SPECTROSCOPIC METHODS FOR EVALUATION OF HOP EXTRACTS AND EXTRACT FROM GONGRONEMA LATIFOLIUM AS SUBSTITUTE IN THE NIGERIAN BEER INDUSTRY.

The potential of Gongronema latifolium as substitute for hops in the Nigerian brewing industry in terms of methanolic extracts was evaluated. The relative proportion of each constituent in hop extracts and that of G. latifolium were investigated using Gas Chromatography - Mass Spectrometry (GC-MS). Quantitative investigation of ten metals was carried out using Atomic Absorption Spectrophotometry (AAS). The GCMS results showed that G. latifolium contained constituents comparable to those of hops, although some constituents [dehydro-cohumulunic acid; 4,4-dimethyl-2-buten-4-olide; 1,2-dimethyl-cyclopropane carboxylic acid; lupulone; 2,5-dimethyl-2-hexanol; 4,4,5,5-tetramethyl-bicyclo hexyl-6-ene-2,3-dione; octadecanoic acid, oxiranyl methyl ester and 1,2-benzenedicarboxylic, bis(-2-ethyl hexyl) ester] present in hops were absent in G. latifolium. Isomerized hop, hop leaf and G. latifolium contained a total number of 14, 11, 10 constituents respectively. The AAS results showed that the concentration of metals investigated in all the samples were calcium (16.300–18.400ppm), sodium (92.019–98.245ppm), potassium (8.297–206.838ppm), magnesium (19.331-22.188ppm), lead (Not detected), manganese (0.426-38.628ppm), cobalt (0.004–0.012ppm), zinc (0.963-17.944ppm), mercury (Not detected) and iron (0.547-8.614ppm). These results indicate that there are minor differences in the chemical constitution of hop extracts and extracts from G. latifolium while there is an insignificant difference among the extracts with respect to metal concentration. Hence the result of the analyses presented extract from G. latifolium as suitable substitute for hops in the Nigerian beer industry. Consequently, academic activity in the area of mixing/blending of this extract with hop extracts which mimic very closely hop taste is strongly recommended.