Combinations of Intervention Treatments Resulting in 5-Log ₁₀ -Unit Reductions in Numbers of Escherichia coli O157:H7 and Salmonella typhimurium DT104 Organisms in Apple Cider

Abstract

The U.S. Food and Drug Administration (FDA) recently mandated a warning statement on packaged fruit juices not treated to reduce target pathogen populations by 5 log10 units. This study describes combinations of intervention treatments that reduced concentrations of mixtures of Escherichia coli O157:H7 (strains ATCC 43895, C7927, and USDA-FSIS-380-94) or Salmonella typhimuriumDT104 (DT104b, U302, and DT104) by 5 log10 units in apple cider with a pH of 3.3, 3.7, and 4.1. Treatments used were short-term storage at 4, 25, or 35°C and/or freeze-thawing (48 h at −20°C; 4 h at 4°C) of cider with or without added organic acids (0.1% lactic acid, sorbic acid [SA], or propionic acid). Treatments more severe than those for S. typhimurium DT104 were always required to destroy E. coli O157:H7. In pH 3.3 apple cider, a 5-log10-unit reduction in E. coli O157:H7 cell numbers was achieved by freeze-thawing or 6-h 35°C treatments. In pH 3.7 cider the 5-log10-unit reduction followed freeze-thawing combined with either 6 h at 4°C, 2 h at 25°C, or 1 h at 35°C or 6 h at 35°C alone. A 5-log10-unit reduction occurred in pH 4.1 cider after the following treatments: 6 h at 35°C plus freeze-thawing, SA plus 12 h at 25°C plus freeze-thawing, SA plus 6 h at 35°C, and SA plus 4 h at 35°C plus freeze-thawing. Yeast and mold counts did not increase significantly (P < 0.05) during the 6-h storage at 35°C. Cider with no added organic acids treated with either 6 h at 35°C, freeze-thawing or their combination was always preferred by consumers over pasteurized cider (P < 0.05). The simple, inexpensive intervention treatments described in the present work could produce safe apple cider without pasteurization and would not require the FDA-mandated warning statement.

Antimicrobial Efficiency of Essential Oil and Freeze–Thaw Treatments against Escherichia coli O157:H7 and Salmonella enterica Ser. Enteritidis in Strawberry Juice

“…Strawberry juice was diluted, sterilized, and inoculated with bacterial culture as described previously. Twenty-five milliliters of the inoculated juice were dispensed into 100 mL sterile glass bottles and subjected to a freeze-thaw treatment described by Uljas and Ingham (1999) with some adjustments: freezing at −23 • C for 24 or 48 h followed by thawing at 7 ± 1 • C for 4 h. The juices were then stored at 7 ± 1 • C for microbial testing. The total storage time was 8 d by including the 24 and 48 h freezing times.…”

Antimicrobial Activity and Synergistic Effect of Cinnamon with Sodium Benzoate or Potassium Sorbate in ControllingEscherichia coliO157:H7 in Apple Juice

“…Malic acid, sodium benzoate, potassium sorbate, and their combinations significantly reduced the D (decimal reduction time) value of E. coli O157:H7 in apple cider (Dock and others 2000;Steenstrup and Floros 2002). Uljas and Ingham (1999) showed that combinations of short-term storage at 4, 25, or 35°C, freeze-thawing (48 h at -20°C and 4 h at 4°C), and organic acids (0.1% lactic acid, sorbic acid, and propionic acid) achieved a 5-log reduction in E. coli O157:H7 in apple cider.…”

Survey of Apple Growing, Harvesting, and Cider Manufacturing Practices in Wisconsin: Implications for Safety

“…In Wisconsin, only a few cider mills (3%) owned equipment for UV-light treatment of cider. Preservatives commonly added to cider, sodium benzoate or potassium sorbate, may have only a small initial effect on survival of E. coli 0157:H7 in refrigerated cider (Miller and Kaspar 1994;Zhao et al 1993), but their effectiveness has been shown to increase when used in combination over a period of several days (Zhao et al 1993) or in combination with prior short-term warm storage and/or freezinghawing of cider (Uljas and Ingham 1999). Preservatives were used by 18% of the cider mills (30% of total cider produced in WI), with potassium sorbate (63%) used more often than sodium benzoate (37%).…”

“…Of all Wisconsin cider mills surveyed, 15% froze 1549% of their cider, and 22% of mills froze more than one half of their cider. Freezing and thawing can reduce populations of E. coli 0157:H7 in cider (Sage and Ingham 1998) and the potential for a freezehhaw cycle in contributing to a 5 log-unit reduction in pathogen cell numbers when used in combination with short-term warm storage and/or addition of preservatives has been demonstrated (Uljas and Ingham 1999). The results showed that 31% of the total cider produced in Wisconsin was manufactured without pasteurization, UV-light treatment, preservatives, or an implemented HACCP system.…”

“…Alternative methods investigated recently include application of irradiation (Buchanan et al 1998), application of dimethyl dicarbonate, sulphur dioxide, and sodium benzoate (Fisher andGolden 1998), high-pressure (Garcia-Graells et al 1998) and microwave energy (Kozempel et al 1997) to cider; treating apples with techniques such as steam or hot water dips, acid dips or sprays, or treatment of cider with high voltage pulsed electric field, high pressure, or combination treatments (Cony et al 1995). Our recent study described the use of sequential combinations of traditional preservation methods, such as short-term warm storage, addition of preservatives, and freezing and thawing, towards 5-log unit reduction of E. coli 0157:H7 and Salmonella typhimurium DT104 in cider (Uljas and Ingham 1999).…”