20 Abstracts of the Articles Printed in NIPPON NOGEIKAGAKY KAISHI

ea were examined. Forty compounds were detected Caramel color prepared by ammonium-sulfite process Dm the oil of each Mentha gentilis L., and the com contains some imidazoles including toxic 4-methyl- osition of pulegone (1) and 8-hydroxy-3-p-menthene(2) imidazole. The imidazoles are combined both with each oil collected in the different seasons was shown acidic low-molecular-weight substances and high- follows: 1(82.5% and 86.2%) and 2(1.8% and molecular-weight coloring matters. On ultrafiltration 6%) in August, whereas 1(64.0% and 68.6%) and of the caramel color solution, the imidazoles bound (19.2% and 11.7%) in October and 1(48.5% and •¬ with low-molecular-weight substances can permeate .6 %) and 2(26.1% and 24.0%) in November, respec through the membrane but ones bound with high- •¬ ely. molecular-weight coloring matters are retained in the On the basis of the seasonal variation of these com concentrate. ments in the oil of each plant, 2 seems to be derived The latter bound imidazoles were completely released om 1 via cis-pulegol in the biosynthetic pathway. from the coloring matters when sulfuric acid or sodium hydroxide was added to 10% diafiltered caramel color solution until its concentration reached 0.1 N. The Release of Bound Imidazoles in Caramel Color lowest concentration of sulfuric acid required for the

(Ultrafiltration of Caramel Color Part IV) complete release of the bound imidazoles was 0.55 N

(p. 273•`275) and 0.025 N for 10% original and diafiltered caramel Shiro KisHIHARA, Satoshi Funs and Masahiko color solution, respectively. KOMOTO It is possible that caramel color freed from the toxic Department of Agricultural Chemistry, Faculty of imidazole may be prepared by a combination of sulfuric Agriculture, Kobe University, Nada-ku, Kobe 657, acid addition with ultrafiltration. Japan

ERRATUM

Vol. 43, No. 7, p. 1407, Title for read Benz[a]anthracene Benz[a]anthraquinone