Antilisterial effects of gravinol-s grape seed extract at low levels in aqueous media and its potential application as a produce wash.
Grape seed extract (GSE) is a rich source of proanthocyanidins, a class of natural antioxidants reported to have wide-ranging bioactivity as anti-inflammatory, anticarcinogenic, and antimicrobial agents. The ability of GSE to rapidly inactivate Listeria monocytogenes in vitro and the generally recognized as safe status of GSE make this extract an attractive candidate for control of Listeria in or on foods. Previously, GSE has been used at relatively high concentrations (1%) in complex food matrices and in combination with other antimicrobials. We sought to characterize the antilisterial effects of a commercial GSE preparation (Gravinol-S) alone at much lower concentrations (0.00015 to 0.125%) in aqueous solution and to test its possible use as an antimicrobial wash for fresh produce surfaces. Based on broth microdilution tests, the MICs of GSE against L. monocytogenes Scott A and Listeria innocua ATCC 33090 were as low as 50 and 78 mug ml(-1), respectively. GSE was evaluated in 0.85% saline against live cells of L. innocua via flow cytometry, using propidium iodide as a probe for membrane integrity. At sub-MICs and after only 2 min of exposure, treatment with GSE caused rapid permeabilization and clumping of L. innocua, results that we confirmed for L. monocytogenes using fluorescence microscopy and Live/Dead staining. At higher concentrations (0.125%), GSE reduced viable cell counts for L. monocytogenes by approximately 2 log units within 2 min on tomato surfaces. These results suggest the potential for GSE as a natural control of Listeria spp. on low-complexity foods such as tomatoes.
Department of Food Science and Human Nutrition, Iowa State University, 2312 Food Science Building, Ames, Iowa 50011, USA.
Bledar
B
Bisha
Natalia
N
Weinsetel
Byron F
BF
Brehm-Stecher
Aubrey
A
Mendonca
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004357:Drug Synergism; D005434:Flow Cytometry; D005506:Food Contamination / Q000517:prevention & control; D005511:Food Handling / Q000379:methods; D005519:Food Preservation / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology; D056604:Grape Seed Extract / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D018551:Solanum lycopersicum / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence; D044945:Proanthocyanidins / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D005520:Food Preservatives; D056604:Grape Seed Extract; C511402:Grape Seed Proanthocyanidins; D044945:Proanthocyanidins