Solubility pattern of simmondsins, proteins and phenolics of defatted jojoba meal.

摘要

Defatted jojoba meal contains toxic compounds, mainly simmondsin and simmondsin 2-ferulate. The aim of this study was to investigate the solubility patterns of simmondsin, simmondsin 2- ferulate, protein, non-protein N and phenols present in Jojoba meal at pH ranging from 1 to 12. Both supernatants and precipitates resulting from extraction at various pH values were analysed for the above components. Simmondsins were identified and quantified by TLC. Antimicrobial activities of the extracts were also evaluated. Precipitates with the lowest simmondsin contents (0.55, 0.55 and 0.74 g/100 g meal) were obtained at pH 1, 2 and 12, respectively. Contents of simmondsin 2-ferulate were 0. 67, 0.72 and 0.72 g/100 g meal, at pH 9, 1 and 2, respectively. The isoelectric point of jojoba meal protein was between pH 3 and 4; at this point, the lowest concn. of solubilized protein (14.26-14.08%) and highest level of precipitated protein (17.74-17.92%) in the residue were observed. Non-protein N levels ranged between 2 and 3.5% in the supernatant and between 7 and 8.6% in the precipitate. Phenolic compounds extracted in the supernatant increased with increasing pH, except at pH 4 and 8 where decreases occurred; phenolic compounds in the residues tended to follow the opposite trend. Extract at pH 1 inhibited growth of the 5 tested bacterial strains. Extracts of jojoba meal obtained at pH 2, 5, 6 and 8 showed inhibition of only 1 of the 5 bacterial strains tested. Results suggest that simmondsins can be effectively removed from jojoba meal at pH 1, 2 and 12, and that jojoba extract at pH 1 possesses good antibacterial activity.