Nisin and/or chitosan were coated, in 3% concentrations, onto paper with a binder medium of vinyl acetate–ethylene co‐polymer to provide antimicrobial activity for use in food packaging. The combined use of nisin and chitosan in the coating was an attempt to give a wide antimicrobial spectrum that could inhibit the growth of several food spoilage and poisonous microorganisms. The migration of the preservative from the coatings to water was evaluated at 10°C and related to the suppressed microbial growth in the water and microbial medium. After 8 days, 8.1–8.3% of nisin and 1.0–1.2% of chitosan had migrated, and the migration of each was not affected by the presence of the other. The paper coated with nisin was more effective than the chitosan‐coated paper in inhibiting the Gram‐positive bacterium, Listeria monocytogenes, whereas the latter was more effective against Escherichia coli O157:H7. Combined inclusion of nisin and chitosan in the coating gave antimicrobial activity against both bacterial strains, and could improve the microbial stability of milk and orange juice stored at 10°C. Copyright © 2003 John Wiley & Sons, Ltd.

Nisin was incorporated into binder solutions of acrylic polymer and vinyl acetate-ethylene co-polymer, and then coated on to paper. Diffusive migration of incorporated nisin and the antimicrobial activity of the polymer coatings were investigated in order to understand the way of controlling nisin migration and the extent of microbial suppression by the coated paper. Vinyl acetate±ethylene copolymer exhibited a faster rate and higher degree of migration into aqueous food simulant solutions compared to acrylic polymer, and also exhibited a higher degree of suppression against Micrococcus¯avus ATCC 10240 inoculated into the microbial medium. Addition of NaCl, sugar and citric acid to water signi®cantly reduced the rate of diffusion of nisin in the case of acrylic polymer, while only slight change was observed due to the additive for vinyl acetate-ethylene copolymer. The simulant type slightly affected the equilibrated migration level of nisin. When the nisin-incorporated coatings were in contact with pasteurized milk and orange juice at 10°C, signi®cant suppression of total aerobic bacteria and yeasts was observed without any noticeable difference between the two types of coatings.

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Keeping certain level of carbon dioxide concentration along with a desired oxygen concentration in food packages is helpful in preserving a variety of foods, and thus, active packaging technology to control CO 2 has been reviewed here in perspective of optimized package design. For whatever product packages, tailoring interaction among the gas, food product and packaging material is essential for realization of positive role and function of CO 2 : antimicrobial activity, prevention of oxidation, preferred sensory quality, maintenance of package integrity and extension of shelf life.Gas absorbers, emitters or active valves may be applied for this purpose, and commercial products are available in market. However, these active devices should be applied in harmony with food's CO 2 production and dissolution. Elements or factors involved in the design process are examined by looking over scientific literature.Mass balance relationship combined with dissolution equilibration for active food package has been presented to control CO 2 concentration and package wholesomeness in beneficial and desired way. Atmosphere estimation of roasted coffee packages was presented as case study for tackling the task of attaining the desired condition.

The effectiveness of modifi ed atmosphere packaging (MAP) was evaluated for a combination prepared food (Korean braised green peppers with dry anchovies). From a preliminary storage test of the ready-to-eat dish at 10°C, the aerobic bacterial count on the green peppers was selected as a primary quality index. The effect of MAP with different CO 2 concentrations on the product quality at 10°C was also studied. MAP with a CO 2 concentration of ≥30% extended the lag time and/or reduced the growth rate of bacteria. Finally, the effect of different storage temperatures (5, 10, 15 or 20°C) on the shelf life of the product was investigated. Mathematical modelling of bacterial growth curves under stretch-wrap air packaging and MAP with 60% CO 2 /40% N 2 showed that MAP increased the hypothetical minimum temperature in the square root model that describes the temperature dependence of the lag time and growth rate. MAP conditions of 60% CO 2 /40% N 2 extended the shelf life at 10°C by 130% (to 18.4 days) relative to that achieved with stretch-wrap air packaging (7.9 days) based on the time taken to reach the quality limit of an aerobic bacterial count of 10 5 CFU/g. The relative extension of shelf life achieved with MAP was greater at lower temperatures.

The comprehensive mass balances of differential equations involving gas diffusion and hydraulic convection through package perforation, gas permeation through polymeric film, and produce respiration have commonly been used to predict the atmosphere of perforated fresh produce packages. However, the predictions often suffer from instability, and to circumvent this problem, a simplified diffusion model that omits the convective gas transfer and empirical models based on experimental mass transfer data have been developed and investigated previously by several researchers. This study investigated the potential and limitations of the simplified diffusion model and two empirical models for predicting the atmosphere in perforated produce packages. The simplified diffusion model satisfactorily estimated the atmosphere inside the perforated packages of fresh produce under the aerobic conditions examined. Published empirical models of the mass transfer coefficients of the perforation seem to be valid only for the measured conditions and thus should be used carefully for that specific purpose.