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La physique et la chimie au service de l'élaboration des pâtes alimentaires

La valeur semoulière d’un lot de blé dur rend compte de son potentiel de rendement en semoule et de la pureté de ses produits. Elle dépend d’un grand nombre de facteurs qui déterminent le comportement des blés durs en mouture. La compréhension des mécanismes sous-jacents offre des perspectives pour sa maîtrise et son optimisation. Au-delà de l’identification des facteurs influents, le développement de méthodes de mesure des caractéristiques des grains en vue de déterminer leur valeur semoulière demeure un enjeu majeur pour les industries de première transformation. Cet article décrit l’état des connaissances sur la valeur semoulière, ainsi que l’évolution des méthodes de mesure permettant de l’apprécier.

This thesis describes an investigation of the mechanistic differences of hard and soft wheat varieties in the course of dough formation. These two classes of wheat exhibit dissimilar end-use, as hard wheat flour is known for its bread making attributes, whereas soft wheat flour is suitable for cake and cookie production. This difference is related to the grain hardness, protein content and property of gluten, in addition to chemical interactions that are occurring during dough making. Covalent and hydrophobic interactions, as well as hydrogen bond formation, are the main interactions that take place during dough mixing. However, the contribution of each interaction in dough formation of hard and soft wheat is not known. One variety of hard and one variety of soft wheat flour were mixed to their optimum hydration level (500 BU), as determined by farinograph. The extent of covalent interactions of gluten proteins during dough mixing was examined by monitoring changes in the solubility of flour proteins in a 2% Sodium Dodecyl Sulfate (SDS) media. Moreover, the contribution of thiol groups to covalent bond was examined by measuring the changes in the accessible thiols throughout the mixing. Lower extractability of proteins and accessible thiols of hard wheat dough, compared to soft wheat dough, indicated the predominant role of covalent interactions in hard wheat dough. The complementary results from Size Exclusion High Performance Liquid Chromatography (SE-HPLC) indicated that covalent interaction of hard wheat dough primarily occurs between Low Molecular Weight (LMW) and High Molecular Weight (HMW) gluten proteins, whereas this interaction mainly occurs among LMW proteins in soft wheat doughs. Fewer hydrophobic interactions in hard wheat dough in compare with soft wheat measured by Front-face fluorescence spectroscopy indicated that this interaction is more dominant in soft wheat dough. Study of the conformational change in secondary structure of protein (indirect approach to monitor hydrogen bond) by fourier transform infrared (FTIR) spectroscopy showed that β-sheets are formed in both varieties at their optimum dough strength. In hard wheat dough this structure resulted mainly from disulfide linkages, whereas in soft wheat dough this structure is more likely the result of hydrophobic interactions.

Une approche scientifique multidisciplinaire pour répondre aux enjeux de la production, la transformation et la consommation de la filière blé dur. Rencontres Salon International de l'Agriculture (SIA) 2013

Le transfert de connaissances, et la formation d’une nouvelle génération. Rencontres Salon International de l'Agriculture (SIA) 2013

