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The current structural models of the cellulose microfibril as well as its mechanical and thermal properties are reviewed. The cellulose microfibril can be considered as a single thin and long crystalline entity with highly anisotropic physical properties. The contribution and limit of different methods employed such as electron microscopy, infrared spectroscopy, X-ray scattering and diffraction, solid state nuclear magnetic resonance spectroscopy, and molecular modeling are also discussed.

El yogur y el queso son dos productos lácteos altamente consumidos. Debido a sus características, representan una excelente estructura para la incorporación de diversos nutrientes, un alimento líquido y un alimento sólido.  El objetivo de este estudio fue fortificar, yogur asentado y queso Panela con nanopartículas de hierro, zinc y calcio, para realizar una comparación de su incorporación en forma nanoparticulada y en forma convencional (micro) y así determinar su efecto sobre las propiedades fisicoquímicas y reológicas, durante 28 días de almacenamiento. El pH del yogur disminuyó, la acidez aumentó durante el almacenamiento. La densidad y la humedad no mostraron diferencias entre muestras, tampoco en almacenamiento. El color varió en yogur con hierro, el cambio neto aumentó en almacenamiento para todas las muestras. La sinéresis aumentó significativamente en yogures con micro-minerales y fue menor en nano-fortificados; en almacenamiento aumentó significativamente. El modelo de Herschel-Bulkley mostró mejor ajuste para el comportamiento no newtoniano del yogur. Los yogures con nanopartículas de calcio y zinc aumentaron su consistencia y firmeza, ambos parámetros disminuyeron durante el almacenamiento; el esfuerzo de cedencia y el índice de flujo no cambiaron significativamente durante el almacenamiento. El pH, la acidez y la humedad del queso, se mantuvieron estables y no se observaron variaciones durante el almacenamiento. Los parámetros de color mostraron variaciones en los quesos con hierro (nano y micro), las muestras fortificadas con calcio y zinc no mostraron diferencias; durante el periodo de almacenamiento hubo un incremento en el cambio neto de color. La textura de muestras con el nivel más alto de calcio, registró mayor dureza y menor adhesividad; durante el almacenamiento se observó un incremento significativo en dureza y una disminución en adhesividad en todas los quesos. En general, la fortificación con nanopartículas mostró ventajas sobre la fortificación convencional.

Chromium has been studied since the end of the 19th century, when carcinogenic effects of hexavalent Cr were discovered. Essentiality of trivalent Cr was demonstrated in 1959; Cr3+ has been studied in humans and laboratory animals since the 1970s and it is only since the 1990s that Cr has been studied as an essential element in livestock animals with the same intensity. Trivalent Cr is essential to normal carbohydrate, lipid and protein metabolism. It is biologically active as part of an oligopeptide - chromodulin - potentiating the effect of insulin by facilitating insulin binding to receptors at the cell surface. Cr absorption is low, ranging between 0.4 and 2.0% for inorganic compounds while the availability of organic Cr is more than 10 times higher. Absorbed Cr circulates in blood bound to the beta-globulin plasma fraction and is transported to tissues bound to transferrin. Absorbed Cr is excreted primarily in urine, by glomerular filtration; a small amount is excreted through perspiration, bile and in milk. This review describes Cr metabolism, the different biological functions of Cr and symptoms of Cr deficiency.

We investigate the biostability of phenolic acids from a kenaf (Hibiscus cannabinus L.) seed extract using an in vitro model simulating the physicochemical (pH, temperature and bile salts) and biological (gastric and pancreatic enzymes) gastrointestinal conditions. Some of the antioxidants in the kenaf seed extract were not relatively stable in the intestinal phase of the gastrointestinal tracts. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and total phenolic content (TPC) assays displayed similar trends as the biostability of phenolic acids, which decreased during the digestion process. The overall percentage loss of selected phenolic acids was 8.4–49.4% in the intestinal phase. For the overall in vitro digestion system, significant correlations between phenolic acids, total phenolic content (TPC) and antioxidant activity (DPPH) were obtained in all digestion phases with the exception of the gastric phase.

In order to improve the functional properties of soybean protein isolates (SPI), microwave-assisted phosphorylation (MAP) was applied. The results showed that after microwaving at 600 W for 3 min, the phosphorylation level of SPI reached 35.72 mg/g, emulsifying activity and stability were increased 2 times and 1.4 times, respectively, the solubility was increased by 26.0% and the apparent viscosity was decreased by 13.5%. The charge density, content of sulfhydryl groups, and surface hydrophobicity increased significantly. The infra-red spectroscopic analysis indicated PO4**3- primary and lysine residues for phosphoric acid esterification. The change of amide bond Ι and fluorescence spectrum of variation suggested that the MAP made the secondary and tertiary structures of SPI into a compact conformation. Compared to the regular phosphorylation, the preparation time applied in MAP of SPI was much shorter. These results indicated that MAP can be used as an efficient method to improve the functional properties of SPI.

