The Implications of Sample Preparation on the Quantification of Resistant Starch Type 1 and Related Nutritional Starch F
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The Implications of Sample Preparation on the Quantification of Resistant Starch Type 1 and Related Nutritional Starch Fractions in Plantain (Musa AAB) Ebun-Oluwa Oladele 1
Received: 14 June 2016 / Accepted: 13 December 2016 # Springer Science+Business Media New York 2016
Abstract Sample preparation is a critical step in any analysis and could influence the reliability of results. Analysing some dietary carbohydrates using flours and milled samples could affect the results obtained. The resistant starch type 1 (RS1) content from many foods has not been reported. This may be due to the fact that many investigations on the quantification of resistant starches have been centred on measuring resistant starch in starches/flours, and the consequences are that intact food matrices that would have aided the identification of RS1 in the foods would have been disrupted by milling. In this study, enzyme hydrolysis was used to quantify RS1 in raw and boiled plantain, and two sample pre-treatments were compared. The two types of samples used were (i) samples prepared in the ‘as eaten’ manner, which reflect in vivo conditions in exactly the way the food is consumed and (ii) samples prepared in the conventional dry powder method. RS1 was quantified in the samples analysed on ‘as eaten’ basis, while RS1 was not detected in the dried and powdered samples. Raw unripe plantain had the highest quantity of RS1 (7.3 ± 2.9 g/100 g) while no RS1 was detected in boiled ripe plantain. Dry powder analyses of boiled unripe plantain samples indicated a loss of RS1, slowly digestible starch (SDS) and a corresponding increase in rapidly digestible starch (RDS). The implication of this is that available carbohydrates will be overestimated using this method, which may further affect glycaemic index (GI) measurements.
* Ebun-Oluwa Oladele [email protected]; [email protected] 1
Food Chemistry Unit, Department of Chemistry, Federal University of Technology, PMB 704, Akure, Nigeria
Keywords RS1 . Sample preparation . Rapidly digestible . Resistant starch . Plantain . Glycaemic index
Introduction Resistant starch was initially discovered and defined as starch that was remaining undigested together with non-starch polysaccharides in in vitro dietary fibre analysis despite rigorous digestion treatments with amylases to remove starch completely (Englyst et al. 1982). Thereafter, Englyst and Cummings (1985, 1986, 1987) carried out studies on ileostomists that provided more evidence that not all starch ingested is completely digested and absorbed in the human small intestine. Some of the starch in some foods, e.g. cereals, potato and banana, were recovered in effluents collected from ileostomists. Furthermore, the amount of undigested starch recovered in vivo was usually more than that obtained in vitro from the dietary fibre analysis. Partial hydrolysis products namely, maltose, maltotriose and dextrins accounted for up to 69 ± 9% of ingested starch in some of the effluents. On the basis of these observations, a redefinition for resistant star
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