In every agroforestry system, the tree canopy reduces the incident radiation forthe crop. However, cereal varieties were selected, and most crop growth modelswere designed for unshaded conditions, so both may be unsuited to agroforestryconditions and performance. In southern France, durum wheat productivity wasmonitored over 2 years in an agroforestry system including walnut trees andunder artificial shade conditions. Yield components were measured in both fulland reduced light conditions. The cereal yield was always decreased by shade; byalmost 50% for the heaviest shade conditions (31% of light reduction). The maineffect of the shade was the reduction in the number of grains per spike (35% atthe most) and in the weight of grains (16% at the most). The mean grain weightwas moderately affected, while the protein content was increased in shaded con-ditions (by up to 38% for artificial shade). Consequently, the protein yield perhectare was less reduced by the shade than the dry matter grain yield. A cropmodel (STICS) was also used to simulate the crop productivity in full light andshaded conditions, but the crop LAI and the yield components were not correctlysimulated in the shade. The simulations emphasized the sensitivity of the wheatgrain filling to shade during the critical period, 30 days before flowering, for yieldelaboration. Further experimental and modelling studies should take intoaccount the heterogeneity of shade intensity due to the shape of the tree crown,the width of the crop alley and the orientation of the tree rows and the modifica-tion of carbon allocation inside the plant.IntroductionConcerns over the long-term sustainability of intensivemonoculture systems have resulted in a heightened interestin agroforestry systems that integrate trees into short-termproduction systems, in temperate areas. Recent studiesshow that tree-based intercropping systems, which inte-grate hardwood species, offer many benefits for the envi-ronment, such as reducing soil erosion and N leaching, andincreasing carbon sequestration (Albrecht and Kandji2003) and landscape biodiversity (Quinkenstein et al.2009). Agroforestry systems create a wide range of biophys-ical interactions between the crop and the trees. Some ofthe competitive interactions for resources (water, light andmineral elements) have been documented for a variety ofpractices in the tropics (Cannell et al. 1998, Albrecht andKandji 2003, Bellow and Nair 2003). Moreover, the differ-ent species may improve each other’s environment. This isknown as ‘facilitation’ (Vandermeer 1989).The water and N availability have often been studied intemperate and Mediterranean agroforestry systems (Joseet al. 2000a,b, Miller and Pallardy 2001, Livesley et al.2004). In Mediterranean areas, water stress is one of themain production constraints for cereals, particularlydurum wheat. This is a consequence of the variability ofthe frequency and amount of rainfall during the growingseason (Garcia del Moral et al. 2005, Katerji et al. 2008).Light availability is greatly modified in agroforestry sys-tems compared to cropping systems based on annual cropssuch as soybean (Rivest et al. 2009), corn (Reynolds et al.

Wheat bugs are widely distributed in various areas of Europe, Asia and North Africa. Species belonging to the genus Eurygaster and Aelia pierce wheat kernels affecting protein quality. The effects of these insects' feeding activity have been studied mainly in bread wheat (Triticum aestivum L.). This study provides information on the degradation of prolamin proteins (glutenins and gliadins) of bug-damaged durum wheat (Triticum turgidum L. var durum) in six cultivars grown in Sardinia (Italy). Samples of whole flour mixture of 70% sound wheat and 30% damaged wheat were hydrated and incubated at two temperatures (45 and 4 deg C), for different periods of time (0, 1 and 3 h). Glutenin and gliadin content was analysed using free zone capillary electrophoresis. The presence of bug-damaged kernels had influence on the quality of durum wheat proteins. Glutenins were rapidly degraded independently to incubation temperature. Gliadin degradation, however, took place with dependence on temperature and incubation time. Therefore glutenin degradation was possibly not due solely to the activity of proteolytic enzymes but also to some other as yet unknown factor linked to wheat bugs' feeding activity., Los chinches de los cereales tienen una amplia distribución en diversas áreas de Europa, Asia y Norte de África. Especies pertenecientes a los géneros Eurygaster y Aelia se alimentan picando los granos de trigo afectando a la calidad de las proteínas. Esta alteración se ha estudiado principalmente en trigo blando (Triticum aestivum L.). El presente estudio aporta información sobre la degradación de las prolaminas (gluteninas y gliadinas) del trigo duro (Triticum turgidum L. var durum) dañado por los chinches de los cereales en seis variedades cultivadas en Cerdeña (Italia). Muestras de harina integral, con un 70% de trigo sano y un 30% de trigo dañado se incubaron a dos temperaturas (45 y 4 grados C), y a diferentes tiempos (0, 1 y 3 h). El contenido de las gluteninas y gliadinas se analizó mediante electroforesis capilar zonal. La presencia de granos picados por los chinches de los cereales influyó en la calidad de las proteínas del trigo duro. Las gluteninas se degradaron rápidamente, con independencia de la temperatura de incubación. En cambio, la degradación de las gliadinas resultó ser dependiente de la temperatura y del tiempo. Ante estos resultados, cabe plantearse la posibilidad de que la degradación de las gluteninas no sea debida sólo a la actividad de las proteasas sino también a algún otro factor ligado a la actividad alimenticia de los chinches de los cereales, todavía por determinar.

