Shrimp is a fresh and delicious seafood with high nutritional value. However, the formation of black spots and oxidation of lipids are factors that inhibit shrimp survival. To overcome this limitation, people used black-turning point inhibitors. Currently, most inhibitors are synthetic chemical additives, so there is a need to use natural antioxidant additives to meet the export requirements and ensure hygiene and safety for consumers.

In the country, there are studies of natural antioxidants from fruits and vegetables. However, very little research has been done on extracting antioxidant compounds from spice vegetables. While these are popular, easy to grow, inexpensive vegetables, and packed with antioxidants.

Before that fact, Dr. Phan Thi Anh Dao's team prepared extracts of 10 different herbs (lettuce, spicy basil, basil, basil, oregano, mugwort, cilantro) hemp, hippocampus, coriander, perilla) with water and ethanol. After screening, the team found 5 high-ethanol samples of lettuce, lettuce, wormwood, perilla, and basil with the strongest antioxidant activity. In particular, high in ethanol with lettuce shows stronger activity than used for research, preserving white leg shrimp for 7 days at 2 ° C.

As a result, high extraction of ethanol from lettuce has the ability to limit lipid peroxide, and limit the increase in pH value; in particular, limits the growth of aerobic microorganisms and inhibits some spoilage bacteria commonly found in shrimp (Pseudomonas aeruginosa and Entorobacteriaceae). In addition, lettuce extract also reduces the formation of black spots in shrimp (usually occurs in crustaceans only a few hours after catching and during the process of freezing and frozen) when stored at temperature 2 ° C.

The study results also showed that sodium metabisulfite preservatives and lettuce extract both have the same ability to limit and slow the oxidation of fat in shrimp. The total number of aerobic organisms in the shrimp samples preserved with lettuce extract was 5 times lower than that of the control sample (without preservatives), meeting the TCVN 5289: 2006 on the hygiene requirements of frozen seafood.

Currently, the group is continuing to expand the research on other laksa leaves and herbs and the preservative ability of ethanol extracts on other foods, such as fish, meat, and etc.