Lakkakula N Rao, Lima Marybeth, Walker Terry
Department of Biological and Agricultural Engineering, Room 149, E.B. Doran Building, Louisiana State University AgCenter, Baton Rouge, LA 70803-4505, USA.
Bioresour Technol. 2004 Apr;92(2):157-61. doi: 10.1016/j.biortech.2003.08.010.
Ohmic heating has been shown to increase the extraction yields of sucrose from sugar beets, apple juice from apples, beet dye from beet root, and soymilk from soybeans. Rice bran is a byproduct of the rice milling process that has economic potential by virtue of highly nutritious rice bran oil contained within the bran. In this study, ohmic heating was used to stabilize rice bran and to improve rice bran oil extraction yield as compared to microwave heating and a control (no heating). Results showed that ohmic heating is an effective method for rice bran stabilization with moisture addition. Free fatty acid concentration increased more slowly than the control for raw bran samples subjected to ohmic heating with no corresponding temperature rise, indicating that electricity has a non-thermal effect on lipase activity. Ohmic heating increased the total percent of lipids extracted from rice bran to a maximum of 92%, while 53% of total lipids were extracted from the control samples. Lowering the frequency of alternating current significantly increased the amount of oil extracted, probably due to electroporation. Ohmic heating was successfully applied to rice bran despite its high oil content. This could have important implications for the enhanced extraction of non-polar constituents.
欧姆加热已被证明能提高从甜菜中提取蔗糖、从苹果中提取苹果汁、从甜菜根中提取甜菜色素以及从大豆中提取豆浆的产率。米糠是碾米过程的副产品，由于米糠中含有高营养的米糠油，因而具有经济潜力。在本研究中，与微波加热及对照（不加热）相比，采用欧姆加热来稳定米糠并提高米糠油的提取率。结果表明，欧姆加热是一种添加水分来稳定米糠的有效方法。对于未伴随相应温度升高而进行欧姆加热的生米糠样品，游离脂肪酸浓度的增加比对照样品更缓慢，这表明电流对脂肪酶活性具有非热效应。欧姆加热使从米糠中提取的脂质总量百分比最高达到92%，而对照样品提取的脂质总量为53%。降低交流电频率显著增加了油的提取量，这可能是由于电穿孔作用。尽管米糠含油量高，但欧姆加热仍成功应用于米糠。这对于增强非极性成分的提取可能具有重要意义。
