We’ve always been told that deveining shrimp before cooking is important. But did you know that this practice can have a significant impact on the quality and freshness of the final product?
A recent scientific study published by researchers from Zhejiang Ocean University (China), Hainan University (China), and Prince of Songkla University (Thailand) has revealed a significant impact of deveining on the quality preservation of Pacific white shrimp (Litopenaeus vannamei). The researchers analyzed protein degradation during refrigerated storage of shrimp with and without intestines, using advanced techniques such as label-free peptidomics.
The Shrimp Gut Ecosystem: A Double-Edged Sword
The microorganisms responsible for shrimp spoilage fall into two main categories: exogenous and endogenous. Exogenous microorganisms are those that contaminate the shrimp during harvesting and transportation processes, while endogenous microorganisms are naturally carried by the shrimp itself.
On the other hand, a key component of the shrimp microbiota is its gut, which hosts a diverse microbial community including symbiotic, non-symbiotic bacteria, food-associated microorganisms, and potential pathogens.
When the shrimp is alive, these microbial communities interact, maintaining a dynamic balance in the gut ecosystem that plays a vital role in food digestion and absorption. However, after the shrimp’s death, these microbial communities can become a major source of microbial spoilage, raising significant concerns for the quality of shrimp muscle during storage.
Previous research has primarily focused on external factors contributing to shrimp spoilage, overlooking the potential impact of the shrimp’s internal environment. This new study aims to shed light on how the post-mortem gut microbial community influences the quality of shrimp muscle during refrigerated storage.
Challenges in Shrimp Preservation: Cold Storage and Protein Degradation
Cold storage at 4°C is a commonly used technique to slow down biochemical changes in shrimp and to inhibit bacterial growth in muscle tissues. However, as cold storage time prolongs, it is common to observe the emergence of unpleasant odors, texture degradation, and even total spoilage of the product, mainly due to microbial degradation of shrimp muscle proteins.
Protein degradation is an extremely complex process, especially when it involves numerous intermediate products with different molecular weights, subunits, structures, and spatial conformations. This complicates the analysis and explanation of specific changes in protein degradation processes using traditional methods.
A Deep Molecular Analysis of Shrimp Spoilage
To understand the intricate processes involved in shrimp spoilage, researchers employed advanced peptidomics techniques. By analyzing the breakdown of proteins in shrimp muscle at the molecular level, they could identify specific changes linked to the influence of the gut.
This approach offers an unprecedented view of the complex cascade of events that occur as shrimp deteriorates. By identifying the target proteins affected by gut bacteria, scientists can develop strategies to mitigate spoilage and extend shelf life.
The Key Role of the Gut
Shrimp is a highly perishable food. During refrigerated storage, shrimp muscle proteins begin to break down, affecting its texture, flavor, and food safety.
Researchers analyzed two groups of shrimp: one with intact intestines (control group) and another deveined (treatment group). The results were surprising.
Deveining: A Protective Shield
Deveined shrimp showed remarkable resistance to protein degradation. Levels of spoilage indicators, such as total volatile basic nitrogen (TVB-N) and trichloroacetic acid (TCA)-soluble peptides, increased more slowly compared to shrimp with intestines. Additionally, fewer bacteria were observed.
The results showed that in both groups, the total bacterial count, volatile basic nitrogen levels (a freshness indicator), and soluble peptides gradually increased with storage time. However, in the final stages of storage, deveined shrimp exhibited significantly lower levels of these spoilage indicators, suggesting that deveining effectively extends the product’s shelf life.
A Molecular-Level Insight
To better understand the mechanisms involved, scientists analyzed protein changes using peptidomics. They identified 396 peptides with significant differences between shrimp with and without intestines. Deveining inhibited protein breakdown, as reflected by a lower number of released peptides.
Implications for the Shrimp Industry
These findings have important implications for the shrimp industry. Deveining, a common practice in shrimp preparation, not only improves the product’s appearance but also contributes to its preservation. By understanding the molecular changes associated with degradation, researchers could develop new strategies to further extend shrimp shelf life and ensure its quality.
Conclusion
Deveining Pacific white shrimp before cold storage proves to be an effective treatment for maintaining muscle quality, reducing protein degradation, and limiting bacterial growth. This study provides a scientific basis for the application of deveining techniques in the processing industry to improve shrimp preservation and shelf life during storage.
The study was funded by the National Natural Science Foundation of China, the National Keypoint Research and Invention Program of China, and the Zhejiang Leading Training Program of China.
Contact
Bin Zhang
No.1, Haida South Road, Lincheng Changzhi Island
Zhoushan, Zhejiang province 316022, PR China.
Email: zhangbin@zjou.edu.cn
Reference
Wu, Y., Du, Q., Dong, R., Liao, Y., Li, C., Benjakul, S., & Zhang, B. (2024). Role of the intestines on the muscle quality of Pacific white shrimp (Litopenaeus vannamei) during chilled storage: Physicochemical and label-free–based peptidomics analyses. Food Chemistry, 460, 140507. https://doi.org/10.1016/j.foodchem.2024.140507
