• Journal of Biosystems Engineering
• /
• v.37 no.2
• /
• pp.82-89
• /
• 2012

Purpose: The simulation model of a pneumatic conveying drying (PCD) for sawdust was developed and verified with the experiments. Method: The thermal behavior and mass transfer of a PCD were modeled and investigated by comparing the experimental results given by a reference (Kamei et al. 1952) to validate the model. Momentum, energy and mass balance, one dimensional first order ordinary differential equations, were coded and solved into Matlab V. 7.1.0 (2009). Results: The simulation results showed that the moisture content reduced from 194% to 40% (dry basis), air temperature decreased from $512^{\circ}C$ to $128^{\circ}C$ with the particle residence time of 0.7 seconds. The statistical indicators, root mean square error and R-squared, were calculated to be 0.079, and 0.998, respectively, between the measured and predicted values of moisture content. The relative error between the measured and predicted values of the final pressured drop, air temperature, and air velocity were only 8.96%, 0.39% and 1.05% respectively. Conclusions: The predicted moisture content, final temperature, and pressure drop values were in good agreement with the experimental results. The developed model can be used for design and estimation of PCD system for drying of wood dust particles.

• Korean Journal of Plant Resources
• /
• v.35 no.6
• /
• pp.778-784
• /
• 2022

Wild vegetables, such as Cirsium setidens, and Aster scaber, are commonly distributed as dried materials because the wild vegetables lose their freshness quickly after harvest and distribution. Dried wild vegetables require rehydration to use as a food ingredient, and the quality of rehydrated wild vegetables is affected by pre-drying and drying methods. Here, we introduce the newly developed pre-drying and drying method, termed "micro oil sprayed thermal air (MOTA) technique". The three wild vegetables processed by the MOTA technique showed improved rehydration rate and reduced time to achieve maximum rehydration rate. Color characteristics were also improved in C. setidens. These results indicate that the MOTA technique improves the overall quality of rehydrated wild vegetables. It is expected that our findings could enhance the marketability of dried wild vegetables by improving overall quality and reducing preparation time.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2022.09a
• /
• pp.115-115
• /
• 2022

The Food and Agriculture Organization (FAO) has been estimating the potential of insects as human food and animal feed for convincing food security since 2010. On account of this reason, Tenebrio molitor larvae have been gaining considerable attention as an alternative protein source for various foods. However, consumers do not prefer them because of their disgusting appearance. Therefore, it is necessary to develop a method that improve their appearance as to lead to T. molitor larvae consumption. In this study, T. molitor larvae which is prepared for optimally sampling conditions (shade drying, 30 min boiling after hot air drying, 30 min steaming after hot air drying), were cultured with Cordyceps militaris mycelia, and measured growth and density of mycelial. Also analyzed the cordycepin and adenosine content compared with commercial C. militaris. As a result, T. molitor larvae cultivated with C. militaris mycelia showed the highest cordycepin content (13.75 mg/g) was observed in optimal sampling conditions (shade drying). Therefore, we report that the methods which T. molitor larvae cultivated with C. militaris mycelia not only improve their appearance but also increase cordycepin content, which can be contributed to lead T. molitor larvae consumption.

• Food Science and Preservation
• /
• v.11 no.4
• /
• pp.508-515
• /
• 2004

In this study, salting conditions and dehydration methods were investigated. Salting time, concentration and temperature could be considered to variables in salting conditions. The diffused salt amounts to beef jerky depending on time are sharply increased in two hours. This result is caused by the difference decrease of concentration gradient between bulk solution and beef jerky. The increase of salting concentration and temperature resulted also in the increase of a diffused salt. The deeper bulk concentration made diffusion to beef easily with the bigger driving force and the movement of molecules is more active according to temperature increase. Dehydration is conducted with various methods such as natural drying, cold air drying and hot air drying. Comparing with color and texture among the drying methods, cold air drying showed superior quality in color and texture. Beef jerky by cold air drying colored more reddish than other drying methods and good cutting shear stress and tensile strength. In case of hardness and chewiness, hot air drying method showed the highest value, which means the worst texture.

