Influence of content of [beta] conglycinine subunits on technological and functional properties of soybean proteins

Zbog značajne nutritivne vrednosti i visokog sadržaja proteina, antioksidanasa i nezasićenih masnih kiselina soja se svrstava u kategoriju funkcionalne hranu. Zdravstveni efekti soje u humanoj ishrani su brojni: doprinosi smanjenju koncentracije glukoze i holesterola u krvi, pokazuje antioksidativni efekat, povoljno utiče na održavanje hormonske ravnoteže, sprečava osteoporozu i deluje preventivno na različite tipove kancera. Na tehnološki značajne funkcionalne osobine proteina semena soje najviše utiču dva glavna rezervna proteina: glicinin (11S protein) i β konglicinin (7S protein). I 11S i 7S proteini se javljaju u više izoformi. Molekul glicinin čine dva neglikozilovana heksamera koji se sastoje iz parova kiselih i baznih polipeptida povezanih disulfidnim mostom.β konglicinin je glikozilovani trimerni protein koji se sastoji iz tri podjedinice- α, α' i β. Pojedine sorte soje, među kojima su naročito brojne domaće sorte, sintetišu dodatnu β' podjedinicu. Premda je efekat ostalih podjedinica β konglicinina na tehnološka funkcionalna svojstva proteina soje intenzivno proučavan, u literaturi postoji veliki broj kontradiktornih podataka. O efektima β' podjedinice na rastvorljivost, emulgujuća i gelirajuća svojstva sojinih proteina veoma malo se zna. Cilj ovog rada bio je da se ispita efekat polipeptidnog sastava glicinina i β konglicinina na rastvorljivost, emulgujuća i gelirajuća svojstva proteina na različitim pH vrednostima (3, 5, 6 i 8) na seriji od 9 različitih genotipova soje gajenih u dve sukcesivne godine. Uspostavljanje korelacija između specifičnih podjedinica sojinih proteina i željenog svojstva pri datoj pH vrednosti, omogućilo bi ne samo selekciju sorti pogodnih za dati tehnološki proces, već bi uticalo i na osobine gotovih proizvoda. Povećana rastvorljivost obezbeđivala bi lakše usvajanje aminokiselina i bolju svarljivost. Pored povećane biološke vrednosti, visoka rastvorljivost je u pozitivnoj korelaciji sa funkcionalnim svojstvima poput geliranja i penivosti...Because of its nutritive value and high content of proteins, antioxidants and unsaturated fatty acids, soybeans have been regarded as functional food. Health benefits of inclusion of soy in human diet are numerous: it helps diminishing concentration of glucose and cholesterol in blood, has antioxidative effect, helps in regulating hormonal balance, prevents osteoporosis and has protective influence against different types of cancers. The strongest influence on technological functional properties of soybean proteins is exhibited by two reserve proteins: glycinin (11S protein) i β conglycinin (7S protein). Both 11S and 7S protein are present in different isoforms. Glycinin molecule is composed of two non-glycosilated hexamers that contain pairs of acidic and basic polypeptides linked together by disulfide bonds. β conglycinin is glycosilated trimeric protein composed of three types of subunits - α, α' and β. Some varieties of soybean, among them numerous varieties grown in Serbia, are synthesizing additional β' subunit. Although effects of other subunits of β conglycinin on technological functional properties of soybean proteins have been extensively studied, there is still a high number of contradictory data in literature. Little is known about influence of β' subunit on solubility, emulsifying and gelling properties of soybean proteins. The aim of this work was to examine effect of polypeptide composition of glycinine and β conglycinine on solubility, emulsifying and gelling properties of soybean proteins at different pH values (3, 5, 6 and 8) on series of 9 different genotypes grown in two successive years. Establishing correlation of specific subunit of soybean protein with desired characteristic on given pH value would allow not only selection of varieties of soybean suitable for particular technological process, but would also have impact on properties of finished product. Higher protein solubility would allow better usage of amino acids and would also give higher digestibility..