Wheat bugs are widely distributed in various areas of Europe, Asia and North Africa. Species belonging to the genus Eurygaster and Aelia pierce wheat kernels affecting protein quality. The effects of these insects' feeding activity have been studied mainly in bread wheat (Triticum aestivum L.). This study provides information on the degradation of prolamin proteins (glutenins and gliadins) of bug-damaged durum wheat (Triticum turgidum L. var durum) in six cultivars grown in Sardinia (Italy). Samples of whole flour mixture of 70% sound wheat and 30% damaged wheat were hydrated and incubated at two temperatures (45 and 4 deg C), for different periods of time (0, 1 and 3 h). Glutenin and gliadin content was analysed using free zone capillary electrophoresis. The presence of bug-damaged kernels had influence on the quality of durum wheat proteins. Glutenins were rapidly degraded independently to incubation temperature. Gliadin degradation, however, took place with dependence on temperature and incubation time. Therefore glutenin degradation was possibly not due solely to the activity of proteolytic enzymes but also to some other as yet unknown factor linked to wheat bugs' feeding activity. Los chinches de los cereales tienen una amplia distribución en diversas áreas de Europa, Asia y Norte de África. Especies pertenecientes a los géneros Eurygaster y Aelia se alimentan picando los granos de trigo afectando a la calidad de las proteínas. Esta alteración se ha estudiado principalmente en trigo blando (Triticum aestivum L.). El presente estudio aporta información sobre la degradación de las prolaminas (gluteninas y gliadinas) del trigo duro (Triticum turgidum L. var durum) dañado por los chinches de los cereales en seis variedades cultivadas en Cerdeña (Italia). Muestras de harina integral, con un 70% de trigo sano y un 30% de trigo dañado se incubaron a dos temperaturas (45 y 4 grados C), y a diferentes tiempos (0, 1 y 3 h). El contenido de las gluteninas y gliadinas se analizó mediante electroforesis capilar zonal. La presencia de granos picados por los chinches de los cereales influyó en la calidad de las proteínas del trigo duro. Las gluteninas se degradaron rápidamente, con independencia de la temperatura de incubación. En cambio, la degradación de las gliadinas resultó ser dependiente de la temperatura y del tiempo. Ante estos resultados, cabe plantearse la posibilidad de que la degradación de las gluteninas no sea debida sólo a la actividad de las proteasas sino también a algún otro factor ligado a la actividad alimenticia de los chinches de los cereales, todavía por determinar.

