Bio-functional components in the processed pre-germinated brown rice by a twin-screw extruder

Abstract

Development of a novel foodstuff from pre-germinated brown rice by a twin-screw extruder was investigated. The characteristics of the components of the materials and the products are as follows: (1) Pre-germinated brown rice was prepared by soaking in water for 72 h at 30 °C followed by drying to 13–15% moisture content at 15 °C in a low-humidity artificial weather-control room. Total dietary fiber, total ferulic acid and gamma-aminobutyric acid (GABA) contents of the pre-germinated brown rice were higher than those of ordinary brown rice or polished rice. (2) The pre-germinated brown rice was processed with a twin-screw extruder. The puffed pre-germinated brown rice contained more oryzanol, inositol, total ferulic acid and total dietary fibers compared with the un-puffed polished rice. The product prepared by the co-extrusion of pre-germinated brown rice (90%) and beer yeast (10%) contained more free amino acids, such as GABA, glycine, alanine, aspartic acid and glutamic acid, compared with polished rice, brown rice and puffed pre-germinated brown rice. (3) Extrusion cooking was shown to sterilize the germinated brown rice by the incubation test, which would lead to the development of consumer-oriented rice products in terms of food safety. (4) The wheat bread prepared with 30% of the puffed pre-germinated brown rice contained more GABA, free sugars, such as maltose, compared with the ordinary wheat bread. The extrudate bread was shown to be sweeter ( P < 0.05 ) and equivalently palatable ( P < 0.05 ) as a result of organoleptic test. These results show that novel foodstuff from the extruded pre-germinated brown rice would be acceptable to consumers or the food industry as a promising foodstuff containing more nutritional and bio-functional components than ordinary rice products.