Production of biomaterials from seafood waste for application as vegetable wash disinfectant

The production of seafood waste was studied by analyzing calcium oxide from the shells of tropical oyster and chitosan from the shells of white shrimp to use as a vegetable wash disinfectant. The preparations used were: natural oyster shell powder (NOSP), calcined tropical oyster shell powder in a programmable furnace for 2 h at 700 °C (OSP₇₀₀), 800 °C (OSP₈₀₀) and 900 °C (OSP₉₀₀) including white shrimp shell chitosan (CS). The physical properties of all biomaterials were analyzed using Thermogravimetric analysis, X-ray diffraction and Fourier-transformed infrared spectrometry. The results showed that NOSP and OSP₇₀₀ were calcite calcium carbonate crystal, but OSP₈₀₀ and OSP₉₀₀ were transformed to calcium oxide and calcium hydroxide. The amino group found in the chitin from white shrimp shell was deacetylated to chitosan. By investigating the qualitative antibacterial activity of OSP₉₀₀ and CS, the inhibition zone of OSP₉₀₀ against E. coli was higher than that of CS (p < 0.05); however, the inhibition zone of CS against S. aureus was higher than that of OSP₉₀₀ (p < 0.05). In addition, OSP₉₀₀ had significantly higher quantitative antibacterial activity against E. coli than S. aureus. The MIC of OSP₉₀₀ against E. coli and S. aureus for 15 min were 2.5 and 5 mg/mL, respectively; furthermore, the MBC of OSP₉₀₀ against E. coli and S. aureus were 5 and 10 mg/mL, respectively. However, the inhibitory activity of CS against S. aureus was higher than against E. coli with MIC and MBC values of 5 and 10 mg/mL, respectively, for 15 min. When testing the biomaterials, OSP₉₀₀ and CS, to inhibit the bacteria on kale and lettuce, 2.5 mg/mL of OSP₉₀₀ for a vegetable-washing time of 15 min had the highest E. coli inhibition for both vegetables, while 2.5 mg/mL of CS for the same washing time had the highest S. aureus inhibition for both vegetables. Therefore, this research indicated that biomaterials prepared from tropical oyster shell and white shrimp shell wastes could be used as effective wash disinfectants to eliminate contaminated bacteria on vegetables.