INFLUENCE OF SKIM MILK POWDER/RECODAN RS RATIO ON THE VISCOELASTICITY OF GROUNDNUT OIL-IN-WATER IMITATION MILKS

Imitation milks were prepared with different ratios of skim milk powder (SMP) and Recodan RS (R) as emulsifiers while keeping their total concentration constant. The ratio employed influenced the viscoelastic properties of the milks, as derived from creep compliance-time studies, the electrophoretic mobility of the oil drops and the interfacial tension between the oil and aqueous phases. Optimum values of the viscoelastic parameters were obtained when the SMP/R ratio was between 4/1 and 8/1. Association occurs between the SMP and R under these conditions and stabilization of the flocculated oil drops is primarily by a steric mechanism. During storage of the milks the viscoelastic parameters initially increased due to continued growth of the flocculated oil drop structures, but subsequently the parameters decreased as drop coalescence became the predominant factor.     

BOOK REVIEWS

Food Hydrocolloids, Volume 1. Martin Glicksman, ed.
Food Carbohydrates. D.R. Lineback and G.E. Inglett (eds).
Microeconomics: Resource Allocation and Price Theory. Barbara J. Redman and John C. Redman.     

THE RELATIONSHIP BETWEEN THE RHEOLOGICAL AND SENSORY PROPERTIES OF A LEMON PIE FILLING

A range of lemon pie fillings containing the ingredients corn starch, sugar, egg yolk, lemon juice and water were prepared using a constant weight mixture design. There were five ingredients in the system and four ratio variables were employed resulting in 25 formulations. Dynamic rheological and sensory measurements were performed. The latter used magnitude estimation to evaluate the characteristics of thickness, sweetness and lemon flavour. The relationship between the complex viscosity (η*) and perceived thickness was in good agreement with previous work on simpler model systems. Perceived sweetness showed a greater decrease than perceived lemon flavour with increased viscosity. The decrease in sweetness with increasing viscosity increased with increasing sucrose concentration, but was less than has been observed for systems thickened by random coil polysaccharides. An attempt has been made to explain this in terms of solution structure.