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Inactivation of Escherichia coli O157:H7 during storage or drying of apple slices pretreated with acidic solutions.
Int J Food Microbiol. 2005 Mar 01; 99(1):79-89.IJ

Abstract

Inactivation of Escherichia coli O157:H7 was evaluated on inoculated apple slices without pretreatment or pretreated by immersing in water or acid solutions commonly used to help retain apple color during dehydration, then stored at ambient temperature or dried for 6 h. Half-ring slices (0.6 cm thick) of peeled and cored Gala apples were inoculated by immersion for 30 min in a three-strain composite inoculum of E. coli O157:H7 (7.8-8.0 CFU/g). Inoculated slices received (1) no pre-drying treatment (control); or a 10-min immersion in solutions of (2) sterile water, (3) 2.8% ascorbic acid, (4) 1.7% citric acid, (5) 50% commercial lemon juice, or (6) 50% commercial lemon juice with preservatives. Drained slices were placed in sterile plastic bags and stored at room temperature (25+/-2 degrees C) for up to 6 h or dehydrated (62.8 degrees C) for up to 6 h. Samples were plated on tryptic soy agar (TSA) and sorbitol MacConkey agar (SMAC) for direct enumeration of surviving bacteria at various time intervals. Immersion in sterile water or acidic solutions caused initial bacterial reductions of 0.9-1.3 log CFU/g on apple slices. Between 0 and 6 h of storage at room temperature, slices dipped in acidic solutions showed minor changes in bacterial populations (-0.2 to +0.6 log CFU/g) compared to a 1.1 log CFU/g increase for slices dipped in sterile water. The no treatment samples (control) showed an increase in bacterial populations of 1.3-1.5 CFU/g over the 6-h holding time. For apple slices dried at 62.8 degrees C, bacterial populations were reduced by 2.5 (SMAC) and 3.1 (TSA) log CFU/g in the control (no pre-drying treatment) samples following 6 h dehydration. The slices immersed in sterile water showed a 5.8 (SMAC) and 5.1 (TSA) reduction after 6 h of dehydration. In contrast, after 6 h of dehydration bacterial populations on the four acid-pretreated products were reduced by 6.7-7.3 log CFU/g. The results showed that acidic treatment alone was not effective in destroying E. coli O157:H7 on apple slices but did inhibit growth of the organism during holding before drying. However, pretreatment of the apple slices with common household acidulants enhanced destruction of E. coli O157:H7 during drying compared to slices dried without treatment.

Authors+Show Affiliations

Derrickson-Tharrington E
Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, CO 80523, United States.
Kendall PA
No affiliation info available
Sofos JN
No affiliation info available

MeSH

Ascorbic AcidCitric AcidColony Count, MicrobialDose-Response Relationship, DrugEscherichia coli O157Food HandlingFood PreservationHydrogen-Ion ConcentrationMalusTemperatureTime FactorsWater

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

15718031

Citation

Derrickson-Tharrington, Elizabeth, et al. "Inactivation of Escherichia Coli O157:H7 During Storage or Drying of Apple Slices Pretreated With Acidic Solutions." International Journal of Food Microbiology, vol. 99, no. 1, 2005, pp. 79-89.
Derrickson-Tharrington E, Kendall PA, Sofos JN. Inactivation of Escherichia coli O157:H7 during storage or drying of apple slices pretreated with acidic solutions. Int J Food Microbiol. 2005;99(1):79-89.
Derrickson-Tharrington, E., Kendall, P. A., & Sofos, J. N. (2005). Inactivation of Escherichia coli O157:H7 during storage or drying of apple slices pretreated with acidic solutions. International Journal of Food Microbiology, 99(1), 79-89.
Derrickson-Tharrington E, Kendall PA, Sofos JN. Inactivation of Escherichia Coli O157:H7 During Storage or Drying of Apple Slices Pretreated With Acidic Solutions. Int J Food Microbiol. 2005 Mar 1;99(1):79-89. PubMed PMID: 15718031.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Inactivation of Escherichia coli O157:H7 during storage or drying of apple slices pretreated with acidic solutions. AU - Derrickson-Tharrington,Elizabeth, AU - Kendall,Patricia A, AU - Sofos,John N, PY - 2003/08/30/received PY - 2004/06/01/revised PY - 2004/07/08/accepted PY - 2005/2/19/pubmed PY - 2005/4/9/medline PY - 2005/2/19/entrez SP - 79 EP - 89 JF - International journal of food microbiology JO - Int J Food Microbiol VL - 99 IS - 1 N2 - Inactivation of Escherichia coli O157:H7 was evaluated on inoculated apple slices without pretreatment or pretreated by immersing in water or acid solutions commonly used to help retain apple color during dehydration, then stored at ambient temperature or dried for 6 h. Half-ring slices (0.6 cm thick) of peeled and cored Gala apples were inoculated by immersion for 30 min in a three-strain composite inoculum of E. coli O157:H7 (7.8-8.0 CFU/g). Inoculated slices received (1) no pre-drying treatment (control); or a 10-min immersion in solutions of (2) sterile water, (3) 2.8% ascorbic acid, (4) 1.7% citric acid, (5) 50% commercial lemon juice, or (6) 50% commercial lemon juice with preservatives. Drained slices were placed in sterile plastic bags and stored at room temperature (25+/-2 degrees C) for up to 6 h or dehydrated (62.8 degrees C) for up to 6 h. Samples were plated on tryptic soy agar (TSA) and sorbitol MacConkey agar (SMAC) for direct enumeration of surviving bacteria at various time intervals. Immersion in sterile water or acidic solutions caused initial bacterial reductions of 0.9-1.3 log CFU/g on apple slices. Between 0 and 6 h of storage at room temperature, slices dipped in acidic solutions showed minor changes in bacterial populations (-0.2 to +0.6 log CFU/g) compared to a 1.1 log CFU/g increase for slices dipped in sterile water. The no treatment samples (control) showed an increase in bacterial populations of 1.3-1.5 CFU/g over the 6-h holding time. For apple slices dried at 62.8 degrees C, bacterial populations were reduced by 2.5 (SMAC) and 3.1 (TSA) log CFU/g in the control (no pre-drying treatment) samples following 6 h dehydration. The slices immersed in sterile water showed a 5.8 (SMAC) and 5.1 (TSA) reduction after 6 h of dehydration. In contrast, after 6 h of dehydration bacterial populations on the four acid-pretreated products were reduced by 6.7-7.3 log CFU/g. The results showed that acidic treatment alone was not effective in destroying E. coli O157:H7 on apple slices but did inhibit growth of the organism during holding before drying. However, pretreatment of the apple slices with common household acidulants enhanced destruction of E. coli O157:H7 during drying compared to slices dried without treatment. SN - 0168-1605 UR - https://www.unboundmedicine.com/medline/citation/15718031/Inactivation_of_Escherichia_coli_O157:H7_during_storage_or_drying_of_apple_slices_pretreated_with_acidic_solutions_ DB - PRIME DP - Unbound Medicine ER -