Natural almonds (Maisie Jane’s, CA) were kindly provided by the Almond Board of California and stored in the dark. Natural almond skins (NS) were

removed by treatment with liquid nitrogen as described previously (Mandalari et al., 2009). The skins were milled using an analytical mill (Janke & Kunkel A10). Blanched and dried almond skins (BS) produced by ABCO Laboratories (almond skin powder 1912) were supplied by the Almond Board of California. Simulated gastrointestinal digestions of NS and BS were performed using the protocol described previously (Mandalari et al., 2008a). Briefly, for the gastric digestion, 1.5 g of each almond skin product (NS, BS) was suspended in 12.4 mL acidic saline (150 mM NaCl, pH 2.5) and readjusted to pH 2.5 with HCl as required. Phosphatidylcholine vesicle suspension, pepsin and gastric Selleck PD0332991 lipase analogue were then added so that the final concentrations RG-7388 in the aqueous phase were 2.4 mmol L−1, 146 and 60 U mL−1, respectively. The samples were placed in an orbital shaking incubator (170 r.p.m., 37 °C) for 2 h. The in vitro gastric digesta

of NS and BS were used as the starting material for the simulated duodenal digestion. The pH was increased to 6.5 by addition of NaOH and solutions of bile salts, CaCl2, Bis-Tris and enzymes in 150 mmol L−1 NaCl added, so that the final concentrations were as follows: 4 mmol L−1 sodium taurocholate, 4 mmol L−1 sodium glycodeoxycholate, 11.7 mmol L−1 CaCl2, 0.73 mmol L−1 Bis-Tris buffer (pH 6.5), 5.9 U mL−1α-chymotrypsin, 104 U mL−1 trypsin, 3.2 μg mL−1 colipase, 54 U mL−1 pancreatic lipase and 25 U mL−1α-amylase. The samples were placed in an orbital shaking incubator (170 r.p.m., 37 °C) for 1 h. Each in vitro digestion Fossariinae was performed at least three times with the solid material recovered for analysis. Total lipid of NS

and BS post in vitro gastric and gastric plus duodenal digestion was determined gravimetrically by extraction with n-hexane and reported as % dry weight (Mandalari et al., 2008a). The total protein contents of NS and BS and solid residues recovered after in vitro gastric and duodenal digestion were analysed for total nitrogen by micro-Kjeldahl as reported previously (Mandalari et al., 2008a). Values were expressed as N× 6.25. Total dietary fibre (TDF), insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) were measured in defatted samples of NS, BS and post in vitro gastric and duodenal digestion using the enzymatic–gravimetric AOAC method as described previously (Mandalari et al., 2008a). Briefly, triplicate defatted samples of NS and BS were incubated at 100 °C with a heat-stable α-amylase, then at 60 °C with protease and finally with an amyloglucosidase solution. TDF, IDF and SDF were corrected for residual protein and ash. Experiments were carried out in duplicate.