Low water activity foods usually do not support growth of pathogens. However, in recent years, a number of outbreaks associated with low water activity foods occurred, making people have a new understanding of microorganisms about low water activity foods and resulting in the safety of these foods becoming a major concern. Traditional thermal sterilization methods are difficult to be applied in low water activity foods because of its poor heat transfer and strong heat resistance of microorganisms. Radio frequency (RF) is considered as one of the most potential technologies in food industry and has an excellent prospect on content of the advantages of rapid and uniform heating. The Principle of RF-Sterilization is similar to Microwave, but RF has lower frequency and wider wavelength, therefore RF penetration depth is more suitable for Sterilization. For the pre-packaged food, there is few report on the effect of RF on the food and packaging materials. This presentation aims to discuss the influence of RF through comparing to Microwave.

Food quality indicator is a simple device to communicate information of food quality to consumers. Change of specific gas composition in the headspace of food packaging can be considered as a food quality indication. For examples, level of carbon dioxide (CO2) increases in the headspace of packaged kimchi which is fermented over time during storage. The elevated ammonia (NH3) level inside a food package is an indication of spoilage. In this study, CO2 indicators and NH3 indicators were developed to monitor food quality and their performance were evaluated. Especially, the correlation between the food quality change and the indicator change were studied during storage. Two types (chitosan-based and whey protein isolate-based) of CO2 indicators was developed to monitor the CO2 concentration in the headspace of a food package. The CO2 indicators showed a visual change depending on CO2 level in the package headspace and were installed on the packaged kimchi and the packaged makgeolli in order to notify their ripening stage. NH3 indicators were developed to monitor the headspace NH3 concentration in the packaged fishery products such as fermented skate. The NH3 indicators showed a prominent color change depending on NH3 level as the skate was fermented over time. In addition, the polylactic acid (PLA)-based package box installing NH3 indicator was developed for the fermented skate and the color change of the indicator was evaluated at different storage temperatures over time. In conclusion, the gas indicators incorporated into the package was able to simply inform food quality over time.

The purposes of this study are to develop a chitosan suspension for the carbon dioxide (CO2) concentration indication of packaged food and to investigate the changes in the CO2 indication corresponding to 2-amino-2-methylpropan- 1-ol (AMP) or 2-aminoethanol (monoethanolamine, MEA) addition. Chitosan suspension was prepared by adding chitosan (0.1, 0.2, and 0.4%) to distilled water and subsequently the pH of the suspension was adjusted to 7.0 after the addition of AMP or MEA. Changes in the pH and the turbidity of the chitosan suspension were measured over time under exposure in a normal atmosphere or 100% carbon dioxide environment. The pH of the chitosan suspension exposed at 100% carbon dioxide environment decreased rapidly up to approximately 6.3 in the initial CO2 exposure. The transmittance values of 0.1 and 0.2% chitosan suspensions with 5% AMP increased from 32 to 99% and from 19 to 86%, respectively. The addition of 5% AMP improved the visual indication performance of the chitosan suspension since it increased significantly the width of the transmittance value before and after CO2 exposure. The chitosan suspension with AMP has a potential to be used as a quality indicator of the packaged foods which produce carbon dioxide during storage and distribution.

국내 도시락 공장을 조사 분석하여 대량생산에 적합토록 그 문제점을 보완 개선했다. 특히 식품위생법과 건축법상의 공장허가 사항을 고려해서 3가지 면적별로 모델 도시락 공장을 설계하였다. 작업장은 하나의 개방공간에 배치된 기기류를 오염지역, 준청결지역, 청결지역으로 나누어 작업중의 2차오염 문제를 배제시켰고, 기기류는 밥급속냉각기, 냉장고 겸 냉각기를 설치하여 위생안전성을 부여했으며, 청결실에 멸균(집진)기를 설치하여 완제품의 초기 미생물 농도를 줄이고 2차오염 요인을 제거함으로써 위생적인 도시락 생산유통이 가능한 도시락 생산공장을 설계하였다.