The influence of carotene and bacteriopheophytin c addition on paths of nonradiative and radiative deexcitation of the oil from Amarantus seeds

The absorption, fluorescence emission and excitation as well as steady state photoacoustic spectra (PAS) of the oil from Amarantus seeds, without and with carotene and bacteriopheophytin c (BPhe c) addition, have been measured. The oil investigated originally contains only some amount of carotene but no admixtures of chlorophyll-like pigments. As follows from the dependence of the photoacoustic signal multiplied by the frequency of light modulation on this frequency, the kinetics of thermal deactivation (TD) of oil depends on the pigment contents. The relative values of thermal deactivation calculated for the samples with pigments added to that of the original oil depend on the type of the pigment added. The relative yields of fluorescence have been also calculated. The results suggest that also the photochemical reactions taking place in various illuminated samples could be different. This suggestion has been experimentally confirmed. The photochemical stability of the oil sample increases when carotene is added. The information about the oil stability is important in order to establish proper conditions for oil storage and transportation.