34-2

S.-Q. LI¹, Q. H. Zhang¹, Y.-Z. Lee², J. A. Bomser³, S. J. Schwartz¹, V. M. Balasubramaniam¹, and C. P. Dunne⁴. (1) Dept. of Food Science and Technology, Ohio State Univ., 2015 Fyffe Ct., 110 Parker Food Science Bldg., Columbus, OH 43210-1007, (2) Biofoods, Stolle Milk Biologics, Inc, 6954 Cornell Rd., Ste. 400, Cincinnati, OH 45242, (3) Dept. of Human Nutrition, Ohio State Univ., 325 Campbell Hall, 1787 Neil Ave., Columbus, OH 43210, (4) U.S. Army Natick Soldier Center, U.S. Army Research, Development and Engineering Command, Combat Feeding Innovative Science Team, Kansas St., Bldg. 36, Rm. E-108, Natick, MA 01760-5020

Immunoglobulin-rich foods may provide health benefits to consumers. To extend the refrigerated shelf-life of functional foods enriched with bovine immunoglobulin G (IgG), Pulsed Electric Field (PEF) or High Pressure Processing (HPP) may offer advantages to thermal processing for microbial reduction. To compare effects of PEF, HPP or heat on isoflavones and immunoactivity of bovine IgG in an enriched soymilk product at similar levels of microbial reduction and identify the mechanism that causes loss of IgG activity. OSU-4A PEF unit with co-field flow chambers, a QFP-6 HPP unit and 1.5mL aluminum TDT tubes were used to provide selected treatments. Bovine IgG activity, from SMBI MicroLactinTM, was measured using ELISA. Isoflavone concentration was measured using HPLC with a Nova-PakŪ C18 column and a Waters 2696 photodiode array detector. To achieve a 5-log reduction in inoculated E. coli 8739, PEF, HPP or heat treatment required 40kV/cm for 60 microseconds at 42° C, 379MPa for 4min at 30° C and 70° C for 20s, respectively. To achieve a 5-log reduction in natural flora in the enriched soymilk, PEF, HPP or heat treatment needed 41.1kV/cm for 54microseconds, 552MPa for 4min and 78.2° C for 120s, respectively. At equivalent levels for a 5-log reduction in E. coli, PEF, HPP and heat treatment caused no significant, 25% and no detectable loss in bovine IgG activity, respectively. However, at equivalent levels for a 5-log reduction in natural flora, PEF, HPP and heat resulted in no significant, 65% and 85% of loss of bovine IgG activity, respectively. HPP and heat treatment showed significant influences on soy isoflavone profiles. The results indicate that PEF pasteurization retains immunoactivity of bovine IgG. HPP retains IgG activity when pressure is lower than 276MPa. This study facilitates the understanding of the relative benefits of nonthermal technologies for extending shelf life of functional foods.

Session 34, Nonthermal Processing: General I
9:00 AM - 12:00 PM, Monday AM Room 396

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana