• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.367-372
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• 2008

Yukwa were added with non-fermented tea (Bucho-cha and Okro-cha), semi-fermented tea (Ooreung-cha), and fermented tea (black tea) to investigate the effect of different kinds of tea powder on quality characteristics of Yukwa during storage. Yukwa samples were used for analysis such as crude lipid, moisture, texture, antioxidative property (TBA value), and sensory test. There were no significant differences on crude lipid, moisture, and texture analysis. Green tea powder treatment showed strong antioxidant activity. In particular, antioxidant property of non-fermented tea exhibited a higher antioxidative effect than that of the other samples. Sensory evaluation showed that sensory scores of samples added with non-fermented tea were significantly higher than the other samples, indicating that the addition with 0.1% of non-fermented tea powder could contribute to the improvement of quality and shelf-life of Yukwa during storage.

• Preventive Nutrition and Food Science
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• v.9 no.2
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• pp.113-120
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• 2004

Selected microbiological and biochemical characteristics of the steeping process for the production of yukwa, a traditional Korean oil-puffed snack made of waxy rice, were investigated during steeping of waxy rice in water for 15 days. The lengthy steeping process was largely predominated by lactic acid bacteria (LAB), particularly, Lactobacillus and Leuconostoc. The predominat type of bacterium isolated was the Y26 strain tentatively identified as Lactobacillus plantarum. The titratable acidity of the steeping medium increased from 0.01 to 1.13%, in parallel with the decrease in pH ranging from 6.3 to 4.2 as the steeping period increased from 0 to 15 days. A high amount of lactic acid and to a much lesser extent, butyric acid, acetic acid, propionic acid, and succinic acid were detected during the steeping process. The amount of reducing sugars in the steeping medium increased from 0.61 to 10.43 mg/mL, whereas sucrose decreased from 0.46 mg% to an undetectable level. Starch degradation products including glucose, maltose and oligosaccharides ranging G3-G7 were not initially noticed, but their content increased during the steeping process until completion. However, no oligosaccharides larger than G8 were detected in the steeping medium. The activities of $\alpha$-amylase, $\beta$-amylase and protease in the steeping medium of waxy rice tended to rise increase with time during the steeping process. From these results, the lengthy steeping process in yukwa production can be characterized as the spontaneous fermentation, dominated by lactic acid bacteria, which is a necessary process for inducing biochemical modification of waxy rice.

• Proceedings of the SOHE Conference
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• 2004.12a
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• pp.87-87
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• 2004

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.452-458
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• 2010

This study aimed at improving the packaging technology of Yukwa to improve the quality and extend the shelflife using secondary packaging. After packaging the Yukwa using an OPP film, P2, P3, and P4 packaging materials were applied secondarily. Various films including (1) P1: OPP (oriented polypropylene), (2) P2: P1+OPP/LLDPE (linear low density polyethylene), (3) P3: P1+PET (polyethylene terephthalate)/NY (nylon)/CPP (cast polypropylene) and (4) P4: P1+PET/AL (aluminum)/NY/CPP (P4) were used for packaging Yukwa. The experiment was conducted at $25^{\circ}C$ for 12 weeks. P1 showed the highest acid value score (1.26 mg KOH/g), and P3 had the highest peroxide value score (32.91 meq/kg) among all packaging groups. Nevertheless, these values did not exceed the guideline values of 2.0 g KOH/g and 40 meq/kg specified in the Korean food code. The overall color difference showed a tendency for decreasing Hunter 'L' values and increasing 'a' and 'b' values; however, no noticeable difference in the outer appearance was observed in any of the packaging treatments except in the P1 for greater than 10 weeks of storage. Some texture defects were observed in the Yukwa when the moisture contents dropped below 5%. The P4 packaging treatment had the lowest moisture permeability and showed the least rheological deterioration change, followed by P3 and P2. In conclusion, the use of a secondary packaging with less gas and moisture permeability was more effective for maintaining the quality and extending the shelf-life of Yukwa than other types of packaging material.

• Journal of the Korean Society of Food Culture
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• v.10 no.2
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• pp.83-88
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• 1995

This study was conducted to examine the effects of additives and drying methods in Yukwa's manufacture. Additives had significant effects on hardness, and bean water and bean powder added group rated better than the baking powder and boiled bean added group. Sensory evaluation test showed that bean water and bean powder added group produced higher desirability. Drying methods had significant effects on all attribute of sensory evaluation, natural drying and incubative plate drying produced higher uniformity, denseness and overall desirability.

• Korean Journal of Food Science and Technology
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• v.38 no.3
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• pp.385-391
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• 2006

Physicochemical properties of hydroxypropylated waxy rice starches were investigated to reduce steeping-time of yukwa (Korean oil-puffed rice snack) processing. Swelling power of hydroxypropylated waxy rice starch increased at relatively higher temperature $(60^{\circ}C)$ than native waxy rice starch $(70^{\circ}C)$. Solubility of hydroxypropylated waxy rice starches increased with increasing propylene oxide content. Pasting temperature $(66.3-66.9^{\circ}C)$ and peak viscosity (216-232 RVU) of hydroxypropylated waxy rice starch were higher than those of native starch (179 RVU) and increased with increasing propylene oxide content. DSC thermal transitions of hydroxypropylated waxy rice starches shifted toward higher temperature. Amylopectin melting enthalpy of hydroxypropylated waxy rice starch (8.4-9.2 J/g) was similar to native starch (9.0 J/g). X-ray diffraction patterns of native and hydroxypropylated waxy rice starches showed typical A-type pattern with no significant differences between them, suggesting hydroxypropylation only affected amorphous region. Results suggest hydroxypropylated waxy rice starch is not applicable for yukwa due to low puffing efficiency and dark color.

