• Korean Journal of Food Science and Technology
• /
• v.34 no.1
• /
• pp.91-95
• /
• 2002

Effects of freeze-drying time on the microbiological, sensory, and other characteristics of freeze-dried kimchi were investigated to optimize freeze-drying time for kimchi. Quality attributes of freeze-dried kimchi, including number of lactic acid bacteria (LAB), pH, sensory properties, brittleness, rehydration property, moisture content, and microstructure of Chinese cabbage were observed for 24, 48 and 72 h, respectively. Number of LAB and pH of the kimchi freeze-dried for 24 h were significantly changed in comparison with those of the kimchi not freeze-dried. However, further freeze-drying did not change markedly number of LAB and pH. Overall acceptability of the sample freeze-dried for 48 of 72 h was better than that of the sample freeze-dried for 24 h. As freeze-drying time increased, brittleness of the dried sample increased, and rehydration property was improved while dried weight and moisture content of the sample decreased. In conclusion, the sample freeze-dried for 48 h was better than the sample freeze-dried for 24 or 72 h, based on sensory properties and other characteristics.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2011.05a
• /
• pp.95-95
• /
• 2011

도막의 건조는 용액의 조건, 설비특성, 제품의 요구특성에 맞게 다양하게 적용되고 있다. 일반적으로 열풍에 의한 건조방식이 적용되고 있으나 Induction Heater, UV, EB 및 NIR방식 등 다양한 건조방식이 적용되고 있다. 여기서는 건조방법중 NIR에 의한 건조방식을 이용하여 품질특성에 미치는 인자를 검토하였다.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.1
• /
• pp.58-66
• /
• 2016

This study was performed to investigate drying characteristics and quality properties of dried persimmon with vacuum drying process. Drying characteristic curve of the dried persimmon showed that the constant rate drying period and falling rate drying period exist definitely. $_{\circ}Brix$, sugar content and hardness value of the dried persimmon increased as the vacuum pressure and heating temperature increased, but L value of the dried persimmon lower. The results indicated that the optimal conditions were at vacuum pressure of 40~50kPa abs., heating temperature of $30^{\circ}C$ and drying time of 3~4days.

• Korean Journal of Food Science and Technology
• /
• v.28 no.6
• /
• pp.1126-1134
• /
• 1996

The physical characteristics changes of carrots during drying were studied to minimize the quality degradation by applying improved drying process and pretreatment method. Physico-chemical properties of the product were analyzed, and then, drying mechanisms were explained by diffusion coefficients and drying models. In hot air drying process, the drying and rehydration efficiencies were high at low relative humidity and high temperature. Browning degree and specific volume also showed similar trend to drying efficiency. Diffusion coefficient, which describes moisture transfer, was also high at low relative humidity and at high temperature. It was verified using. Arrhenius equation that drying process was influenced by temperature. It was also observed during experiment that temperature changes were more effective in drying than relative humidity changes. Quadratic model was the most fittable in explaining the process. As a result of analyzing the experimental data with respect to the drying time, the contents of carotene and moisture could be modeled as a polynomial. As the air velocity increased, drying performance and rehydration efficiency increased.

• Korean Journal of Poultry Science
• /
• v.20 no.3
• /
• pp.141-149
• /
• 1993

In order to develop a poultry manure dryer, a pilot dryer was designed and drying experiments were conducted to investigate the drying characteristics of poultry manure. According to the results, the pilot dryer could be operated without any air pollution problems. When poultry manure was dried from 79.2%(w.b. basis) moisture content, the final moisture content ranged from 38.7% to 57.9% depending upon the drying conditions. The drying results showed that drying rate was 189.8~198.0 kg/h and moisture evaporation rate was 124.0~125.4kg-$H_2$O/L. For this drying, electricity requirement was 9.5~19.3 Wh/kg and fuel consumption rate was 6.9~9.3 kg-$H_2$O/L with 50.2~65.1% thermal efficiency.

• Food Science and Preservation
• /
• v.12 no.5
• /
• pp.417-423
• /
• 2005

To replace the traditional drying method with improving the qualities of dried squid, warm air drying method was investigated comparing with natural drying method. In respect of drying rate, about 12 hrs were taken to obtain 25% moisture content -which was considered as proper moisture content to control microbial and quality degradation- by warm air drying at 35$^{\circ}C$. However, 120 hrs were taken to obtain such moisture content by natural drying. The squid dried by warm air showed little color difference and was seemed to be raw squid meat color. TBA values were more rapidly increased but final values were lower, inversely. Free amino acid contents were higher, and cholesterol content was lower in warm air drying.

• Food Science and Preservation
• /
• v.6 no.3
• /
• pp.319-323
• /
• 1999

This study was conducted to minimize the deterioration of dried kiwifruit quality. Osmotic dehydration was carried out as pretreatment before drying. After the kiwifruits were pretreated under optimized osmotic dehydration conditions, they were dried by three drying methods(hot air drying, vacuum drying, freeze drying). Hot air drying and vacuum drying were superior to freeze drying in the drying speed. But vacuum and freeze drying preserved more vitamin C than hot air drying. Also, osmotic dehydrated kiwifruit kept better quality than nontreated kiwifruit. Diffusion coefficient which describes moisture transfer, was high in drying process pretreated with osmosis. The changes of vitamin-C followed the second-order reaction rate equation with high RE, respectively.

• Korean Journal of Food Science and Technology
• /
• v.33 no.2
• /
• pp.245-251
• /
• 2001

This research was conducted to study the changes in physical characteristics of mushrooms (Agaricus bisporus) as influenced by drying methods. Samples were dried using either hot air drying, vacuum drying, or freeze drying and changes in the color, browning index, hardness and rehydration rate were evaluated by response surface methodology. Hot air drying resulted in the fastest drying of sample as compared to other methods. The rate of drying was most affected by the environmental temperature rather than air velocity or vacuum pressure. The overall color difference increased as the temperature and air velocity increased. The overall color changes of the freeze dried samples were minimal as compared to those of fresh mushrooms. The hot air dried samples showed the greatest changes in the overall color, browning index as well as hardness. The freeze dried samples showed the best rehydration characteristic and maintained the best overall quality after drying.

• Culinary science and hospitality research
• /
• v.22 no.2
• /
• pp.104-114
• /
• 2016

In this study, the quality characteristics of different drying methods of Cirsium setidens Nakai, which contains large amounts of biological substances, were investigated for the improvement of their practical use. During the drying period, the weight reduction was the highest with hot-air drying(82.7%). As for the general component and mineral contents analysis results of Cirsium setidens Nakai, there were no significant difference. Cyclic low pressure drying resulted highest amount of total phenolic components and 1,1-diphenyl-2-picrylhydrazyl (DPPH). Hence, cyclic low pressure drying method is the best method for enhancing antioxidant activity of Cirsium setidens Nakai.

• Korean Journal of Food Science and Technology
• /
• v.30 no.4
• /
• pp.877-882
• /
• 1998

To establish optimum drying methods for Korean yam, freeze drying, cool air drying and hot air drying methods were compared by determining some quality criteria. The native color, odor, taste and viscosity of raw yam were preserved by only freeze drying at less than $40^{\circ}C$. The native white color of yam changed to brown and odor and taste of yam decreased largely by cool air drying and hot air drying. Especially cooked and roasted flavor was developed in hot air dried yam. The viscosity of cool and hot air dried yam was about half than that of freeze dried yam. Conclusively freeze drying method was shown optimum to preserve quality properties of yam such as viscosity, color, odor and taste. The physical properties of yam powder such as dispersiveness and solubility was the best in $40{\sim}60{\;}mesh$ particle size.