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Scattering efficiency of a cloudy apple juice: Effect of particles characteristics and serum composition

Author:
Benitez, E.I., Genovese, D.B., Lozano, J.E.
Source:
Food research international 2007 v.40 no.7 pp. 915-922
ISSN:
0963-9969
Subject:
apple juice, apple cider, apples, turbidity, clarity, particle size, glucose, pectins, malic acid, dispersions, soluble solids, absorbance
Abstract:
The effect of particles and serum characteristics on turbidity of natural, or “regular”, and modeled cloudy apple juices was studied in this work. Modeled apple juices were made by re-dispersing a determined quantity of apple particles in a simplified serum (mainly glucose, hydrolyzed pectin, and malic acid in water). Only glucose was found to have a significant effect on turbidity. Particle size was affected by soluble solids concentration, which was attributed to conformational changes in juice particles aggregates, simultaneously with a reduction in particle solvatation. Scattering efficiency was determined in natural and modeled cloudy apple juice both experimentally from a nephelometric method, Q*(av), and theoretically with the Mie theory, Q(Mie). Decrease in juice specific turbidity at increasing soluble solids concentrations (X), was governed by the decrease of Q*(av) at increasing refractive index of the liquid medium n(m). As predicted by theory, the scattering efficiency increased at increasing particle size, for a constant n(m). Finally, calculated values of Q*(av) and Q(Mie) followed a power law relationship when correlated. This non-linear behavior was explained by considering that Q(Mie) is the theoretical scattering efficiency of monodisperse-homogeneous spheres, while Q*(av) is the experimental nephelometric scattering efficiency of polydisperse-irregular particles.
Agid:
715020