• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.583-587
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• 2011

This study evaluated the quality characteristics of yukwa pellets and yukwa bases on the ratio of soju addition (0, 25, 50, 75, and 100% v/v). Yukwa base with 50% ratio of soju addition displayed the highest diameter, volume and specific volume. The yukwa base with 75% ratio of soju addition displayed the longest in length. The weight of yukwa base increased as the ratio of soju increased. Lightness increased in yukwa pellet and yukwa base as the ratio of soju increased. Lightness of yukwa base was higher than yukwa pellet, but yellowness and redness of yukwa base were lower than yukwa pellet. Air cell size of yukwa base decreased as the ratio of soju increased. The compression and cutting force of yukwa base with 50% ratio of soju addition were lowest, while yukwa base with 0% soju was highest. In the sensory evaluation, preference of color increased as the ratio of soju addition increased. Yukwa base with 50% ratio of soju addition was the highest in internal compactness, mouth-feel, and overall preference. The results show that a soju ratio of 50-75% addition for total liquid is useful in the production of high quality yukwa base.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.5
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• pp.407-417
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• 2016

Effects of resistant starch as a functional substitute on the quality of Yukwa were determined. Replacement ratios of resistant starch were 2, 4, and 6% of glutinous rice flour. Regarding pasting properties of Yukwa dough replaced with resistant starch, initial pasting temperature significantly increased and peak viscosity significantly decreased with increasing resistant starch. The moisture contents of bandegi and Yukwa base replaced with resistant starch were higher than that of the control. The expansion ratio of Yukwa base replaced with resistant starch significantly decreased with increasing resistant starch, and there were no significant differences in the oil absorption ratio. Lightness (L) of Yukwa base replaced with resistant starch increased significantly with increasing resistant starch. Appearance of Yukwa base replaced with resistant starch showed a shortened length and increased width with increasing resistant starch, and cross-section showed an oval shape, fine air cell distribution, and increased outer layer thickness. Hardness and peak number increased significantly with increasing resistant starch. The overall acceptability of Yukwa base replaced with 6% resistant starch was the highest among the samples, but the result was not significant. The above results show that resistant starch substitution in Yukwa improved the texture and further could improve health functionality due to its dietary fiber content. Resistant starch was appropriate as a 6% replacement for glutinous rice flour in Yukwa.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.6
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• pp.1029-1040
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• 2015

Effects of punching and drying process on quality of Yukwa were determined. Lightness (L) of Yukwa dough with punching was higher than that with no punching. Air cell distribution of Yukwa dough was fine with higher punching. Microstructure of Yukwa dough showed a broken surface structure with increasing punching. Hardness and adhesiveness of Yukwa dough decreased after 5 min of punching and then increased with higher punching. Expansion ratio of Yukwa base with punching at 155 rpm for 5 min was highest among the samples. Appearance of Yukwa base with no punching showed a poor shape and cross section, whereas Yukwa base with punching at 95 rpm for 10 min showed the best appearance and cross section and Yukwa base with punching at 155 rpm for 5 min also showed good appearance. The moisture content of Yukwa Bandegi after 24 hr of drying was 14.93%. Microstructure of Yukwa Bandegi showed a broken surface structure and empty spaces with increased drying time. Expansion ratio of Yukwa base with 24 hr of drying at $40^{\circ}C$ was highest among the samples. Overall, optimum punching conditions were 10 min of punching at 95 rpm or 5 min of punching at 155 rpm and optimum drying condition was 24 hr of drying at $40^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.12
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• pp.1760-1766
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• 2009

Physical properties of Yukwa base extruded with glutinous rice flour, rice flour, defatted soy flour, and salt using an twin-screw extruder were investigated. The ingredients were extruded at various moisture contents (16-18%), screw speeds (300 & 400 rpm) at 43.4 kg/hr feed rate. Length and specific volume of Yukwa base increased with decreasing moisture contents. Hunter's color L* values of Yukwa base was higher whereas $a^*\;and\;b^*$ values were lower with increasing moisture content. Water absorption index of Yukwa base increased with increasing moisture contents. X-ray diffraction of Yukwa base showed B type moisture content of 16% and 17% while it showed A type moisture content of 18%. Degree of crystallinity and breaking strength of Yukwa base were the lowest in the moisture content of 16% while the lowest value for hardness was found in the moisture content of 16% and of 17% with screw speed 400 rpm for all samples. In the microstructure of cross section of Yukwa base, air cell size was larger and cell wall was thicker as moisture content increased. The sensory evaluation of the Yukwa base showed that color and flavor were not significantly different among samples, while taste, appearance, mouth feel, and overall preference were higher as moisture contents decreased.

