Starch is composed of amylose and amylopectin and deposited as granules of different sizes and shapes with semi-crystalline and amorphous concentric layers that show the 'maltese cross'. Starches from different sources show variable chemical composition as well as the structure of their components that are involved in thermal properties. Amylose, lipids, phosphorylated residues and long lateral chain amylopectin interact among them avoiding water uptake. In contrast, high amylopectin contents, especially with short lateral chains, allow hydration via hydrogen bonds to form gels with the tendency to retrogradation. Smaller starch granules have a larger superficial area, surface pores, and channels that enhance water uptake. High hydration increases the swelling, viscosity, and gelatinization ability of starch granules. The knowledge of those properties allows the selection of the most appropriate starch for a specific end use. This review discusses the relationship between the physicochemical composition of the starch and their rheological properties. Características Estructurales de Almidones y sus Propiedades Funcionales RESUMEN El almidón está compuesto de amilosa y amilopectina y es depositado en forma de gránulos de diferentes tamaños y formas con capas concéntricas que pueden ser semi-cristalinas o amorfas donde se observa la llamada cruz de Malta. Los almidones de diferentes fuentes varían en composición química, así como también en la estructura de sus componentes que están involucrados en las propiedades térmicas. La interacción entre amilosa, lípidos, residuos fosforilados y cadenas largas de amilopectina disminuye la absorción de agua. Lo opuesto sucede cuando se tiene un alto contenido de amilopectina con cadenas laterales cortas, gránulos de almidón pequeños, así como la existencia de poros superficiales y canales. Una alta hidratación de los gránulos de almidón aumenta el hinchamiento, viscosidad, habilidad de gelatinización y la retrogradación del gel después de largos tiempos de almacenamiento. El conocimiento de estas propiedades permite la selección de la fuente de almidón apropiada para un uso final específico.

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The nanoprecipitation method has been investigated to obtain particles in a nanometric and micrometric scale. The particles obtained by this method have been applied in recent years in the food and agricultural industries. Variations of the method as flash nanoprecipitation (FNP) and two-step nanoprecipitation are explained in this article, besides its relation with the ouzo effect.This work presents an overview of the nanoprecipitation method, its advantages, and the potential applications in the food and agricultural industries for improving the quality of food products.

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In the mitochondrial F(O)F(1) ATP-synthase/ATPase complex, subunits α and β are part of the extrinsic portion that catalyses ATP synthesis. Since there are no reports about genes and proteins from these subunits in crustaceans, we analyzed the cDNA sequences of both subunits in the whiteleg shrimp Litopenaeus vannamei and their phylogenetic relationships. We also investigated the effect of hypoxia on shrimp by measuring changes in the mRNA amounts of atpα and atpβ. Our results confirmed highly conserved regions for both subunits and underlined unique features among others. The ATPβ deduced protein of shrimp was less conserved in size and sequence than ATPα. The relative mRNA amounts of atpα and atpβ changed in shrimp pleopods; hypoxia at 1.5 mg/L caused an increase in atpβ transcripts and a subsequent decrease when shrimp were re-oxygenated. Results confirm that changes in the mRNAs of the ATP-synthase subunits are part of the mechanisms allowing shrimp to deal with the metabolic adjustment displayed to tolerate hypoxia.

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