86). These studies showed greater losses of ascorbic acid in enamel-lined cans than in plain tin cans. The difference was attributed to the protective effect of the tin, in that oxygen reacted with tin in one case and with ascorbic acid in the other. 

Figure 8. Ascorbic acid retention in single-strength orange juice stored at 23.9°C f( Oj 1.36-1 metal can 7.0-7 foil-lined Brik (aseptic))...

Concentration of fruit juices should not result in marked loss of ascorbic acid if the pressed juice is deaerated and and evaporated at low temperatures (100). Ascorbic acid retentions in excess of 90% have been reported for concentration and freezing processes (38,101) and can be expected for freeze concentration processes (100). 

Figure 3> Ascorbic acid retention in orange juice at 25°C in various packaging materials. (BLANK=GLASS)...

Figure 7 The effect of orange juice with carton strips on ascorbic acid retention, stored at 25°C.

Because of the reduced pressures, transfer of heat depends on methods other than convection. Radiation and conduction are other modes however, conduction may not be efficient because the drying materials shrink, thus reducing the contact area. This method of drying is not very common in the food industry because of high costs. The method has been applied for dehydration of citrus juices, apple flakes, and various heat-sensitive products in which the ascorbic acid retention is important. 

Bissett, O. W. Berry, R. E. (1975). Ascorbic acid retention in orange Juice as related to container type. J. FoodScL, 40(1), 178-180. 

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. 

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. 

Figure 1. Ascorbic acid (AA) retention in orange juice aseptically packed into glass jars and carton packs, stored at 25°C.

Samples of several juices are chromatographed directly on a strong-base anion exchange column using a UV detector at 254 nm. By comparison of retention times with that of a vitamin C standard (Z-ascorbic acid), the presence or absence of vitamin C is ascertained. Peak area measurements are used for quantitative determination of the concentration of vitanoin C in those juices in which it is found. 

Choi et al. (2002) studied the retention of ascorbic acid with storage in blood oranges and observed a linear reduction in concentration with time. Fan et al. (2002) also observed a linear degradation of ascorbic acid in orange juice with time, whether irradiated or not. 

Alwazeer, D., Delbeau, C., Divies, C., and Cachon, R. 2003. Use of redox potential modification by gas improves microbial quality, color retention, and ascorbic acid stability of pasteurized orange juice. Int. J. Food Microbiol 89, 21-29. 

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