Changes in polyphenolics during maturation of Java plum (Syzygium cumini Lam.)

Java plum (Syzygium cumini Lam.) is a rich source of polyphenolics with many purported health benefits, but the effect of maturation on polyphenolic content is unknown. Freeze-dried samples of Java plum from seven different maturity stages were analyzed for anthocyanin, flavonol, flavanonol and hydrolysable tannin composition by HPLC. Anthocyanins were first detected at the green-pink stage of maturity and increased throughout maturation with the largest increase occurring from the dark purple to black stages of maturation. Levels of gallotannins, ellagitannins, flavonols, gallic acid and ellagic acid were highest at early stages of maturation and decreased as the fruit ripened. For production of antioxidant-rich nutraceutical ingredients, fruit should be harvested immature to obtain extracts rich in hydrolysable tannins and flavonols. The exceptional anthocyanin content of black fruit may prove useful as a source of a natural colorant.

Studies on tape ketan--an Indonesian fermented rice food

Preparation of a tape ketan starter material called ragi tape was described by using pure cultures of A. rouxii, S. cerevisiae, P. anomale (HA 122) and P. anomale (HA 893) grown on rice. In a fermentation experiment this self-produced ragi tape was compared with a commercial available ragi tape (NKL). In addition to that, the growth of fungi, yeast and bacteria as well as the biochemical changes during the fermentation process of tape ketan were monitored. To do this, samples were taken periodically after 0, 5, 10, 15, 24, 36, 48 and 60 h fermentation with a commercially available starter (Tebu) at 30 degrees C. Samples were analysed for DM, ash, total N, soluble N, glucose before and after hydrolysis, ethanol, lactic acid, pH and viable cell count. Results show that a palatable product was ready for consumption after 48 h. Finally, tape ketan was prepared using two different samples of Indonesian ragi tape (Tebu) as inoculum and the products were compared by their nutritional constituents.