Article

In vitro effect of phenolic antioxidants on germination, growth and aflatoxin B1 accumulation by peanut Aspergillus section Flavi. J Appl Microbiol

Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas Físico Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, 5800 Córdoba, Argentina.
Journal of Applied Microbiology (Impact Factor: 2.39). 02/2005; 99(3):682-91. DOI: 10.1111/j.1365-2672.2005.02661.x
Source: PubMed

ABSTRACT The effectiveness of the food-grade antioxidants butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB), propyl paraben (PP) and butylated hydroxyanisole (BHA) at 1, 10 and 20 mmol l(-1) concentrations on germination, growth, and aflatoxin B(1) (AFB(1)) production by Aspergillus section Flavi strains was determined.
Assays on the lag phase of germination, germination percentage, germ tube elongation rate, lag phase, growth rate and AFB(1) production by three strains of Aspergillus flavus and three of Aspergillus parasiticus were carried out in vitro on peanut extract meal agar conditioned at different water activities (a(w): 0.982, 0.971, 0.955, 0.937). The antioxidants PP and BHA efficiently inhibited the germination of the two species tested at the doses 10 and 20 mmol(-1). The antioxidants PP and BHA at 1 mmol l(-1) and THB at 20 mmol l(-1) reduced the germ tube elongation rate most effectively, regardless of a(w) levels. An increase in the lag time and a reduction in the growth rate of 100% of the strains was observed, this was due to the action of BHT at the doses 10 and 20 mmol(-1) at 0.982, 0.971 and 0.955 a(w), although these treatments stimulated the AFB(1) accumulation in most of the fungi tested. The more effective antioxidants were PP and BHA, which increased the lag phase, reduced the growth rate and AFB(1) production in all of the strains at the four a(w) assayed. At concentrations 10 and 20 mmol l(-1), these antioxidants totally inhibited fungal development.
The study shows that the antioxidants BHA and PP are effective fungal inhibitors to peanut Aspergillus section Flavi in wide range of water activity.
The results suggest that phenolic antioxidants, BHA and PP, can be effective fungitoxicants on aflatoxigenic strains in peanut at industrial level.

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    • "Thirty grams of ground peanut per liter was boiled for 45 min and the resultant mixture filtered through a double layer of muslin . The volume was made up to 1 L and agar‐agar at 2% (w/v) was added (Passone et al., 2005). The water activity (a W ) of the basic medium (0.99) was adjusted to 0.98, 0.95 and 0.93 with known amounts of glycerol (Dallyn and Fox, 1980). "
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    • "The basic medium used in this study was 3% peanut meal extract agar (PMEA), made by boiling 30 g of dried peanut meal in 1 l water for 60 min. The resulting mixture was filtering through a double layer of muslin, and 15 g l À1 agar was added (Passone et al., 2005). "
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    • "Phenolic antioxidants also inhibit ochratoxin A production by Aspergillus spp. (Palumbo et al., 2007; Passone et al., 2005). Ascorbate enhances aflatoxin biosynthesis by Aspergillus parasiticus, yet caffeine, flavonoids, gallic acid and phenolics repress its biosynthesis (Holmes et al., 2008; Patel et al., 1990). "
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