• Korean Journal of Food Science and Technology
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• v.46 no.5
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• pp.636-640
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• 2014

This study was conducted to provide basic information about the drying methods (daylight, hot-air, and freeze drying) used for Platycodon grandiflorum radix. We investigated the mineral, free sugar, and saponin contents of dried P. grandiflorum. The potassium and calcium contents of hot-air-dried samples were the highest (22.6 and 9.2 mg%, respectively), when compared to those of daylight- or freeze-dried samples. Glucose and sucrose contents were the highest in freeze-dried samples (1,552 and 145.0 mg%, respectively), while fructose content was the highest in hot-air-dried samples (611.9 mg%). Platycodin D content was the highest in hot-air-dried samples (622.0 mg%); however platycodin D3, polygalacin D, and deapioplatycodin D contents were the highest in daylight-dried plant (113.5, 756.6, and 109.2 mg%, respectively). Glucose content was highly negatively correlated (p<0.01) with platycodin D, platycodin D3, and deapioplatycodin D (-0.924, -0.957, -0.861, p<0.01, respectively). These results suggest that the drying method affects the saponin content of P. grandiflorum and daylight and hot-air drying methods are more suitable and beneficial than freeze-drying.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.67-73
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• 2014

Mulberry fruits were semi-dried using hot air ($60-100^{\circ}C$) or cool air ($20-40^{\circ}C$), and the effects of the drying temperature and processing time on the quality of the final dried mulberry fruits were investigated. Response surface methodology was employed to establish a statistical model and predict the conditions resulting in minimal loss of the total phenolic content (TPC) and ascorbic acid. Thus, using overlapped contour plots, the optimal conditions for producing semi-dried mulberry fruits, which reduced the moisture residue to 45% and minimized the nutrient losses of TPC and ascorbic acid, were determined for the hot-air process ($60.7^{\circ}C$ for 5.4 h) and cool-air process ($34.8^{\circ}C$ for 23.3 h). Plus, a higher drying temperature was found to lead to a faster loss of moisture and ascorbic acid, while the TPC was significantly decreased in the cool-air dried mulberry fruits due to the higher activity of polyphenol oxidase between 30 and $40^{\circ}C$.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1191-1196
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• 2006

Analysis of drying characteristics has been carried out with one-dimensional model in the dryer using the principle of the refraction of radiation. The dryer is composed of hot water tank, a plastic film conveyer belt, drying material, etc. The model considers the conduction and radiation within the plastic film and drying material. The film is semitransparent to radiation and the drying material is assumed to be semitransparent or opaque to radiation. The results shows that the effect of radiative transfer on the drying rate is relatively large when the thickness of drying material is small and the water temperature is high. When the material is thin, the drying rate by only conduction is also enhanced so that drying time can considerably be reduced.

• Food Science and Preservation
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• v.2 no.1
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• pp.155-161
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• 1995

We examined the drying characteristics and the drying rate model equation of garlic(allium sativum L.) using computer aided convective drying. The drying chanacteristic curve of garlic divided into constant rate drying period and 2 stage of falling rate drying period. The drying rate was fairly affected by hot air temperatures during the total drying period, but air flow rates has nearly no effect on the drying rate except initial drying period. Of the several model equation, r2 values of page model equation was the highest, and the estimated drying profiles were comparatively coincided with the observed drying profiles. Page model equation was suitable to predict the drying rate and moisture content during drying of sliced garlic.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.227-232
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• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) of moisture contents to 16.7%(w.b), by prototype dryer and the average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to a conventional natural air dryer in which grains were not mixed during drying periods. The dryer performance evaluation index was 738.3kJ/(kg.water), which was more effective than that of grain circulation type hot air dryer(3,500∼5,000 kJ/kg.water)

• Korean Journal of Medicinal Crop Science
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• v.19 no.5
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• pp.354-361
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• 2011

In order to product dry goods of Gastrodiae Rhizoma with high quality, tubers were treated with various dry methods such as cutting, drying methods and steaming. In cutting than no cutting, they were shown shorter drying hours and lower drying yield. Drying hours in freeze drying was shorter than those of hot air and far-infrared ray. Total polyphenol content was higher in cutting than no cutting. According to steaming, it was increased in freeze drying but decreased rapidly in the other dry methods. Among all treatments, hot air dry treatment with cutting and no steaming had the highest total polyphenol content. Gastrodin and 4-hydroxybenzyl alcohol contents generally were similar or higher in cutting than no cutting. By steaming, gastrodin content in freeze drying was decreased but 4-hydroxybenzyl alcohol content was increased. But hot-air and infrared ray dry, they were shown opposite results. Gastrodin and 4-hydroxybenzyl alcohol contents showed opposite reaction to each other and were shown various response by dry methods.

