Impact of Chocolate Coating on the Survival of Salmonella on Dried Nuts and Fruits
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EmailThe majority of research on Salmonella survival in low-moisture foods has focused on select single-ingredient products.
Introduction: The majority of research on Salmonella survival in low-moisture foods has focused on select single-ingredient products. Less is known about Salmonella survival in multi-ingredient low-moisture foods, or whether single-ingredient-based research is applicable when incorporated into a multi-ingredient product.
Purpose: The objective of this study was to investigate Salmonella survival on low-moisture foods (nuts and dried fruits) that are subsequently chocolate coated.
Methods: Almonds, dried cherries, peanuts, and raisins were spot inoculated with a 5-serovar cocktail of Salmonella, air-dried for 1 hour, and equilibrated for 7 days (water activity, aw = ~0.45). 3/4 of the samples were covered in a dark, milk, or candy-coating chocolate (tempered/maintained at 42-45ºC prior to use) and allowed to set on wax paper. Samples were then stored (~24ºC up to 42 d), homogenized, serially diluted, plated on non-selective differential media, and survivors enumerated after incubation (48 h, 37ºC). The experiment was performed in triplicate and mean Salmonella survivor data were analyzed via analyses of variance and covariance.
Results: Almond, dried cherry, peanut, and raisin samples (5 particles each) were coated until completely encapsulated in chocolate product and yielded average weights of 11.8, 7.45, 4.52, and 4.8 g, respectively. Salmonella survival was not impacted by chocolate coating type, or presence of chocolate (p > 0.05). Salmonella survival was affected by the product type (almond, peanut, raisin vs. cherry), with cherries yielding faster rates of decline (p < 0.05).
Significance: The persistence of Salmonella on products subsequently coated in chocolate depended on the initial product. This complicates the application of existing Salmonella survivor research to multi-component products.
