Evaluation of biocontrol capacity of Pseudomonas graminis CPA-7 against foodborne pathogens on fresh-cut pear and its effect on fruit volatile compounds

Abstract

The application of microorganisms to control the growth of foodborne pathogens is an alternative to the use of chemical additives. In this work, Pseudomonas graminis CPA-7 was tested as a biocontrol agent against Salmonella enterica and Listeria monocytogenes on fresh-cut pear under conditions that simulate its commercial application at 5 ± 1 °C (under a modified atmosphere and antioxidant solution). The quality of the fresh-cut fruit, including the ethanol and acetaldehyde contents and the volatile profile, was determined. After the storage period, the L. monocytogenes population was reduced by 1-log unit by the presence of CPA-7; however, CPA-7 was not found to have antagonistic activity against S. enterica. The fruit quality (total soluble solids content and titratable acidity) was not negatively affected by CPA-7. The ethanol and acetaldehyde contents increased during the shelf-life of the fruit regardless of the presence of CPA-7. Some volatile compounds were key factors for discriminating samples from the two groups (the control group and the group that was inoculated with CPA-7). Some components are common in the volatile profile of pear (methyl acetate, 3-methylbutyl acetate, 1-butanol, 1-hexanol, and hexanal), and thus increases in their contents could enhance consumers flavour perception.

Prevalence of Antibiotic-resistant Salmonella in Vegetables and Fermented Foods and their Control by Lactic Acid Bacteria

“…Bacteriocin works mainly against Gram-positive bacteria 38 . Many bacteriocins are heat stable, and the widely studied bacteriocin from LAB has gained increased attention as an alternative means to inhibit pathogens growth in foods 39 . In this study, the antimicrobial effect of CFS against Salmonella might also involve bacteriocin activity since the inhibition remained after the CFS was heated at high temperatures.…”

Evaluation of Pseudomonas graminis CPA-7 as a biopreservation method for fresh-cut pear: Physicochemical, enzymatic, and nutritional quality

“…As previously described by Iglesias et al. (2018), pears were cleaned, sanitized by immersion into a 0.1 g L −1 NaOCl solution adjusted to pH 6.5 using citric acid, rinsed, and dried prior to cutting.…”

“…As previously described by Iglesias et al (2018), pears were cleaned, sanitized by immersion into a 0.1 g L À1 Food Science and Technology International 25(4) NaOCl solution adjusted to pH 6.5 using citric acid, rinsed, and dried prior to cutting. Pears were peeled and cut into 10 wedges using a handheld apple corer and slicer.…”

“…The CPA-7 strain of P. graminis (deposit number CBS 136973, Centraalbureau voor Schimmelcultures, CBS, Utrech, The Netherlands), isolated in our lab from the surface of an apple (Alegre, Viñas, Usall, Teixidó, et al, 2013), was used as antagonist. It was grown and inoculated as previously described (Iglesias et al, 2018).…”

“…We have divided this objective into two parts. The first (Iglesias et al., 2018) addresses the effect of these treatments on foodborne pathogens and volatile compounds. In that paper, it was demonstrated that neither CPA-7 nor CaCl 2 postharvest treatment was found to have an effect against Salmonella enterica under the same conditions.…”