TITLE:
Evaluating Kombucha and Fruit Juice Blends for a 5-Log Reduction of Acid-Adapted Escherichia coli O157
AUTHORS:
Sujan Acharya, Brian A. Nummer
KEYWORDS:
Kombucha, Fermentation, Kombucha-Fruit Blend, Refrigeration, Acid-Adapted E coli O157
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.13 No.7,
July
12,
2022
ABSTRACT: This study examined the survival of acid-adapted E. coli O157 in kombucha during
fermentation and refrigerated kombucha mixed with fruit juices. Acidic and
non-acidic kombucha mixes were fermented at 25°C using
a commercially available starter culture and inoculated with a 5-strain mixture
of acid-adapted E. coli O157. There was >5-log reduction in the pathogen count for both starter mixes within 7 days of
fermentation. For the kombucha-juice blends at refrigerated temperature, 14 ml
of lemon, apple, orange, and mango juices were mixed with 186 ml kombucha
separately. The treatments were inoculated with a 5-strain mixture of
acid-adapted E. coli O157 and incubated at 5°C for 14 days. >5-log
reduction in the pathogen count was observed in lemon, control, and mango juice
blend after
1, 3, and 14 days, respectively.
The total reduction in pathogen count in the apple and orange juice blend after 14 days was 4.43 and 4.12 log CFU/ml, respectively. The inability of the
kombucha fruit blend to cause a 5-log reduction of E. coli O157 suggests
the need for following strict hygienic and good sanitation practices during
blending and bottling for home fermenters and an approved HACCP plan for foodservice operators to ensure
product safety.