Preparation And Properties Of Carrageenan-based Blend Film With Simultaneously Anti-oxidation And PH-response Properties

In this paper,biodegradable films were prepared using natural polysaccharides κ-carrageenan(κC)and hydroxypropyl methylcellulose(HM)as film-forming substrates.The effects of glycerol,sorbitol,and PEG400 on the film-forming properties were discussed,and the appropriate type and mass fraction were determined from them.Meanwhile,a pH response κC-based intelligent film material with resistant to foodborne pathogen was prepared by using the Prunus maackii fruit juice(PM)or Prunus maackii pomace extract(EPM)as the natural pH indicator and the corktree extract(BER)as the antibacterial agent.Through the microstructure characterization and physical property measurement of the κC-based intelligent film,the interaction between the film-forming substrates was explored.The application of κC-based intelligent film in delaying lard oxidation and real-time freshness monitoring of pork expanded the application field of natural degradable polysaccharide carrageenan and responded to national opinions on plastic pollution control.The results of adding different contents of glycerol,sorbitol and PEG400 showed that the three plasticizers destroyed the entanglement structure between κC and HM molecular chains,and formed new hydrogen bonding with κC and HM molecules.In addition,the plasticizing effect of glycerin and sorbitol was better than PEG400.TG results showed that sorbitol significantly increased the thermal decomposition temperature of κC.And SEM results showed that the cross-section of κC/HM flexible film with glycerol or sorbitol was smoother and denser than that of κC/HM flexible film with PEG400.The tensile strength and barrier properties of κC/HM flexible film decreased with the increased of the amount of plasticizer added,but the elongation at break significantly increases to 49.22%.Comprehensive consideration,we choose sorbitol as a plasticizer,and determine the appropriate addition amount was 40%(w/w,κC/HM based).In order to impart intelligence to κC/HM flexible films,PM and EPM were selected as natural indicators,respectively.Meanwhile,κCH/PM intelligent films and κCH/EPM intelligent films were prepared,and the differences in structural properties were explored and compared.The results show that the addition of PM or EPM destroyed the dense structures between the film-forming substrates and forms new hydrogen bonding with them.The addition of PM or EPM gave the film material antioxidant activity and pH response,and improved the flexibility and barrier properties of the film material,and made it have a certain ultraviolet shielding effect.In addition,κCH intelligent film materials had certain DPPH free radical scavenging ability,and effectively inhibited the degradation of lard in the sealed lard packaging test.The κCH intelligent films showed a color change from red to purple accompanying the process of pork spoilage in the pork freshness test,indicating that it has potential application value in monitoring pork spoilage.Comprehensive consideration,EPM was determined to be a natural indicator,and the appropriate addition amount was 8%(w/w,κC/HM based).In order to improve the defect that the polysaccharide-based intelligent film using the natural dye anthocyanin as the pH response component is easily infected by bacteria,which contaminates the food and leads to the failure of the indicator function,the natural active ingredient BER was selected as an antibacterial agent to prepare a κCHE/BER intelligent film capable of resisting the invasion of foodborne germs.The results showed that the addition of BER improved the elongation at break and UV blocking ability of the film material,but the tensile strength and barrier properties decreased slightly.Meanwhile,the addition of BER gave the film material excellent antioxidant properties and resistance to foodborne bacteria,guaranteed the sensitivity of the intelligent film indicator function,and extended the life of the intelligent film.In addition,the κCHE/BER intelligent film remained responsive in monitoring pork freshness tests.It shows that κCHE/BER intelligent film has anti-oxidant,antibacterial and pH indicating performance.