Distinguishing Between Fresh and Frozen-thawed Smoked Salmon: Histology to Detect Food Adulteration in High-Value Products

Abstract

ABSTRACT The issue of food safety has acquired increased importance, and fraud is a major concern for the food industry. Among different types of food adulteration, there is the sale of frozen-thawed smoked salmon product as fresh, which not only decreases the quality of products but also misleads consumers and may involve associated health risks. In response to this problem, we tested the performance of histology to identify smoked salmon as fresh or frozen-thawed as a valid analytical method, so food business operators and official controllers can reliably and correctly classify the storage state of the product. Three groups of samples were prepared: group A (n = 36), fresh samples; group B (n = 36), frozen at −18°C for 30 days; and group C (n = 36), stored at −3°C for 30 days after packaging. Two histopathologists examined all samples in blind evaluations and classified them as fresh or frozen-thawed. Sensitivity, specificity, and interrater agreement were calculated. Results show high performance with the test: 80.6% sensitivity (95% confidence intervals [CI]: 64 to 91.8%); 95.6% specificity (95% CI: 89.1 to 98.8%); and Cohen's kappa was 0.81 (95% CI: 0.64 to 0.98%). Histology is a reliable and highly accurate method to differentiate fresh from frozen-thawed smoked salmon and could be used by the industry and official controllers to verify the labeling of the commercial product. HIGHLIGHTS