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Evaluation of the microbial aspects of ammonium hydroxide when used in brine solutions

Cerruto-Noya, Claudia A.

Scope and Method of Study: Ammonium hydroxide (AH) is considered a safe and suitable ingredient as a pH agent in brines for meat products up to final brine pH 11.6. However, its impact on microbial aspects of meats injected with a brine containing AH was not fully addressed previously. Four studies were conducted to determine whether AH possesses an antimicrobial effect when injected into meats. First, striploins were injected with 1% AH-brine or a phosphate-based-brine, and then MAP-packaged to evaluate APCs, Gram(-), LAB, and coliform counts. Subsequent studies focused on the pathogen Escherichia coli O157:H7. A multi-nozzle spray system was used to spray water, 1%, 2%, and 3% AH solutions onto inoculated meat-disk-samples with E. coli O157:H7. Next, striploins were pre-cored and inoculated with E. coli O157:H7 before they were injected with 1% AH-brine and then stored aerobically. The final study evaluated E. coli O157:H7 reductions over time.

Findings and Conclusions: AH-steaks had lower psychrotrophic, mesophilic, and Gramnegative counts than control (phosphate-steaks). All 1%, 2%, and 3% AH-solutions were effective in reducing E. coli O157:H7 compared to the control (water) and its effectiveness increased with time. When 1% AH-brine was injected into inoculated striploins with E. coli O157:H7, no-differences were found between AH-brine and control (no-AH brine) on days 0 and 1. The long term effect showed that the 1%-AH-surface samples had lower counts of E. coli O157:H7 than controls only when initial meat pH was < 5.7. These data suggests that 1%-AH-brine, when applied thorough needle injection, did not promote nor enhance the growth of E. coli O157:H7 under the conditions of these studies. The use of 1%-AH-brine may have several advantages for the industry such as: production of a clearer label, reduction of up to 50% of the sodium content in the brine, production of a phosphate-free brine, and an antibacterial effect against E. coli O157:H7. It is also important to point out the observation that AH has same effect on E. coli O157:H7 populations regardless the initial pH and this is an additional advantage because initial meat pH is highly variable.