Effect of Roasting Hass Avocado Kernels on Nutritional Value and Volatile Compounds

Abstract

Because of the lack of commercial food applications of Hass avocado (Persea americana Mill) kernel, which are a useful agricultural waste and a good source of bioactive compounds, this study investigated the influence of roasting on the chemical composition, antinutritional factors, antioxidant activity, colour, and GC-MS profile in avocado kernels after roasting at 180 °C for 30 min. The nutritional data revealed a significant increase (p < 0.05) in the oil extract, crude fibre, total phenolic compounds, Ca, K, P, Na, Zn, browning index, and redness/greenness after roasting. Conversely, a significant decrease (p < 0.05) was noticed in crude protein, total flavonoids, Fe, antinutrients, lightness, and yellowness/blueness after roasting. The 94 volatile compounds separated by GC-MS included 51 compounds from raw Hass kernels and 65 compounds from roasted kernels. The identified compounds constituted 96.21% and 93.25% in raw and roasted Hass kernels, respectively. The most compounds in the roasted Hass kernels were 3,7,11, trimethyl-8,10-dodecedienylacetate (6.28%), 2-methylbutan-1-ol (5.89%), 2-decanone, O-methyloxime (3.73%), 2-methyl-pyrazine (3.62%), and n-hexane (3.51%). Esters were the most common volatile compounds present in both raw and roasted Hass avocado kernels extract, we found 15 and 14 of these compounds (27.53 and 20.36%), respectively. This indicates that roasted Hass kernel flour is nutritionally and organoleptically suitable for food applications, including pastries and beverages, especially coffee drinks.