Food Protection Trends - August 2010 - 481

TABLE 2. Mean populations of salmonellae in low (3.6) or high (4.1) pH orange juice samples stored at 4 or 10°C Average Population of Salmonellae (log CFU/ml) pH 3.6, 4°C Control CaL-TCP CaL-CC CaL-CG CaL Average 2.14a 1.81ab 1.38ab 1.25ab 1.14b 1.54 pH 3.6, 10°C 3.76a 1.54b 1.18b 1.01b 1.01b 1.70 pH 4.1, 4°C 3.37a 2.96a 2.36b 2.38b 1.93c 2.60 pH 4.1, 10°C 4.77a 2.51c 1.88c 3.65b 1.61c 2.88

CaL-TCP: calcium lactate-tricalcium phosphate (1:3); CaL-CC: calcium lactate-calcium citrate (1:1); CaL-CG: calcium lactate-calcium gluconate (1:1); CaL: calcium lactate.
*

Means in the same column not followed by the same letter are statistically different.

cell membranes tend to be more permissible to the calcium supplements at 10°C than at 4°C or because the solubility of calcium supplements at 4°C was slightly lower than the solubility at 10°C, with the result that more inhibition of salmonellae occurred in calcium-fortified juice samples stored at 10°C. In the high pH juice, however, a similar phenomenon was observed only in the samples supplemented with CaL or CaL-CC (Table 2). CaL-CG, a relatively new calcium supplement, has the highest solubility among all the calcium salts commonly used for beverage fortification (12). CaL, when applied alone or at high amounts, tends to impart a bitter taste to the beverage due to free calcium ion concentrations. CaL-CG, in contrast, provides a neutral taste to beverage products even at high concentrations. This is primarily due to the ability of CaL-CG to shield the reactive free calcium ions. Gluconic acid has a pKa value of 3.86, similar to that of lactic acid. As a highly polar molecule, it is unable to penetrate the bacterial cell membrane (2). Gluconate itself is therefore not an effective antimicrobial agent. The precise mechanism behind the anti-Salmonella activity of CaL-CG is not precisely known. However, it could be related to the presence of undisassociated forms of organic acids in the orange juice samples.

While CaL-CG could be used as a calcium supplement in both high (pH 3.6) and low acidity (pH 4.1) beverages stored at refrigeration temperatures, it might be particularly useful as a substitute for CaL in low pH (ca. pH 3.6) beverages, in which it would be more soluble, inhibit microbial growth, and reduce sourness as well as avoiding the detrimental effect of lactate on the taste of orange juice. Further studies are needed to investigate the interaction among concentrations of calcium supplements, juice pH and storage temperatures.

REFERENCES
1. Birkhead, G. S., D. L. Morse, W. C. Levine, J. K. Fudala, S. E. Kondracki, H. Chang, M. Shayegani, L. Novick, and P. A. Blake. 1993. Typhoid fever at a resort hotel in New York: a large outbreak with an unusual vehicle. J. Infect. Dis. 167:1228–1232. 2. Breidt, F. Jr., J. S. Hayes, and R. F. McFeeters. 2004. The independent effects of acetic acid and pH on the survival of Escherichia coli O157:H7 in simulated acidified pickle products. J. Food Prot. 67:12–18. 3. Centers for Disease Control and Prevention. 1975. Salmonella Typhimurium outbreak traced to a commercial apple cider — New Jersey. Morbid. Mortal.Wkly. Rep. 24:87.

4. Centers for Disease Control and Prevention. 1995. Outbreak of Salmonella Hartford infections among travelers to Orlando, Florida. EPIAID Trip Rpt. 95–62. 5. Centers for Disease Control and Prevention. 1996. Outbreak of Escherichia coli O157:H7 infections associated with drinking unpasteurized commercial apple juice — British Columbia, California, Colorado and Washington, October 1996. Morbid. Mortal.Wkly. Rep. 45:975. 6. Centers for Disease Control and Prevention. 1997. Outbreak of Escherichia coli O157:H7 infection and cryptosporidiosis associated with drinking unpasteurized apple juice — Connecticut and New York, October 1996. Morbid. Mortal.Wkly. Rep. 46:4. 7. Centers for Disease Control and Prevention. 1999. Outbreak of Salmonella serotype Muenchen infections associated with unpasteurized orange juice — United States and Canada, June 1999. Morbid. Mortal. Wkly. Rep. 48:582–585. 8. Duncan,T. G., J. A. Coull, E. R. Miller, and H. Bancroft. 1946. Outbreak of typhoid fever with orange juice as the vehicle, illustrating the value of immunization. Am. J. Pub. Health 36:34–36. 9. Oyarzábal, O. A., M. C. Nogueira, and D. E. Gombas. 2003. Survival

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