71A-46 |
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S. ARGIN-SOYSAL and Y. M. Lo. Dept. of Nutrition and Food Science, Univ. of Maryland, Food Bioprocess Engineering Lab., 3407 Marie Mount Hall, College Park, MD 20742 Known to beneficially affect the host by improving its intestinal microbial balance, probiotics are consumed either in food products or as dietary supplements. To act as probiotics, the bacteria must arrive in the intestines alive and in sufficient number, which is suggested as 106 - 107 cfu/g. However, the processing and storage conditions of the food carriers, as well as the acidic gastrointestinal tract conditions, cause low levels of viability of probiotics. Microencapsulation of probiotics in hydrocolloid beads has been found to improve the viability; nonetheless, scale-up difficulties as well as lack of mechanical strength and susceptibility to ions have greatly hindered its applicability. The objective was to develop microcapsules using xanthan-chitosan polyelectrolyte complex (PEC) gels to improve the viability of probiotics. The combination of xanthan-chitosan PEC gel was optimized against chitosan solution properties (pH and concentration) and xanthan concentration using quadratic response surface design. Capsules were formed by the dropwise addition of xanthan and Pediococcus acidilacticici cell mixture (9:1 v/v) into chitosan solution. The release mechanism was determined based on the capsule strength and swelling ratios after exposing the capsules to different pH values (from 2 to 8) for 1 hr. The cell viability was evaluated after subjecting the capsules to low pH, freezing temperature, and 60 ºC. The concentration of xanthan was found the most crucial, whereas chitosan solution properties were negligible, in determining the optimal formulation. However, with xanthan concentration exceeding 1.25 wt/v%, only amorphous beads were formed. Encapsulated cells could be completely released in 0.1% peptone at pH 8 after 1 hr. The PEC gels improved cell viability at pH 2 by two logs compared to suspending cells. Protective effects were observed at freezing temperature and at 60 ºC. An effective protective shield capable of proper delivery and release of probiotics to the target destination is critical in ensuring probiotic benefits.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |