Pectin is a complex polysaccharide that functions in-vivo in the maintenance of plant cell structural integrity and in-vitro as a rheology modifier, emulsifier or encapsulant.  Pectin's core structural element is a backbone of a-( 1,4)-galacturonic acid residues, though its carbohydrate composition and presented topology can be quite variable. Due to its relative abundance and functionality pectin is incorporated into a wide variety of food (jams, jellies, and cloudy beverages) and pharmaceutical (encapsulants and coatings) products.  Structural modifications prior to end-product formulation can alter pectin's functionality, enabling it to be tailored to particular applications.  Those occurring in-situ during product formulation or storage may reduce functionality and lead to quality defects.  The latter are often a result of incomplete enzyme inactivation and subsequent pectin modification (demethylesterification) which in cloudy beverages (citrus juices) leads to cloud destabilization and clarification. Here we provide an overview of the composition, macro-/nano-molecular structure, and degree of methyl-esterification (DM) of pectin in cloud material of frozen concentrated orange juice (FCOJ) during the process of juice cloud destabilization.  We focus on the relationships between cloud state, DM, and methyl-ester distribution, as quantified by degree of blockiness, degree polymerization for charged blocks, etc.  We report on a series of pectin samples from FCOJ with corresponding cloud state ranging from intact to fully compromised pectin and DMs ranging from 83% to 33%.

Characterization of macro- and nano-structural changes in pectin during juice cloud destabilization in frozen concentrated orange juice

246th National Meeting (2013)

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