Antioxidant Antioxidant activity of thermal or non-thermally treated strawberry and mango juices by Saccharomyces cerevisiae growth based assays

The antioxidant activity of strawberry or mango juice [untreated or treated by high intensity pulsed electric fields (HIPEF) or heat] has been studied on a Saccharomyces cerevisiae yeast strain exposed to different oxidants (tert-butyl hydroperoxide, diamide and diethyl maleate). Cellular biomass production was higher in the juices compared to the synthetic medium, which contained all required amino acids, nitrogen bases and vitamins needed for growth, indicating that growth-limiting nutrient concentrations in the natural juices were higher. In addition, the inhibitory effect of tert-butyl hydroperoxide or diamide in yeast growth was lower in the juices compared to synthetic medium, supporting an antioxidant effect of both juices. In contrast, juices did not confer significant protection against diethyl maleate. HIPEF or thermal treatments did not negatively influence the antioxidant activity of the juices. In fact, HIPEF-treated strawberry juices presented enhanced antioxidant effect on yeast cell growth in the presence of tert-butyl hydroperoxide compared to fresh juice in terms of adaptation period and the final cellular biomass. (C) 2016 Elsevier Ltd. All rights reserved.