• Korean journal of food and cookery science
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• v.19 no.6
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• pp.729-736
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• 2003

This study was performed to improve the quality and extend the shelf life of Yukwa and Salyeotgangjung, traditional Korean cookies, by using fine hot salt instead of oil as the popping medium. Yukwa and Salyeotgangjung were popped with fine salt, and the size, sensory evaluation, color values and textural properties were then compared with those popped in oil. The results showed that the Yukwa base with salt was popped the most at 140C and the rice was popped at 240C. The Yukwa base in salts was smaller in size and larger in density than in oil but the popped rice in salts had a similar size and a smaller density than that popped in oil. In the sensory test, the Yukwa base and popped rice expanded in the salts were preferred to those popped in oil but there was little difference in only popped rice. In terms of color, there was a difference between those popped in salt and in oil. In terms of texture, only popped rice expanded in the salts was harder than in oil, and the Yukwa popped in oil was more cohesive than in the salts. In brittleness, there were no differences between in salt and in oil.

• Korean journal of food and cookery science
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• v.20 no.5
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• pp.462-467
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• 2004

This study was carried out to improve the qualities and extend the shelf life of Yukwa and Salyeotgangjung, traditional Korean cookies, using fine hot salt instead of oil as the popping medium. The Yukwa and Salyeotgangjung that had been popped using fine salt were stored at 25\ulcornerfor one or two months, and then compared their sensory evaluation, lipid contents and acid and peroxide values with those popped in oil. In the sensory test, the Yukwa base and popped rice expanded in the salts and stored for one month were preferred to those expanded in oil with regard to flavor and overall acceptability. With respect to the whiteness, off-flavor, and crispness, these properties those expanded in salt had stronger whiteness and crispness but a weaker off-flavor compared to those expanded in oil. The lipid contents of the Yukwa base and popped rice expanded in oil were 37.73 and 49.65%, respectively, which were significantly higher than in those expanded in salts (0.10 and 0.53%, respectively). The acid and peroxide values were larger in those expanded oil than in salts after 8 weeks storage. In view of the above results, the conclusion was reached that the Yukwa base and popped rice expanded in salts were less likely to provide a calorie intake and to become rancid over a long storage time.

• Korean journal of food and cookery science
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• v.24 no.3
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• pp.340-348
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• 2008

The purpose of this study was to develop new method for the manufacture of Yukwa, a Korean oil-puffed rice snack with a soft texture, using a far infrared ray electric roaster. The Yukwa base is traditionally expanded using oil, but the Yukwa base tends to develop unpleasant rancid odors or off-flavors during storage. In this study, the DPPH radical scavenging activity of mugwort powder was evaluated. Baked and fried Yukwa samples were added with 0.5, 1.0, 1.5, and 2.0% of mugwort powder and left untreated as a control, and then tested for moisture content, expansion rate, color, hardness, and sensory evaluations. The samples with higher concentrations of mugwort powder, evidenced a more profound tendency toward DPPH radical scavenging activity. The moisture content of Yukwa dough tended to increase with the addition of mugwort powder. As the mugwort powder content increased, the moisture contents of the Yukwa base and the Baked Yukwa increased. The moisture content and expansion rates of the fried Yukwa did not differ significantly. The samples containing the mugwort power evidenced a lower expansion rate than was observed in the control group. The lightness of the baked and fried Yukwa was reduced with increased mugwort powder content. The greenness of the baked and fried Yukwa was at a minimum upon the addition of 2.0% mugwort powder. The yellowness of the baked Yukwa did not differ significantly between the samples. As the mugwort powder content increased, the yellowness of the fried Yukwa increased. The hardness of the baked and fried Yukwa tended to increase with the addition of mugwort powder. In the sensory evaluations, the baked Yukwa scored higher than the fried Yukwa, and all of the sensory characteristics of baked Yukwa scored highest in the samples without mugwort powder, but also scored fairly well with 1.0 and 1.5% mugwort powder. In conclusion, these results demonstrated that 1.0～1.5% of mugwort powder should be added to Yukwa baked in a far infrared ray electrical roaster in order to optimize physiological functions and keep overall acceptability reasonably high.

