Search

Buckwheat (Fagopyrum esculentum) is a pseudoceral. It grains are nutritionally rich and boast great technological potential for use in the food industry in infant and backed food as well as ingredient of functional products. Flour is considered as an alternative to celiacs because it does not contain gluten. It is an option for the growing appeal for a healthy diet, as well as containing starch as a major component. Starches in native form have restricted use in the industry. So modifications are made to increase their application. These modifications can be chemical or physical. Physical modification is preferable and accepted by consumers. Heat-moisture treatment (HMT) consists of heating starch above gelatinization point with insufficient moisture (<35%). The main objective was extract buckwheat starch, modify by HMT and assess its physico-chemical, thermal and morphological properties. The starch granules from buckwheat have spherical or polygonal shape, with an average size around 1 - 7.5 µm. Morphology of buckwheat starch granules was not altered. The XRD technique showed no signifficative differences between main peaks in diffractograms however the relative crystallinity decrease. DSC analysis allowed to observe that according HMT the enthalpy decrease and gelatinization occurs in higher temperatures. [ABSTRACT FROM AUTHOR]

Introduction. The aim of this study was to evaluate the main morphological and structural properties of native and modified starch by heat-moisture treatment (HMT) of "pinhão" seeds. Materials and methods. "Pinhão" starch was extracted from seeds of Araucaria angustifolia. Amylose content was determined by iodine affinity. Humidity, ashes, protein and fats were determined by the Association of official analytical chemists (AOAC) methods. The microscopic techniques used were Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). For structural evaluation of the granules, X-ray Powder Diffraction (XRD) was used. Results and discussion. The "pinihão" starch extracted from aqueous methodology showed an amylose content of 26.3%. The samples showed low moisture (<8.5%) content as well as ash content (<1.44%). By SEM and AFM, the largest average diameter (da) was for untreated "pinhão" starch granules; 10.85 and 10.64 μm, respectively. The smallest granules were those treated with 10% humidity for 60 min and 120 °C. The medium roughness (ra) studied by AFM increased according to HMT, from 321.68 to 470.06 μm, respectively. A reduction in the relative crystallinity (Rc) was observed according to the HMT performed. Conclusions. Round and oval shapes were found for the starch granules, with a flat face. Similarities were found in the mean diameter values (da) between the techniques. The average diameter of the granules increased as humidity increased during the modification by HMT. The mean roughness (ra) increased with the HMT while the relative crystallinity (RC) decreased. [ABSTRACT FROM AUTHOR]

Introduction. After the process of the starch extraction from pinhão seeds, the generated residues are discarded. The aim of this study was to add these by-products as a potential substitute for wheat flour in a cookie formulation. Materials and methods. Pinhão seed were purchased from local businesses in Ponta Grossa-PR (Brazil), and after the aqueous extraction of starch, the residues retained in the sieve were milled to produce a flour. The cookies were elaborated from a simplex-centroid experimental planning using wheat flour, whole pinhão flour and residual flour after the extraction of the pinhão. Results and discussion. The flours produced with both pinhão and the bagasse obtained after the extraction of starch had high fibre content, and consequently, this was also seen in the cookies produced with the addition of these flours. Wheat flour had a higher protein (13.59±0.38%) and lipid (2.00±0.02%) content than pinhão and bagasse flours. Formulations using wheat flour and bagasse; or pinhão and bagasse had high lipid content (18.44±0.32% and 18.82± 0.09%, respectively). After cooking, the added bagasse biscuits showed a decrease in apparent and specific volume. The addition of pinhão flour to the biscuits provided greater softness, unlike the addition of bagasse. Differences were observed in the colour of the flours, especially in the luminosity and chromaticity a*. The wheat flour showed lower brightness possibly due to its higher ash content, impacting directly on the low brightness of biscuits produced with its addition. Besides making it difficult to grow the dough, the bagasse flour from starch extraction also made the cookies harder. The addition of the three flours, in equal proportion, showed interesting results for application in biscuits. Conclusions. Both pinhão flour and bagasse obtained after starch extraction are potential sources of replacement for wheat flour, allowing adding value to this raw material considered endangered, as well as to the elaborated product. [ABSTRACT FROM AUTHOR]

Starch modification studies have been carried out to overcome the shortcomings of native starches and to increase the usefulness of starch for industrial applications. The thermal, structural and pasting properties of starch from chestnut fruits ( Castanea sativa, Mill), which were modified by mixtures of water-HCl, methanol-HCl and ethanol-HCl at different concentrations, were assessed. The thermogravimetry (TG) results showed that the chestnut starches had lower thermal stability when compared to starch from other botanic sources; however, after treatment, this stability increased. The differential scanning calorimetry results confirmed the gradual degradation of the amorphous areas of the starch granules by the acid-water mixture, which was enhanced by acid-ethanol treatment, leading to more crystalline residues that needed higher enthalpy to gelatinise. Using X-ray powder diffractometry, it was possible to observe a C-type starch and a reduction in relative crystallinity values when compared to native starch. In addition, the pasting viscosities decreased in all the modified starches, as was expected. However, obvious defects or signs of damage on the surface of the granules were not observed after treatment. This study is helpful to better understand the relationships between structure and functional properties in relation to the eventual industrial application of chestnut starches. [ABSTRACT FROM AUTHOR]

The physical, chemical, or enzymatic modified starches are well suited for industrial applications. Acid hydrolysis changes the physicochemical properties without impairing the granular structure of starch. The acid hydrolysis in alcoholic solution can recover the granule starches after modification. Starch, the most abundant carbohydrate in grains, roots and tubers, is composed by amylose and amylopectin. Corn starch represents 85% of the global starch market. The aim of this study was to evaluate the effects of soft acid, acid-ethanol and acid methanol solutions, considering its application in the paper industry. One sample remained as native. The other six samples were modified with acid, acid-ethanol and acid-methanol solutions, at concentrations of 0.1 and 0.5 mol L (hydrochloric acid). The acid treatment changed the thermal (TG) and rheological (RVA) properties of the corn starch. The TG/DTG results showed shifted (up to 8 °C) stability temperature ranges for the samples treated with a higher concentration of HCl in ethanol and methanol solutions. The RVA results for final viscosity of the treated samples showed an intense reduction of 1405 cP related to the native sample. DSC curves demonstrated that the treatments slightly modified the gelatinization behavior of the starch. The micrographs showed small changes in granules average diameter size after the modification process. Acid hydrolysis did not change the crystalline pattern of corn starch, and its relative crystallinity was slightly affected. According to the results obtained for the acid/alcohol, modified starches present suitable properties for their application in the paper industry. [ABSTRACT FROM AUTHOR]