• Food Science and Preservation
• /
• v.22 no.1
• /
• pp.1-11
• /
• 2015

Raspberries are a good resource of polyphenols and have a powerful antioxidant activity, but shelf life for raspberries is short which brings a lot of economic losses. In this study, we try to use cool-air ($20{\sim}40^{\circ}C$) or hot-air ($60{\sim}100^{\circ}C$) to produce semi-dried raspberries with extended shelf life, and to determine the best method for improving fruit quality by minimizing nutrient losses during drying processes. The effects of process variables (drying temperature and processing time) on the quality of final dried raspberries were investigated. Response surface methodology was employed to establish statistical models for simulating the drying processes, and the moisture residue content and the loss ratios of total phenolic content (TPC), vitamin C (VC), and ellagic acid (EA) that result from the drying processes of raspberries using either hot or cool-air were predicted. Superimposed contour plots have been successfully used in the determination of the optimum zone within the experimental region. Optimal conditions determined for achieving minimal losses of TPC, VC, and EA, and a final moisture residue of 45% using the hot-air drying process were a drying temperature of $65.75^{\circ}C$ and a processing time of 4.3 hr. While for the cool-air process, the optimal conditions predicted were $21.3^{\circ}C$ and 28.2 hr. Successful application of response surface methodology provided scientific reference for optimal conditions of semi-drying raspberries, minimizing nutrient losses and improving product quality.

• The Korean Journal of Food And Nutrition
• /
• v.34 no.2
• /
• pp.165-173
• /
• 2021

Centella asiatica (CA) has been used as a nutritional plant as well as a traditional herbal medicine around the world. This study, quality component (proximate composition, total polyphenol, and triterpenoid compound), and antioxidant and anti-inflammatory activities of CA dried using various methods were investigated. Proximate compositions of CA with different drying methods included a large amount of carbohydrates, crude protein, crude ash, and crude fiber. Among the drying methods, cold drying provided the highest total polyphenol content and antioxidant activity, while hot-air drying at 75℃ provided the lowest total polyphenol content and antioxidant activity. In addition, when the major triterpenoid compounds of CA were analyzed, the highest content of asiaticoside of triterpenoid glycoside was obtained with all drying methods. With respect to the total triterpenoid, the highest content was obtained with cold drying (68.8 mg/g) whereas natural drying (31.4 mg/g) provided the lowest content. In anti-inflammatory activity of LPS-stimulated RAW 264.7 cells, EtOH extract of cold drying showed a significantly higher inhibitory activity in comparison to the other drying methods. In conclusion, it is considered that the cold drying method is suitable for industrial preparation of functional materials with high physiological ingredients, and antioxidant and anti-inflammatory activities from CA.

• Journal of the Korean Ceramic Society
• /
• v.14 no.3
• /
• pp.163-168
• /
• 1977

As a wet chemical drying process "hot petroleum drying method" was applied and developed for preparing uniformly fine oxide powder with high purity and sinterreactivity. Using this method solution of sulfates was dried in hot petroleum bath (~17$0^{\circ}C$) to sulfate powder from which corresponding mullite doped by Fe3+ ion was formed. Particle size, shape, decomposition by heat, and phase identification of sulfate andoxide powders determined by DTA, TGA, X-ray diffraction, analysis and electron microscopy: sulfate powder prepared by this drying method is an intimate mixture of the amorphous form of uniformly and finely distributed spherical particles (0.05-0.1$\mu$). Mullitization with the sulfate powder occurs at 110$0^{\circ}C$ in air. The morphology of mullite particle made by firing the sulfate powder at 135$0^{\circ}C$ in oxygen atmosphere is granular of 0.1-0.3$\mu$ in size. This drying process proved to be a very effective method for preparing fine, homogeneous, and highly sinterreactive multicomponent oxide powder without conventional ceramic process of mixing, milling, and granulating. This process can be also applied for preparing electronic ceramic materials which are requisite for high purity and homogeneity.mogeneity.

