Microbiological quality and presence of foodborne pathogens in fresh-squeezed orange juice samples purchased from street vendors and hygienic practices in Morelia, Mexico

DOMINGUEZ-GONZALEZ, Karla Gabriela; AGUILAR-CHAIREZ, Salvador; CERNA-CORTES, Joel; SORIA-HERRERA, Ricardo Jiovanni; CERNA-CORTES, Jorge Francisco

doi:10.1590/fst.10222

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Food Science and Technology

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Original Article • Food Sci. Technol 42 • 2022 • https://doi.org/10.1590/fst.10222 copy

Microbiological quality and presence of foodborne pathogens in fresh-squeezed orange juice samples purchased from street vendors and hygienic practices in Morelia, Mexico

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Few studies have screened fresh orange juice for the presence of foodborne pathogens. This study therefore evaluated the microbiological quality and occurrence of Salmonella, Shigella, Escherichia coli, and diarrheagenic E. coli pathotypes (DEP) in fresh-squeezed orange juice purchased from street vendors in Morelia, Michoacan, Mexico. The general hygienic practices of street vendors were poor. All 100 samples analyzed were positive for aerobic mesophilic bacteria, with concentrations ranging from 2.41 to 6.03 log CFU/mL. A total of 90 (90%), 35 (35%), and 14 (14%) samples were positive for total coliforms, fecal coliforms, and E. coli, respectively, present with concentrations ranging from < 1 to 4.84 log CFU/mL, < 3 to > 1,100 MPN/mL, and < 3 to 210 MPN/mL, respectively. Salmonella was not detected in any of the samples, whereas Shigella sonnei was isolated from one sample. Two samples were positive for DEP; one harbored ETEC strains and the other STEC strains. Our results highlight the elevated risk for consumer health associated with the ingestion of fresh-squeezed orange juice.

Keywords:
street-vended orange juice; microbiological quality; foodborne pathogens; hygienic practices

Microorganisms	Presumptive test or primary enrichment	Confirmatory test or secondary enrichment	Selective medium for isolation	Identification test	Results reported as
Aerobic mesophilic bacteria	NR^a a NR: not required;	Plate count agar (Bioxon^TM, BD, State of Mexico, Mexico) for 48 h at 35 °C	NR	NR	CFU/mL^b b CFU/mL: colony-forming units per mL;
Total coliforms	NR	Violet red bile agar (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	NR	NR	CFU/mL
Fecal coliforms	Lactose broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	E. coli broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 44.5 °C	NR	Gas production	MPN/mL^c c MPN/mL: most probable number per mL.
Escherichia coli	Lactose broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	E. coli broth with MUG (4-methylumbelliferyl-β-D-glucuronide) (Difco^TM, BD, Sparks, MD, USA) for 48 h at 44.5 °C	Eosin methylene blue agar and MacConkey agar (Bioxon^TM, BD, State of Mexico, Mexico) for 24 h at 35 °C	Indole production, methyl red test, Voges–Proskauer test, and citrate utilization (Bioxon^TM, BD, State of Mexico, Mexico) for 24 h at 35 °C	MPN/mL
Salmonella/ Shigella	225 mL of Universal Pre-Enrichment broth for 24 h at 35 °C	Rappaport–Vassiliadis broth and Muller–Kauffmann tetrathionate broth (Difco^TM, BD, Sparks, MD, USA) for 24 h at 42 and 43 °C, respectively	Hektoen enteric agar (Difco^TM, BD, Detroit, MI, USA), Salmonella–Shigella agar, xylose lysine desoxycholate agar, and MacConkey agar (Bioxon^TM, BD, State of Mexico, Mexico) for 24 h at 35 °C	Indole production, methyl red test, Voges–Proskauer test, motility test, and citrate utilization. Urease production, lactose and glucose utilization, H₂S production, and lysine decarboxylase production (Bioxon^TM, BD, State of Mexico, Mexico) for 24 h at 35 °C	Presence/absence in 25 mL

DEP	Target gene	Primers (5´- 3’)	Amplicon size (pb)	Multiplex PCR assay
ETEC	lt	F: GGC GAC AGA TTA TAC CGT GC	450	1
ETEC	lt	R: CGG TCT CTA TAT TCC CTG TT	450	1
	st	F: ATT TTT CTT TCT GTA TTG TCT T	190	1
	st	R: CAC CCG GTA CAA GCA GGA TT	190	1
STEC	stx1	F: CTG GAT TTA ATG TCG CAT AGT G	150	1
STEC	stx1	R: AGA ACG CCC ACT GAG ATC ATC	150	1
	stx2	F: GGC ACT GTC TGA AAC TGC TCC	255	1
	stx2	R: TCG CCA GTT ATC TGA CAT TCT G	255	1
EPEC	bfpA	F: AAT GGT GCT TGC GCT TGC TGC	324	1
EPEC	bfpA	R: GCC GCT TTA TCC AAC CTG GTA	324	1
	eaeA	F: GAC CCG GCA CAA GCA TAA GC	384	1
	eaeA	R: CCA CCT GCA GCA ACA AGA GG	384	1
EIEC	ial	F: GGT ATG ATG ATG ATG AGT CCA	650	1
EIEC	ial	R: GGA GGC CAA CAA TTA TTT CC	650	1
EAEC	aggR	F: CTA ATT GTA CAA TCG ATG TA	457	2
EAEC	aggR	R: AGA GTC CAT CTC TTT GAT AAG	457	2
	aap	F: CTT GGG TAT CAG CCT GAA TG	310	2
	aap	R: AAC CCA TTC GGT TAG AGC AC	310	2
	attA	F: CTG GCG AAA GAC TGT ATC AT	629	2
	attA	R: CAA TGT ATA GAA ATC CGC TGT T	629	2
DAEC	afaC	F: GGC TTT TCT GCT GAA CTG G	809	2
DAEC	afaC	R: CGG TCT CAT AAT CAT GTC C	809	2

Microorganisms	Minimum	Median	Maximum	Number of positive samples (%)
AMB	2.41	4.51	6.03	100 (100)
TC	< 1	3.69	4.84	90 (90)
FC	< 3	< 3	> 1,100	35 (35)
E. coli	< 3	< 3	210	14 (14)
DEP	< 3	< 3	9.2	2 (2)

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[1] *Corresponding author: jcernac@ipn.mx