M. C. Elias

Development of oxidised and heat-moisture treated potato starch film.

This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.

Polishing and parboiling effect on the nutritional and technological properties of pigmented rice

This study aims to evaluate the effects of polishing and parboiling on proximate composition, structure, phenolic compounds, antioxidant activity, cooking time and hardness of IAC-600 black rice cultivar and MPB-10 red rice lineage. Proximate analysis and light micrographs revealed higher migration of red rice proteins than black rice proteins to the endosperm as a result of parboiling. Parboiling reduced the ash content of red rice while no difference was determined in black rice. Gelatinized starch granules from both genotypes showed similar appearance. There was a decrease in relative crystallinity on both black and red rice subjected to parboiling, which was an indicative of crystallites disruption. Polishing removed more than 90% of free phenolics for both genotypes, while parboiling allowed the partial preservation of free phenolics content in polished rice. Parboiling induced an increase in the cooking time of red rice, but a decrease in the cooking time of black rice.

Characteristics of starch isolated from maize as a function of grain storage temperature.

Considering the importance of maize starch and the lack of knowledge about the effects of storage temperature on the isolated starch properties; maize grains were stored during 12 months at different temperatures (5, 15, 25 and 35 °C). The extraction yield and the physicochemical, thermal, pasting, crystallinity and morphological properties of starches were determined. The starch isolated from grains stored at 35 °C was yellowish and showed a 22.1% decrease in starch extraction yield compared to freshly harvested maize grains. At 35 °C, a reduction in crystallinity was observed by the end of 12 months, despite a parallel rearrangement of the starch chains which resulted in an increase in X-ray peak intensities, gelatinisation temperatures and enthalpy. The starch isolated from maize grains stored at 35 °C appears to have smaller granules, which presents some points in their surface, potentially attributed to the protein matrix compressing the granules within maize grains.

Efeito do período de maturação de grãos nas propriedades físicas e reológicas de trigo

The aim of this study was to investigate the effect of the maturation period of grains on the physical and rheological properties of wheat flour analyzed by determining the hectoliter weight, weight of thousand grains, experimental milling, proteins, ashes, moisture, color, falling number, alveography, farinography, and damaged starch. Samples of genotypes BRS 179, Rubi, Fundacep 30, Fundacep 51, and 2006/2007 crop, were stored in Kraft paper bags with 10 kg of wheat, at environment temperature of 22 oC and air humidity between 65-75%. Each treatment consisted of one genotype and the measurements were made at zero, 15, 30, 60, and 90 days of maturation. The experiment was carried out in fully randomized factorial design at 4 x 5. The results were analyzed by variance analysis (Anova) and the means compared by Tukeys test at 5% probability. With the increase in the maturation period of wheat, the flour presented the best physical and rheological properties assessed by the changes of the falling number, color, alveography, and farinography. The results of the enzymatic activity, luminosity, yellow intensity, and general gluten strength were effective in the evaluation of physical and rheological properties while the assessments of damaged starch and stability were not appropriate indicators. The wheat should not be sold after harvest, since its commercial classification improvement indicates a maturation period of 60 days. The genotypes of wheat BRS 179 and Fundacep 51 genotypes changed from bland to bread and from Rubi bread to improved indicating higher technological and commercial value with the increase in the maturation period of the wheat grains.

Oxidação dos amidos de mandioca e de milho comum fermentados: desenvolvimento da propriedade de expansão

Cassava and corn starches were fermented in the laboratory at 20 °C, and a fraction was in the sun while another fraction was oxidized with hydrogen peroxide and dried artificially to develop the expansion property. Fermentation in 0, 10, 30 and 50 days was checked and the expansion property was evaluated by the baking test and viscoamilograph behavior (RVA). Fermentation was found to cause changes that help the oxidation of cassava and corn starches, increasing the products titrable acidity. The fermented cassava starch, oxidized by exposure to sunlight or hydrogen peroxide, may develop the expansion property, but the corn starch did not display that ability under these conditions. The best results for the expansion property were obtained with cassava starch oxidized with hydrogen peroxide after 50 days of fermentation.

Efeito da umidade e do período de armazenamento hermético na contaminação natural por fungos e a produção de micotoxinas em grãos de aveia

Com o presente trabalho, objetivou-se avaliar a contaminacao natural por fungos, producao de micotoxinas, composicao em acidos graxos e concentracao de CO2 intergranular em graos de aveia armazenados no sistema hermetico por 12 meses. Graos de aveia, da cultivar UPF 18 foram colhidos com 16% de umidade e realizado a secagem estacionaria em prototipo silo-secador ate as umidades de 15%, 12% e 9%. Para os tratamentos com 18% e 21% de umidade foi realizada a reidratacao pela colocacao dos graos em atmosfera saturada por cinco dias. Determinou-se a composicao centesimal aproximada, composicao em acidos graxos, contaminacao natural por fungos, presenca de micotoxinas e concentracao de CO2 intergranular. Os resultados foram analisados pela analise de variância, comparacao de medias pelo teste de Tukey e analise de regressao. Nao foi detectada a presenca das micotoxinas aflatoxina B1, B2, G1, G2, zearalenona e ocratoxina A. A quantidade de CO2 na atmosfera intergranular apresentou comportamento linear e foi proporcional a umidade dos graos e tempos de armazenamento. O aumento do tempo de armazenamento e da umidade dos graos intensificou a reducao de acidos graxos insaturados, com predominância de acao sobre linoleico e linolenico.

