Antimicrobial and antioxidant screening of curcumin and pyrocatechol in the prevention of biodiesel degradation: oxidative stability

ABSTRACT

Owing to its hygroscopicity biodiesel may accumulate water during storage, which becomes favorable to the growth of microorganisms. In order to control microbial contamination, use of various chemical biocides has been studied. However, the addition of a natural substance simultaneously with antioxidant and microbial growth inhibition could prove advantageous in the prevention of biodiesel oxidation and microbial contamination. Curcumin and pyrocatechol are antioxidant agents, which also exhibit microbial growth inhibition abilities. This research effort aimed at evaluating the addition of curcumin and pyrocatechol to biodiesel produced from various vegetable sources (waste frying oil, soybean oil, cottonseed oil, sesame oil, macaúba almond oil and microalgae oil). The combined addition of 1% (w/w) water and curcumin (viz. 0.2% (w/w) for biodiesel from spent frying oil, 0.5% (w/w) for biodiesel from soybean oil, 0.1% (w/w) for biodiesel from cotton seed oil, 0.5% (w/w) for biodiesel from sesame seed oil, 0.2% (w/w) for biodiesel from macaúba almond oil, and 0.2% (w/w) for biodiesel from microalgae oil) were those processing variables that promoted the best fungistatic and antioxidant effects, allowing maintenance of an unfavorable environment for microbial growth in biodiesel inoculated with the ubiquitous filamentous mold Paecilomyces variotii Bainier.

KEYWORDS:

• Biodiesel
• curcumin and pyrocatechol
• microbial growth inhibition
• oxidative stability and antimicrobial activity
• refractive index

Acknowledgments

Project funding by CNPq (National Council for Scientific and Technological Development - Brazil) (CNPq Ref. No. 404808/2013-1, Project ‘Studies on Biodiesel: Development of analytical methods for the characterization and quality control, and research of new natural additives to improve the quality of this biofuel’), is hereby gratefully acknowledged. This work received support from CNPq, National Council for Scientific and Technological Development – Brazil, in the form of Research Productivity (PQ) fellowships granted to Victor M. Balcão (Ref. No. 306113/2014-7) and Marco V. Chaud (Ref. No. 309598/2014-1). The authors have no conflicts of interest whatsoever to declare.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

Project funding by CNPq (National Council for Scientific and Technological Development - Brazil) (CNPq Ref. No. 404808/2013-1, Project ‘Studies on Biodiesel: Development of analytical methods for the characterization and quality control, and research of new natural additives to improve the quality of this biofuel’), is hereby gratefully acknowledged. This work received support from CNPq, National Council for Scientific and Technological Development – Brazil, in the form of Research Productivity (PQ) fellowships granted to Victor M. Balcão (Ref. No. 306113/2014-7) and Marco V. Chaud (Ref. No. 309598/2014-1). The authors have no conflicts of interest whatsoever to declare.