Cronobacter sakazakii reduction by blueberry proanthocyanidins

Area of Science:

• Food microbiology
• Natural product chemistry
• Antimicrobial agents

Background:

• Foodborne pathogens like Cronobacter sakazakii pose significant health risks.
• Blueberry polyphenols, including proanthocyanidins (PAC), are known for antimicrobial properties.
• Limited data exists on the efficacy of blueberry compounds against C. sakazakii.

Purpose of the Study:

• To evaluate the antimicrobial activity of blueberry juice (BJ) and blueberry proanthocyanidins (PAC) against Cronobacter sakazakii.
• To compare the effectiveness of BJ and PAC with control substances.

Main Methods:

• Two strains of C. sakazakii (ATCC 29004, 29544) were treated with BJ (pH 2.8) or blueberry PAC (5 mg/ml).
• Controls included phosphate-buffered saline (PBS, pH 7.2) and malic acid (pH 3.0).
• Bacterial cultures were incubated with treatments for 30 min, 1 h, 3 h, and 6 h at 37°C, followed by CFU/ml enumeration and scanning electron microscopy.

Main Results:

• BJ and blueberry PAC achieved approximately 1–1.5 log CFU/ml reduction within 30 minutes.
• Both C. sakazakii strains were reduced to undetectable levels after 1 hour of treatment with BJ or PAC.
• Malic acid (pH 3.0) showed a modest reduction of ~1.3 log CFU/ml.
• Scanning electron microscopy revealed cell membrane damage, including clumping and blebbing, in treated bacteria.

Conclusions:

• Blueberry juice and blueberry proanthocyanidins exhibit potent antimicrobial effects against Cronobacter sakazakii.
• These findings suggest the potential of blueberry bioactives for preventing and treating C. sakazakii infections.
• Further in vivo studies are warranted to confirm these promising results.