Effect of different roasting conditions on the physicochemical properties, acrylamide concentration, and mineral bioaccessibility of nuts

Abstract

The effect of different roasting conditions (temperature and time) on the physico-chemical properties, aflatoxin and acrylamide contents, and mineral bioaccessibility (BA) of different nuts (almond, hazelnut, cashew, roasted chickpea (leblebi)) was investigated. Moisture content and water activity of all nuts decreased with roasting. A crispier texture was obtained in all nuts due to the decreased hardness and brittleness after roasting. A significant decrease in L* values of all nuts was accompanied by visible darkening. Although roasting affected a* and b* values of nut samples, the differences depended on nut type. No aflatoxin was detected in control nuts. Acrylamide concentration was increased as the nuts darkened. Highest acrylamide contents (ppb) were found in the darkest samples of cashew (148.59), chickpea (148.63), almond (120.25), and hazelnut (67.33). Considering mineral contents, highest concentrations (ppm) of Ca (2518.97), P (8340.68), and K (13902.70) were found in almonds, Ag (1.51), Mn (88.68), and Se (5.60) in hazelnuts, Cu (6.99), Fe (107.53), Mg (1813.26), and Na (1139.09) in cashews, and Zn (177.57) in chickpeas. Although the mineral content of chickpea was generally lower than other nuts, it showed the highest BA for Ca (38.8 %), Zn (38.2 %), P, (37.3 %) Se (41.8 %), and K (39.8 %), while the highest BA of Fe (21.4 %), Mg (46.8 %) and Mn (48.5 %) was observed in almonds and cashews, respectively. The roasting process generally decreased the BA values of minerals. As a conclusion, since the roasting conditions and food matrix have a direct effect on the absorbed amount of minerals, a product-based evaluation is crucial.