Chemical composition, toxic/antimetabolic constituents, and effects of different treatments on their levels, in four provenances of Jatropha curcas L. from Mexico

Abstract

Jatropha curcas L. is a multipurpose shrub of significant economic importance because of its several potential industrial and medicinal uses. Four provenances of J. curcas from different agro-climatic regions of Mexico (1. Castillo de Teayo, 2. Pueblillo 3. Coatzacoalcos and 4. Yautepec), that differed in morphological characteristics, were studied. The seed kernels were rich in crude protein, CP (31–34.5%) and lipid (55–58%). The neutral detergent fibre contents of extracted J. curcas meals were between 3.9% and 4.5% of dry matter (DM). The gross energy of kernels ranged from 31.1 to 31.6 MJ/kg DM. The contents of starch and total soluble sugars were below 6%. The levels of essential amino acids, except lysine, were higher than that of the FAO/WHO reference protein for a five year old child in all the meal samples on a dry matter basis. The major fatty acids found in the oil samples were oleic (41.5–48.8%), linoleic (34.6–44.4%), palmitic (10.5–13.0%) and stearic (2.3–2.8%) acids. We also found previously unreported cis-11-eicosenoic acid (C20:1) and cis-11,14-eicosadienoic acid (C20:2) in the oil. Phorbolesters were present in high concentrations in the kernels of Coatzacoalcos (3.85 mg/g dry meal), but were not detected in the samples from Castillo de Teayo, Pueblillo and Yautepec. Trypsin inhibitors (33.1–36.4 mg trypsin inhibited g −1 dry meal), phytates (8.5–9.3% of dry meal as phytic acid equivalent), saponins (2.1–2.9% of dry meal) and lectins (0.35–1.46 mg/ml of the minimum amount of the sample required to show the agglutination) were the other major antinutrients present in all the seed meals. Different treatments were attempted on the seed meal samples to neutralize the antinutrients present in them. Trypsin inhibitors were easily inactivated with moist heating at 121 °C for 25 min. Phytate levels were slightly decreased by irradiation at 10 kGy. Measured saponin contents were reduced by ethanol extraction and irradiation. Extraction with ethanol, followed by treatment with 0.07% NaHCO 3 considerably decreased lectin activity. The same treatment also decreased the phorbolester content by 97.9% in seeds from Coatzacoalcos. The in vitro digestibility of defatted meal (DM) was between 78.6% and 80.6%. It increased to about 86% on heat treatment.