Antifungal activity of flaxseed and flaxseed extracts

Antifungal activity of flaxseed and flaxseed extracts

Full title: 

Antifungal activity of flaxseed and flaxseed extracts
Antifungal activity of flaxseed and flaxseed extracts

Author: 

Xu, Yingying

Year: 

2008

Reference type: 

Thesis

Publisher: 

North Dakota State University

ISBN/ISSN: 

9780549523222

Abstract: 

Flaxseed ( Linum usitatissimum ) has never been considered as a food preservative. The objective of this study was to investigate the antifungal activity of flaxseed and flaxseed extracts, including the stability of the antifungal activity. Strains of Penicillium chrysogenum, Aspergillus flavus, Fusarium graminearum , and a Penicillium sp. isolated from molded noodles were used as test microorganisms. Flaxseed (6-15%) significantly inhibited all molds in potato dextrose agar. Flaxseed (8805;9%) also significantly inhibited all molds, and reduced the mold count of fresh noodle during storage. At 15%, it had a similar preserving effect as a 0.2% propionic acid. Differences in the degree of mold inhibition were found among flaxseeds obtained from different sources and cultivars. The protein extract (1%) inhibited all molds, where the most effective extraction pH values were pH 5 and 10. The crude phenolic extracts affected the growth of the fungi. The 60% methanol was the most effective solvent. Partial purification of the 60% methanol extracts improved the antifungal activity. Flaxseed gum and cyanogenic glycosides did not inhibit the growth of the molds. Response surface methodology was used to evaluate the antifungal activity stability of flaxseed and flaxseed protein extract. Statistical models were developed to predict the effect of treatments (i.e., heat and pH) of flaxseed or flaxseed protein extract on antifungal activity. For flaxseed, linear terms of variables (i.e., heating temperature and time) and the quadratic terms of the heating temperature had significant ( p <0.05) negative effects on all fungi and the mold count log-cycle reduction of fresh noodles. Sixty percent of the antifungal activity was retained after flaxseed was heated at 100 °C for 15 min. For flaxseed protein, the treatment temperature and time had significant ( p <0.05) negative effects on the residual antifungal activity (RAA), whereas that of pH had a significant ( p <0.1) positive effect. At the pasteurization condition, 8805; 50% activity of flaxseed protein was retained except for P. chrysogenum . These results suggested that flaxseed and flaxseed protein had certain degrees of stability. Therefore, flaxseed and flaxseed extracts may be promising as natural multifunctional ingredients due to their health benefits and preserving effect.