Aquaculture, 60 (1987) 73-83 73 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands zyxwvutsrqponmlkjihgfedcb Stability of L-Ascorbic Acid (Vitamin C) and its Forms in Fish Feeds During Processing, Storage and Leaching A.K. SOLIMAN’, K. JAUNCEY and R.J. ROBERTS Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA (Great Britain) ‘Present address: Department of Animal Production, Faculty of Agriculture, University of Alexandria, Alexandria (Egypt) (Accepted 9 September 1986) ABSTRACT Soliman, A.K., Jauncey, K. and Roberts, R.J., 1987. Stability of L-ascorbic acid (vitamin C) and its forms in fish feeds during processing, storage and leaching. Aquaculture, 60: 73-83. The stability of several forms of L-ascorbic acid to processing, storage and leaching was inves- tigated. Percentage retention of ascorbic acid after processing was increased with increasing die- tary ascorbic acid level. Ascorbic acid 2-sulphate (AAPS) and glyceride-coated ascorbic acid (GCAA) were more stable than ascorbic acid (AA) and its sodium salt (NaAA). The stability of AA, NaAA, GCAA and AA2S under different storage conditions was, in descending order; freezer ( - 20’ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA C) , refrigerator (5-8” ) , room temperature in black bags (22-24” C) , and room temperature in clear bags (22-24” C) . Leaching of dietary ascorbic acid increased with increasing immersion time and water temperature. Evaluation of stability of each ascorbic acid form sug- gested that GCAA is to be preferred for use in fish feeds. INTRODUCTION zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA L-Ascorbic acid(vitamin C) is an essential dietary nutrient in fish feeds (FFI, 1984). This vitamin is extremely labile and consideration of its chem- istry suggests that its rate of destruction would be a function of factors such as time, temperature, oxygen, pH and light (Herreid et al., 1952; WannirGger, 1972). Eva et al. (1976) reported that 20% of the L-ascorbic acid added to feeds was lost during processing and that after 6 weeks of storage at room temperature only 35% of the supplemented vitamin remained. However, Hil- ton et al. (1977) found that after processing and 6 weeks of storage at room temperature all of the ascorbic acid was lost in feeds supplemented with 20-1280 mg of ascorbic acid/kg. Attempts have been made to improve retention of ascorbic acid activity in 0 1987 Elsevier Science Publishers B.V.