By Aquaculture Magazine Editorial Team
Shrimp is the most-consumed seafood product in the United States, yet research into the short-weighting and mislabeling of shrimp in the commercial market is limited. This study investigated Country of Origin Labeling (COOL) compliance, species authentication, market names, net weights, and glaze percentages in 106 frozen shrimp packages from Southern California grocery stores. Results showed high COOL compliance but highlighted issues with species mislabeling and short-weighting.
Shrimp is the top-consumed seafood in the U.S., accounting for one-fourth of annual per capita seafood consumpmarket includes species like whiteleg shrimp, giant tiger prawn, and giant freshwater prawn, with over 90% farmed and imported. Seafood fraud, including mislabeling, poses risks such as exposure to allergens and economic deception.
The FDA`s Seafood List and DNA barcoding help ensure accurate labeling. Despite regulations, studies show high rates of species misrepresentation and COOL noncompliance. Additionally, overglazing and short-weighting of frozen seafood are common, impacting net weight accuracy.
This study aims to investigate COOL compliance, species labeling, glazing, and short-weighting of frozen shrimp sold in Orange County, CA. It is the first to assess these combined factors in prepackaged frozen shrimp.
Materials and Methods
Sample collection
A total of 106 frozen uncooked shrimp samples were collected from 37 PACA-licensed grocery retailers in Orange County, CA. Samples were categorized by size descriptors: small, medium, large, extra-large, jumbo, extra-jumbo, colossal, and extra/super colossal. Four additional samples had non-standard size descriptors. COOL compliance and species labeling were reviewed based on package labels and store signage. Samples were transferred to Chapman University and stored at -20°C until processing.
Deglazing and net weight determination
Net weight determination followed AOAC International methods for IQF and block frozen shrimp using an Ohaus Scout H-5853 Balance Scale. Samples were weighed to determine glazed weight, deglazed under cold water, drained, and weighted again to determine net weight. Block frozen samples were processed similarly, using nylon mesh bags and a controlled water bath for thawing. Net weights were compared to declared weights, and samples exceeding NIST`s MAV were considered shortweighted. Percent glaze was calculated and shrimp counts verified against declared counts.
DNA extraction of deglazed shrimp
A 20-30 mg tissue sample was taken from each shrimp and DNA was extracted using a DNeasy Blood and Tissue kit with modifications for smaller volumes. DNA was eluted and stored at -20ºC. Negative controls were included in each batch.
Results and Discussion
COOL compliance
The study found that 94.3% of products were compliant with the Country-of-Origin Labeling (COOL) requirements. Among the six noncompliant products, issues included conflicting country of origin listings, missing procurement method information, and retail stickers covering crucial product information. Out of the 37 retailers involved, only four were noncompliant, with two noncompliant products originating from the same store.
The discrepancies in country of origin were notable, such as labeling a product as from Bangladesh on the packaging but from India on the placard. Such inconsistencies confuse consumers and prevent informed purchasing decisions. These errors might stem from retailers not updating placards when new or updated products are displayed.
Two products failed to mention the procurement method. One of these products lacked this information due to stickers covering the necessary details. The other did not use the COOL-required terms of “farmed” or “farm-raised,” instead referring to “naturally grown in mangrove forests.” The high level of compliance (94%) aligns with previous studies on seafood, showing similar compliance rates between 90% and 99%.
However, lower compliance rates were noted in some studies, like Warner et al. (2014), which reported 41% compliance, likely due to focusing on prepackaged products where labels are applied at processing facilities rather than at retail levels.
Shrimp size category
There is no industry-wide standard for shrimp size labeling. The National Conference for Weights and Measures (NCWM) suggests including a count-per-pound statement alongside size descriptors. Of the 106 products examined, 13.2% listed only the size descriptor without the count-per-pound statement, potentially causing confusion for consumers.
Most products (90.6%) had accurate shrimp counts within the declared range, although some discrepancies were found, such as products declaring 51-60 shrimp per pound but containing only 30. Establishing standardized nomenclature for shrimp sizes and ensuring clear count-per-pound information on packaging is recommended to improve consumer clarity.
