Yanfeng Jiang

Synergistic Antimicrobial Activities of Natural Essential Oils with Chitosan Films

The synergistic antimicrobial activities of three natural essential oils (i.e., clove bud oil, cinnamon oil, and star anise oil) with chitosan films were investigated. Cinnamon oil had the best antimicrobial activity among three oils against Escherichia coli , Staphylococcus aureus , Aspergillus oryzae , and Penicillium digitatum . The chitosan solution exhibited good inhibitory effects on the above bacteria except the fungi, whereas chitosan film had no remarkable antimicrobial activity. The cinnamon oil-chitosan film exhibited a synergetic effect by enhancing the antimicrobial activities of the oil, which might be related to the constant release of the oil. The cinnamon oil-chitosan film had also better antimicrobial activity than the clove bud oil-chitosan film. The results also showed that the compatibility of cinnamon oil with chitosan in film formation was better than that of the clove bud oil with chitosan. However, the incorporated oils modified the mechanical strengths, water vapor transmission rate, moisture content, and solubility of the chitosan film. Furthermore, chemical reaction took place between cinnamon oil and chitosan, whereas phase separation occurred between clove bud oil and chitosan.

Study of the physical properties of whey protein isolate and gelatin composite films.

The relationships between the microstructural and physical properties of the whey protein isolate and gelatin (WPI/gelatin) composite films were investigated in the present work. Through the electrostatic effects at pH 8, WPI and gelatin molecules could form compact aggregates in solution, where a remarkable shrinkage of the gelatin molecules was observed, when the WPI/gelatin mass ratio was close to 50W:50G. FT-IR analysis indicated that hydrogen bonding also involved the aggregation and film-forming process. The melting temperature of the 50W:50G composite film increased by 9 degrees C compared with the single component films. However, this aggregation process also made the film network microstructure discontinuous, and led to a decline of the puncture strength of the film near 50W:50G; in contrast, the deformation and water vapor permeability of the composite films increased with the gelatin content, while the moisture content and solubility did not show significant variations.

Design and characterization of controlled-release edible packaging films prepared with synergistic whey-protein polysaccharide complexes.

This paper describes an investigation into the properties of a doubly emulsified film incorporated with protein-polysaccharide microcapsules, which serves as a multifunctional food packaging film prepared using common edible materials in place of petroleum--based plastics. The relationships between the microstructural properties and controlled release features of a series of water-in-oil-in-water (W/O/W) microcapsulated edible films prepared in thermodynamically incompatible conditions were analyzed. The hydrophilic riboflavin (V(B2)) nano-droplets (13-50 nm) dispersed in α-tocopherol (V(E)) oil phase were embedded in whey protein-polysaccharide (WPs) microcapsules with a shell thickness of 20-56 nm. These microcapsules were then integrated in 103 μm thick WPs films. Different polysaccharides, including gum arabic (GA), low-methoxyl pectin (LMP), and κ-carrageenan (KCG), exhibited different in vitro synergistic effects on the ability of both films to effect enteric controlled release of both vitamins. GA, which showed a strong emulsifying ability, also showed better control of V(E) than other polysaccharides, and the highly charged KCG showed better control of V(B2) than GA did.

Study of the Encapsulation Efficiency and Controlled Release Property of Whey Protein Isolate--Polysaccharide Complexes in W1/O/W2 Double Emulsions

The complexes of whey protein isolate (WPI) with guar gum (GG) or gum arabic (GA) were used to prepare water-oil-water double emulsions. Lipid-soluble vitamin E (VE) and water-soluble vitamin B2 (VB2) were encapsulated together in these two systems. The abilities of these complexes to control the release rates were compared. When the ratio of WPI/polysaccharides increased from 5:0.1 to 5:0.5, the encapsulation efficiency (EE) of VE increased from 73 to 88 percent, and EEVB2 from 61 to 68 percent in WPI-GG system; whereas only minor changes were in both EEVE and EEVB2 in WPI-GA system. In the controlled release study, WPI-GG complexes showed better resistance to the attack of the enzymes than WPI-GA complexes did. These phenomena were attributed to the formation of compact aggregates promoted by electrostatic effects.