High hydrostatic pressure assisted by food-grade enzymes as a sustainable approach for the development of an antioxidant ingredient

Apple is one of the most important fruits in the world. The elaboration of apple-based products such as cider or apple juice generates around 3–4.2 million tonnes of apple by-product that are annually discarded. Apple byproduct has been described as an interesting source of bioactive compounds, including polyphenols. These valuable components, once extracted, could enable the usage of the apple by-product as a natural antioxidant ingredient. The aim of the present work was to address the effect of high hydrostatic pressure (HHP), and HHP assisted by two alternative food-grade enzymes, Celluclast®, and Ultraflo®. For that purpose, the total phenolic content was measured by Folin-Ciocalteu and Fast-Blue BB assays. Furthermore, antioxidant capacity was determined by three analytical methods (DPPH, ORAC and FRAP) and the characterization of phenolic compounds was carried out by Chromatography and Mass Spectrometry analysis. Results indicated a significant increase of the total phenolic content and the antioxidant capacity after the HHP aided by Celluclast® or Ultraflo® treatment. Conversely, the exclusive application of HHP induced minor changes. Thus, the combination of HHP and the food-grade enzymes Celluclast® or Ultraflo®, has proved to be an effective strategy for the extraction of natural antioxidant compounds from the apple by-produc