• Korean journal of food and cookery science
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• v.18 no.5
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• pp.529-533
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• 2002

Yukwa was prepared with the glutinous rice by the addition of different ratio of pigmented rice (0, 3, 5, 7, 10%) and were steeped for 7 days at 20$^{\circ}C$. No significant differences were found among the samples when the textural properties of Yukwa dough and base were measured using a texture analyzer. But the crispness was decreased with tile increase of the addition level of pigmented rice. The redness (a value) and yellowness (b value) of the dough and Yukwa base were increased and the lightness (L value) was decreased as the addition levels increased. The expansion rate of Yukwa was decreased with the increase of addition levels. The overall acceptability of Yukwa prepared with the addition of 7% pigmented rice was the best in the sensory evaluation.

• The Korean Journal of Community Living Science
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• v.24 no.2
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• pp.251-258
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• 2013

Korean oil and honey Yukwa has been paid attention as formal cake for traditional national seasons' holiday and religious service. Quality of Yukwa, however, has been maintained arbitrarily by each Yukwa manufacturer. Since even same Yukwa had severe differences in size, weight, and pattern, it has given the negative effect to the consumer. Yukwa industries need to setup the quantitative quality specifications instead of qualitative ones to maintain the uniformity of Yukwa quality. Efficient and economical inspection and process control system should be developed. In developing quality standards of Yukwa, features which can measure quality quantitatively in real time should be properly chosen. Existing quality features such as acidity, oxidization, hardness, viscosity, and texture were measured by the chemical or physical base destructive methods. Many research and developments have been performed in investigating and analyzing chemical transition states of those quality features as environment or storage condition changes. Most methods, however, require either off-line or complex treatment or time consuming process of analysis in evaluating quality features. Consumer, however, selects products mostly based on the external features such as shape, size, and color. Therefore, critical visual quality features should be chosen and the efficient real time measurement system must be developed. In this paper, computer image acquisition and processing system were developed and software modules were developed to extract the quantitative data of those features in real-time. Computer image processing system will promote in maintaining uniform quality of Yukwa and establishing quality standards of Yukwa.

• Korean journal of food and cookery science
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• v.24 no.3
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• pp.382-391
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• 2008

Yukwa samples, made with additions of 0, 10, 20, and 30% Rubus coreanus Miquel extract, were puffed by different puffing methods(convection oven, microwave oven, and fryer) and were then examined for quality characteristics such as moisture content, expansion rate, color, hardness, and sensory qualities, in order to determine the optimal ratio of Rubus coreanus Miquel extract in the formulation and the optimal expansion of Yukwa. The moisture contents of Yukwa base increased as the level of Rubus coreanus Miquel extract increased. And the Yukwa puffed by convection had higher moisture than the samples puffed by microwave oven or frying, with the exception of the sample containing 20% Rubus coreanus Miquel extract. When comparing the expansion rates of samples, no significant differences were found between the control and extract-containing samples puffed by convection, microwave, and frying methods, respectively. However, the sample puffed by frying had the highest expansion rate, whereas the convection-, microwave-puffed samples showed no significant differences. In the convection-, microwave-, and fryer-puffed samples, lightness and yellowness decreased, but redness increased, as the level of Rubus coreanus Miquel extract increased. And the sample puffed by microwave oven had greater lightness as compared to the samples puffed by convection and frying. In terms of hardness, no significant differences were found the control and extract-containing samples puffed by convection and microwave methods. However, hardness was maximal in the sample puffed by convection and lowest in the sample puffed by frying, in which it increased according to the addition of Rubus coreanus Miquel extract. In the consumer acceptance evaluations and characteristics intensity rating tests, the samples puffed using convection and microwave methods showed higher scores for the majority of evaluated characteristics as compared to the samples puffed by frying. And the samples containing Rubus coreanus Miquel extract obtained fairly good scores. In conclusion, the results indicate that additions of 10$\sim$20% Rubus coreanus Miquel extract are optimal for Yukwa that is puffed by convection and microwave methods, as this range provides good physiological properties and reasonably high overall consumer acceptability.