10-4 |
Improved properties of natamycin upon formation of cyclodextrin inclusion complexes |
J. L. KOONTZ1, J. E. Marcy1, W. E. Barbeau2, and S. E. Duncan1. (1) Dept. of Food Science & Technology, Virginia Polytechnic Institute & State Univ., 118 FST Bldg., Mail Code 0418, Blacksburg, VA 24061-0418, (2) Dept. of Human Nutrition, Foods & Exercise, Virginia Polytechnic Institute & State Univ., 327 Wallace Hall, Mail Code 0430, Blacksburg, VA 24061-0430 Degradation of natamycin and its deficient delivery systems onto the shredded cheese surface results in decreased product quality. In the dairy industry, natamycin is used as an antimycotic that does not contribute negative sensory qualities. The very low aqueous solubility of natamycin (30 mg/L) requires its application as an aqueous suspension to the shredded cheese surface, which results in clogging of spray nozzles and a nonuniform distribution to the cheese surface. The objective was to increase the water solubility and stability of natamycin by forming molecular inclusion complexes with b-, hydroxypropyl b-, and g-cyclodextrins (CDs). Solubility isotherms were constructed using excess natamycin present in aqueous solutions of increasing CD concentration. 1H NMR shift titrations were utilized to prove the formation of true inclusion complexes and determine the stoichiometry of natamycin:CD complexes. The stability of natamycin and its CD complexes was monitored by quantitative HPLC. Molecular inclusion complexes of natamycin were formed with b-, hydroxypropyl b-, and g-CDs which allowed large increases in aqueous solubility without the use of organic co-solvents or surfactants. The water solubility of natamycin was increased 16-fold, 73-fold, and 152-fold with b-CD, g-CD, and hydroxypropyl b-CD, respectively. The natamycin:CD inclusion complexes resulted in nearly equivalent in vitro antifungal activity as free natamycin. The stoichiometry of natamycin:b-CD complex and natamycin:g-CD complex was determined to be 1:1. 92.2% natamycin remained in aqueous solution after 14 days of storage in darkness at 4 °C. Aqueous solutions of natamycin:b-CD complex and natamycin:g-CD complex were significantly more stable (p < 0.05) than free natamycin when stored in darkness at 4 °C. These increases in solubility and stability should allow a more uniform distribution of natamycin onto the cheese surface and a prolonged biological activity of the antimycotic, resulting in increased product quality to the consumer.
Session 10, Carbohydrate: General
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