AOAC RI ERP E-Book - DS DF

K-RINTDF.2016_11_K-RSTAR.DATA.NEW 27/09/2016 11:54 Page 2

OMAMAN-38 C: Instructions for Use Expert Review Panel Use Only September, 2017

GENERAL INTRODUCTION:

It is generally believed 1-3 that an increased consumption of dietary fiber (DF) will lead to a reduction in conditions such as constipation, diabetes, obesity, coronary heart disease and others. In the 1970’s Trowell had developed a definition of dietary fiber which evolved in 1976 3 to: “Dietary fibre consists o f the remnants o f edible plant cells, po lysaccharides, lignin, and associated substances resistant to digestion by the alimentary enzymes o f humans.” This definition defines a macro constituent of foods which includes cellulose, hemicellulose, lignin, gums, modified celluloses, mucilages, oligosaccharides, pectins and associated minor substances such as waxes, cutin, and suberin. On the basis of this definition 3 , appropriate methodology for the measurement of DF was developed by a consortium of researchers in Europe and USA. This led to AOAC Official Methods 985.29 and 991.43 4,5 . The aim of these methods was to give an accurate measurement of the content of total dietary fiber (TDF) in plant products and food materials by hydrolysing and removing starch and protein. Fats were removed by the solvents employed to recover the non-hydrolysed material. From the outset, it was realised that all protein was not hydrolysed, so each sample was analysed in duplicate and residues recovered and weighed. One of these residues is analysed for ash content and the other for protein. These weights are subtracted from the average of the residue weights. It was also recognised (Englyst et al . 6 ) that for some samples a portion of the starch was not completely hydrolysed and removed. This starch was termed resistant starch (RS) 6 . Since RS escapes digestion in the human small intestine, the general consensus is that it should be accurately measured and included as part of DF. Since AOAC Official Methods 985.29 and 991.43 underestimate RS, alternative methods for the measurement of this component were developed and evaluated. While most of these new methods gave similar results for a range of RS containing samples, none of the methods survived the rigours of interlaboratory evaluation except that of McCleary et al. 7 (AOAC Method 2002.02), which also gave results in line with those obtained from ileostomy patients 8 . Since it is generally agreed that dietary fiber should also include non- digestible oligosaccharides (NDO), specific methods were developed for a range of NDO including fructan and fructo-oligosaccharides (FOS) (AOAC Methods 997.08 and 999.03) 9,10 , galacto- oligosaccharides (GOS) (AOAC Method 2001.03) 11 , resistant maltodextrins (RMD) (AOAC Method 2001.03) 12 and Polydextrose ® (AOAC Method 2000.11) 13 . The development of these methodologies was very useful for ingredient developers, food manufacturers and analysts measuring the specific component. AOAC Research Institute ERP Use Only

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