Study On The Preservation Effect Of Polylactic Acid Nanocomposites On Edible Fungi

Poly lactic Acid(PLA),titanium dioxide(TiO2),nano-silver(Ag),and rosemary(Rosmarinus offcinalis L.)as raw materials and making different composite films by solvent casting methods.In the case of Agaricus bisporus and Tremella aurantia,studying the effect of new poly lactic acid nano-antimicrobial films on the preservation of edible fungus.To extend the shelf life and maintain its quality,edible funguses are stored at 4±1? for 16 days.The research results are as follows:(1)The PLA composite films were characterized by mechanical properties,thermodynamics properties,barrier properties,bacteriostatic activity.And the analysis of electron scanning microscope image and fourier infrared scanning spectroscopy of the PLA composite films.With the addition of nanoparticles,the tensile strength of the composite film decreased,while the elongation of the rupture increased slightly.With the increase of nanoparticle content,the composite films have more white spots and more holes,and the barrier properties of the composite film have declined slightly.By using infrared spectroscopy,nano-TiO2 and nano-Ag influence the structure of the composite film through the intermolecular forces,and the properties of the composite film are changed.At the same time,the addition of nanoparticles caused the thermal stability of the composite film to decrease,and the crystallinity increased.Because nano-TiO2 and nano-Ag have good antibacterial property,the PLA nano-composite films show excellent antibacterial properties.The metal particles in the composite membrane migrate to the food simulator in a much lower amount than the national standard,so they are safer.(2)In the Agaricus bisporus preservation experiment,the measured properties include weight loss,soluble solid content,firmness,pH value,vitamin C,total plate count,and reducing sugar content.The results indicated that the package of PLA/A film can retard the harmful change of soluble solid content,vitamin C,reducing sugar content,firmness,pH value and total plate count.In the aspect of antibacterial,the effect was significant(p<0.05).The antibacterial properties of the PLA/A composite film can effectively inhibit the growth and reproduction of microorganisms in the Agaricus bisporus during preservation,so that the total number of microorganisms is lower than that of other packaging.The results show that the PLA/A3 film can extend the expiration date of Agaricus bisporus to 16 day at 4±1 ?,more effective compare with LDPE film.(3)In the Tremella aurantia preservation experiment,the measured properties include weight loss,firmness,vitamin C,color,microbiological,and sensory quality.The results indicated that the package of PLA/REO/A film can retard the harmful change of firmness,vitamin C,color,microbiological,and sensory quality.Because the water vapor permeability of PLA/REO/A composite film more than several other films,it is effective to prevent the formation of condensation and to inhibit microbial growth.At the same time,the PLA/REO/A composite film has a significant antibacterial effect that effectively inhibits the reproduction of microorganisms during the Tremella aurantia storage.The results show that the PLA/A film can extend the expiration date of Tremella aurantia to 16 day at 4±1?.