Caracterização química de cariopses de aveia (Avena sativa L) da cultivar UPF 18

This research was aimed to determine the chemical characteristics of the new oat cultivar UPF 18, which became recommended by the Brazilian Oat Research Committee in 1999. Oat grains from the 1999 cropping season were dehulled, the caryopses ground to a granulometry below 0.250mm, and the resulting flour evaluated regarding its composition, amount of amino and fatty acids, index of solubility in nitrogen, in vitro protein digestibility, chemical score, and metabolizing energy. The cultivar UPF 18 presented a high protein content (15.07%). The levels of soluble (5.59%) and insoluble (7.73%) dietary fiber were also high, making the amount o starch low (41%). The amino acid composition was similar to the FAO theoretic standard in most of the amino acids, where lysine was the first limiting. This cultivar also showed high levels of unsaturated fatty acids, with linoleic, oleic, and palmitic acids representing 96.06% of the total. The in vitro protein digestibility reached 98.86%, the chemical score 52.2%, and the metabolizing energy 326.56 kcal/100g.

The revisited levels of free and bound phenolics in rice: Effects of the extraction procedure

The effects of the type of solvolytic solution and number of extraction steps on the recovery of free phenolics, anthocyanins and proanthocyanidins from different rice samples were evaluated. Moreover, bound phenolic acids were determined as a function of enzymatic and/or alkaline hydrolysis treatment of the rice residue obtained after the extraction of free phenolics. The Acetone/Water (70:30 v/v) was the most effective solvolytic solution for extracting free phenolics from pigmented rice, as well as anthocyanins from black and wild rice, and proanthocyanidins from red rice. The application of three extraction steps increased the recovery of free phenolics up to 10%. The adoption of an enzymatic treatment, with α-amylase in order to reduce the paste viscosity of the residue, increased the extractability of bound phenolics. α-Amylase at 37°C during 15min followed by an alkaline hydrolysis at 37°C was the best treatment for the recovery of bound phenolics.

Modelos matemáticos para a secagem intermitente de arroz em casca

This study aimed to adjust mathematical models to experimental values in function of the water content and study the effects of intermittent relations in drying of paddy grains in the efficiency of operation. Paddy grains produced in the southern region of Rio Grande do Sul were used. The samples with approximately 20% water content were dried under three intermittent relation conditions: 1:1, 1:2, 1:4. In all these conditions the same thermal procedures were utilized, gradual increase in air temperature 70, 90, 110 ± 5 ÂoC respectively, in the 1st, 2nd and 3rd hour. For the adjustments of the mathematical models, a non linear regression analysis through the Simplex and Quasi-Newton methods was carried out. The values of the parameters of the models being estimated in function of the temperature of the drying air. A comparison was carried out of the adjusted coefficient of determination (R²adjusted), the relative mean error (P), the estimated mean error (SE) and the distribution of residues. The results showed that the intermittent relation modifies the operating time and the houRLy rate of drying of the rice grains and the MidiLλi model was the one which best represented the intermittent drying of paddy.

Effect of alkali and oxidative treatments on the physicochemical, pasting, thermal and morphological properties of corn starch.

BACKGROUND Few studies on starch modifications using different chemical agents are available in the literature, and no reports were found on the combined effect of oxidation and alkaline treatment of corn starch. Thus this work evaluated the physicochemical, pasting, morphological, cystallinity and thermal properties of chemically modified corn starch, after either the isolated or combined action of alkaline (sodium hydroxide) and oxidative (sodium hypochlorite) treatments. RESULTS The highest values for the sum of carbonyl and carboxyl and enzymatic hydrolysis occurred in starches submitted to oxidative treatment at high active chlorine concentrations. The alkali treatment in isolation modified the pasting properties, reduced the paste temperature and increased the peak viscosity, breakdown, final viscosity and setback of starches. Starch modified by the action of sodium hypochlorite and hydroxide in combination presented more severe damage on granule surfaces. CONCLUSION The results show that corn starch modified by the combined action of oxidative and alkaline treatments should be studied more, especially at the concentration limit of sodium hydroxide where gelatinization occurs. Under these conditions the effect of oxidation can be more intense and thus allow the production of starches with different properties and an increase in their industrial applications.