• 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 $40^{\circ}C$.

• Korean Journal of Human Ecology
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• v.7 no.2
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• pp.149-159
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• 1998

This study was carried out to examine the role soy milk in the preparation of Yukwa, possibility of substitution of soy milk to isolated soy protein and the effect of drying condition of Yukwa dough on the quality of Yukwa for the purpose of standardization of Yukwa preparation process. Although isolated soy protein did not make any particular effect on the gelatinization characteristics of waxy rice flour, soy milk lowered peak viscosity to half of waxy rice flour. The optimum moisture content of dried Yukwa dough was about 25%, and it can be reached by drying at $60^{\circ}C$ under atmosphere pressure for $4{\sim}5$ hours. On the basis of the results of morphological observations, mechanical and sensory measurement of hardness, and sensory test of the internal structure, mouthfeel and overall acceptability, soy milk was more desirable than isolated soy protein for the quality improvement of yukwa.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.6
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• pp.617-624
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• 1990

Proper processing condition of Yukwa(oil popped rice snack) for mass production and pop-ping mechanism of it were tested with Shinsun (waxy, Japonica type rice) which was excellent for Yukwa making. Optimum steaming time of dough was 15 min among 4 to 60 min and reasonable moisture content of the dough before steaming was 4895 among 48 to 53% which had good and fine texture. Acceptable stirring time of steamed dough was not significantly different among 1 to 4 min, but no stirring with much larger volume was shown very poor and too soft in texture. At the simplification test of milling method, wet milling was better then dry milling in expansion rate and high temperature treatment of dough at 6$0^{\circ}C$ gave negative effect on their quality. Extending high temperature treatment of dough, reducing sugars in the dough increased and it might be caused of starch degradation. In addition of some other protein sources to dough, Yukwa quality were in proportion to the protein content of the beans. At the long term storage of the Yukwa base, moisture absorption was different depending upon RH of atmosphere and the quality of Yukwa was inferior by storage time. By addition of some alcoholic beverage, such as Makkoli, Soju and Chungju, expansion rate and their texture were somewhat improved by increasing addition amount of them from 15% to. 30％ on dough (w/w).

• Journal of the East Asian Society of Dietary Life
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• v.25 no.4
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• pp.643-650
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• 2015

The principal objective of this study was to evaluate the quality of Yukwa prepared with mulberry leaf (Morus alba Linne) powder. The moisture, crude protein, crude lipid, crude ash, dietary fiber, and rutin contents of used mulberry leaf powder were 6.65%, 19.50%, 3.26%, 18.24, 38.91 and 0.54%, respectively. The tested concentrations of mulberry leaf powder were 0, 3, 5, and 7%. The Yukwa were stored at $45^{\circ}C$ for 40 days. Yukwa dough prepared with mulberry leaf powder had a lower pH compared to the control group. As more mulberry leaf powder was added, the spread ratio, moisture content, and volume increased. As more mulberry leaf powder was added, L-value decreased while a and b values increased with increasing mulberry leaf powder content. The hardness of Yukwa made with 7% mulberry leaf powder was the highest among the samples. In the sensory tests, Yukwa with 5% mulberry leaf powder received the highest scores. The acid value and peroxide values were lower in Yukwa prepared with mulberry leaf powder than control. Yukwa prepared with mulberry leaf powder strongly inhibited oxidation of lipids. The thiobarbituric values were lower in Yukwa prepared with 5% mulberry leaf powder than in Yukwa prepared with 3% and 7% mulberry leaf powders and control Yukwa. These results suggest that mulberry leaf powder can be applied to Yukwa to achieve high quality and functionality.

• 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 Korean Society of Food Culture
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• v.29 no.5
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• pp.428-436
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• 2014

This study was conducted to investigate the use of sugar alcohols (sorbitol, erythritol, and xylitol) as alternative sweeteners for replacing sucrose in Yukwa (traditional Korean oil-puffed rice snack). The moisture contents of Bandegi (dried Yukwa dough) and Yukwa containing sugar alcohols were higher than that of control (containing only sucrose). The microstructures of control and Bandegi containing sugar alcohols showed uniformly and finely distributed air holes. Expansion ratio and oil absorption of Yukwa containing sorbitol and 30% erythritol were higher than those of control. Appearance and cross section of control and Yukwa containing sorbitol, 30% erythritol, and 30% xylitol showed a good shape. The lightness (L) of control was significantly lower than Yukwa containing sugar alcohols, whereas redness (a) and yellowness (b) were higher than those in Yukwa containing sugar alcohols. Hardness of Yukwa containing sugar alcohols was significantly lower than that of control, and that of Yukwa containing sorbitol was the lowest. Peak number of Yukwa containing sugar alcohols was significantly lower than that of control, and that of Yukwa containing 60% erythritol and 60% xylitol was the lowest among all samples. In the sensory evaluation, color of control was deepest, whereas that of Yukwa containing 60% xylitol was lightest. Volume and air hole uniformity of Yukwa containing 60% erythritol and 60% xylitol were inferior than those of other samples. Sweetness of Yukwa containing sugar alcohols was lower than that of control, whereas oily flavor was stronger. Hardness of Yukwa containing sugar alcohols was lower than that of control, and Yukwa containing xylitol showed the lowest hardness among the samples. Crispness of Yukwa containing sugar alcohols was lower than that of control. There were no significant differences in overall acceptability between control and Yukwa containing 30% sorbitol and 30% erythritol. Overall, sorbitol and erythritol were appropriate as a 30% replacement for sucrose when preparing Yukwa.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.212-216
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• 1991

Whipping and bandaekee making process were known to a bottle neck for yukwa(deep-fat fried waxy rice snack) making process. For mechanization of the process, a machine was designed and manufactured with conveyer. Some functions of the machine were compared. The continuous whipping and bandaekee making machine was developed by modification of chopper. The chopper was substituted with specially designed plates and die. The newly designed plates were suitable for continuous whipping of dough and making bandaekee without showing any quality different at the final stage. The width and thickness of bandaekee could be controlled by speed of conveyer. The proper conveyer speed was 87.3 mm/sec when amount of extrudate of dough was 221.8 g/sec (MW 51%) from chopper. A shape of knife and plate among components of chopper was not seriously influenced on whipping effect. Expectable thickness of bandaekee for good quality was $3.0{\sim}3.5\;mm$. The number of passing through the chopper was not effected on yukwa quality·but no whipping showed bulky volume with too soft texture.

• 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 Science and Technology
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• v.34 no.4
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• pp.597-603
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• 2002

The analysis of traditional process for a Korean puffed rice snack (Yukwa) is needed to develop an advanced process for Yukwa-making. Steeping and punching (Koarichigi) processes, consume time and labor in Yukwa-making, were analyzed on this study. Steeping of waxy rice at $15^{\circ}C$ for 3 days was required to equilibrate moisture absorption in waxy rice kernel. However, steeping for more than 6 days was required soft texture and small air cell distribution of Yukwa. Protein content at pericarp on endosperm of waxy rice kernel was decreased and starch granule was damaged during steeping. RVA paste viscosity was the highest at 6 day steeping after than decreased. Expansion ratio of Yukwa was increased with the increase in steeping time. Air bubbles in dough after punching were uniformly distributed and kneading energy input was decreased with the increase in steeping time. Soft texture, unique texture of Yukwa could be controlled by controlling steeping time and kneading energy input during punching process.