• The Korean Journal of Food And Nutrition
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• v.13 no.3
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• pp.213-220
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• 2000

본 연구는 찹쌀가루액에 효소처리 및 미생물 접종을 시킴으로써 유과의 제조시 수침과정을 거치지 않고도 유과를 만들수 있는 새로운 방법을 개발하기 위하여 시도되었다. 찹쌀 수침액에 분포된 미샐울은 Bacillus sp와 Lastobacillus spp.로 나타났다. 찹쌀 수침액에 인위적으로 상기 미생물을 배양하였을 대 유과를 제조하기 위한 최적 조건은 3$0^{\circ}C$에서 18시간 이었다. 이때 찹쌀수침액의 PH는 배양시간이 증가함에 따라 증가하였다. 이 찹쌀 수침액에서는 수침시간이 증가함에 따라 $\alpha$-amylase 활성이 증가하여 효소처리된 시료액의 효소 활성화 유사한 경향을 나타내었다. 유과의 팽화도는 효소처리시킨 혼합 접종처리 군을 제외한 모든 처리군에서 28일간 수침한것과 유사하게 나타났다. 경도와 peak수는 모든 처리순에서 28일간 수침시킨 대조군에 비해 유의적으로 더 낮게 나타났다.(P<0.05). 미세구조에서 기공수는 효소처리시킨 단독 접종군이 다른 모든 처리군에 비해 더 많은 기공수를 지니고 있었고 기공의 둘레 및 면적도 유의 적으로 낮은 수치를 나타내었다. .(P<0.05). 따라서, 수침공정을 대폭 단축할 수 있었으며, 향후 미생물 접종을 고려한 효소처리 조건을 정밀 분석한다면 수침공정이 없어도 유과의 품질특성을 나타내는것이 가능할 것으로 보인다.

• Journal of the Korean Society of Food Culture
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• v.29 no.1
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• pp.61-83
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• 2014

The aim of this study was to review Byung-Kwa-Ryu recipes in old cookbooks of the head & noble family (Jong-Ga). As for details and classification, we examined the materials and recipes of Byung-Kwa-Ryu. To accomplish this, old cookbooks of the head & noble family ("Soowoonjabbang", "Eumsikdimibang", "Onjubub", and "Jusiksiui") were reviewed. The introduced Byung-Kwa-Ryu recipes numbered 47 total; four from "Soowoonjabbang", 18 from "Eumsikdimibang", nine from "Onjubub", and 16 from "Jusiksiui". We classified the foods (Byung-Kwa_Ryu) into two categories, Tteok-Ryu (Korean rice cake) and Kwa-Jung-Ryu (Korean traditional cookie), on the basis of previous studies. These were further classified into 11 categories: Tteok-Ryu (Jjin-tteok, Salmeun-tteok, Chin-tteok, Jijin-tteok), Kwa-Jung-Ryu (Yumilkwa, Yukwa, Jeongkwa, Dasik, Kwapyun, Dang (Yeot), and others. The most common Byung-Kwa-Ryu type was Jjin-tteok in Tteok-Ryu (14). The next most common Byung-Kwa-Ryu types were Yukwa in Kwa-Jung-Ryu (6) and Yumilkwa in Kwa-Jung-Ryu (5).

• Journal of the Korean Society of Food Culture
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• v.8 no.3
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• pp.243-248
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• 1993

Yukwa, one of the favorite Korean traditional snacks, is a oil puffed rice cooky used for sacrifies, ceremony or celebration of an event. It had been prepared by most of house-wives for a long time fellowing old reference and still be made by some skilled persons in country side these days. The preparation methods of the Yukwa differ a little each other region by region. This survey was conducted to excarvate any hidden traditional methods and collect different cases as many as possible through pre-made questionaire. 151 questionaires were collected at 7 provinces and evaluted by similar items.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.728-736
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• 2001

Effects of packaging material and oxygen absorbant on physical and chemical properties of Yukwu were studied during storage to develop packaging conditions. The packaging materials used were PET/EVOH $(16\;{\mu}m)/PL$ : P1 and PET/EVOH $(24\;{\mu}m)/PL$ : P2 with or without oxygen absorbent (E1A : P1 and E2A : P2 for w/ $O_2$, absorbent, E1EA : P1 and E2EA : P2 for w/o $O_2$, absorbent). Color values for Yukwu indicated that L values of E1A, E1EA, E2A and E2EA were decreased during storage while those b values were increased. Hardness and chewiness of Yukwa were generally decreased, however those of E1A and E1EA were rather increased after 6 weeks of storage. Acid value of E2A had maintained less than 2.0 during 12 weeks of storage. E1A, E2A had the below of 20 in peroxide during 12 weeks. Aroma data by using electronic nose showed that there was no difference after 6 week storage time in different packaging materials. Sensory evaluation (Yukwa odor and rancid odor) showed very similar results with electronic nose one. E2A had the highest value of overall acceptability for sensory evaluation. Hardness and cheweness in physical measurement results had the highest correlation with hardness, crispness, overall-acceptability in sensory evaluation results.