14B-27

P. C. ONYENEKWE, Food Science and Technology Programme, Institute for Agricultural Research,Ahmadu Bello University, P.M.B.1044, Zaria, Nigeria

Piper guineense belongs to the group of varieties of Piper species called "false cubebs". Its berries are often used as substitute for black pepper (Piper nigrum). It has been reported to have some degree of nutritive value because of its fairly high protein and fat content. However, it is mostly consumed because of the flavour and aroma it imparts to food and the bite characteristics. On steam distillation the berries yield an aromatic essential oil. The differences in chemical composition of oils depend on the origin, variety, cultivar, method of isolation and analysis. The presence of other components that had never been identified in the spice is reported.

The objectives were to determine the constituents of P. guineense essential oil and the effect of method of analysis on the resolution and identification of the constituents.

The oil obtained by hydrodistillation was analyzed by GC and GC/MS. Two chromatographs equipped with either a split - splitters injector plus a DB-5 column (30m) or an "on column" injector plus a supercowax 10M column (30m). The identity of each compound was determined by kovats indices using either our data bank or data from literature.

The oil was found to contain 62 constituents. The sesquiterpenes are the most abundant - b-caryophyllene, germacrene D, a-copaene, b- elemene and a-caryophyllene. Limonene and d-carene are the main monoterpenes. Few oxygenated compounds were also observed. A number of terpenes not previously reported in P. guineense oil were identified including aromadendrene, a-caryophyllene, a- and b-selinene, b-cubebene, allo-aromadendrene, a-amorphenes, viridiflorene, a-fernesene, g-cadinene and E-calamenene. The split - splitters injector plus a DB-5 column set up gave a better resolution.

The result shows that there could still be more unidentified constituents of P. guineense oil. It also confirms the significance of method and condition of analysis in resolution of the constituents.