After 40 years of using different rates and ratios of nitrogen, phosphorus and potassium in a long-term stationary trial, we studied the effects of these treatments on the levels of biogenic macro- and micro-elements in the flag leaf and grain of hard wheat. Our study showed that the treatments had more effect on the levels of said elements in the flag leaf than the grain. Of the three nutrients, nitrogen had the largest influence. The levels of the elements studied were the lowest in the control treatment and the one where only potassium fertilizer had been used. Increasing fertilizer rates of all three nutrients increased to varying degrees the levels of all macro- and micro-elements under study. Nitrogen affected grain yield the most. With the exception of nitrogen, the use of different rates and ratios of N, P and K did not have any major effect on the levels of the elements studied in the grain. The nitrogen content was the smallest in the control treatment nitrogen-free treatments and treatments with the smallest nitrogen rate. In spite of the long-term incorporation of N, P and K, which exceeded the amounts of these elements removed by yield, there was no interaction between the three nutrients and the elements studied. According to the results of our study, even after long-term fertilization with increased N, P and K rates when chernozem has a good supply of phosphorus and potassium and a medium supply of nitrogen, nitrogen will be the element with the largest influence on the grain yield of hard wheat as well as on its chemical composition, as N levels increase in both the flag leaf and grains of this crop. U stacionarnom, dugotrajnom poljskom ogledu posle četiri decenije primene različitih doza i odnosa azota, fosfora i kalijuma, ispitan je njihov uticaj na sadržaj biogenih makro i mikroelemenata, u listu zastavičaru i zrnu. Primena različitih doza i odnosa azota, fosfora i kalijuma u većoj meri je uticala na sadržaj ispitivanih elemenata u listu zastavičaru nego u zrnu. Od ispitivana tri hraniva azot je ispoljio najveći uticaj. Najmanji je bio sadržaj ispitivanih elemenata kod kontrole i varijante kod koje je primenjivano samo kalijumovo đubrivo. Sa povećanjem doza primenjenih hraniva povećao se sadržaj u manjoj ili većoj meri svih ispitivanih elemenata. Azot je u najvećoj meri uticao i na prinos zrna. Primena različitih doza i odnosa azota, fosfora i kalijuma nije ispoljila veći uticaj na sadržaj ispitivanih elemenata u zrnu, osim u slučaju azota. Sadržaj azota bio je najmanji kod kontrole, varijanata kod kojih nisu primenjivana azotna đubriva i pri upotrebi najmanje doze azota. I pored višegodišnje primene doza azota fosfora i kalijuma koje premašuju njihovo iznošenje prinosima nije došlo do interakcije između primenjenih i ispitivanih elemenata. Na osnovu dobijenih rezultata može se zaključiti da na černozemu dobro obezbeđenog u fosforu i kalijumu i osrednje u azotu, i posle višegodišnje primene povećanih doza azota, fosfora i kalijuma najveći uticaj ne samo na prinos zrna već i na hemijski sastav ima azot, povećavajući pre svega njegov sadržaj kako u listu zastavičaru tako i u zrnu.

Established and supported under the Australian Government’s Cooperative Research Centre Program

Bu araştırmada çevresel adaptasyon yeteneği ve verimi yüksek makarnalık buğday çeşitlerinin geliştirilmesi amacıyla yürütülen ıslah programında elde edilen hat/arın, 1993-1996 yılları arasında yürütülen verim denemesi sonuçları değerlendirilmiştir. Çalışmada her bir deneme yılı bir çevre, her yıla ili4kin ortalama değerler ise çevresel indeks olarak ele alınmıştır. Tane verimi için adaptasyon ve stabilite parametreleri olarak; doğrusal regresyon katsayısı (b), regresyondan sapma (S d) ve belirleme katsayısı (r2) değerleri regresyon analizinden hesaplanmıştır. Elde edilen bulgulara göre, incelenen hatlar ve kontrol çeşitleri arasında ortalama tane verimi ve stabilite değerleri açısı/dan, Gökgöl x Amasya kombinasyonundan 39 ve 70; Gökgöl x Çanakkale kombinasyonundan ise 65 nolu hattın yüksek verimli ve stabil oldukları saptanmıştır. Bu genotipler tane verimi ve uyum yetenekleri yönünden ümitar hatlar olarak değerlendirmişlerdir. The results of these yield experiments carried with hard wheat strains obtained from breeding programmes which were conducted in order to develop hard wheat varieties with high yield and hith adaptation ability were evaluated in the years from 1993 to 1996. In this study, each of the experimental year's average values of each year were treated as an environment and a . eıvironmentl index, 1 respectively. The parameters of adaptatıon and stabılıty for seed yıeld were calculated by a regression equation including i Linear r1,resio coe!fcient (b), deviation from regressıon (S d) and coefficıent of det{mınatıon (r ). According to the findings from study, two strains such as 39 and 70 resulted from Gökgöl x Amasya combination and the Stalin 65 of Gökgöl x Çanakkale combination were determined to be high yielding and stable ones. They were evaluated as promising strains in respect of seed yield and adaptable values.