Optimization of thermal treatments of cold vegetables soups from Spain to preserve their quality, bioactivity and phytochemical composition

The aim of this work was to determine the effect of different heat treatments ( 1) 90oC and cooled down immediately to a final temperature of 30oC, 2) 90oC during 15s. and immediately cooled down to a final temperature of 30oC, and 3) commercial treatment) on the colour, pH, total soluble solids, antioxidant capacity, and phenolic compounds of three different vegetal food products: 1.carrot, orange and coriander soup (COS); 2.gazpacho (typical Spanish vegetable soup made mainly with tomato, pepper, cucumber, olive oil, vinegar and garlic (GAZ); and 3.tomato, mint and basil soup (TMS). The results showed that the mentioned parameters were influenced by the heat treatments studied in, depending on the temperature and time of each one, and the different products which were applied. COS and TMB showed the highest antioxidant capacity values in their respective commercial samples. However, GAZ treated at 90oC and 90oC/15s. kept the same antioxidant capacity levels that the tank sample (untreated). The colour, pH and total soluble solids parameters remained practically without significant changes produced by the different heat treatments applied, demonstrating that the applied treatments can be more effective than commercial in order to preserve shelf life of these products, and keeping the majority of their crucial properties in these kinds of foods. For that, the results here presented are of significant interest for agro-food industry.