36B-25 |
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S. A. IBRAHIM, J. P. Carr, E. D. Wilson, T. S. F. Tse, and C. W. Seo. Food Science & Nutrition Program, North Carolina A&T State Univ., Dept. of Human Environment & Family Sciences, 171-B Carver Hall, Greensboro, NC 27411-1064 Production on large bacterial cell mass is required in many industrial fermentation processes. Large scale bacterial production associated with fermentation creates great amounts of acid during growth that leads to a reduction in pH, which in turn can reduce bacterial growth. The use of buffers in fermentation systems is key to preventing this sort of growth inhibition. There is a considerable amount of data available concerning the buffering capacity (BC) of several substances, but very little pertaining to the BC of amino acids as individual ingredients. The objective of this study was to determine the BC of 19 amino acids against acidic conditions. Nineteen amino acids (asparagine, methionine, proline, cystiene, alanine, arginine, serine, glycine, valine, threonine, glutamic acid, isoleucine, tyrosine, leucine, phenylalanine, aspartic acid, tryptophan, histidine) were tested for their ability to resist pH change when titrated with 0.1 M HCl. Amino acid solution was prepared by mixing 1.0 g in 100 ml deionized water. The pH of the solution was then adjusted to 7 using NaOH in solution. A standard solution of 0.1 M HCl was used to titrate the amino acid solution at 1.0 ml intervals using a bottle top burette until pH 2.0 was reached. The buffering capacity was calculated as the amount of acid required to reach pH 2.0 divided by the overall change in pH. A buffering capacity over 20 was considered significant. Results showed that of the 19 amino acids, tyrosine had the lowest BC at 5.0 and glycine and aspartic acid had the highest BC at 33.3 and 34.5 respectively. Four amino acids in addition to aspartic acid and glycine (serine, glutamic acid, phenylalanine, valine) had BCs above 20. Several amion acids might be good candidates as a buffer system for use in large-scale fermentation processes to reduce damage to bacterial cells due to acid production and increase cell mass production.
Session 36B, Biotechnology: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |