Caprez A, Fairweather-Tait S J
Br J Nutr. 1982 Nov;48(3):467-75. doi: 10.1079/bjn19820132.
The effect of heat treatment of bran on the true zinc absorption was measured using an isotope-dilution technique. A bran-based breakfast cereal (heated to 204 degrees for 40 min during manufacture) was incorporated into a semi-synthetic diet at a level of 180 g/kg. A parallel diet was formulated containing an identical weight of untreated bran from the same source plus other ingredients used to make the cereal. 2. Young male Wistar rats (mean weight 80 g) were injected intramuscularly with 65Zn to label body Zn. They were given the heat-treated- and untreated-bran diets for 9 d. During the last 6 d of this period Zn intakes and faecal and urinary Zn were measured in order to calculate apparent Zn retention. True Zn retention was measured by taking into account losses of Zn of endogenous origin (labelled with 65Zn), by measuring faecal and urinary radioactivity of endogenous origin. 3. Heat treatment of bran removed approximately one-third of the phytate, but this was not enough to improve Zn absorption from the diet. True Zn retention measured by isotope dilution was significantly higher (P less than 0.02) than apparent Zn retention measured by the conventional balance technique. 4. The hypothesis that a reduction in particle size of bran would improve mineral availability was tested by feeding coarse and milled bran (100 mg/kg diet) in a semi-synthetic diet to rats and measuring true Fe and apparent Zn absorptions. The importance of phytate was also investigated by feeding a diet containing dephytinized bran. 5. Male Wistar rats (mean weight 172 g) were given diets containing coarse, milled or dephytinized bran for 9 d. Fe and Zn intakes were measured and faeces and urine collected for Fe and Zn analysis. 6. Rhe mean (+/- SE) particle size of the bran was reduced on milling from 3.5 (+/- 1.8) to 0.2-0.5 mm. There were no differences in the fraction of Fe retained between the three groups. Particle size had a small effect on Zn retention which was marginally higher in rats on the milled-bran diet (0.126 (+/- 0.023)) than in those on the coarse-bran diet (0.087 (+/- 0.012)). Total removal of phytate had a greater effect and apparent Zn retention from the dephytinized-bran diet was significantly higher (0.182 (+/- 0.027), P less than 0.001).
采用同位素稀释技术测定了麸皮热处理对锌真实吸收率的影响。将一种以麸皮为基础的早餐谷物（在生产过程中加热至204摄氏度并持续40分钟）以180克/千克的水平添加到半合成日粮中。配制了一种平行日粮，其中含有相同重量的来自同一来源的未处理麸皮以及用于制作谷物的其他成分。2. 对2只年轻雄性Wistar大鼠（平均体重80克）进行肌肉注射65Zn以标记体内锌。给它们喂食热处理麸皮日粮和未处理麸皮日粮，为期9天。在此期间的最后6天，测量锌摄入量以及粪便和尿液中的锌含量，以计算锌的表观保留率。通过测量内源性来源（用65Zn标记）的粪便和尿液放射性，考虑内源性锌的损失来测定锌的真实保留率。3. 麸皮热处理去除了约三分之一的植酸盐，但这不足以提高日粮中锌的吸收率。通过同位素稀释测定的锌真实保留率显著高于（P<0.02）通过传统平衡技术测定的锌表观保留率。4. 通过在半合成日粮中给大鼠喂食粗麸皮和磨碎麸皮（100毫克/千克日粮）并测量铁的真实吸收率和锌的表观吸收率，来检验麸皮粒度减小会提高矿物质利用率这一假设。还通过喂食含去植酸麸皮的日粮来研究植酸盐的重要性。5. 给雄性Wistar大鼠（平均体重172克）喂食含粗麸皮、磨碎麸皮或去植酸麸皮的日粮，为期9天。测量铁和锌摄入量，并收集粪便和尿液进行铁和锌分析。6. 麸皮研磨后的平均（±标准误）粒度从3.5（±1.8）减小到0.2 - 0.5毫米。三组之间铁保留率没有差异。粒度对锌保留率有较小影响，磨碎麸皮日粮组大鼠的锌保留率（0.126（±0.023））略高于粗麸皮日粮组大鼠（0.087（±0.012））。植酸盐的完全去除有更大影响，去植酸麸皮日粮的锌表观保留率显著更高（0.182（±0.027），P<0.001）。
