Inactivation of Salmonella Typhimurium during low heat convection drying of winged kelp (Alaria esculenta)

Highlights

• The best-fitted drying models for convection drying are Page and Weibull.

• A fraction of a Salmonella population can resist low-temperature drying.

• Based on AIC, the Geeraerd with tail described the inactivation kinetics best.

• GAB desorption models fit the experimentally obtained data of winged kelp.

Abstract

Processing of seaweed often includes low-temperature drying to stabilise the product by inactivation and inhibition of the growth of microorganisms due to the low water activity. Salmonella is known to resist dry conditions, persist in low-moisture food, and has been linked to foodborne outbreaks from seaweed. Yet, no information is available on the inactivation kinetics of Salmonella during the convection drying of seaweed. Here, we present experimentally obtained drying and desorption models for thawed Alaria esculenta and a model to describe the inactivation kinetics of S. Typhimurium during low heat (<40 °C) convection drying. To describe the drying process, the best-fitting drying models were Weibull (α 20.0, β 0.513) and Page (k 0.215, n 0.513). The Guggenheim-Anderson-de Boer (C 1.031, k 0.958, X₀ 0.265) was the best-suited desorption model. The Geeraerd inactivation model with a tail best described the inactivation kinetics of S. Typhimurium (N₀ 0.04, k_max −0.13, N_res −3.98). These findings can be applied to predict the rates of drying of kelp and inactivation of S. Typhimurium. With no other control measures, pre-drying contamination of the seaweed with levels of S. Typhimurium >2.6 log(CFU g⁻¹) could present a risk due to the potential survival of the pathogen during drying.