Effect of Citrus wilsonii Tanaka extract combined with alginate-calcium coating on quality maintenance of white shrimps (Litopenaeus vannamei Boone)

• Composition profile of the methanol extract of Citrus wilsonii Tanaka.
• Broad-spectrum antimicrobial activity of the extract of C. wilsonii.
• Specific bacterium Lysinibacillus sphaericus responsible for the shrimp spoilage.
• Preservative potential for the shelf life and good quality of the shrimps.

The combined effect of Citrus wilsonii extract and alginate-calcium film coating on microbiological, chemical and sensory changes of white shrimps (Litopenaeus vannamei) was studied over 6 days of storage at 4 °C. A specific spoilage microorganism Lysinibacillus sphaericus S1 was isolated from local shrimp samples, which could cause the appearance of orange spoilage spots. The methanol extract of C. wilsonii exhibited significant antimicrobial activity against L. sphaericus S1, as well as several other food-borne pathogens. GC–MS analysis showed a high percent of furandione and furfural compounds in the extract. The extract with edible alginate-calcium coating was effective in delaying the quality deterioration of the shrimps stored at 4 °C. Total viable count of the treated shrimps was more than 10 times lower than the negative untreated control. The lower rate of the increase in pH and total volatile base nitrogen (TVB-N) was also observed in shrimps treated with the extract compared to the control group shrimps. After 6 days of refrigerated storage, shrimps treated with the extract combined with coating had the significant higher sensory score for odor, color and texture. The results suggest that the methanol extract from C. wilsonii may be promising to be developed as a new eco-friendly preservative that might be applied to extend the shelf life of shrimps maintaining good quality.