Dynamic Approach for Assessing Food Quality and Safety Characteristics: The Case of Processed Foods

摘要

Thermal processes applied to foods focus on the destruction of target microorganisms. Besides theseprocesses often occur under time-varying temperature environments, inactivation of microorganisms iscommonly assessed under isothermal conditions. The development of mathematical models that describemicrobial kinetics under dynamic temperature conditions is of utmost importance for processes design. Inthis work thermal inactivation data of Listeria innocua (used as a surrogate of the pathogenic L.monocytogenes) in parsley was used as case-study. Isothermal and non-isothermal conditions were tested anda Gompertz-based model was used in data fitting. Different temperature profiles, typical of pasteurizationfood processes, were imposed within the range 20 – 65 °C. Results corroborated model adequacy, being themodel able to describe/predict Listeria inactivation under dynamic temperature conditions.Another process applied with the purpose of preserving foods is frozen storage. Pumpkin, broccoli andcarrots were stored under isothermal (-7, -15 and -25 °C during 140 days of storage) and non-isothermalfrozen conditions (step-stress within the temperature range from -30 °C to -5 °C, during 57 days of storage).Quality alterations, such as texture, colour, vitamin C and drip loss were evaluated throughout both frozenregimes.Models based on zero and first order kinetics, and fractional conversion models accurately describeddegradation of quality characteristics analyzed, both under isothermal and dynamic frozen conditions.