Effect of Hermetia illucens meal on gilthead seabream (Sparus aurata) flesh sensory profile. An innovative approach using electronic senses and data fusion

Use of insects as alternative protein source for aquaculture feed production is an excellent example of circular economy. With the aim to evaluate the effect of fishmeal (FM) replacement with Hermetia illucens meal (HIM) in the diet of Sparus aurata farmed offshore on the organoleptic quality of fillets, two isolipidic (18%, as fed) and isoproteic (42% as fed) diets were tested at farm scale: a control diet with no HIM, and an experimental diet with 35% of HIM in substitution to FM. At the end of the trial, the organoleptic properties of fresh fillets from 12 fish per each group were evaluated using a sensor-based instruments platform consisting of E-eye, E-nose with 18 MOS sensors and a potentiometric E-tongue with 7 chemical sensors. The artificial senses platform was used to detect the organoleptic fingerprint of the fillets of the 2 groups (HIM vs. FM) in terms of color, volatile fraction and taste. For each instrument, all sensors data was analyzed by principal component analysis (PCA) to highlight similarities and differences between the groups; then, the pattern discrimination index and organoleptic distance (based on Mahalanobis distance), were calculated. PCA graphical representation of the E-eye and E-nose results showed nearly overlapping color and odor profiles of the 2 groups. The organoleptic distance and the pattern discrimination index between the 2 groups were for the color 5.39 and 3.88% (p =3.78) and for the volatile profile 0.08 and 2.36% (p=0.08), respectively. Instead, regarding the taste, the PCA of the E-tongue showed a clear distinction between the fillets of the FM and HIM groups and the first two principal components accounted for 94.61% of the variance. Specifically, the vector that mostly identified the fillets of the HIM group was the AHS sensor, particularly sensitive to astringency, while for the fillets of the FM group, the PKS, NMS and CTS sensors, respectively metallic, umami and salty taste indicators. The organoleptic distance and the pattern discrimination index were also significantly high (837.15 and 55.64% respectively; p =0.001). The results highlighted that the diet with 35% of HIM meal in substitution to FM influenced the taste of fillets confirming E-senses as powerful instruments for organoleptic evaluation.