Molecular and air-water interfacial properties of potato protein upon modification via laccase-catalyzed cross-linking and conjugation with sugar beet pectin

peer reviewedFoaming-related functionalities of potato proteins are important for the development of innovative food products. The main purpose of current study was to investigate the effects of laccase-catalyzed modifications on the tertiary structural property, the thermal property, the air-water interfacial adsorption kinetics and the film rheological characteristics of potato protein at selected pH values. The cross-linking of potato protein (PPT) with or without the presence of ferulic acid (FA) as mediator and its conjugation with sugar beet pectin were biocatalyzed by fungal laccases (Trametes versicolor or Coriolus hirsutus). As compared to the native potato protein, all modified proteins were unfolded, and a decrease in the structural compactness was observed. The conjugation of potato protein with sugar beet pectin (PPT-SBP-H/-L) exhibited stabilization effect against unfolding and heating, which also promoted the adsorption of potato protein, while the cross-linked potato proteins (MPPT24h, MPPT24hFA) contributed to high surface dilatational elasticity of the interface, at neutral pH condition. The extended laccase-cross-linking treatment (MPPT48h, MPPT48hFA) resulted in a higher structural stability of the proteins than the other modified ones. At acidic pH conditions, these protein samples exhibited relatively high surface dilatational moduli. This study provided insights into the impact of laccase-catalyzed modifications on the functionalities of potato protein from molecular and mesoscopic aspects. © 2020 Elsevier Lt

Effect of powder properties on the physicochemical and rheological characteristics of gelation inulin–water systems

peer reviewedThis study investigates the influence of physical properties of powder on the potential functionality of inulin as a polymeric gelator. Inulin powder was characterized using high-performance anion exchange chromatography, wide-angle X-ray, and particle size. Moreover, the inulin–water system was described using rheological properties, optical microscopy, and textural analysis. Four commercial inulins (LC, Instant, Fib97, and HP) were characterized and dissolved in distilled water at three different concentrations (15, 20, and 25%, w/w) at 25 °C. Inulin LC (degree of polymerization, 18.80; semi-crystalline state) and HP (degree of polymerization, 23.74; amorphous state) formed a gel from a concentration of 15% (w/w) and 20%, respectively. Inulin Fib97 (degree of polymerization, 6; amorphous state) and Instant (degree of polymerization, 8; amorphous state) were not able to develop a gel structure. This indicates the significant effect of polymer chain length to form a gel. Textural properties as well as wide-angle X-ray scattering and optical microscopy ascertained a difference in inulin HP– and LC–water system properties. This dissimilarity is related to the different physical properties of powders such as crystallinity and particle size. Indeed, new inulin powders were produced, having the same chemical composition but different physical states (amorphous or crystalline) or particle sizes. The results showed that an amorphous powder with a bigger particle size gave a greater gelation of inulin–water systems. However, beyond a certain size of particles, the systems lose their gelation properties. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature

Rheological Properties of a Fibro-Protein Extract from Male date Palm Flowers

peer reviewedFibro-protein extract from male date palm flowers (FPE-MDPF) was obtained by alkali extraction followed by isoelectric precipitation. The FPE-MDPF consisted mostly of carbohydrates (64.67%) andproteins (26.82%). The extract dispersions showed shear-thinning behaviour which was pronounced with the concentration increase. The Herschel Bulkley model was used for the viscosity curves evaluation and the obtained parameters indicated a remarkable deviation from the Newtonian regime. Both viscosity and viscoelastic moduli were influenced by the modification of extrinsic conditions. In fact, it was revealed that the concentration increase (2 up to 6 %), the acidic condition (pH 4) as well as the salt addition (0.5 M) contribute to the increase of viscosity and the strengthening of the obtained gels. Moreover, after a heating process, FPE-MDPF dispersion showed a stable behaviour during the cooling step (90 to 20°C) suggesting that the material could be used in food system which requires heat toleranc

Influence of monopalmitin on the isothermal crystallization mechanism of palm oil

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