In this study we investigate the effect that Agave fructans as new prebiotics have on mineral absorption improvement. Forty-eight 12-week-old C57BL/6J mice were used in this study. Forty mice were ovariectomized and eight were sham-operated controls. Mice were fed standard diets or diets supplemented with 10% Agave fructans or 10% inulin fructans. Calcium and magnesium were evaluated as well as their excretion in feces. Osteocalcin levels were also measured; femur structure was studied by scanning electron microscopy. Other parameters, such as food intake, body weight, glucose, and short-chain fatty acid content, were recorded. Calcium in plasma and bone increased in Agave fructan groups (from 53.1 to 56 and 85 mg/L and from 0.402 to 0.474 and 0.478 g/g, respectively) and osteocalcin increased in all fructan groups (>50%). Scanning electron microscopy showed that fructans were able to mitigate bone loss. In conclusion, we demonstrated that supplementation with Agave fructans prevents bone loss and improves bone formation.

Corn starches were isolated using three different methods: water steeping, alkaline steeping, and acid steeping. The effects on their structural, micro structural, thermal, and chemical properties were evaluated, with especial emphasis in the alkaline process that is close related to the nixtamalization process. The isolation method influences the amylose content, crystallinity, and enthalpy of the starch granules. Scanning electron microscopy showed that the isolation method produced changes on the surface of the granules, and in some cases there were holes on the surface. Method 2 (the alkaline method) produces the starch granules with low protein and fat content and there was an increase in the enthalpy for this method, that can be explained in terms of thermodynamics by the increase of particles into the starch granules, which was confirmed by an increase in the ash content. A negative correlation between these variables was found (r ¼ 70.99), while a positive correlation between enthalpy and amylose content was also found (r ¼ 1).Keywords: corn starch; isolation method; functional properties of starch; amylose; amylopectin Almidones de maı´z fueron aislados por tres diferentes me´todos: usando reposo en agua, reposo alcalino y reposo a´cido. Se evaluaron los efectos de estos me´todos sobre las propiedades estructurales, microestructurales, te´rmicas y quı´micas en los gra´nulos de almido´n. Los resultados mostraron que los me´todos de obtencio´n de almido´n tienen fuerte influencia en el contenido de amilosa en los almidones aislados, ası´como en su estructura cristalina obtenida mediante difraccio´n de rayos X, ası´como cambios en la superficie de los gra´nulos observados por microscopia electro´nica de barrido, se tiene especial e´nfasis en el proceso alcalino, por que es cercano al proceso de nixtamalizacion. El me´todo alcalino produjo gra´nulos de almido´n con bajo contenido de proteı´na y grasa. En el caso del tratamiento alcalino, en te´rminos termodina´micos, el incremento en la entalpia tambie´n puede ser explicado por el incremento de las partı´culas dentro de los gra´nulos de almido´n, resultado que es confirmado por el incremento del contenido de cenizas. Finalmente, se encontro´una correlacio´n (r ¼ 70,99) tomando en cuenta los valores de cristalinidad y entalpia, y una correlacio´n positiva (r ¼ 1) entre entalpia y contenido de amilosa.Palabras clave: almido´n de maı´z; me´todo de aislamiento; propiedades funcionales de almido´n; amilosa; amilopectina

The objective of this work was to study the physicochemical modifications of starch during the malting of barley. The results showed that malting modifies the physicochemical properties of the starch over time by the action of barley enzymes. The gelatinisation temperature of starch increased as a function of the malting time owing to the selective enzymatic attack. The viscosity of starch decreased through malting. During germination, scanning electron microscopy showed that the enzymes degrade some starch granules which exhibited micro-holes on the surface. X-ray diffraction showed an apparent increase in the crystallinity during the first three days of germination, reflecting the consumption of amorphous regions. Such changes have not been previously reported. Infrared spectroscopy (1200-1500 cm À1 ) showed the unfolding of carbohydrates as a result of enzymatic action. Such changes in the physicochemical properties of starch indicate that the amorphous area is consumed in the early stages of malting.

Mechanical, microstructural properties, mineral content and bone mineral density (BMD) of the femur were evaluated in growing rats fed with Opuntia ficus indica (L.) Mill. (Cactaceae) cladodes at different maturity stages as calcium source. Male weanling rats were fed with cladodes at early maturity stage (25 and 60 days of age, belonging to groups N-60 and N-200, respectively) and cladodes at late maturity stage (100 and 135 days of age, belonging to groups N-400 and N-600, respectively) for 6 weeks. Additionally, a control group fed with calcium carbonate as calcium source was included for comparative purposes. All diets were fitted to the same calcium content (5 g/kg diet). The failure load of femurs was significantly lower (p ≤ 0.05) in groups N-60 and N-200 in comparison to N-400, N-600 and control groups. The cortical width (Ct.Wi) and trabecular thickness (Tb.Th) of the femurs in control and N-600 groups were significantly higher (p ≤ 0.05) than Ct.Wi and Tb.Th of femurs in groups N-60 and N-200. Trabecular separation of the femurs in N-60 and N-200 groups showed the highest values compared with all experimental groups. The highest calcium content in the femurs were observed in control, N-600 and N-400 groups; whereas the lowest phosphorus content in the bones were detected in N-200, N-600 and N-400 groups. Finally, the BMD in all experimental groups increased with age; nevertheless, the highest values were observed in N-600 and control groups during pubertal and adolescence stages. The results derived from this research demonstrate, for the first time, that the calcium found in Opuntia ficus indica cladodes is actually bioavailable and capable of improving mineral density and mechanical and microstructural properties of the bones. These findings suggest that the consumption of cladodes at late maturity stage within the diet might have a beneficial impact on bone health.