Effect of the Addition of High-Protein Hydrolyzed Flour from Oncorhynchus mykiss Byproducts on the Properties of an Extruded Feed.

This work aims to evaluate the effect of the addition of a high-protein hydrolyzed (HPH) flour from the chemical silage of trout (Oncorhynchus mykiss) residues on the parameters of the extrusion system physicochemical transformations and the microstructure of the extrudate. During the extrusion process, the materials used for the study were the HPH flour obtained from trout by chemical silage, fishmeal, and cassava starch. The extrudate's microstructural changes were evaluated by determining the porosity, scanning electron microscopy, the chemical changes, the amino acid profile, residual formic and lactic acid content, the molecular mass profile, the grade of hydrolysis, and in vitro digestibility. The results showed pellets with high durability due to the cohesiveness of the hydrolyzed protein flour but at the same time with low hardness due to the high porosity achieved. The monitoring carried out to the changes in the protein, such as the degree of hydrolysis, water-soluble protein, and molecular mass profile, verify the binding effect of the high-protein hydrolyzed flour during the extrusion process. Finally, the high-resolution optical microscopy methodology presented a high correlation with the phenomena presented in the experiment.

Thermomechanical characterization of an amylose-free starch extracted from cassava (Manihot esculenta, Crantz).

The aim of this study was to determine and compare the melting (Tm), glass transition (Tg) and mechanical relaxation (Tα) temperatures of a new waxy cassava starch. Thermal transitions measurements were obtained by Differential Scanning Calorimetry (DSC) and Dynamical Mechanical Thermal Analysis (DMTA). The experimental data showed a high correlation between water volume fraction and melting temperature (Tm) indicating that the Flory-Huggins theory can be used to describe the thermal behavior of this starch. The Tm of waxy cassava starch-water mixes were lower than a waxy corn starch-water reference system, but differences were not statistically significant. The mechanical relaxation temperatures taken at tan δ peaks were found 29-38°C larger than Tg. The Tα and Tg measured for waxy cassava starch exhibited similar properties to the ones of waxy corn starch, implying that waxy cassava starch can be used in food and materials industry.

Evaluación de l retrogradación del almidón en harina de yuca precocdda / Evaluatin of staarch retrogradation in cassava flour from precooked parenchyma / Avaliação a retrrogradação do amido em farinha de mandioca precozida

Las modificaciones del almidón, que ocurren durante el proceso de elaboración de harina de yuca precocida, se evaluaron utilizando técnicas como calorimetría diferencial de barrido (CDB), difracción de rayos X, comportamiento al empastamiento y capacidad de formación de complejo con yodo. La harina precocida se obtuvo a partir de trozos de parénquima de yuca cocinados en vapor o en agua a ebullición, los cuales fueron posteriormente almacenados a 5 ºC o a -20 ºC por 24 h. La temperatura utilizada durante el periodo de almacenamiento del parénquima cocinado no es un factor significativo en los resulta dos de retrogradación del almidón. La entalpía de fusión y cristalinidad del almidón retrogradado de la harina proveniente del parénquima cocinado en vapor fue ligeramente mayor, comparado con la elaborada a partir de parénquima cocinado en agua a ebullición para el periodo de almacenamiento a 5 ºC. Por otra parte, en el periodo de almacenamiento a -20ºC, el método de cocción no tuvo efecto significativo sobre la entalpía de fusión del almidón retrogradado, la cristalinidad y el índice del valor azul.

Starch modifications during the processing of precooked cassava flour was monitored using techniques as differential scanning calorimetry (DSC), pasting behaviour, wide angle X-ray diffraction and iodine binding capacity. Cassava flour was obtained from parenchyma pieces cooked either in steam or in boiling water and then stored either at 5 ºC or at -20 ºC for 24 h. The temperature during the rest period of the cooked parenchyma was not a significant factor in the starch retrogradation results. For a rest period at 5 ºC, flour from parenchyma cooked in steam presented a slightly higher melting enthalpy of retrograded starch and crystallinity as compared to that from parenchyma cooked in boiling water. Whereas for conditioning period at -20 ºC, the cooking method had no significant effect on the enthalpy of retrogradation, crystallinity and blue value index.

As modificações do amido durante o processo de elaboração de farinha de mandioca precozida, foram avaliadas utilizando as técnicas de calorimetria diferencial de varredura (CDV), difração de raios X, comportamento no empastamento e capacidade de formação de complexo de iodo. A farinha precozida obteve-se de troços do parênquima da mandioca cozidos com vapor o em água em ebulição, os quais foram armazenados depois a 5 ºC ou -20 ºC por 24 h . A temperatura do armazenamento do parênquima cozido no foi um factor significativo nos resulta dos de retrogradação do amido. A entalpia de fusão e cristalinidade do amido retrogradado da farinha proveniente do parênquima cozido no vapor foi levemente maior, do que aquela elaborada do parênquima cozido em água em ebulição e armazenada a 5 ºC. Além disso, o método de cozimento não teve efeito significativo na entalpia de fusão do amido retrogradado, na cristalinidade o no índice de valor azul (IVA).