Characterisation of a highly saturated Irvingia gabonensis seed kernel oil with unusual linolenic acid content.

The search for new sources of oil with improved characteristics has focused our attention on the characterisation of Irvingia gabonensis seed kernel oil. Physicochemical analysis have revealed the following assets: refractive index (1.42 ± 0.00), free fatty acids (2.3 ± 0.8%), peroxide value (3.33 ± 0.57 meq O(2)/kg), iodine value (32.43 ± 1.22 g I(2)/100 g), saponification value (233.75 ± 2.60 mg KOH/g), unsaponifiable matter (1.5 ± 0.02%), carotenoids (63 ± 0.01 mg ß-carotene/100 g) and phospholipids (2.1 ± 0.01%). Absorbance of this oil decreased abruptly in the range of UV-B and UV-A wavelengths. Gas chromatography analysis showed that the major fatty acids were saturated, being mainly composed of lauric (C12:0, 39.35 ± 0.01%) and myristic acids (C14:0, 20.54 ± 0.01%). Nevertheless, an unusually high amount (6.44 ± 0.02%) of linolenic acid was also noted. Mass spectrometer analysis of volatile compounds highlighted the presence of various aromatic and aliphatic organic compounds. I. gabonensis seed kernel oil also showed oxidative stability at 60 °C after 12 days of storage with maximum peroxide value of 34.66 meq O(2)/kg. In view of these interesting characteristics, I. gabonensis seed kernel could be used as an alternative source of oil for lipid industries.

Alpha-mannosidases from the digestive fluid of Rhynchophorus Palmarum larvae as novel biocatalysts for transmannosylation reactions.

Two biological fluids, namely hemolymph and digestive fluid from the larval stage of Rhynchophorus palmarum Linneaus, a serious pest in agroecosystem exploiting oil palm, were screened for hydrolytic activities, by the use of synthetic and natural glycoside substrates. Several exo and endoglycosidase activities were observed but, the interesting alpha-mannosidase activity (0.41 +/- 0.04 UI) had attracted our attention. So, we have previously demonstrated that this activity harbours four distinctive alpha-mannosidase isoforms named RpltM, RplM1, RplM2 and RplM3. We have extended this work to determine the ability of these enzymes to catalyze synthesis reactions. Finally, we have revealed that, alpha-mannosidases from the digestive fluid of R. palmarum larvae catalyze transmannosylation reactions. The stability of the enzymes and the optimization of the transfer product yield were studied as functions of pH, enzyme unit, starting concentration of donor or acceptor and time. It was shown that, in experimental optimum conditions, average yields of 12.34 +/- 0.75, 12.15 +/- 0.79, 5.59 +/- 0.35 and 8.43 +/- 0.50% were obtained for the alpha-mannosidases RpltM, RplM1, RplM2 and RplM3, respectively. On the basis of this work, alpha-mannosidases from the digestive fluid of Rhynchophorus palmarum larvae appear to be a valuable tool for the preparation of neoglycoconjugates.