Sensory and physicochemical assessment of wild and aquacultured green and black lip abalone (Haliotis laevigata and Haliotis rubra)

Abalone is a highly valued food product in many countries, in large part a result of its unique sensory properties. Wild and cultured abalone both attract premium prices, but generally this is not based on sensory characteristics. Yet, abalone aquaculture is developing to provide an alternative to a dwindling supply of wild abalone, and this provides an opportunity to optimize the sensory properties if they are better understood. In most natural food products, farming practices and growing environment are responsible for the sensory properties of the final product; therefore, the comparison of both wild and aquacultured abalone's sensory characteristics could contribute to a better understanding of the impact of the growing and farming practices on the sensory properties. Our study focused on the development of a descriptive sensory analysis methodology to measure abalone sensory properties, and the observation of differences among the abalone sampled. Wild and aquacultured abalone were prepared according to a standardized cooking protocol. A sensory panel of trained assessors developed and defined a descriptive vocabulary and a method of assessment, and then quantified the sensory properties of abalone. A vocabulary of 16 terms describing aroma, texture, flavor, and aftertaste of the abalone was developed. Very significant differences were found between abalone sourced from the wild and aquacultured abalone from different sources. The wild-caught blacklip abalone, which were larger in size, were perceived as more firm, springy, and chewy, but also rated significantly higher in aroma, flavor, and aftertaste impact as well as earthy and metallic flavors. Significant differences in sensory properties were also found between cultured abalone fed different diets. Compositional analysis showed significant differences between abalone in their content of glycogen (range, 4.8%-23.2% of dry weight (DW)), moisture (69.4%-73.7% live weight), and taste-active free amino acids, especially glycine (3.4-18.2 mg/g DW) and glutamate (1.0-3.6 mg/g DW). Correlations were found between sensory attributes and some chemical compounds. This study indicates that growing conditions as well as growing techniques may have a large influence on abalone sensory characteristics. However, because the design of the study was not balanced for key growth or production variables, additional studies are required to identify and quantify which factors were most influential. The descriptive sensory method developed was successful in measuring the sensory properties of abalone and can now be applied more broadly.