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

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 bioaccessibility 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.
This research was supported by the Ministerio de Ciencia e Innovación (Spain), reference AGL2006-12758-C02-02/ALI and AGL2006-12758-C02-01/ALI. Rodríguez-Roque thanks the financial support from the Secretaría de Educación Pública, Dirección General de Educación Superior Universitaria for a research stay within the project PROMEP-UACH-PTC-362 agreement OF-17-8204 (Mexico).