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) sam- ples 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 sam- ples 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. 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 poly- saccharides 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 prod- ucts 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 starch was therefore generated so as to include all the starch that escaped digestion in the human small intestine (Englyst and Cummings 1990). This definition was later adopted and modified by the European Resistant Starch Research Project (EURESTA) (1992) as ‘the sum of starch and products of starch degradation not absorbed in the small intestine of healthy individuals’. Various attempts were thereafter made to develop in vitro models that would mimic the human di- gestive system in order to save the huge cost of carrying out in vivo studies. The studies that gave resistant starch portions that matched the mean values of starch recovered in ileostomy studies were those reported by Englyst et al. (1996) and Silvester et al. (1995). * Ebun-Oluwa Oladele epoladele@futa.edu.ng; peaceademme@live.com 1 Food Chemistry Unit, Department of Chemistry, Federal University of Technology, PMB 704, Akure, Nigeria Food Anal. Methods DOI 10.1007/s12161-016-0761-6