engleski

Influence of High Intensity Ultrasound on Bioactive Components and Enzymatic Browning of Millet Bran

Millet is an unexploited cereal with a great potential in the agro-food industry due to its high nutritional value, as well as the resistance to drought and harsh climate conditions. In particular, millet bran is a concentrate of various nutrients with potential health benefits, but is rarely used in human nutrition. In order to exploit the potential for development of functional foods using millet by- products, we investigated high intensity ultrasound (HIU) treatment for releasing bioactives from their insoluble/bound to soluble/free forms, and followed its effect on enzymatic browning. Millet bran was treated with 400 W ultrasound probe during 5, 12.5, or 20 min, with the amplitude of 60, 80, or 100%. Total phenolic content, antioxidant activity, insoluble and soluble dietary fiber content, color, and polyphenol oxidase activity were monitored. HIU treatment of millet bran for 12.5 min with 80% amplitude significantly increased (by 15%) the antioxidant activity as measured by FRAP test, as well as the total phenolic content (by 16%). The impact on the dietary fiber solubility was evident only after the 100% amplitude and 20 min treatment, causing a rise of non-digestible oligosaccharides by 38%. HIU treatments caused a temperature rise and browning which positively correlated with polyphenol oxidase activity (r = 0.85 ; r= - 0.88, respectively). HIU treatment can have a positive effect on millet bran nutritional value, but needs to be optimized in order to minimize browning and make it suitable for implementation in the food industry.

enzymatic browning, high intensity ultrasound, millet bran, polyphenol compounds, soluble dietary fiber

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