Ascorbic acid retention temperature

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)...

Temperature of storage is important in maintaining the ascorbic acid content of potatoes. In general, potatoes are stored at relatively high temperatures (40-50°F), which results in better ascorbic acid retention as well as better quality (67). 

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). 

Kramer et al. (108) measured ascorbic acid retention at constant ( 1°C) and fluctuating (it5°C each 20 min) temperatures in Salisbury steaks stored for 3 or 6 months (Table VI). They found good retention of vitamin C stored at constant — 20°C or lower for 3 months. At higher temperatures, or at fluctuating temperatures, there was substantial reduction of vitamin C within 3-months storage. No other studies of vitamin C retention under both constant and fluctuating temperature were found. 

Villota, R. Karel, M. (1980). Prediction of ascorbic acid retention during drying. I. Moisture and temperature distribution in a model system. Journal of Food Processing and Preservation, 4, 111-134. 

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. 

Figure 8. Storage of CSM containing brand a effect of moisture content and temperature on retention of ascorbic acid, (Reproduced, with permission, from Ref. 385. Copyright 1970, American Association of Cereal Chemists, Incorporated.)...

The effects of drying temperature, bed thickness, and recycle ratio on water content and ascorbic acid/carotenoids retention were studied. Energy consumption per mass of water evaporated was evaluated considering only the energy used for heating ambient air to the inlet temperature. 

Thiamine is particularly sensitive to thermal processing the published retention values range from 0 to 95% (Killeit, 1994). Wheat flour extruded with no added water suffered large thiamine losses, and increased barrel temperature decreased the vitamin only at the slowest feed rate used (250 g/min versus 500 and 750 g/min) (Andersson and Hedlund, 1990). In the same study, extrusion conditions did not affect the content of riboflavin (B2) or niacin ascorbic acid (C) decreased with higher temperatures at 10% moisture. Since enriched wheat flour is an important source of B vitamins in the United States, care must be taken to protect these vitamins. Relatively little is known about the stability of synthetic vitamins compared with natural sources, or the effects of added vitamins as opposed to endogenous nutrients. 

The present chapter deals with the study of edible films based on deacylated and/or acylated forms of gellan gum to support L-(+)-ascorbic acid (AA) in view of natural antioxidant protection of foods, by leveraging its activity as a vitamin in the human metabolism. Kinetics of AA-destruction and subsequent non enzymatic browning development were studied in the films stored at constant temperature (25 C) and relative humidity (33.3, 57.7 or 75.2%) and their relationship with the microstructure, at the macromolecular and molecular levels, was also analyzed with the purpose of ensuring a better AA retention as well as lower browning rate as a consequence of controlled water mobility in the polymeric networks. 

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