Effect of zinc formulations, sodium chloride, and hydroxytyrosol on the growth/no-growth boundaries of table olive related yeasts. (August 2016)

• Record Type: Journal Article
• Authors: Romero-Gil, V.; Rejano-Zapata, L.; Garrido-Fernández, A.; Arroyo-López, F.N.
• Is Part Of: Food microbiology. Volume 57(2016:Aug.)
• Page Start: 71
• Page End: 80
• Publication Date: 2016-08
• Subjects: Growth/no-growth interfaces -- Logistic regression -- Zinc interaction -- NaCl -- Hydroxytyrosol -- Preservatives; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2016.01.007
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: This study uses a mathematical approach to assessing the inhibitory effect of Zn 2 + (0–10 mM, obtained from ZnCl2 and ZnSO4 ) in presence of NaCl (0–8%) and hydroxytyrosol (0–2588 mg/L), on a yeast cocktail formed by species Pichia galeiformis, Pichia kudriavzevii, Pichia manshurica and Candida thaimueangensis obtained from spoilt green olive packages. The logistic/probabilistic models were built in laboratory medium using a total of 1980 responses (1188 for NaCl and 792 for hydroxytyrosol). ZnCl2 showed significantly higher inhibitory effect than ZnSO4 in the presence of both NaCl (p < 0.033) and hydroxytyrosol (p < 0.009). NaCl did not interfere the effect of Zn 2 + while hydroxytyrosol, at high levels, had a slight antagonistic effect. According to models, Zn 2 + inhibits (p = 0.01) the yeast cocktail in the range 4.5–5.0 mM for ZnCl2, or 8.5–9.5 mM for ZnSO4 . Therefore, this work confirms the fungicidal activity of zinc compounds (mainly ZnCl2 ) in synthetic medium, and also shows that the loss of zinc effectiveness in real green Spanish-style olive packaging is not due to the presence of NaCl or hydroxytyrosol, two of the most abundant chemical compounds in the product. Highlights: A logistic model for yeasts as a function of Zn, NaCl, and hydroxytyrosol contents was built. The model was obtained in synthetic media using two zinc salts formulations. ZnCl2 showed greater inhibitory effects than ZnSO4 . No interaction between Zn and NaCl was observed. A slight antagonistic effect between Zn and high hydroxytyrosol content was noticed.