Innovative process combining roasting and tempering to mechanically dehull jicaro seeds (Crescentia alata K.H.B)

Abstract

An innovative process combining roasting and tempering was proposed to promote puffing and mechanical dehulling of jicaro seeds. Roasting was performed at three temperatures (120 °C, 140 °C, and 160 °C) and for six residence times (80–180 s). A previous seed tempering was performed at 15% moisture content for 24 h, by spraying the seeds with an amount of water calculated to reach the final moisture content of 15%. The following parameters were monitored as a function of time to optimize the roasting operation: percentage of open seeds, whiteness of cotyledons, and content of two volatile compounds, 2,5-dimethylpyrazine and ethyl-2-methylbutyrate which are considered as the key jicaro note. The optimal roasting was achieved at 160 °C for 150 s with 90% open seeds. The optimal mechanical dehulling was achieved after tempering the roasted seed at 10% moisture content with a yield of 75%. The lightness evolution followed a zero-order kinetic with an activation energy of 103 kJ mol−1. Ethyl-2-methylbutyrate and 2,5-dimethylpyrazine increased with the temperature and period of roasting.