High intensity ultrasound assisted extraction of anthocyanins from peruvian purple corn, their encapsulation and stability.

CUETO, MARIO; DOS SANTOS, CRISTINA; SCHLEINING, PAUL; FARRONI, ABEL; MAZZOBRE, MARÍA FLORENCIA; BUERA, MARÍA DEL PILAR

Concordia, Entre Ríos

Conferencia; III Conferencia Internacional de Innovación en Alimentos (FoodInnova 2014).; 2014

Purple corn of variety Zea mays (L. Kculli) has been used as food from thousands of years in Peru,and recently has gained great interest because of its properties as antioxidant, hypotension and hypoglucemic agent. The high polyphenols and anthocyanins content, makes purple corn extracts interesting for its employment as nutraceutic food additive. The objective of present work was to optimize ultrasound assisted extraction for obtaining anthocyanins and phenolic compounds from purple corn and to study the stability of extracts encapsulated in calcium alginate beads. Purple corn cobs were dry-milled and the obtained flours passed through a 200 μm mesh. The anthocyanin content was evaluated by the differential pH method, and the ployphenols content by Folin Ciocalteu. Antiradical capacity was evaluated by two scavenging techniques, DDPH and ABTS. Conditions that maximized the extraction of anthocyanins and polyphenols were the ultrasonication of 4% w/v aqueous purple corn flour suspensions, 125 m amplitude and 130 W/cm2 power, for 5 minutes at 25°C. The extracted anthocyanin content was of 275 mg/100 g of purple corn flower and the total polyphenol content of the extract was of 230 mg galic acid/100ml. In a further extraction less polyphenols and more anthocyanins were obtained. The release and stability of the encapsulated extract in fresh, frozen and vacuum-dried calcium alginate beads was also studied during storage. The anthocyanins release from the fresh beads was completed in 15 minutes and followed an exponential kinetics, while the frozen beads had much lower content and the release was completed in 10 minutes.In dried beads the anthocyanins release was slower than in fresh or frozen ones and followed a first order kinetics. The antiradical capacity of the extracts was directly correlated with anthocyaninconcentration and it was higher than that of a commercial grape formulation. The ultrasound assisted method allowed a good anthocyanins and polyphenols extraction, and has the advantage of low processing time and temperature, avoiding the employment of organic solvents. Present results are promising for the use of purple corn extracts as natural additive for functional foods development.