July 21/Madrid, Spain/Food Business Week -- According to recent research from Madrid, Spain, "The combined effect of high hydrostatic pressure (HHP) and controlled temperature on total (TDF), soluble dietary fiber (SDF) content, and its associated hydration properties were assayed in okara, a rich-in-insoluble dietary fiber residue from the soydrink- and tofu-making process of soybean. TDF in starting unprocessed okara was 45.7%, and its SDF to TDF ratio was 4.6."

"When dry, hydrated and autoclaved okara samples, were subjected to HHP-treatment (200 and 400 MPa) at 30 and 60 degrees C, the amount of SDF went up by more than eight-fold. At 200 MPa, TDF was not significantly different from control, but at 400 MPa, values varied from 38.1-64.8%. In vitro physicochemical properties of okara were also modified by HHP-treatment. Therefore, the effect of a combined treatment with hydration, temperature and HHP-technology on the improvement of the soluble fiber fraction (%) and functionality of certain vegetable by-products from the food industry could be very useful for the elaboration of food ingredients with potential health-promoting effects.

"Industrial relevance: This article deals with the effect of HHP-treatment on dietary fiber fractions and associated physicochemical properties in okara by-product from soybean. It suggests that the higher the hydrostatic pressure and temperature applied, the higher the ratio of soluble to total dietary fiber in okara," wrote I. Mateosaparicio and colleagues.

The researchers concluded, "Likewise, the effect of combined hydration, mild temperature, and HHP-treatment could increase the soluble fraction (%) of other rich-in-insoluble dietary fiber vegetable by-products, which could potentially be used as valuable ingredients of new functional foods."

Mateosaparicio and colleagues published their study in Innovative Food Science & Emerging Technologies ("High Hydrostatic Pressure Improves the Functionality of Dietary Fiber in Okara By-product from Soybean." Innovative Food Science & Emerging Technologies, 2010;11(3):445-450).

For additional information, contact P. Ruperez, CSIC, Metab & Nutrition Department, Institute Frio IF ICTAN, Jose Antonio Novais 10, Ciudad University, E-28040 Madrid, Spain.

From the August 2, 2010, Prepared Foods E-dition