This　paper　describes　an　edible　nanocomposite　packaging　film　fabricated　with　simultaneously　extracted　protein-polysaccharide　(biopolymers)　from　the　marine　red　alga　Gracilaria　lemaneiformis　and　TiO2　nanoparticles.　Both　proteins　and　polysaccharides　were　synchronously　extracted　using　the　alkali　extraction　method.　Different　amounts　of　TiO2　nanoparticles　(TiO2　to　biopolymer　content　ratio　of　3.33,　5.00　and　10.0%　w/w)　were　added　to　prepare　the　TiO2-protein/polysaccharide　nanocomposite　film.　The　addition　of　TiO2　nanoparticles　increased　the　tensile　strength　and　decreased　the　water　vapor　permeability　of　the　film.　This　was　because　the　uniformly　embedded　TiO2　nanoparticles　interacted　strongly　with　the　biopolymers　which　enhanced　the　mechanical　properties　of　the　film,　whereas　the　particles　increased　the　diffusion　pathway　distance　and　lead　to　lower　water　permeability.　These　hypotheses　were　confirmed　by　UV　spectra,　FTIR,　and　X-ray　diffraction　studies.　Antibacterial　measurements　against　food-borne　pathogenic　bacteria　revealed　that　the　growth　of　Escherichia　coli　and　Staphylococcus　aureus　was　effectively　inhibited　by　the　TiO2-biopolymer　nanocomposite　film.　Additionally,　nutrition　retention　and　quality　improvement　were　observed　in　cherry　tomatoes　when　coated　with　the　TiO2-biopolymer　nanocomposite　film.　These　findings　suggested　that　this　alga-sourced　nanocomposite　film　could　serve　as　a　promising　coating　material　in　the　food　industry.　©　2016,　Springer　Science+Business　Media　Dordrecht.