Inhibitory effects of essential oils of oregano (Origanum vulgare), mint (Menta arvensis), basil (Ocimum basilicum), sage (Salvia officinalis) and coriander (Coriandrum sativum), on the mycelial growth and ochratoxin A production by Aspergillus ochraceus NRRL 3174 were studied. Cultures were incubated on yeast extract‐sucrose (YES) broth, at concentrations of 0, 500, 750 and 1000 p.p.m. of essentials oils during 7, 14 and 21 d at 25 °C. At 1000 p.p.m., oregano and mint completely inhibited the fungal growth and ochratoxin A production up to 21 d, while basil was only effective up to 7 d. At 750 p.p.m., oregano was completely effective up to 14 d, whereas mint allowed fungal growth but no ochratoxin A production up to 14 d. At 500 p.p.m., no evident inhibition could be observed with any of the essential oils under analysis. Sage and coriander showed no important effect at any of the concentrations studied. These inhibitory effects are interesting in connection with the prevention of mycotoxin contamination in many foods and they could be used instead of synthetic antifungal products.

Aims: To evaluate the effects of the extrusion cooking process on the inactivation of mycotoxins in corn¯our. Methods and Results: Samples of corn¯our experimentally contaminated with a¯atoxin B 1 (AFB1) (50 ppb) and deoxynivalenol (DON) (5 ppm) were extruded. The effects of three extrusion variables (¯our moisture, extrusion temperature and sodium metabisulphite addition) were analysed according to a two-level factorial design. The process was effective for the reduction of DON content (higher than 95%) under all the conditions assessed, but was only partially successful (10±25%) for the decontamination of AFB1. Conclusions: Extrusion cooking is effective for the inactivation of DON but is of limited value for AFB1, even if metabisulphite is added. More severe extrusion conditions are needed for the detoxi®cation of AFB1. Signi®cance and Impact of the Study: As contamination with DON occurs mainly in the ®eld prior to harvesting and that of AFB1 is normally produced during grain storage, maize is often contaminated with DON but not with AFB1. Under these conditions, the described extrusion process can be used for the detoxi®cation of DON. The addition of sodium metabisulphite did not signi®cantly affect the inactivation of AFB1. Extrusion cooking is therefore an appropriate treatment for vomitoxin-contaminated maize in countries where, because of the prevailing conditions, these are the only toxins present.

No abstract

No abstract

No abstract

The principal agents of Fusarium head blight in the main cropping area of Argentina were investigated in heavily infected samples. The ability of the isolates to produce trichothecenes was determined by GC and HPLC. Fusarium graminearum was the predominant species and of 33 isolates, 10 produced deoxinivalenol (DON) (0.1-29 mg kg ), 10 produced Fusarenone X (0.1-2.4 mg kg -1 ) and 7 produced zearalenone (0.1-0.6 mg kg -1 ). These results suggest that F. graminearum strains isolated from the wheat growing regions in Argentina belong to DON chemotype. Although some strains produced both deoxinivalenol and nivalenol, nivalenol was produced in lower levels. The natural occurrence of nivalenol in wheat affected by head-blight collected in the main production area during two years (2001)(2002) was also determined. From 19 samples 13 were contaminated with deoxinivalenol in a range of 0.3 to 70 mg kg -1 and 2 samples with both deoxinivalenol (7.5 and 6.7 mg kg -1 ) and nivalenol (0.05 and 0.1 mg kg -1 ), respectively. This is the first report of natural occurrence of nivalenol in wheat cultivate in Argentina.

Aims: The origin of a mould responsible for the contamination of an Argentinian cheese factory was identi®ed and several antifungal treatments were assessed. Methods and Results: Moulds were isolated and identi®ed from vacuum-packed hard cheeses, from the environment and from the surfaces of the factory. A suspension conidia test containing different fungicides was performed; another assay involved the fumigation with p-OH fenilsalicidamide. Only Phoma glomerata was found in all of the mouldy cheeses, and was also obtained from different environments and machine surfaces. The most effective treatments against P. glomerata isolates were 0á5% (w/v) natamycin and 2% (v/v) parabens. Fumigation with p-OH fenilsalicidamide showed no satisfactory results. Conclusions: P. glomerata is an important thread mould-contaminating agent in vacuumpacked hard cheeses. Signi®cance and Impact of the Study: Taking into account the survival of the conidia of the P. glomerata isolates to different antifungal treatments, the sources of contamination need to be controlled by designing a good factory layout.

No abstract