Impact of food grade antioxidants on fungal colonization of stored peanut seeds

PASSONE, A.; PONZIO, V.; NESCI, A.; DOPRADO, M.; BLUMA, R.; ETCHEVERRY, M.

Villa Carlos Paz, Córdoba, Argentina

Congreso; MYCO-GLOBE Advances in research on toxigenic fungi and mycotoxins in South America ensuring food and feed safety in a myco-globe context; 2006

Chulze, Dalcero, Resnik, Pacín

The combined effect of butylated hydroxyanisole (BHA), propyl paraben (PP) and butylated hydroxytoluene (BHT) on the growth of fungal pathogens in stored peanut were determined. Four antioxidants mixtures (BHA 10 mM; BHA-PP 10:10 mM; BHA-PP-BHT 10:5:10; 10:10:10 mM) were applied on 200 kg of stored peanut. A control peanut container without antioxidant was made. Representative samples (10 samples per month) were taken with a sampling device once a month during five months. Temperatures changes were recorded once a week. Water activities (aW) and pH values of the grains were determined. Quantitative enumeration of fungal propagules was done on the solid media (dichloran-rose bengal-chloramphenicol and dichloran-18% glycerol) using the surface spread method. The results were expressed as CFU per gram of peanut. Taxonomic identification of the different genera was made according to Pitt and Hocking (1997) and Samson et al. (2002). The predominant genera, in the control samples were Penicillium spp. (84.6%) and Aspergillus spp. (27.6%), followed by Fusarium spp. (4.1%), among other genus isolated in a minor percentage. Between the 1th and 6th sampling, total fungal count for control samples increased from 3.6 x103 to 1.7 x 104 UFC g-1. This behavior positively correlated with the storage temperature, which increased from 7 to 20°C, meanwhile, the grains aW to be maintained relatively constant during all the experience about 0.73. The pH values of the grains were all between 6.5 and 7.15, a range in that there is about 99% of antioxidants dissociation (Silliker et al., 1980) and they present the best antimicrobial activity. The antioxidant effect increased at the same way the storage time passed. During the 1th storage month the application of BHA at 10 mM reduced fungal growth at 65%, but a reduction of 97.5% was observed at the end of the experience. Similarly, a high predominance of the genera Penicillium spp. (74.3%) was observed in the container with BHA-PP (10:10 mM). At 6th sampling this mixture significantly reduced (P=0.05) fungal growth with a 95.5% of reduction. The mixtures with three antioxidants significantly reduce (P=0.05) fungal growth in all peanut samples evaluated. Between the 1th and 4th month of storage, the efficacy enhanced from 81 to 99% and from 93 to 100% for the mixture BHA-PP-BHT at 10:5:10 mM and 10:10:10 mM, respectively. The data from this study show that food grade antioxidants, particularly the mixture of BHA-PP-BHT, may be considered as effective fungitoxicants, especially in neutral pH foods such as peanut and utilized such preservatives as part of the post-harvest control of spoilage in the peanut production chain.   References Pitt, J.I. y Hocking, A.D. (ed.) (1997) Fungi and Food spoilage pp. 339-417. Samson, R.A., Hoekstra, E.S., Frisuad, J.C., Fitenborg, O. (2002) Introduction to food-and airborne fungi pp. 1-269. Silliker, J.H., Elliot, R.P., Baird-Parker, A.C., Bryan, F.L., Christina, J.H.B., Clark, P.S., Olson, J.C. Jr and Roberts, T.A. (1980) Factores que afectan la supervivencia de los microorganismos en los alimentos pp. 132-142.