Dissertation (MSc Chemistry)Food loss due to spoilage by microorganisms is still a problem in most developing countries. Antimicrobial nanoparticles (NPs) can be used to make edible coatings that are subsequently applied to fruits and vegetables to increase their shelf life and improve storage quality. This study aimed to synthesize and analyze carrageenan/TiO2 nanocomposite as food additives for antimicrobial purposes. The combination of metal oxides and polysaccharides is gaining and drawing more attention. A substantial research focus has been on understanding the relationship between polysaccharides and metal oxides, aiming at mastering the pore size distribution, morphology, configuration and composition of hybrid materials. In this study, a highly crystalline anatase/rutile mixed phase carrageenan/TiO2 nanocomposite having a larger surface area has been synthesized by the sol-gel process followed by calcination at 450°C and 650°C. The nanocomposites obtained were analyzed for their functional groups and phase formation using Fourier Transform Infrared Spectroscopy (FTIR) and the X-ray Diffraction (XRD). Furthermore, the specific surface area of synthesized materials was analyzed by using Brunauer-Emmett-Teller (BET), while the surface morphology, dispersions, and elemental characteristics were done by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). FTIR spectra revealed variations in bond frequencies in the nanocomposite materials compared to their reference samples, while the XRD pattern revealed the existence of both rutile and anatase phases of titanium dioxide in the composite materials. The surface of the nanocomposite was observed to be morphologically porous by SEM, while the EDX proved the presence of titanium, oxygen and carbon elements in the composite calcined at 450°C and 650°C. The carrageenan/TiO2 nanocomposites calcined at 450°C showed excellent antibacterial activity against selected bacteria (Staphylococcus aureus and Escherichia coli). These findings suggest that the potential of carrageenan/TiO2 nanocomposites to inhibit bacteria is influenced by their crystalline nature, porosity, surface area, and small size. Its antimicrobial property makes it a promising candidate as a food additive in the food industry.