Shelf life prediction of oxygen-sensitive products: The influence of moisture on prediction accuracy for freeze-dried coffee

摘要

Optimised packaging requires that properties are matched to the protection requirements of food for its shelf life duration. Benefits include reduced packaging costs, use volumes, and potentially improved environmental performance. The ability to predict product shelf life in different materials can assist in selecting optimal packaging. However, the availability of such tools is limited, and risk for over packing exists. The aim with this work is to develop a prediction approach which can be applied to assist users to select more optimal packaging materials. Soluble coffee was used to develop the approach, where oxygen consumption of the product is used as a quality indicator. The effect of moisture content on O-2 consumption was studied to determine its influence on prediction accuracy. Samples were prepared with different levels of moisture content. O-2 consumption rates were measured, and a notable influence of moisture was observed. A model was developed to predict the O-2 consumption of the product when packed in a pouch. The model considers oxygen and moisture permeation properties of the packaging film, O-2 and moisture differential between the interior and exterior of the packaging, and the evolution of the O-2 consumption rate as a function of moisture increase. To test model accuracy, coffee samples were packed in flexible pouches, and O-2 consumption was measured which showed that predicted and measured values shared the same trend characteristics. We show that considering both moisture and O-2 ingress simultaneously leads to more precise shelf life prediction as oxidation rate is influenced by moisture content.