Impact of Foam-Mat Drying on Plant-Based Foods Bioactive Compounds: a Review

Plant-based foods are recognized by their remarkable content of bioactive compounds. In an attempt to increase plant-based foods shelf-life, technologies like drying can be used. Foam-mat drying is a mild drying technology that removes water, usually by using hot air, from a foam obtained by the whipping of a liquid or semi-liquid food added with a foaming agent. There are several reports on the use of foam-mat drying for extending plant-based foods shelf-life, including reports on the effect of drying on their bioactive compounds. Therefore, this study aimed at reviewing the literature on the impact of foam-mat drying on plant-based foods bioactive compounds published in the last 10 years. Results show that short foam-mat drying time is beneficial to bioactive compounds retention. In addition, hot air temperature between 40-65 °C, foam thickness between 0.2 and 1 cm and the use of egg white as one of the foaming agents leads to high bioactive retention. Egg white is also the most used foaming agent. Regarding the mathematical models used for fitting the foam-mat drying kinetics, the Page model was shown as the most proper model. Foaming agent concentration is a delicate parameter, as its increase in foam formulation may beneficially enhance drying rates but, at the same time, it dilutes bioactive compounds and may cause their loss by oxidation. In conclusion, foam-mat drying stands out as a suitable technology for producing food powders with high bioactive retention.