The effect of the Fusarium sp. attack on the quality parameters of Romanian wheat

In Romania and in Europe wheat is the most important cereal crop, being grown on an area of about 2 million hectares per year. Most wheat varieties grown in Romania are susceptible to the attack of the following Fusarium species: F. culmorum, F. graminearum and F. avenaceum. Other species reported in Romania are F. verticillioides, F. oxysporum and F. poae. These species can cause significant crop losses, but the main problem is related to the contamination by mycotoxins (deoxynivalenol, zearalenone, fumonisin, etc.) of the food chains which are based on cereals.

Regarding the effect of Fusarium attack on the wheat quality, Wang et al. (2005) have shown that the addition of a liquid contaminated with F. culmorum to the flour, can significantly decrease the Falling Number parameter [1].

Nightingale et al. (1999) have shown through the electron microscopy analysis of wheat grain infected with Fusarium sp. that there exist definite zones of endosperm protein degradation. The proteolytic activity caused by Fusarium sp. is inhibited by chloromercuribenzoate, and not by the  p-trypsin inhibitor from soy, or by the iodoacetic acid, suggesting that the protease in Fusarium is an alkaline protease. The rheology studies of dough prepared from the flour obtained from wheat attacked by Fusarium showed a decrease of dough consistency and its resistance to extension. Also, the bread made from this flour is characterized by a small volume [2].

Wang et al. (2005) studied protease of Fusarium culmorum and identified the optimal range of pH between 6 and 8 and an optimum temperature of 500C for the proteasic activity. Protease is still active in the pH range 4.5 to 8.5 and in the range of temperatures 100C to 1000C [3].

Eggert et al. (2011) showed that the F. graminearum protease hydrolyzes better the glutenins than the gliadins [4]. Papoušková et al. (2011) also showed that the intensity of Fusarium attack is related to the deterioration of dough rheological qualities, evaluated with mixolab. They found a worsening of the mixolabic parameters which are responsible to some extent for the protein quality, especially for the fraction of starch from flour [5].

Considering the importance of the milling and baking industry products to the Romanian people nutrition, we considered useful to undertake a study regarding the effect of Fusarium sp. attack on the quality of Romanian wheat, a study based on data collected by us in the last five years.

There have been analyzed 102 samples of Romanian wheat, coming from the crops of the years 2007-2011, in order to assess the influence of the Fusarium sp. attack on the main quality parameters. In this respect, there have been analyzed the following physical and chemical parameters: Hectolitre mass (kg/hl), Moisture (%), Protein content (%), Wet gluten content (%), Falling Number (sec), Gluten deformation (mm), Gluten Index, as well as the Content of kernels attacked by Fusarium (%). The Fusarium attack ranged from 0.1% to 4.5% and was characterized by very high variability.

The evaluation of Fusarium attack was made through the Spearman statistical test, which showed its significant influence on the amylase activity of wheat (expressed by the parameter Falling Number, r = -0.22 *) and on the proteolytic activity (expressed by the Gluten deformation, r = -0.28 *).

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References
[1] Wang J., Pawelzik E., Weinert J., Wolf G.A., 2005, Impact of Fusarium culmorum on the polysaccharides of wheat flour, J Agric Food Chem. jul 13;53(14):5818-23.

[2] Nightingale M.J., Marchylo B.A., Clear R.M., Dexter J.E., Preston K.R., 1999, Fusarium Head Blight: Effect Of Fungal Proteases On Wheat Storage Proteins, Cereal Chemistry, January/February, Volume 76, Number 1, Pages 150-158

[3] Wang J.,  Wieser H.,  Pawelzik E.,  Weinert J.,  Keutgen A.J., Wolf G.A., 2005, Impact of the fungal protease produced by Fusarium culmorum on the protein quality and breadmaking properties of winter wheat, Eur Food Res Technol, Vol 220, No 5-6, 552-559

[4] Eggert K., Rawel H.M., Pawelzik E, 2011, In vitro degradation of wheat gluten fractions by Fusarium graminearum proteases, Eur Food Res Technol 233:697–705

[5] Papoušková L., Capouchová I., Kostelanská M., Škeriková A. Prokinová E., Hajšlová J., Salava J., Famera O., 2011, Changes In Baking Quality Of Winter Wheat With Different Intensity Of Fusariumspp. Contamination Detected By Means Of New Rheological System, Czech Journal Of Food Sciences, Vol. 29 No. 4 pp. 420-429

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