In vitro bioaccessibility of isoflavones from a soymilk-based beverage as affected by thermal and non-thermal processing

Abstract High Pressure Processing (HPP) and High Intensity Pulsed Electric Fields (HIPEF) are non-thermal processing technologies used for obtaining safe and high-quality foods and beverages. In the present work, the changes on both the concentration and the bioaccessibility of isoflavones from treated (thermally and non-thermally) and untreated soymilk-based beverages were evaluated. Thermal treatment (TT) was applied at 90 °C for 1 min, HPP: 400 MPa at 40 °C for 5 min and HIPEF: 35 kV cm−1 with 4 μs bipolar pulses at 200 Hz for 1800 μs. Later, beverages were subjected to an in vitro gastrointestinal digestion for obtaining the bioaccessibility. Thermal and non-thermal processing increased the isoflavone concentration up to 25-26% in TT and HIPEF treated beverages, and up to 38.52% in HPP treated. After in vitro digestion, the concentration of isoflavones in non-thermally processed beverages was higher (70.55% for HIPEF and 98.77% for HPP) than that TT processed (18.52%). HIPEF processing and HPP increased the isoflavone bioaccessibily up to 35.40 and 47.32%, respectively, regarding the untreated product. These results demonstrate that both non-thermal processing technologies HIPEF and HPP are suitable for obtaining high quality and nutritious beverages by improving their isoflavone bioaccessibility. Industrial relevance A great variety of functional food and beverages are commercialized in supermarkets around the word. Their high nutritional content, as well as their healthy properties have placed these products on the consumers’ preferences. Thermal processing has traditionally been used for inactivating spoilage microorganisms and pathogens. However, several important features of food can be compromised by heat treatment. One of the greatest challenges of the food industry is to find the best processing technology for allowing not only the preservation of bioactive food constituents but also the improvement of nutritional and healthy features. The industrial relevance of the present research is to contribute in elucidating the influence of two non-thermal technologies (high pressure processing and high-intensity pulsed electric fields) on both the concentration and bioaccessibility of isoflavones from a functional beverage, and if they can be used as alternative to thermal processing.