Glaze levels
Glaze levels in the shrimp samples ranged from 0.58% to 63.67%, with an average of 16.58%. While 33 samples were within the recommended 15- 20% glaze range, 28 samples were overglazed (i.e., >20%), with most of these also being short-weighted (Figure 1). Overglazing was more prevalent in farm-raised than wild-caught shrimp and slightly more common in domestic than imported samples. This variation highlights the need for a standardized glaze range to ensure consistency and prevent overglazing, which can inflate product weight artificially.
Short-weighting
Short-weighting was found in 36.8% of the samples, significantly higher than previously reported for frozen fish (9%). Out of the 11 size categories of shrimp tested, eight had at least three short-weighted samples (Figure 2). Among the short-weighed samples, consumers overpaid an average of US$ 1.76/kg, with some instances as high as US$3.26/kg. The extra/super colossal shrimp size category had the highest short-weighting rate (57.1%).
Short-weighting was observed across various brands and was more common in farm-raised (40%) than wild-caught (29%) shrimp. The practice was equally prevalent in imported and domestic products. The need for increased regulatory oversight is evident to protect consumers from overpaying due to short-weighting.
DNA sequencing results
Out of 100 shrimp samples, 96% were identified with ≥98% genetic similarity to species in GenBank. Some sequences showed equivalent genetic matches to multiple species, resolved through UPGMA analysis. For example, whiteleg shrimp were confirmed despite matches to other species. Four samples showed lower genetic identity, suggesting they might belong to related but unrepresented species in GenBank.
Species authentication and acceptable market names
Species labeling errors were found in 37 of the samples. Substitution occurred in 21 products due to errors in packaging/processing stickers on retail price tags. Most substitutions involved labeling whiteleg shrimp as “White Shrimp,” a domestic species more desirable to consumers. Some errors might be due to labeling confusion or supply chain miscommunications.
In cases of species substitution one product labeled as “wild-caught blue shrimp” was identified as whiteleg shrimp, with no clear economic incentive for the substitution. Other products had conflicting market names, such as labeling whiteleg shrimp as “White Shrimp” or “Vanme Shrimp,” which are not acceptable market names.
Species labeling errors were most common in the extra-large shrimp category (60%) and predominantly occurred in imported products (97%). This highlights the need for stringent labeling standards to prevent consumer deception.
Conclusion
This is the first study to present information on COOL compliance, shortweighting, overglazing, and species labeling of frozen shrimp sold in Southern California. Taken together, the results of the current study illustrate the various ways in which labeling errors undermine the fair trading of products and consumer protection. A high level of COOL compliance (94.3%) was observed; however, overglazing and short-weighting of samples were both higher than expected, with rates of 26% and 37%, respectively.
These results suggest that some shrimp processors may be artificially increasing the weight of their product through overglazing and that consumers are unknowingly paying for extra ice while receiving less product than advertised. Species substitution was detected in 21% of products identified with DNA barcoding, meaning that consumers are not always receiving the species they intended to buy.
The use of the name “white shrimp” to erroneously describe the predominantly farmed and imported whiteleg shrimp was found to be a prevalent practice. The results of this study indicate a need for increased scrutiny about shortweighting and species mislabeling to decrease the occurrence of shrimp fraud in the United States. Industrywide training and outreach on the importance of proper labeling of seafood throughout the supply chain is also recommended.
Additionally, implementation of a standardized glaze range for frozen shrimp may assist in lowering the rate of overglazing and short-weighting, while also preventing the dehydration of frozen shrimp for both block frozen and IQF shrimp products. Further research into overglazing, shortweighting, and species mislabeling of frozen shrimp and other shellfish is needed globally to better understand the extent of these practices.
This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “SHORT- WEIGHTING, SPECIES AUTHENTICATION, AND LABELING COMPLIANCE OF PREPACKAGED FROZEN SHRIMP SOLD IN GROCERY STORES IN SOUTHERN CALIFORNIA” developed by: RIVERS, M., CAMPBELL, A., HANEUL LEE, C., KAPOOR, P. and HELLBERG, R. – Chapman University, Schmid College of Science and Technology, Food Science Program. The original article was published, including tables and figures, on SEPTEMBER, 2023, through FOOD CONTROL. The full version can be accessed online through this DOI: 10.1016/j.foodcont.2023.110101
