Proteinski profili pšenice i njihov uticaj na tehnološka svojstva brašna

Abstract

Pšenica je jedna od najvažnijih biljnih kultura koja se koristi u ishrani ljudi kao glavni izvor energije, proteina i dijetalnih vlakana. Uprkos relativno niskom sadržaju proteina (obično 8-15%) hranljivu vrednost proteina pšenice ne bi trebalo pocenjivati. Značaj pšenice uglavnom se pripisuje njenoj sposobnosti da može biti samlevena u brašno i griz koji čine osnovne sastojke hleba, drugih pekarskih proizvoda i testenina. Kvalitet brašna, reološke i funkcionalne karakteristike testa i pekarskih proizvoda umnogome zavise od proteina pšenice. Proteini pšeničnog zrna pokazuju visoku kompleksnost i različit međusobni stepen interakcije zbog čega je njihova karakterizacija teška. Pšenica je jedinstvena među biljnim vrstama jer pšenično brašno sadrži proteinski kompleks „gluten“ koji ima svojstvo da formira testo sa reološkim svojstvima potrebnim za proizvodnju hleba i drugih pekarskih proizvoda. Formiranje viskoelastičnog testa koje ima sposobnost zadržavanja gasa tokom procesa fermentacije u potpunosti zavisi od proteina glutena. Kako je testo veoma složen sistem čije karakteristike zavise od mnogobrojnih komponenata i faktora, reološka ispitivanja testa mogu ukazati na ponašanje testa prilikom zamesa i naknadnih manipulacija u pekari. U cilju karakterizacije strukture i sastava proteina, kao i ispitivanja njihovog uticaja na tehnološka svojstva pšeničnog brašna, u ovom istraživanju korišćeno je pet hlebnih (ZP 87/1, ZP 7/1, ZP 3/1, Cimmyt 266, ZP Zemunska rosa) i pet durum (ZP 120, Cimmyt 7879, Cimmyt 7817, ZP 34/1 rana, ZP DSP/01) genotipova pšenice gajenih tokom dve godine. Elektroforetska karakterizacija albuminsko-globulinske, glijadinske i gluteninske frakcije proteina genotipova hlebne i durum pšenice u dve ispitivane godine pokazala je visoke različitosti, koje se mogu pripisati uticaju spoljnih faktora, genotipa i međusobnim delovanjem genotipa i sredine. Na sadržaj i kompoziciju glijadina i glutenina u genotipovima hlebne pšenice uticaj faktora genotipa je bio dominantan, za razliku od durum pšenica gde je faktor sredine imao veliki uticaj. Mali uticaj sredine na subjedinice glijadina i glutenina je izuzetno povoljan, jer se samim odabirom genotipa sa dobrim kvalitativnim i kvantitativnim odnosom ovih grupa proteina može uticati povoljno na tehnološka svojstva brašna...

Wheat is one of the most important cereal crops worldwide and it is a major source of energy, protein, and dietary fibre in human nutrition. Despite its relatively low protein content (usually 8-15%) the nutritional importance of wheat proteins should not be underestimated. The importance of wheat is mainly attributed to the fact that its seed can be ground into flour and semolina, which form the basic ingredients of bread, other bakery products and pasta. Wheat flour quality, rheological and technological properties of dough and bakery products are largely determined by the proteins. Wheat proteins show high complexity and different interactions with each other, thus making them difficult to characterise. Wheat is unique among the edible grains because wheat flour has the protein complex called „gluten“ that can be formed into a dough with the rheological properties required for the production of bread and other bakery products. The formation of the viscoelastic dough that is capable of retaining gases during the fermentation process depends entirely on the gluten proteins. As the wheat dough is a very complex system whose characteristics depend on many components and factors, dough rheological tests can indicate the behaviour of dough during dough mixing and the manipulation in the bakery. In order to characterize a structure and a composition of wheat proteins, as well as their influence on the technological properties of flour, five bread (ZP 87/1, 7/1 ZP, ZP 3/1, Cimmyt 266, ZP Zemunska rosa) and five durum (ZP 120, Cimmyt 7879, Cimmyt 7817, ZP 34/1 rana, ZP DSP/01) wheat genotypes cultivated in 2010 and 2011 growing seasons, were used. Electrophoretic patterns of albumin-globulin, gliadin and glutenin protein of bread and durum wheat genotypes showed significant differences, which can be attributed to the influence of environmental factors, genotype and the genotype x environment interaction. The content and the composition of gliadin and glutenin fractions of bread wheat genotypes were influenced by a genotype as a dominant factor, while durum wheat genotypes were highly environment dependent. A low influence of environmental factors on gliadin and glutenin subunits is favourable, because selection of genotypes with a good qualitative and quantitative composition of these protein groups could have a good effect on the technological properties of flour.