15C-29 |
Use of non-lactic acid bacterial enzymes to degrade bitter peptides in Cheddar cheese |
B. WEIMER1, P. Joseph1, R. Koka2, and Y. Xie1. (1) Center for Microbe Detection & Physiology, Utah State Univ., Dept. of Nutrition & Food Sciences, Western Dairy Center, Logan, UT 84322-8700, (2) Kraft Foods, Inc., 801 Waukegan Rd., Glenview, IL 60025 Proteolysis is important in Cheddar cheese manufacture and plays a role in flavor and texture development. Hydrolysis of intact caseins is initiated by chymosin and endogenous milk enzymes during manufacture. Subsequently, action of the proteolytic system of the starter and non-starter bacteria further hydrolyze peptides during aging. The interaction between these enzyme systems is directly linked to bitter peptide concentration in Cheddar cheese. These hydrophobic peptides orginate from as1– and b–casein. Two common peptides associated with bitterness are as1–casein f(1-9) and b–casein f(193-209). Hydrolysis of these peptides is associated with decreased bitterness in Cheddar cheese. The aim of this study was to investigate proteolytic enzymes from bacteria associated with dairy products to degrade bitter peptides. Purified extracellular proteases from Pseudomonas fluorescens and Brevibacterium linens were added to pure as1–casein f(1-9) and b–casein f(193-209) and incubated. Peptide hydrolysis was monitored with capillary electrophoresis and RP–HPLC analysis during incubation. Cheddar cheese was made with Lactoccocus lactis ssp. lactis ML3 with and without addition of the purified bacterial enzymes in replicate. Starter and non-starter populations were followed during ripening. RP–HPLC analysis was used to determine as1–casein f(1-9) and b–casein f(193-209) content. Enzymes added to pure peptides degraded the peptides with in 90 minutes. Each peptide rose in the cheese made without added enzymes. However, concentration of the model bitter peptides in cheese made with addition of the bacterial enzymes decreased. The total peptide pool of each cheese differed during aging. These enzyme treatments did not affect the overall flavor acceptability. These studies suggest enzymes from non–lactic acid bacteria impact bitterness during ripening. Addition of these enzymes may be a viable method to reduce bitterness in aging Cheddar cheese. Potential for commercial application of this approach needs to be addressed in the future.
Session 15C, Dairy Foods
|