Isoflavone profile of a high intensity pulsed electric field or thermally treated fruit juice-soymilk beverage stored under refrigeration

A fruit juice-soymilk (FJ-SM) beverage was treated by high intensity pulsed electric fields (HIPEF) (35 kV/cm with 4 μs bipolar pulses at 200 Hz for 800 or 1400 μs) or heated (90 °C, 60 s) in order to evaluate and compare the effects of both technologies on the isoflavone profile along the storage at 4 °C. Total isoflavone content was determined by quantification of aglycone and glucoside forms analyzed with HPLC. Immediately after treatments, all the evaluated samples showed a higher concentration of glucosides than aglycones, genistin being the most abundant glucoside. Heat treated samples showed higher initial concentration of glucosidic forms as compared to the untreated or HIPEF treated beverages. No significant changes were observed in total isoflavone content after the increasing HIPEF treatment time from 800 to 1400 μs. During the storage, genistein, daidzein and daidzin content increased; while genistin showed a slight decrease, irrespective of the treatment applied. In this way, total isoflavone content tend to increase throughout the time in all the evaluated samples. After 56 days of storage, there was no significant difference in HIPEF treated and fresh FJ-SM beverages, the latter being slightly higher in those thermally treated. As a result, HIPEF could be a good technology in order to obtain FJ-SM beverages with a high content of isoflavones and fresh-like characteristics. Considering the great concentration of isoflavones in untreated and treated FJ-SM beverages, their consumption could be a good way to increase the isoflavone daily intake of the population.Industrial relevanceHIPEF processing could be a competent technology in order to obtain FJ-SM beverages with fresh-like appearance and similar isoflavone content than just made products. The fruit juice-soymilk beverage evaluated in the present research has a great isoflavone content regarding to commercial soy based beverages. Its consumption could increase the current isoflavone intake of the population. Industry could apply this non-thermal technology in order to meet current consumers' claims for quality foods with high nutritional values.