Development of species-specific aroma wheels for Cyclopia genistoides, C. subternata and C. maculata herbal teas and benchmarking sensory and phenolic profiles of selections and progenies of C. subternata

Abstract

Sensory profiling of fermented Cyclopia genistoides, C. subternata and C. maculata herbal teas indicated differences in their aroma profiles, supporting the need for species-specific aroma wheels to complement an existing generic honeybush sensory wheel to illustrate differences between Cyclopia species. Descriptive sensory analysis of the hot water infusions of a sample set (n=44) of each species was performed by a trained panel. The defining positive aroma attributes of each species were indicated by scatter plots of the occurrence frequency of an attribute in the sample set against its mean intensity, as well as normal distribution curves fitted on the intensity distribution for each attribute. Collectively, the information captured in these plots directed the choice of attributes for each species-specific aroma wheel. The generic aroma attributes, “fynbos-sweet”, “fynbos-floral” and “woody”, common to the three Cyclopia species, as well as the defining aroma attribute(s) of a species were arranged in a wheel format, with each attribute representing a wedge of the wheel. The width of a wedge represents the relative intensity of an attribute, while wedges expanded length-wise serve as a simple visual identification of the defining attribute(s). The data of C. subternata, used to develop its species-specific aroma wheel, subsequently served as baseline data to benchmark selections and half-sib progenies of C. subternata. The sensory profiles of selections and half-sib progenies displayed higher intensities of the aroma attributes “fruity-sweet”, “apricot” and “hay/dried grass” than the baseline values. Infusions of a large C. subternata sample set (n=74), including the 44 samples used for establishment of the aroma baseline values, were analysed for individual phenolic content to form a phenolic baseline data set. Similarly, the infusions of the selections and half-sib progenies contained higher levels of mangiferin, scolymoside and vicenin-2 than that of the baseline samples. Both sensory and phenolic qualities are evaluation criteria for selection of improved honeybush plant material.