A method of preparing a product, in particular an agrofoods or pharmaceutical product, which comprises a step consisting of the addition of an agent with a sweetening power, characterized in that the agent with sweetening power consists, entirely or partly, of the incorporation into the product of a gas or mixture of gases comprising nitrous oxide N.sub.2O, and in that one or more adjuvants are added to the composition of the product, which adjuvants make it possible to slow the kinetics of desorption of the gas or mixture of gases comprising nitrous oxide N.sub.2O from said matrix once said gas or mixture of gases has been incorporated.