The Impact of Optimizing the Detoxification of Argane (Argania spinosa) Press Cake on Nutritional Quality and Saponin Levels

The use of Argania spinosa press cake for livestock feed is limited due to the presence of saponins, which give it a very bitter flavor and make it unpalatable to livestock. The present study aims to evaluate whether a detoxification method reduces saponin levels of press cake and how that affects its nutrient contents. The response surface methodology was used in this study involved grinding the argane press cake and subjecting it to soaking and boiling in three media: distilled water, sodium bicarbonate solution at different concentrations (0.02, 1.01, and 2%), and citric acid solution at various concentration (0.10, 1.05, and 2%); the respective ratios of argane press cake to the soaking and boiling media were fixed at 1:5, 1:12.5 and 1:20 (w/v, g/mL); the respective soaking times chosen were 1, 24, and 48 h; the boiling temperatures selected were 40, 80, and 120 ˚C, respectively; and the boiling times were, respectively, 10, 25, and 40 min. Experiments showed that soaking in acidic and alkaline media more effectively reduced saponin with averages 93% and 86% respectively, than soaking in distilled water (36%), while we observed significant average reductions amongst boiling solutions. The nutritional contents of argane press cake treated by different treatments decreased slightly than untreated; the crude protein of argane press cake non-detoxified was 48% compared to the detoxified that ranged between 40 to 47%. Therefore, decreasing the levels of saponins will make argane press cake more appetizing for livestock and might ameliorate protein malnutrition, a major animal feed problem in Morocco.