Food Chemistry 35 (1990) 187-195 Assessment of the Saponification Step in the Quantitative Determination of Carotenoids and Provitamins A Mieko Kimura, Delia B. Rodriguez-Amaya* & Helena T. Godoy Departamento de Ci~ncia de Alimentos, Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas, 13100 Campinas, S~o Paulo, Brazil (Received 11 January 1989; revised version receivedand accepted 5 May 1989) A BS TRA C T Tile saponification step in the determination of carotenoids was reassessed. Synthetic carotenoids (~-apo-8'-carotenal, fl-carotene) and food samples (tomato, kale, papaya) were used and different procedures were evaluated. Hot saponification resulted in greater losses and cis- and epoxycarotenoids were formed. The degradation was aggravated by a more direct contact between the carotenoids and the alkali. The A OA C procedure, performed in the presence of acetone, led to complete transformation of fl-apo-8'-carotenal to citranaxanthin. Saponification was unnecessary for kale and tomato but wcrs needed for good separation of papaya carotenoids which included carotenol esters. Saponification of the carotenoids dissolved overnight at room temperature in petroleum ether, with equal volume of lO% methanolic KOH, retained fl-, y-carotene, fl-apo-8'-carotenal and lycopene and completely hydrolysed the carotenol esters. However, even with this mild saj~onification, lutein, zeaxanthin and violaxanthin degraded significantly. These losses could be reduced to insignificant levels by using an atmosphere of nitrogen or antioxidant. INTRODUCTION The persistence of the vitamin A deficiency problem in developing countries and the recognition of a possibly wider physiological role for carotenoids beyond the provitamin A activity has drawn a lot of attention to the analytical procedure for these compounds. Nevertheless, the state of development of the rather complicated methodology involved gives 'conflicting' results (Beecher & Vanderslice, 1984). Part of the problem is that * To whom correspondence should be addressed. 187 Food C,~emistrv 0308-8146/90/$03"50 ~ 1990 Elsevier Science Publishers Ltd, England. Printed in Great Britain