November 4/Food & Farm Week -- "This article investigates the effect of green tea extract (GTE) on biscuits lipid fraction oxidative stability. The antioxidant activity of GTE was compared with commonly used synthetic antioxidant butylated hydroxyanisole (BHA)," scientists in Poznan, Poland, report.

"Biscuits were prepared in three variations. Control samples were prepared without addition of antioxidants. The other variations were prepared by adding BHA (0.02%) and GTE at three different levels: 0.02%, 0.1% and 1%. Biscuits were subjected to sensory studies and instrumental and chemical analysis. Phenolic compounds of GTE characterized powerful antioxidant activities evaluated using free radical, 2,2-diphenyl-1-picrylhydrazyl method, compared with gallic acid and significantly better than BHA. Antioxidants added to the samples clearly slowed down the process of oxidation of fatty acids, inhibiting the monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decomposition. Addition of GTE at the level of 1% gave an excellent antioxidant effect on the biscuits lipid stability, inhibiting hydroperoxides formation by about 47% to 73% compared with BHA, which showed about 16% to 60% inhibition. However, GTE did not improve significantly lipid stability, measured by anisidine value (p-AV), and inhibited formation of secondary oxidation products only by 3.5%. After accelerated storage time, insensitivity of oxidized-like flavor was about two times higher for control samples compared to samples with addition of antioxidants. Moreover, after storage biscuits treated with natural antioxidant received a higher panel score of overall acceptance compared to samples with BHA," wrote S. Mildnerszkudlarz and colleagues.

The researchers concluded, "Using volatile compound formation as a marker of lipid oxidation, both GTE and BHA were effective inhibitors of the decomposition of hydroperoxides."

Mildnerszkudlarz and colleagues published their study in the Journal of Food Science ("Evaluation of Antioxidant Activity of Green Tea Extract and Its Effect on the Biscuits Lipid Fraction Oxidative Stability." Journal of Food Science, 2009;74(8):S362-S370).

For additional information, contact S. Mildnerszkudlarz, Poznan University Life Science, Dept. of Food Science & Nutrition, Wojska Polskiego 31, PL-60624 Poznan, Poland.

From the November 9, 2009, Prepared Foods E-dition