Effet des prétraitements post-récolte des amandes de Pentadesma butyracea (Sabine) sur la technologie d'extraction en milieu réel et la qualité du beurre

Pentadesma butter is still traditionally extracted starting from pretreated almonds by traditional techniques of heating. The aim of this work was to study the effect of the almonds post-harvest pretreatments on the physicochemical characteristics, the extraction yield and the quality of the Pentadesma butter. In addition, the effect of the various unit operations of the extraction technology on the quality of the extracted butter from pretreated almonds was studied. According to the same traditional process of extraction, two various butters of Pentadesma were extracted starting from almonds differing only by the post-harvest pretreatment applied (roasting or boiling). The color, the aspect and the breaking strength of the almonds were different. The butter extraction yield varied according to the pretreatment applied. The best yields (33.5 _ 4.1%) were obtained from boiled almonds, but their transformation was more difficult than that of roasted. The analysis of the samples at different stages of the transformation allowed the appreciation of the effect of the almonds pretreatments on the acidity and the peroxide value variations at each unit operation of the butter extraction. The fatty acid composition and the tocopherol content of the two extracted butters varied with the almonds pretreatments. The roasted almonds provided a richer butter in stearic acid, a and d-tocopherols and less rich in oleic acid than that provided by the boiled almonds. The pretreatments allowed a total loss of the contained linolenic acid, b and dtocopherols in the butters and decreased the oleic acid and a- tocopherol contents. The physico-chemical characteristics of the Pentadesma butter varied according to the almonds pretreatments. Thus, it would be interesting to make a reasoned choice of the most suitable post-harvest pretreatment in order to obtain a butter with a good quality and an acceptable extraction yield. (Résumé d'auteur)