Comparative Bioaccessibility of Phenolic Compounds from Almonds, Peanuts, Pistachios and Their Corresponding Butters

Nuts are an important dietary source of phenolic compounds, which are associated with potential health benefits. In the present study, the bioaccessibility of phenolic compounds from almonds, peanuts, pistachios and their corresponding butters was investigated after in vitro gastro-intestinal digestion. High-resolution mass spectrometry analysis provided a comprehensive picture of the phenolic profiles across samples, with a total of 55–95 compounds identified per matrix. Pistachios showed the highest amount of phenolic compounds (60.603 ± 1.170 mg/100 g), followed by peanuts and almonds. Processing into butter affected phenolic concentration in a matrix-specific manner. Almond and peanut butters showed higher phenolic content compared to whole nuts, whereas pistachio butter exhibited lower levels than the whole nut. After digestion, differences in bioaccessibility were observed. Peanuts showed the highest phenolic bioaccessibility (84.31%), while almonds and pistachios exhibited lower values (<15%). Overall, phenolic bioaccessibility was mainly influenced by nut type and phenolic compound structure, rather than by their initial concentration or processing. These findings are based on an in vitro model representing an estimate of bioaccessibility rather than in vivo absorption. However, nut type and processing appear to influence the release of phenolic compounds, which is relevant for the nutritional evaluation of nuts and nut-derived products.