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151.
Sara Naji-Tabasi Bahareh Emadzadeh Rassoul Kadkhodaee 《Journal of Dispersion Science and Technology》2019,40(2):256-263
Mayonnaise is one of the most well-known dressings in the world and has properly found its impossibility to apply thermal processing, the high level of cholesterol and some consumers’ allergy to egg. In this study, the production of egg- free mayonnaise in model system has been investigated with the emphasis on flocculation enhancement in the system. Flocculation of emulsion droplets can have beneficial or harmful effect on food quality depending on product nature. In this study, influence of flocculation inducing on the stability, microscopic structure, zeta potential, droplet size and rheological properties of egg-free mayonnaise system were evaluated. Xanthan (XG), pectin (PE) and modified starch (MS) biopolymers mixed at different concentrations were used as flocculation inducer in emulsion system. XG-MS and PE-MS mixed polymers created depletion flocculation and reduced the speed of the oil droplets movement in the product and thus increased emulsion stability. In addition, an increase of all gum concentration caused an increment in the stability, consistency coefficient and heat stability values. Depending on the desirable level of xanthan gum and pectin gum for creating depletion flocculation, production of egg-free mayonnaise with properties closely matching those of commercial ones with egg is possible. 相似文献
152.
Polygalacturonases are part of the group of enzymes involved in pectin degradation. The aim of this work was to investigate
some of the factors affecting polygalacturonase production by an Aspergillus giganteus strain and to characterize this pectinolytic activity. Several carbon sources, both pure substances and natural substrates,
were tested in standing cultures, and the best results were obtained with orange bagasse and purified citrus pectin. On citrus
pectin as sole carbon source, the highest extracellular activity (9.5 U/ml and 40.6 U/mg protein) was obtained in 4.5-day-old
cultures shaken at 120 rpm, pH 3.5 and 30°C, while on orange bagasse, the highest extracellular activity (48.5 U/ml and 78.3 U/mg
protein) was obtained in 3.5-day-old cultures shaken at 120 rpm, pH 6.0 and 30°C. Optimal polygalacturonase activity was observed
in assays conducted at pH 5.5–6.5 and 55–60°C. The activity showed good thermal stability, with half-lives of 90 and 30 min
when incubated at 55 and 60°C, respectively. High stability was observed from pH 4.5 to 8.5; more than 90% of the activity
remained after 24 h in this pH range. 相似文献
153.
Pectin is an integral component of plant cell walls. It is believed to form an interconnected network structure independent
of the cellulose–xyloglucan network structure. Pectin gels are often used as a model for the pectin network structure within
the plant cell wall. The middle lamella pectin can be extracted with chelating agents and is believed to be associated through
cooperative binding of calcium ions in the so-called egg-box junction zones. Although a great deal is known about the nature
of the junction zones in pectin gels, less is known about the long-range structure within calcium-set gels. Two plausible
alternative models for long-range order in these gels are a pseudo rubber-like structure and a fibrous network structure.
Atomic force microscopy studies of calcium-induced gel precursors, and fragments released from gels, suggest that association
leads to a branched fibrous structure within the gels. Enzymatic de-esterification of high methoxy pectin in the presence
of calcium ions can induce gelation of the pectin. Thus pectin gel networks may provide a model for a self-assembled network
structure within the middle lamella region of the plant cell wall. 相似文献