Mycoflora and ochratoxin a control in wheat grain using natural extracts obtained from wine industry by-products

Abstract

The aim of this study was to evaluate the effect of some natural extracts obtained from grape pomace (GPE) and grape seeds (GSE) as compared to a synthetic food, antioxidant-butylated hydroxytoluene (BHT), in order to control fungal population and ochratoxin A (OTA) production in naturally contaminated wheat. The results showed that the addition of these extracts was efficient with OTA content decreasing. On treatment with these extracts the loss of OTA content after 14 days was in the range 7.8-28.3% relative to the control sample, but increased up to 26.48-37% after 28 days. The highest loss in OTA content was recorded for treatment with GPE at the 500 ppm level. Regarding the fungal development, the obtained results show that the total fungal populations were significantly reduced by using natural extracts. The most efficient extract was GPE. Both BHT and GPE inhibit the growth of Penicillium verrrucosum, for all doses, but less with Aspergillus genera. GPE affects the growth of other types of moulds such as Rhizopus microsporus, Fusarium graminearum, Alternaria infectoria and Cladosporium herbarum. Our data suggested that GPE and GSE are able to provide fungicidal and fungistatic protection and to control the OTA accumulation in wheat, at least in a similar manner to BHT.

Keywords: butylated hydroxytoluene (BHT); fungus genera; grape pomace extract; grape seed extract; ochratoxin A.

Figure 1

The decline registered in OTA content on treatment with natural extracts (a) GSE; (b) GPE; (c) BHT.

Figure 2

The impact of treatment with GSE, GPE and BHT on Fr of fungus genera during incubation period (a) after 7 days; (b) after 14 days; (c) after 21 days; (d) after 28 days.

Figure 3

The impact of treatment with GSE, GPE and BHT on RD of fungus species of OTA-producers genera (a) after 7 days; (b) after 14 days; (c) after 21 days; (d) after 28 days.

Figure 4

Images of the wheat grain contamination with different treatments applied (a) high level of contamination in control sample; (b) high level of contamination with Eurotium amstelodami (teleomorph of Aspergillus vitis) on DG 18 medium; (c) sample treated with 500 ppm GSE after 7 days; (d) sample treated with 500 ppm GPE after 7 days; (e) high level of Cladosporium and Alternaria in sample treated with 1000 ppm BHT after 14 days; (f) sample treated with 2500 ppm BHT after 21 days.