Antioksidacijski potencijal, maseni udjel i aktivnost antinutrijenata, sastav mineralnih tvari i FTIR spektri leguminoza fermentiranih s pomoću plijesni Rhizopus oligosporus

Research background. Legumes are superior sources of macro- and micronutrients which can be further enhanced by fermentation. This can assist in addressing the food security concerns. The present study aims to determine the effect of fermentation by Rhizopus oligosporus on nutritional and antinutritional composition of some commonly consumed legumes. Experimental approach. Chickpea (kabuli and desi), pigeon pea and soybean were fermented with Rhizopus oligosporus (at 34 °C for 52 h), dried at 45 °C for 16-18 h and milled. Antioxidant potential, phenolic composition, antinutrients, mineral composition and FTIR spectra of fermented and unfermented flour samples were evaluated. Results and conclusions. Fermentation significantly (p<0.05) enhanced the total phenolic and flavonoid contents, and antioxidant properties (radical scavenging activity, reducing power, ferric reducing antioxidant power and metal chelation) of kabuli and desi chickpeas, and soybean. Although fermented pigeon pea exhibited excellent antioxidant properties, the effect of fermentation on such properties was either minimal or insignificant. Additionally, quantification of specific phenolics using HPLC showed higher mass fractions of certain compounds such as chlorogenic, p-hydroxybenzoic, gallic and vanillic acids in fermented legumes. Mass fraction of phytic acid in all the fermented legumes was reduced (p<0.05), while trypsin inhibition increased (p<0.05). In kabuli and desi chickpeas, and pigeon pea, saponin mass fraction increased (p<0.05) while it decreased in soybean. Tannin mass fraction increased (p<0.05) in desi chickpea, pigeon pea and soybean and decreased (p<0.05) in kabuli chickpea. Furthermore, fermentation enhanced the content and estimated bioavailability of minerals. FTIR spectrum of fermented and unfermented legumes showed the presence of several functional groups and modifications in the molecular structure after fermentation. Novelty and scientific contribution. To our knowledge, this is the first study where legume (kabuli and desi chickpeas, pigeon pea and soybean) fermentation by Rhizopus oligosporus has been assessed for nutritional and antinutritional profile and FTIR spectra. We concluded that the treatment resulted in an optimal balance of nutrients and antinutrients. The process proved to be a potential tool for tackling the concerns of nutritional security, and thus can be proposed for the development of novel legume-based functional foods.Pozadina istraživanja. Leguminoze su vrlo bogat izvor makro- i mikronutrijenata, čiji se potencijal može povećati fermentacijom, a time i riješiti problem sigurne primjene tih namirnica. Svrha je ovoga rada bila utvrditi učinak fermentacije s pomoću plijesni Rhizopus oligosporus na nutritivni i antinutritivni sastav najčešće korištenih leguminoza. Eksperimentalni pristup. Slanutak (sorte kabuli i desi), golublji grašak i soja fermentirani su s pomoću plijesni Rhizopus oligosporus (pri 34 °C tijekom 52 h), sušeni na 45 °C tijekom 16-18 h te samljeveni. Zatim su ispitani antioksidacijski potencijal, fenolni sastav, maseni udjel i aktivnost antinutrijenata, sastav mineralnih tvari i FTIR spektri fermentiranih i nefermeniranih uzoraka brašna. Rezultati i zaključci. Fermentacijom su se bitno (p<0,05) povećali udjeli ukupnih fenola i flavonoida, te poboljšala antioksidacijska svojstva (sposobnost uklanjanja slobodnih radikala, redukcijska snaga, antioksidacijska snaga i svojstvo keliranja metala) obiju sorti slanutka i soje. Iako je fermentirani golublji grašak imao odlična antioksidacijska svojstva, učinak fermentacije na ta svojstva bio je minimalan ili neznatan. Osim toga, metodom HPLC određeni su maseni udjeli specifičnih fenola u fermentiranim leguminozama, od kojih su najzastupljeniji bili spojevi poput klorogenske, p-hidroksibenzojeve, galne i vanilinske kiseline. Fermentacijom se smanjio (p<0,05) maseni udjel fitinske kiseline u svim leguminozama, dok se aktivnost inhibitora tripsina povećala (p<0,05). U obje sorte slanutka i u golubljem grašku maseni se udjel saponina povećao (p<0,05), dok se u soji smanjio. Maseni se udjel tanina povećao (p<0,05) u sorti slanutka desi, golubljem grašku i soji, a smanjio (p