Thermodynamic Incompatibility and Complex Formation in Pectin/Caseinate Mixtures

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• 作者：Camila F. Rediguieri ; Osvaldo de Freitas ; M. Paul Lettinga ; Remco Tuinier
• 刊名：Biomacromolecules
• 出版年：2007
• 出版时间：November 2007
• 年：2007
• 卷：8
• 期：11
• 页码：3345 - 3354
• 全文大小：639K
• 年卷期：v.8,no.11(November 2007)
• ISSN：1526-4602

文摘

The instability of polysaccharide/protein mixtures occurs because of either thermodynamic incompatibility orcomplexation. We studied which instability mechanism dominated given the external conditions. Therefore theeffect of temperature, pH, and biopolymer concentration on the phase separation of pectin/caseinate mixtureswas investigated. At pH > 6, thermodynamic incompatibility with spinodal decomposition was observed in pectin/caseinate mixtures resulting in the formation of water-in-water emulsions in intermediate stages of the phaseseparation process. The demixing rate of these emulsions and appearance of two macroscopic phases (lowerphase enriched with caseinate and upper phase with pectin) was retarded when the pectin concentration increasedor when the storage temperature decreased due to a higher viscosity of the mixtures at those conditions. As thepH of the mixture was lowered below 6, pectin accumulated in the caseinate-rich phase. Complexation of pectinand caseinate led to the formation of microparticles (~3 m), whose shape depends on the biopolymer concentrationratio and rate of acidification. These pectin/caseinate particles do not coalesce and are insensitive to salt addition.