Characterization of Apples and Apple Cider Produced by a Guelph Area Orchard

Abstract

Thermal stability of food-borne pathogens in apple cider is influenced by the composition of the product. As a preliminary step to determine the effect of pasteurization of apple cider on the survival of Escherichia coli O157:H7, a study was carried out to characterize apples and unpasteurized apple cider produced by a Guelph area orchard. Samples of commercial unpasteurized cider and the constituent apples were collected over 13 wk from August to November 1998, and unpasteurized laboratory cider was made from the individual apple varieties. pH, titratable acidity, turbidity, total microbial counts, total solids and °Brix for filtered and unfiltered samples were measured. The maximum, minimum, and average values for all unpasteurized commercial cider samples were found as follows: pH, 3.71, 3.17, and 3.43; titratable acidity, 93.47, 49.46, and 69.95 mL of 0.1 N NaOH/100 mL; total solids, 13.21, 10.93, and 11.90%; °Brix, 13.01, 11.17, and 12.02; turbidity, 238.1, 145.1, and 204.9 nephelometric turbidity units; and total plate count, 4.91, 2.61, 3.75 log cfu/mL. There were no significant differences ( P>0.05) between filtered and unfiltered samples. In addition, in commercial unpasteurized cider, there were no significant differences ( P>0.05) with respect to any of the factors with the time of processing. The composition of the unpasteurized laboratory cider made from individual apple varieties was dependent on the variety, but was generally within the ranges from the published literature values. McIntosh apples showed a significant ( P\\le0.05) decrease in titratable acidity with time of harvest. The results suggest that it is necessary to take the composition of commercial apple cider into account when developing thermal inactivation models for food-borne pathogens.