engleski

Complexation of brown rice and milk proteins with Raspberry phenolics

Dry, flour-like matrices were produced by complexation of brown rice or milk (80% of caseins) proteins with raspberry juice in order to prepare functional food ingredients. Prepared ingredients can be added to bakery, fruit and dairy products in order to enrich them with phenolics, improve antioxidant potential, and enhance color. For preparation, amount of juice was constant and the amount of proteins varied (2, 6 and 10%). Content of phenolics and anthocyanins were determined and capabilities of two different proteins to bind those compounds were compared. With an increase in the amount of milk proteins, the amounts of adsorbed phenolics (11, 44 and 65%) and anthocyanins (22, 51 and 61%) increased. In the case of brown rice proteins amounts of adsorbed phenolics were 36, 51 and 51% and anthocyanins 24, 42 and 47%, i.e. there was no or slight difference between the 6 and 10 % levels of proteins used. Adsorption capacity of proteins was also calculated and expressed as mg of adsorbed compound per g of protein (mg/g). The highest adsorption capacity for phenolics was achieved by 2% of brown rice proteins (17.9 mg/g) and 6% of milk proteins (8.8 mg/g). Anthocyanins adsorption capacity decreased with the increase of protein content. The highest anthocyanin adsorption capacity was achieved by 2% of proteins, 3.7 mg/g and 2.5 mg/g for milk and brown rice proteins, respectively. FTIR spectra of dried matrices were recorded in order to compare the structures of proteins and loaded proteins. Some structural changes were observed on both proteins. Peaks at 1, 390 cm-1 and 1, 310 cm-1 that were observed in proteins, in loaded proteins disappeared, and two additional peaks appeared at 820 cm-1 and 780 cm- 1. Additionally, loaded milk proteins missed the peak at 990 cm-1 and had a shift of peak from 1, 070 cm-1 to 1, 050 cm- 1.

brown rice proteins ; milk proteins ; raspberry ; phenolics ; structural changes

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