Rosalia A. Gonzalez-Soto

Resistant Starch Production from Non-conventional Starch Sources by Extrusion

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.

Nanocomposites of rice and banana flours blend with montmorillonite: partial characterization.

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films.

Functional and Beneficial Properties of Corn Tortilla

Corn tortilla is the main staple produced from nixtamalised corn. Nixtamalisation is an ancient process developed by the Mesoamerican cultures. Tortilla was considered a high caloric food due to the high starch content. However, some years ago, it was discovered that the starch present in different foods is not completely digested, and consequently the glucose supply to blood decreases. Additionally, corn has an important amount of non-starch polysaccharides, those present in the dietary fibre, increasing the beneficial effect of tortilla consumption.

Rheology of Film‐Forming Solutions Prepared with Modified Banana Starch and Plasticizer

The physical properties of edible films depend to a great extent on those of their components; the biopolymer and the plasticizer, which define its physical changes during heat processing and handling. The aim of this work was to determine the rheological profile of film forming solutions (FFS) composed of native and modified (oxidized) banana starch and the plasticizer glycerol. Samples of FFS, composed by 4%(w/w) of native and oxidized banana starch and glycerol (4%(w/w) were prepared. Two types of rheological tests were undertaken using a strain controlled Rheometer TA Instruments, model AR1000, with a cone and plate system, 60 mm of diameter and angle of 2°: a) isothermal oscillatory (amplitude and frequency) tests at 25 °C, 90 °C and once cooled down, at 25 °C. b) temperature sweeps, run as the samples were heated up from 25 °C to 90 °C and also when cooled down to 25 °C. The isothermal tests showed that all pastes produced, behaved as weak viscoelastic gel‐like materials, with the elastic modulus (G...