Identification of carbohydrate parameters in commercial unripe banana flour Fabiana A. Hoffmann Sardá a,b , Fernanda N.R. de Lima a , Nathalie T.T. Lopes a , Aline de O. Santos a,b , Eric de C. Tobaruela a,b , Edna T.M. Kato c , Elizabete W. Menezes a,b, ⁎ a Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil b Food and Nutrition Research Center (NAPAN) — USP, Food Research Center (FoRC/CEPID/FAPESP), São Paulo, SP, Brazil c Department of Pharmacy, Faculty of Pharmaceutical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil summary article info Article history: Received 11 February 2015 Received in revised form 6 November 2015 Accepted 15 November 2015 Available online xxxx Unripe banana flour (UBF), which is rich in resistant starch (RS), has shown several positive physiological effects in clinical trials. Although such observations encourage the emergence of UBF in the food market, specific identity or quality standards for the product are still lacking. This work aimed to assess and propose characterization pa- rameters for commercially available UBF. The results showed that three of the brands examined presented a RS content higher than 40%, whereas nine showed a lower content, with two having less than 10% RS and over 80% total starch, which was fully identified as cereal starch by light microscopy (LM). The presence of banana peel in the flour was correlated with the lipid (r = 0.870), ash (r = 0.812), protein (r = 0.704) and total starch (r = -0.761) contents. According to principal components analysis (PCA) and LM identification, the main pa- rameters for the characterization of commercial UBFs are the contents of RS, dietary fiber, lipid and ash. The large variability in RS content (4 to 62%) found in commercial UBFs is one reason why consumers would benefit from additional labeling information, such as the inclusion of the RS and soluble sugar (SS) contents, the unripe banana cultivar used, and indications about use of the peel. Moreover, adulterations could be verified by food in- spection agencies via LM, which can be used as a tool to identify the type and state of the starch present. © 2015 Elsevier Ltd. All rights reserved. Keywords: Light microscopy Quality standard Resistant starch 1. Introduction Functional foods and ingredients with a high content of unavailable carbohydrates, such as resistant starch (RS), have shown promising po- tential for reducing the incidence of non-communicable diseases (NCDs) due to the reduced speed of digestion and absorption of these carbohydrates (Fuentes-Zaragoza, Riquelm-Navarrete, Sánchez-Zapata, & Pérez-Álvarez, 2010; Birt et al., 2013). Over the years, interest and knowledge about the biological utilization of RS have grown in regard to its effects on intestinal physiology (Englyst & Macfarlane, 1986; Topping & Clifton, 2001; Davis & Milner, 2009; Conlon et al., 2012) as well as its ability to promote a reduced glycemic response (Anderson et al., 2010; Klosterbuer, Thomas, & Slavin, 2012) and increased insulin sensitivity (Robertson, Bickerton, Dennis, Vidal, & Frayn, 2005). A cause- and-effect relationship exists between the intake of RS as a replacement for a portion of the available starch in baked goods and a reduction in post-prandial glycemic response (EFSA, 2011). Increased insulin sensi- tivity has also been observed in studies of prolonged RS ingestion (4 to 12 weeks) (Johnston, Thomas, Bell, Frost, & Robertson, 2010; Maki et al., 2012; Robertson et al., 2012). Global banana production was approximately 102 million tons in 2012, and Brazil is the world's fifth largest producer, with an output of 6.9 million tons per year (FAO, 2014). However, of the total amount produced in the country, approximately 30% is lost during the post-harvest phase (Almeida, 2012). Thus, the development and utilization of any technology or process that enhances its use can be advantageous. Different factors are involved in the production of unripe banana flour (UBF), as banana ripening stage and drying process. The carbohy- drate composition of bananas is largely altered during ripening as the starch reserve is hydrolyzed to soluble sugars (Cordenunsi & Lajolo, 1995). As a large proportion of the starch in unripe bananas is in the form of resistant starch, it is important to assess the proper stage of fruit ripening to produce flour with a high RS content (Englyst & Cummings, 1986; Zhang, Whistler, BeMiller, & Hamaker, 2005). The process generally employed for unripe banana flour (UBF) drying uti- lizes a tray dryer or hot-air dryer (Haslinda, Cheng, Chong, & Noor Aziah, 2009). The amount of RS in UBF has been reported in early stud- ies; Englyst, Kingman, and Cummings (1992) evaluated UBF samples and found 57.0% RS, whereas Faisant et al. (1995) reported a value of 54.0%. In Brazil, Tribess et al. (2009) established a process to produce Food Research International xxx (2015) xxx–xxx ⁎ Corresponding author at: Av. Prof. Lineu Prestes, 580, Bloco 14, CEP 05508-000 São Paulo, SP, Brazil. E-mail address: wenzelde@usp.br (E.W. Menezes). FRIN-06086; No of Pages 7 http://dx.doi.org/10.1016/j.foodres.2015.11.016 0963-9969/© 2015 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres Please cite this article as: Hoffmann Sardá, F.A., et al., Identification of carbohydrate parameters in commercial unripe banana flour, Food Research International (2015), http://dx.doi.org/10.1016/j.foodres.2015.11.016