Food processing and digestion: The effect of extrusion process on bioactive compounds in extrudates with artichoke leaf powder and resulting in vitro cynarin and cynaroside bioaccessibility

Although herbal ingredients could be used to increase bioactive compounds in food products, it is more crucial to investigate the effect of processing on their bioaccessibility and their content. In this study, artichoke leaf powder (ALP) was added to wheat flour (WF) at ratios of 0:100, 3:97, 6:94 and 9:91 g ALP:g WF on dry basis. The effect of extrusion process on the bioactive compounds themselves and in vitro bioaccessibilities of cynarin and cynaroside, which are found in ALP, were investigated. Total phenolic content (TPC) and antioxidant activity (AA) of extrudates and raw mixtures were also measured. The extrusion process reduced TPC from the range of 3.4-8.2 to 2.2-6.3 g gallic acid equivalent/kg. Antioxidant activities of the samples with ratios of 3:97 and 6:94 remained the same whereas it decreased from 30 to 24 mmol trolox equivalent/kg for the sample with the ratio of 9:91. The extrusion process also caused a decrease in cynarin and cynaroside contents. The process increased in vitro bioaccessibility of cynarin by 30-44% for all ALP concentrations and that of cynaroside by 38% for both ratios, 6:94 and 9:91. Obtained results could be useful in product and processing design to improve the bioaccessibility of functional compounds.