Influence of high intensity ultrasound treatment on polyphenol oxidase activity, chemical-physical properties and bioactive potential of ultra-fine wheat bran

Pšenične posije predstavljaju vrijedan nusproizvod proizvodnje pšeničnog brašna zbog visokog sadržaja prehrambenih vlakana i bioativnih spojeva pri čemu im se stoga pripisuje blagotvoran učinak na ljudsko zdravlje. Cilj ovog rada bio je ispitati utjecaj ultrazvuka visokog intenziteta na sadržaj slobodnih fenolnih spojeva, antioksidacijsku aktivnost, sposobnost bubrenja u vodi, kapacitet zadržavanja vode, aktivnost enzima polifenol-oksidaze i boju ultra-fino mljevenih pšeničnih posija. Vodena suspenzija pšeničnih posija sobne temperature tretirana je (5, 10 ili 15 min) direktno uronjenom ultrazvučnom sondom (d = 22 mm) pri amplitudama (100%, 80% ili 60%) prema složenom centralnom planu pokusa. Usporedbom tretiranih uzoraka u odnosu na kontrolu utvrđeno je da tretman smanjuje aktivnost polifenol-oksidaze, sadržaj ukupnih fenolnih spojeva, antioksidacijsku aktivnost i L* parameter boje, a povećava a* i b* parameter boje, sposobnost bubrenja u vodi i kapacitet zadržavanja vode. Na taj način bi se mogla povećati stabilnost i primjenjivost pšeničnih posija.Wheat bran represents a valuable by-product of wheat flour production because of its high content of dietary fiber and bioactive compounds, and hence is attributed to a beneficial effect on human health. The aim of this paper was to investigate the effect of high intensity ultrasound on the content of free phenolic compounds, antioxidant activity, water swelling ability, water retention capacity, polyphenol oxidase activity and the color of ultra-fine wheat bran. The aqueous suspensions of wheat bran at a room temperature were treated (5, 10 or 15 min) with a directly immersed ultrasonic probe (d = 22mm) at amplitude (100%, 80% or 60%) according to the complex central plan od the experiment. Comparison of treated samples with respect to a control showed that the treatment decreases polyphenol oxidase activity, the content of total phenolic compounds, antioxidant activity and L* color parameter, a increases the a* and b* color parameters, water swelling ability and water retention capacity.This could increase the stability and applicability of wheat bran