Maki Tanaka

Effects of rice bran hemicellulose on 1,2‐dimethylhydrazine‐induced intestinal carcinogenesis in fischer 344 rats

The effect of rice bran hemicellulose (RBH) on 1,2-dimethylhydrazine- (DMH) induced intestinal carcinogenesis was studied in male Fischer 344 rats. Rats were fed a basal control diet or a diet containing 2% or 4% RBH at five weeks of age. At 6 weeks of age, all animals were given an intraperitoneal injection of DMH (20 mg/kg body wt) at weekly intervals for 20 weeks and autopsied 7 weeks after the last injection. The incidence of DMH-induced colon tumors was significantly lower in rats fed the 4% RBH diet than in rats fed the basal control diet (p < 0.05). The number of colon tumors per rat was also significantly lower in rats fed the 4% RBH diet than in rats fed the basal control diet (p < 0.05). The present study suggested that the water-soluble RBH played a preventive role in DMH-induced large bowel carcinogenesis in Fischer 344 rats.

Effects of ionic strength and pH on the thermostability of lactoferrin

Abstract Lactoferrin retained over 85% of its iron-binding ability after heat treatment at an ionic strength of 0·01 or below and temperatures from 65 to 90°C. At an ionic strength of 0·1, partial precipitation occurred and the iron-binding ability decreased markedly with the increase in temperature. At pH 3·5, lactoferrin was resistant to heating at ionic strengths of 0·37 or below, but turbidity and precipitation occurred at ionic strengths above 0·47. The findings indicated that the thermostability of lactoferrin was dependent on both ionic strength and pH. In addition, the retention of lactoferrin in milk samples was over 95% during storage for 12 weeks, whereas that in acid beverage decreased to 35% after 12 weeks at 5°C and was destroyed after 2 weeks at 37°C. We thus concluded that the most recommendable method for the processing of foods containing lactoferrin was to pasteurize lactoferrin separately at an electrical conductivity below 0·7 mS/cm and mix aseptically with neutral foods.