:  The objective of this research was to improve the solubility of chitosan by Maillard reaction with 1% chitosan and 2% reducing sugar (glucose or glucosamine) dissolved in 0.2 M acetic acid, which was adjusted to pH 6.0, and incubated at either 50°C or 70°C for 1–7 days. The physicochemical and rheological properties of the chitosan–saccharide derivatives were also investigated. Results indicated that the solubility of modified chitosan derivatives was significantly greater than that of native chitosan. The solubility of chitosan–glucosamine was higher than that of chitosan–glucose, and the chitosan–glucosamine derivative remained soluble at pH 10. The degree of deacetylation of the derivatives decreased with increasing reaction time. Rheological investigation revealed that the apparent viscosity of the water‐soluble chitosan derivatives in aqueous solution depended upon system conditions such as pH, ionic strength, and solution temperature. The measured apparent viscosity decreased as all system conditions increased. As calculated by the Arrhenius equation, the activation energy (Ea) of the derivatives in aqueous solution generally decreased with increasing the extent of Maillard reaction with respect to the reducing sugars used.

Six compounds, licarin-B (1), dehydrodiisoeugenol (2), malabaricone B (3), malabaricone C (4), beta-sitosterol (5), and daucosterol (6) were isolated from the seed (nutmeg) of Myristica fragrans and identified. Among them, malabaricone B was identified for the first time in nutmeg. Antioxidant activities of the isolated compounds were studied using oil stability index, reducing power, ABTS*+ scavenging, and DPPH* scavenging methods. The results showed that Malabaricone C is an efficient antioxidant agent which exhibits a stronger antioxidant activity than the commonly used synthetic antioxidants in all studied methods. This compound may have a potential to be used as a natural antioxidant in food.

The potential uses of starches and flours depend on their physicochemical and functional properties. The chemical composition, functional and pasting properties of starch and flours obtained from some newly developed yam varieties from the Crops Research Institute (CRI), Ghana were evaluated, and compared with the existing local varieties. The results showed that the physicochemical and functional properties varied among the varieties studied. The CRI varieties were grouped in a principal component analysis as moisture (afase pa), amylose content (ahodenfo, soanyinto, afase biri), high starch content, bulk density and water absorption capacity (kukrupa, Mankrong pona, CRI pona). Starch pasting characteristics showed that Mankrong pona, CRI pona and afase pa exhibited stable pastes whereas afase biri, Mankrong pona and, afase soanyinto could be utilized for high-temperature processing. Overall, the new CRI varieties showed considerable functionalities that could be explored for potential food and industrial applications as compared to the existing local varieties.

Protein-polysaccharide conjugates were generally prepared by dry-heating. However, it was time-consuming and the sample gained was inhomogeneous. A faster way of preparing protein-polysaccharide conjugates is needed. Accordingly, soy protein isolates (SPI)-acacia gum (GA) conjugates prepared by the wet-heating method were studied in the present work. Physicochemical properties of SPI-GA conjugates were also determined. The results showed that the wet-heating method could improve the rate of the graft reaction of protein and polysaccharide. The solubility of SPI-GA conjugates was significantly higher than that of unreacted SPI-GA mixtures and SPI at the same pH values. The emulsion activity index of the grafted SPI increased remarkably. Moreover, a significant improvement of the emulsifying stability index was observed and emulsions with a smaller droplet size were obtained. No visible flocculation during extended storage (30 days) was observed. The time course of the development of the graft reaction of SPI with GA was also shown by SDS-PAGE.

Four Tremella fuciformis polysaccharides (TPS) fractions named as TPS20, TPS40, TPS60, and TPS80 were obtained by stepwise ethanol precipitation. Their physicochemical and rheological properties were investigated. Results showed TPS60 had the highest contents of polysaccharide (81.12%), protein (0.29%), uronic acid (14.36%), and sulfate (5.92%). Their molecular weights were in a descending order of TPS20, TPS40, TPS60, and TPS80. In a certain range of shear rate, they all presented pseudoplastic fluid and viscosity characteristic at low frequency. Increasing temperature or concentration of salts decreased the viscosity of their solutions. Sucrose concentration less than 6% led to an increasing viscosity of TPS20, TPS40, and TPS60. Both strong acidity and alkalinity could reduce the viscosity of all TPS solutions. TPS80 solution showed the best stability and its viscosity was minimally affected by pH, temperature, salts, and sucrose. These results can provide theoretical references for utilizations of TPS fractions in foods, pharmaceuticals, and cosmetics.