The combined effect of mild heat treatment during the decontamination process (HT) and active modified atmosphere packaging (active MAP) during cold storage (MA) on browning of fresh-cut celery was examined in this study. A sodium hypochlorite aqueous solution at 50℃ was used for the decontamination treatment and regarded as the medium for the mild heat treatment. The initial gas composition and concentrations of active MAP were 9.0% O2, 13.0% CO2, and 78% N2. The results for 9 days of storage showed that the aerobic plate count (APC, Log10CFU/g) during storage for the solo-MA and HT+MA combination was under 6 and comparatively lower than that of the control and solo-HT. This result indicated that solo-HT had a lower role in reducing bacterial growth. In contrast, solo-HT, similar to solo-MA and HT+MA combination, moderated the variation of the hue angle (H°), which is an index of the degree of browning fresh-cut celery surface during storage. Additionally, the solo-HT and HT+MA combination prevented phenylalanine ammonia-lyase (PAL) activity and the relative increase in apparent polyphenol content, which is associated with the reduction of browning during storage. These results showed that the HT+MA combination could extend the storage stability of fresh-cut celery.
It is important to understand the performance of cleaning procedures properly in food industry. A method for evaluating the performance by using the process capability was developed, in which the cleaning performance value was defined. The method was applied to the cleaning data obtained at a food manufacturing site. Based on the analyzed data the validity and the reliability of the evaluation method and the product specification were discussed.
A simplified method for predicting the effect of temperature on the separation performance by chromatography was developed. As a model separation system, two polyphenol component separation by polymer-resin chromatography with ethanol-water mobile phase was chosen. HETP values as a function of mobile phase velocity for a wide range of temperatures 15-45°C were well correlated by a single universal curve in the dimensionless HETP and the dimensionless velocity plots. A simplified equation that can predict the resolution was derived. The equation includes the temperature dependence of the distribution coefficients and the molecular diffusion coefficients. The relative separation performance (resolution) calculated by this equation showed that the existence of the maximum resolution depends on the temperature dependence of the distribution coefficients. Even when the resolution decreases with temperature, higher temperature operations may be advantageous as both the separation time and the separation volume decrease.