| Dried bovine-limed hide collagen fibers are derived from the untanned leather waste in leather production and are generally handled by burying or burning,which is neither economical nor eco-friendly.Due to rich collagen content,they have great application potential in edible packaging film.However,the poor mechanical properties and water resistance as well the inadequate antibacterial and antioxidant functions of pure collagen films would limit their application.Tea polyphenols and dialdehyde starch,as the green natural products,contain a large number of groups in their molecules that can interact with the active groups of collagen fibers,and have certain antibacterial and antioxidant functions.Thus,they can improve the above-mentioned defects of pure collagen films.On basis of this situation,this study prepared edible packaging films using dried bovine-limed hide collagen fibers as the raw material and tea polyphenols or a combination of tea polyphenols and dialdehyde starch as the modifying agents,aiming to improve the mechanical properties,water resistance,antioxidant,and antibacterial performance properties of pure collagen film.The specific research work is described as follows:Preparation and properties of tea polyphenol modified collagen edible packaging films(CCFs)from dried bovine-limed hide fibers.The dried bovinelimed collagen fibers were subjected to rehydration,acid swelling,and pulping treatment,and then fully blended with different mass concentrations(0-20 wt%)of tea polyphenols and 30 wt%glycerol,respectively(amounts of the above materials were all based on the dry mass of collagen).A series of tea polyphenol modified dried bovine-limed hide collagen edible packaging films(CCFs)were prepared by solution casting method,and then characterized by UV spectrophotometry,thermogravimetric analysis,differential scanning calorimetry,water contact angle measurement,and tensile testing machine to illustrate the optical properties,thermal properties,hydrophobicity,and mechanical properties of CCFs.Results showed the transmittance of CCFs decreased and the UV barrier performance increased with the gradual increase of the tea polyphenols amount.The thermal stability of CCFs increased with the increasing amount of the tea polyphenols usage.However,the water content in the films first decreased and then slightly increased,and the water vapor transmittance decreased from 1138 g/m2·day to 843 g/m2·day,while the water contact angle increased from 93.4° to 124.3°,which demonstrates that the hydrophobicity of the films is gradually increased and the water vapor barrier increases.The tensile strength of the films increased from 8.53 MPa to 30 MPa and then decreased to 18 MPa,while the elongation continued to decrease with the increasing amount of tea polyphenols.But the antioxidant and antibacterial properties of the films were gradually improved with the increasing amount of tea polyphenols.This indicates that the mechanical properties and water resistance of the collagen edible packaging films can significantly be improved by using 10 wt%tea polyphenols modification.Furthermore,it can be endowed with multiple functions such as UV resistance,oxidation resistance,and antibacterial.Preparation and properties of tea polyphenol/dialdehyde starch modified collagen edible packaging films(TP/DAS/CCF)from dried bovine-limed hide fibers.A series of tea polyphenols/dialdehyde starch modified collagen edible packaging films(TP/DAS/CCF)from dried bovine-limed hide fibers were prepared using the same method by fully blending 10 wt%tea polyphenols,30 wt%glycerol,and different mass concentrations(0-4 wt%)of dialdehyde starch with collagen fibers.The optical,thermal,hydrophobic,mechanical,and functional properties of a series of TP/DAS/CCF were investigated using the abovementioned instruments.Results showed that the transmittance of TP/DAS/CCF slightly increased while the UV barrier performance slightly decreased with the increase of DAS content.Thermal stability of TP/DAS/CCF was enhanced.Compared to the CCFs.the water content of TP/DAS/CCF increased from 20.35%to 35.52%,and the water vapor permeability slightly increased to 1094 g/m2·day,but they were still lower than those of pure collagen film.Those results suggest that the TP/DAS/CCF has a certain water vapor barrier.More importantly,due to the synergistic cross-linking of collagen fibers with TP and DAS,the tensile strength and elongation at break of TP/DAS/CCF were reached to 52.23 MPa and 72%,which were higher than those of pure collagen films and CCFs.With the increase of DAS dosage,the antioxidant property of the films gradually increased while the antibacterial property gradually decreased.This indicates that the use of tea polyphenols and dialdehyde starch can significantly improve the mechanical properties and thermal stability of collagen edible packaging films due to synergistic modification,and the films also have certain multifunctional properties such as UV resistance and oxidation resistance. |
PDF Full Text Request