Powdered preparations enriched in resistant starch (RS) were obtained from native and lintnerized (prolonged acid treatment) banana starches by consecutive autoclaving/cooling treatments. The preparations were tested for indigestible starch content, swelling and solubility properties, thermal analysis and pasting profile. The autoclaved samples had higher RS content than their parental counterparts, but the chemical modification (lintnerization process) allowed development of higher RS proportions (19%, dry matter basis, dmb). The autoclaved samples (RS‐enriched products) showed similar swelling values (α = 0.05) at the temperatures assessed. These RS‐rich products exhibited a lower solubility in water than the corresponding raw materials. The peak temperatures of the thermal transition were 155.5 and 145.8°C for native autoclaved and lintnerized autoclaved starch, respectively. These values indicate that RS products have a marked thermal stability. The pasting behavior of the RS products was less pronounced than that of the raw counterparts. Hence, their potential use as processed food ingredients should not impact final product viscosity. These RS‐enriched products appear suitable for the formulation of functional foods.

The production of resistant starch from non-conventional sources using an extruder was studied. Starch was isolated from unripe banana and mango fruits, commercial corn starch was used for comparison purposes. Moisture, ash and fat content were higher in non-conventional starch sources than in corn starch, but corn starch presented a lower protein and dietary fibre content than banana and mango starches. Amylose content was higher in banana and mango starches than in corn starch. Besides, mango had the smallest granule size (5–10 m). Extruded mango had the lowest solubility which may be related with the granule size, and in the case of the swelling, extruded products from corn starch had the highest values, a pattern that may be due to the amylose/amylopectin ratio, because corn starch had the lowest amylose content of the starches studied. Extruded products from mango presented a resistant starch (RS) content that decreased when the screw speed increased, for banana starch, the RS values from the extruded products was similar at 30 rpm and 65 rpm, and at 40 rpm it was the highest. In the case of retrograded resistant starch (RRS), the values of the extruded products prepared with non-conventional starches had a defined pattern, because they decreased when screw speed increased.

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg −1 ) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105-142 g kg −1 ), but low WAI values (70-77 g kg −1 ) were obtained at moisture contents between 200 and 300 g kg −1 and high temperatures (140-150 • C). When moisture content and temperature increased, WSI increased (222-332 g kg −1 ), but at high temperature value (120 • C) assayed and the lowest moisture content (150 g kg −1 ), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained.

Mango (Mangifera indica) is a fruit that grows in tropical regions. The aim of this work was to isolate the starch from two varieties of mango highly consumed in Mexico ("criollo" and "manila"), and to evaluate its chemical composition, along with some morphological, physicochemical and functional properties. Mango starch had an amylose content of about 13%, the fat content of "criollo" variety starch (0.1-0.12%), was similar to that of commercial corn starch used as control (0.2%); both mango starches had higher ash amount (0.2-0.4%) than corn starch. Mango starches presented a smaller granule size (10 microm) than corn starch (15 microm), along with an A-type X-ray diffraction pattern with slight tendency to a C-type. All values of water retention capacity (WRC) increased with the temperature. When the temperature increased, solubility and swelling values increased and in general, mango starches had higher values than corn starch. Both mango starches had gelatinization temperatures lower than the control, but "criollo" variety starch presented higher enthalpy values than "manila" variety and corn starches. Overall, it was concluded that due to its morphological, physicochemical and functional properties, mango starches could be a feasible starch source with adequate properties, suitable for using in the food industry.

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