• Korean Journal of Food Science and Technology
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• v.19 no.1
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• pp.5-11
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• 1987

Lipid oxidation is one of the major factors affecting on deterioration of nutritional quality in boiled and dired fish products. In this paper, the relationship between oxidized products of lipid, brown pigments, and available lysine during the drying and the storage of boiled and dried shrimp (Metapenaeus joynri) was investigated. Fresh shrimps were bioled in 5% sodium chloride solution. The boiled shrimps were treated in two ways, sun drying and hot air drying at $30{\pm}5^{\circ}C$. And the two dried products were stored at $30{\pm}5^{\circ}C$ for one month. The results obtained are as follows: TBA value increased up to 20 days and hereafter gradually diminished. POV was increased for processing and increased 15 days of storage. TBA value and POV increased rapidly while available lysine diminished during the sun drying and hot air drying. Brown pigment was increased during lipid oxidation but it was not statistically significant. This result implicits that the drying had greatly influenced on the oxidation of lipid and makes amino acids 'unavailable'. But there is no remarkable difference between the sun dried shrimps and the hot air dried shrimps so far as the lipid oxidation and available lysine.

• Food Science and Preservation
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• v.23 no.5
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• pp.689-695
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• 2016

In this study, the drying characteristics of medicinal (Ganoderma lucidum, Phellinus linteus) and edible (Pleurotus eryngii, Lentinus edodes) mushrooms were investigated. Their shrinkage ratios, Hunter's color values, and rehydration ratios were evaluated. Mushrooms were cut with rectangular (1 cm) and square ($1{\times}1cm$) shapes, and dried in the room temperature and at $50^{\circ}C$ and $70^{\circ}C$ using hot-air dryer. Initial moisture contents of edible mushrooms were higher than those of medicinal mushrooms, whereas final moisture contents were vice versa. Drying rate was the highest when drying at $70^{\circ}C$ (p<0.05). Moreover the drying rate of square slices was higher than that of rectangular slices (p<0.05). The shrinkage ratios of both medicinal mushrooms and edible mushrooms were the least when drying at $50^{\circ}C$ and $70^{\circ}C$, respectively (p<0.05). The changes of color values were less in the medicinal mushrooms dried in the room temperature than in the hot-air dried medicinal mushrooms (p<0.05). However, in case of edible mushrooms, the changes of color values were less in the hot-air dried mushrooms (p<0.05). Rehydration ratios of medicinal mushrooms dried at $50^{\circ}C$ was the highest (p<0.05). In contrast, rehydration ratios of edible mushrooms was the highest when drying in the room temperature (p<0.05). Thus, the hot-air drying at $50^{\circ}C$ would be suggested as the efficient drying method for both medicinal mushrooms and edible mushrooms.

• Culinary science and hospitality research
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• v.20 no.1
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• pp.55-64
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• 2014

This study was performed to determine the effects of drying methods on the quality and physiological activities of blueberry. Blueberries(Vaccinium ashei) were dried by hot-air ($60^{\circ}C$), cyclic low pressure ($50^{\circ}C$), and freeze drying methods. They contained high properties of carbohydrates(68.48~80.00%), crude protein(1.63~5.41%), crude fat(0.58~1.25%), and ash(0.71~1.11%) regardless of the drying methods. There were no differences in pH according to the drying methods. Browning index increased as the drying temperature increased. The L, a values of the freeze-dried sample were higher than those of the other dried samples, whereas the b value of the cyclic low pressure dried sample was higher than that of the other samples. The free sugar contents of the hot-air sample were higher than those of the other samples. Vitamin C content of the freeze dried sample was higher than that of either the hot-air or cyclic low pressure dried sample. The contents of total polyphenols and anthocyanins were higher in the freeze dried sample. The DPPH radical scavenging activity of freeze drying sample was higher than that of either the hot-air or cyclic low pressure dried sample. The result indicated that there were no differences in product quality depending on the freeze-drying and cyclic low pressure drying methods.

• The Korean Journal of Food And Nutrition
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• v.36 no.4
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• pp.327-333
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• 2023

This study investigated the antioxidant characteristics of sweet potato according to different plant parts and drying methods. The sweet potato plant parts were divided into root tubers, stems, stalks, leaves, and tips, and the drying methods were freeze-drying and hot air drying. Total polyphenol and flavonoid contents and radical scavenging activity of the sweet potato plant parts were significantly different depending on the plant parts and drying methods. The total polyphenol content of freeze-dried sweet potato leaves and tips were 52.76 and 46.19 mg chlorogenic acid equivalents/g sample, and the total flavonoid contents were 222.47 and 214.12 mg quercetin equivalents/g sample, respectively, and decreased with hot air drying. DPPH radical scavenging activity was higher in freeze-drying than hot air drying and was significantly different depending on the plant parts. The ABTS radical scavenging activity of freeze-dried sweet potato leaves and tips were 43.48 and 44.68 mg Trolox equivalents/g sample, respectively, and decreased with hot air drying. Therefore, additional studies on the functionality of using by-products from sweet potato cultivation are needed.