• Journal of Food Hygiene and Safety
• /
• v.18 no.4
• /
• pp.243-250
• /
• 2003

S-methylmethionine, vitamin U levels were affected by cultivars, parts fo Korean Chinese cabbages, and drying methods. Among drying conditions, freeze drying method appeared the best condition to maintain bitamin U content compared to oven and air drying methods. In the case of KOrean Chinese cabbages, outward leaves have high levels of chlorphyll and fiber. From this study, the outward parts contained high levels of vitamin U in two cultivars. Leaf parts were 1.1-21.2 times higher in vitamin U levels than midribs in both cultivars. This difference was shown most distinctively in freeze dried outward parts of Winter Pride cultivar. Like vitmnin U, fee amino acids also showed much higher levels in leaves. Levels of amino acids showed irregulatoy changing patterns at different parts and cultivar of Korean Chinese cabbages with various drying methods, Alanine and threonie appeared relatively aboundant amino acids in most parts of samples. Since no distinctive trends were observed in this rsult, it seems no relationship exists between amon oacids and bitamin U levels. Levels of methionine in differnent parts and cultivars of Korean Chinese cabbages dried with various methods did no show clear relationship with tlevel of vitamin U. Moreover, emthionine was not detected in freeze dired outward leaf parts which were the hithest parts of vitamin U levels in Winter Pride and 55 days cultivar. There were simila levels of methionine between overn and freeze drying. Samples prepared by air drying showed significatly lower levels than those by oven and freeze dryting. Methionine as aprecursor of vitamin U, may play a role in an increase of vitamin U during drying of KOrean Chinese cabbages.

• Korean Journal of Medicinal Crop Science
• /
• v.22 no.4
• /
• pp.255-261
• /
• 2014

Cosmetic activities of the leaves of Curcuma longa L. were compared according to different drying methods, to expand the use of the by-products of Curcuma longa L. The highest extraction yield of 29.4% was obtained from vacuum drying process (VD), whose value was very close to 29.2% from freeze drying process (FD). Relatively lower extraction yield were observed as 24.5% and 25.3% from the raw leaf (RL) as control and hot air drying process (HD). The cytotoxicity was observed lower FD and VD than RL and HD. It shows that cytotoxicity was closely related to cosmetic activities such as tyrosinase and melanin inhibition activities by showing much better cosmetic activities of the extracts from both FD and VD than those from the RL and HD. It was interesting that was differences of the cosmetic activities and cytotoxicity between FD and VD, which implies that VD method should be a more efficient process than FD method in terms of drying time and operation costs: 6 hours vs 24 hours and 3-5 times higher extraction costs in drying. It was observed that VD is more excellent dry method than others. This result could be utilized to effectively dry other soft plant biomass.

• Journal of Power System Engineering
• /
• v.21 no.4
• /
• pp.62-69
• /
• 2017

Because the moist foods like anchovy were appeared lower quality by hot air that occurred the lipid oxidation, the drying system by using the cold air has been used widely. This study has been carried out on the performance improvement according to arrangement angle of baffle and location of air duct in the cold air dryer. The main parameters in this study are the arrangement angles which are without, $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$, and the locations of air duct are without, front, center and back. For this study we have conducted the numerical analysis method using fluent in order to obtain the optimal condition of the drying performance. As the arrangement angle of baffle is increased, the relative humidity is proportionally decreased, the value at $40^{\circ}$ is 42.2% that indicate the reduction of about 4% than without it. After the air duct was installed, the decreased relative humidity is showed within 1%, therefore, the effect of air duct for improving the dry capacity is more large than the arrangement angle of baffle. Finally, we have obtained the optimal conditions that the arrangement angle is $40^{\circ}$ with the air duct for a cold air dryer.