Livesey G, Smith T, Eggum B O, Tetens I H, Nyman M, Roberfroid M, Delzenne N, Schweizer T F, Decombaz J
Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney.
Br J Nutr. 1995 Sep;74(3):289-302. doi: 10.1079/bjn19950136.
The performance of methods to determine energy conversion factors for dietary fibre (DF) supplements and fermentability (D) values of their non-starch polysaccharides (NSP) was investigated. Heats of combustion, digestible energy (DE) and D values were determined on five DF supplements in five European laboratories on five separate occasions. In each instance the DF supplements were fed to juvenile male Wistar rats at two doses, 50 and 100 g/kg basal diet, for 3 weeks with food and faeces collected in the 3rd week. Among-laboratory variations in heats of combustion (delta Hc) were < 2%. DE values (kJ/g dry weight) at the upper and lower doses respectively were: 10.4 and 9.9 for a high-methoxyl apple pectin, 9.5 and 9.4 for a sugar-beet DF supplement, 12.2 and 12.7 for soyabean DF supplement, 3.8 and 4.0 for maize bran, and 0.3 and 0.3 for Solka-floc cellulose. Variations among laboratories, among occasions and among animals were < 1, < 2 and < 2.5 kJ/g respectively. The among-occasion: among-laboratory variance ratio for DE was 0.5, suggesting the method performed equally well in all laboratories. There was no evidence of learning of fatigue or fatigue in the performance of the method. D values were also independent of dose and at the high and lower doses were: pectin 0.92 and 0.95, sugar-beet NSP 0.68 and 0.68, soyabean NSP 0.86 and 0.88, maize bran 0.17 and 0.18, cellulose 0.07 and 0.06. Among-laboratory variance tended to increase with decreasing fermentability and ranged from 0.03 to 0.18. The DE and D data were not significantly different from a previously proposed relationship DE = 0.7 x delta Hc x D, where delta Hc is the heat of combustion of the supplement. We conclude that while the among-laboratory variation in the D of difficult-to-ferment NSP is too large for the reliable prediction of energy value the method for the direction determination of DE is both reproducible and repeatable, that DE is independent of dosage of DF supplement up to 100 g/kg diet, and that it is safe to discriminate between energy values with a precision of 3 kJ/g. The conversion of both DE and D to net metabolizable energy for the purpose of food labelling, tables and databases is described.
研究了测定膳食纤维（DF）补充剂能量转换因子及其非淀粉多糖（NSP）发酵性（D）值的方法的性能。在五个欧洲实验室，分五次对五种DF补充剂测定了燃烧热、可消化能量（DE）和D值。每次实验中，将DF补充剂以50和100 g/kg基础日粮两种剂量喂给幼年雄性Wistar大鼠，为期3周，并在第3周收集食物和粪便。实验室间燃烧热（ΔHc）的差异<2%。上下剂量时的DE值（kJ/g干重）分别为：高甲氧基苹果果胶为10.4和9.9，甜菜DF补充剂为9.5和9.4，大豆DF补充剂为12.2和12.7，玉米麸为3.8和4.0，Solka - floc纤维素为0.3和0.3。实验室间、实验次数间和动物间的差异分别<1、<2和<2.5 kJ/g。DE的实验次数间与实验室间方差比为0.5，表明该方法在所有实验室的表现同样良好。没有证据表明该方法在执行过程中存在学习效应或疲劳效应。D值也与剂量无关，高剂量和低剂量时分别为：果胶为0.92和0.95，甜菜NSP为0.68和0.68，大豆NSP为0.86和0.88，玉米麸为0.17和0.18，纤维素为0.07和0.06。实验室间方差倾向于随着发酵性降低而增加，范围为0.03至0.18。DE和D数据与先前提出的关系DE = 0.7×ΔHc×D没有显著差异，其中ΔHc是补充剂的燃烧热。我们得出结论，虽然对于难发酵NSP的D值，实验室间差异过大，无法可靠预测能量值，但DE的测定方法具有可重复性和可再现性，DE在日粮中DF补充剂剂量高达100 g/kg时与剂量无关，并且以3 kJ/g的精度区分能量值是安全的。还描述了为食品标签、表格和数据库目的将DE和D转换为净代谢能量的方法。
