Trace element concentrations in white leg shrimp Litopenaeus vannamei from retail stores in the EU, UK, and USA and the ability to discern country of origin with classification models

The role of species and geography in the elemental profiles of farm-raised shrimp from Indonesia

Elemental profiling is being explored as a traceability tool in many seafood products. However, the extent that elemental profiling can be used at finer geographical scales in cultured shrimp is unknown. Additionally, few studies have included multiple species in the same discriminant models, which would be useful in applications where one species is common, and the other is not. Here, elemental profiling was used to discern the provenance of black tiger shrimp Penaeus monodon and whiteleg shrimp Litopenaeus vannamei from the regions of North Kalimantan, Sulawesi Seletan, and Aceh in Indonesia. ICP-MS was used to determine elemental concentrations of 41 elements in shrimp muscle tissue and was the basis for multivariate and univariate statistical analyses. A MANOVA showed that multivariate differences exist in regions and between species of shrimp sampled. Univariate comparisons were utilized after the significance of the MANOVA and showed that 19 of the 24 elements above detection limits had significant differences. Classification via random forest was used to access the ability to discern, region, species, and region × species group combinations. The lowest model accuracy was the region × species combinations at 78.9%, while the highest accuracy was species irrespective of geographical origin at 93.59%. Elements that were routinely important in classification included As, B, Ba, Li, Na, Rb, Se, and Zn. Elemental profiles of white leg shrimp and black tiger shrimp are varied and potentially should not be used in the same classification models. Altogether, these results suggest that elemental profiling of farmed shrimp at finer geographic scales needs refinement as a traceability tool.

Sources of variation in elemental profiles of whiteleg shrimp (Litopenaeus vannamei) and their potential effects on the accuracy of discriminant analysis

BACKGROUND

Elemental profiling is a tool that has been proposed to improve the traceability of seafood products. Small sources of variation can affect the outcome of elemental profiling and therefore pose to lower the overall accuracy of analyses. Here, we investigate two potential sources of variation through three experiments: laboratory variation (intra-, interlaboratory variation, and tissue matrix) and tissue variation.

METHODS AND RESULTS

Samples of whitleleg shrimp (Litopenaeus vannamei) were obtained from 20 farms in Ecuador and two farms in Alabama to be analyzed. In the first experiment of the study, samples from Ecuador were analyzed at three different laboratories and compared. Two out of the five elements reported were statistically different across the three laboratories (Cu and Se). In the second experiment, the effect of tissue matrix (ground vs whole tissue during acid digestion) was investigated. Altogether, five out of 29 elements analyzed were statistically different. In the third experiment, samples from two farms in Alabama were analyzed to understand the variation in element concentrations in different tissues (head on shell on (HOSO), headless shell on (HLSO), headless peeled (PLD) and headless peeled and deveined (PLDV)). Elemental concentrations varied across tissues, and patterns in elemental concentrations were site specific. The samples from the two farms were analyzed with a Random Forest classification model to site x tissue groupings with 94% accuracy.

CONCLUSION

The result of this study highlights the following: 1. Consistency in laboratory analysis important in studies that involve element concentrations, as minor differences in methodology can propagate as significant differences in results. 2. In shrimp, elements are compartmentalized in different tissues and elemental profiling should consistently use the same type of tissue.