Earticle

Fruit and vegetables are subjected to complex dynamic stresses in the transportation environment. During a long journey from the production area to customers using parcel delivery service, there is always some degree of vibration present. Vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serous fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonance frequencies of the fruit and vegetables may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. Instrumentation and technologies are described for determining the vibration response characteristics of the fruits with frequency range 3 to 150 Hz. The resonance frequency of the pear ranged from 53 to 102 Hz and the amplitude at resonance was between 1.08 and 2.48 G. The resonance frequency and amplitude at resonance decreased with the increase of the sample mass, and they were slightly affected by mechanical properties such as bioyield deformation and rupture deformation. Regression analysis was performed among the relatively high correlated parameters from the results of correlation coefficient analysis.

RTE(ready-to-eat)형 전자레인지 가열용 제품들의 가열 조리시 특정 부위의 열 변형이 발생하여 전자레인지 포장재 의 재질 및 형태별 가열 패턴을 조사하였다. 국내에서 유통되고 있는 시료 9종 중 5개의 시 료에서 열 변형이 발생되었 고, 국외에서 유통되고 있는 시료 11종 중 8종에서 열 변형 이 발생되었다. 국외 시료의 경우 국내 시료보다 열 변형 정 도는 덜 하였지만 일부 발생되는 것을 확인하였다. 또한 트 레이 타입 용기에 열 변형이 발생하는 소스를 담고 전자레 인지로 가열하였을 때도 리드지 및 컵에서 열 변형이 관찰 되었다. 국내외에서 유통되고 있는 전자레인지 가열용 제품 의 염도, 당도, pH 및 점도를 측정한 결과 열 변형 발생 유 무 및 정도에 따른 일정한 경향은 없었다. 하지만 극히 낮거 나 높은 점도를 가진 시료에서 열 변형이 나타나지 않았고 내용물의 형태 및 포장재의 형태에 따라 열 변형의 차이가 있었다. 따라서 제품의 열 전환 및 열전달을 고려하여 포장 재의 깊이 등 설계를 반영하여 포장 내 전자파의 집중을 방 지하는 등의 기술 도입이 필요할 것으로 판단된다.

Thermal deformation of packaging materials was observed in some ready-to-eat food products for microwave use. Therefore, the deformation patterns depending on packaging types and shapes of 9 domestic and 11 foreign products after microwave heating were investigated. Among the domestic and foreign products, thermal deformations of packaging material were observed in 5 and 8 samples, respectively. Besides, thermal deformation occurred on the lid and cup body of tray filled with a spicy chicken sauce after having microwaved where previously no deformation had been observed with other food types. No consistent results of thermal deformation were obtained by the analysis of salinity, brix, pH and viscosity of RTE products for microwave heating. However, thermal deformations of packages were less found in the packages used for the RTE foods contained very high or low viscosity than those with medium viscosity. Furthermore, the degree of thermal deformations was dependent on the food composition and shape as well as package type. In order to prevent the thermal deformation of packaging materials, therefore, technological advances and further studies are required to develop the heat-resistant packaging system and to improve the non- uniformity during microwave heating of RTE foods.

This work focused on the study of thermal properties and kinetic behavior of LDPE- nanoclay composite films. The effect of nanoclay content (0.5, 1, 3, and 5 wt%) on thermal stability and crystallization characteristics of the nanocomposites were investigated by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results from endothermic curve showed that the nanoclay played an important role in the crystallization of nanocomposites by acting as nucleating agent. From exothermic curve, there was a crystallization temperature shift which was attributed to crystallization process induced by nanoclay. The TGA results showed that the addition of nanoclay significantly increased the thermal stability of LDPE matrix, which was likely due to the characteristic of layered silicates/ clays dispersed in LDPE matrix as well as the formation of multilayered carbonaceous- silicate char. A well-known Coats- Redfern method was used to evaluate the decomposition activation energy of nanocomposite. It was demonstrated that introducing of nanoclay to LDPE matrix escalated the activation energy of nanocomposite decomposition resulting in thermal stability improvement.

In this experiment, sliced yams (5 mm size) were used for research. Alcohol treatment and blanching treatment were used in this experiments. Color change, hardness, microorganism total count, and PPO activity of the packaged yam were measured. In result, colors of the treated yam were significantly changed in alcohol treatment with different concentration. 5% alcohol treatment is better than 10% alcohol treatment in browning inhibition of fresh-cut yam. But in blanching treatment, color change had no significant different. PPO activity of 1 min blanching packaged yam were decreased 50% and PPO activity of 5 min blanching packaged yam were decreased 85%. In the case of hardness were decreased in both experimental groups. especially 1 min, 3 min and 5 min blanching films, hardness were decreased more than 10 N. Also, both treatments are inhibited the growth of microorganisms effectively.