Characterization of chocolate milk spoilage patterns

Standard plate counts (SPC) and psychrotrophic plate counts (PPC) from choc olate milk samples were compared with those of unflavored milk samples plat ed within 24 h of processing and at 7, 10, and 14 days of storage at 6 degr ees C using marched samples collected over four time periods from four milk -processing plants. Bacterial numbers within 24 fi of processing were not s ignificantly different in unflavored and in chocolate milk samples (P > 0.0 01), with SPC less than 1,000 CFU/ml and PPC below 10 CFU/ml for both types of products. SPC and PPC were higher in chocolate milk samples than in unf lavored milk samples collected from all four plants after 14 days of storag e (P < 0.001). To examine the effects of chocolate milk components on bacte rial numbers, SPC for days 0, 7, 14, and 21 were monitored in samples of ex perimentally prepared unflavored milk, milk with chocolate powder and sucro se (chocolate milk), milk with sucrose only, and milk containing chocolate powder only. At days 14 and 21, SPC were higher in both chocolate milk and in milk with chocolate powder only, than in either the unflavored milk or m ilk with sucrose only (P < 0.001). These findings suggest that; the additio n of chocolate powder to milk can contribute to a greater relative increase in bacterial numbers in pasteurized chocolate milk than in identically pro cessed unflavored milk at 14 days postprocessing.