Ruth Hollender

THE ROLE OF PARTICLE SIZE DISTRIBUTION OF SUSPENDED SOLIDS IN DEFINING THE SENSORY PROPERTIES OF MILK CHOCOLATE

The melting of chocolate in the mouth is a dynamic process. The time evolution of the perceived flavor and texture of chocolate during fat melting and sugar dissolution has been observed and quantified using time-intensity sensory methodology. Five milk chocolates varying in particle size distribution and rheology were prepared. Additionally, two chocolates varying in particle size were standardized to the same viscosity. Particle size and rheology significantly influenced effort, thickness, chocolate and sweetness attributes, although in some unanticipated ways. Averaging time-intensity responses to produce consensus curves generally yielded the same conclusions as averaging parameters extracted from individual curves. However, the later were amenable to statistical analysis using ANOVA and partial least squares regression. Multivariate analysis was a useful technique for identifying those physical properties most correlated with sensory perception.

Photooxidative Stability of Vitamin A Fortified 2% Lowfat Milk and Skim Milk

Lowfat milk and skim milk were fortified with either oil- or aqueous-based carrier blends of vitamins A and D, in 1-gal poly-ethylene containers, and illuminated up to 72 h with 1080 1× (100 ft-c) at 5°C in a commercial display case. Vitamin A measurments and sensory analyses showed that vitamin A was more stable in 2% lowfat milk than in skim milk regardless of the carrier. The aqueous-based carrier provided more stability in lowfat milk while the oil-based carrier gave more stability in skim milk. Skim milk fortified with the aqueous-based vitamin A had 69% loss, while the unexposed control exhibited only 15% loss of the vitamin. Off-flavors were evident after 6 h in light-exposed 2% lowfat milk with the oil-based vitamin A, but the same milk with aqueous-based vitamin A did not exhibit off-flavors until after 12 h. Both 2% lowfat and skim milk samples exposed to light received similar lowered preference scores compared to nonexposed control samples. When both fortified and nonfortified 2% lowfat and skim milk samples were tasted after exposure to light, the flavor was not significantly different, but were in the unacceptable range.