• Korean journal of food and cookery science
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• v.23 no.3 s.99
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• pp.369-377
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• 2007

The aims of this study were to develop and standardize the manufacturing procedures and ingredient formulation of non-fried, extrusion-puffed Yukwa. The quality and storage stability of the non-fried Yukwa (NF) were characterized and compared against a traditional deep-fried Yukwa (F). The moisture contents of both the NF and F were almost comparable at 5.12${\sim}$6.22% after the final product preparation. The textural hardness values of the NF samples were one-half to two times as hard as those of F, although no clear distinctions were reported between the two products by the sensory evaluation results (p<0.05). During storage, the acid value of F was 1.68 KOH mg/g on day 7, and then it rapidly increased to 5.52 KOH mg/g on day 14. In contrast, the acidity values of NF were 1.21 and 2.62 KOH mg/g on day 7 and 14, respectively. The peroxide values of the samples increased from 23.5 to 62.0 meq/kg (F) and from 2.0 to 2.5 meq/kg (NF) during the two weeks of storage after preparation, suggesting excellent fat stability for the NF product. Regarding the sensory evaluation results of the products, no significant (p<0.05) differences were noted between F and NF with scores of approximately 3.1 out of 5.0 points for the overall quality characteristics of the final products. Accordingly, we conclude that extrusion puffing technology could be adopted as an alternative to conventional deep fat frying as a partial manufacturing process of Yukwa.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.288-293
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• 2001

${\alpha}-amylase$ activities of bean water was not significantly influenced by bean water concentrations but they were remarkably influenced by different temperatures and substrates. ${\alpha}-amylase$ activities of bean water on cooked starch were significantly higher than those on raw starch. ${\beta}-amylase$ and glucoamylase activities in 14% bean water were significantly higher than those in 7% bean water. Yukwa paste is glutinous rice flour paste. Bean water was added to Yukwa paste by 0, 7, 14% and incubated 0, 3, 6, 9, 12 hours at $60^{\circ}C$. The pH of Yukwa paste increased with bean water concentration and decreased with the incubation time. The viscosity decreased with bean water concentration and incubation time. The ruducing sugar content of Yukwa paste increased with bean water concentration and incubation time. The changes of reducing sugar content in cooked Yukwa paste were much higher than those in the raw one. ${\alpha},\;{\beta}-amylase$glucoamylase activities of Yukwa paste also increased with bean water concentration, and their activities were much higher on the cooked glutinous rice flour than those on the raw one. The SEM observation on the freeze-dried flour of Yukwa paste showed breakdown of amylopectin structure by addition of bean water in the paste.

• Korean Journal of Food Science and Technology
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• v.25 no.3
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• pp.243-246
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• 1993

For extending the shelf-life of Yukwa (oil puffed rice cake) which is one of the most favorable Korean traditional rice snack, the Yukwa was packed in $O_2$ preventive container and substituted the air with $N_2$ gas or packed with $O_2$ absorbent (ageless sachet). The quality of Yukwa stored at $35^{\circ}C$ was evaluated by POV, AV and TBA including sensory evaluation. The POV of oil in Yukwa of $N_2$ substitute pack and absorbent sachet included were 5.3 and 11.9 meq/kg, respectively, while no packing (control) was 195.5 meq/kg after 90 days storage at $35^{\circ}C$. AV and TBA were also same trend but the gap with the control was not so big. The Yukwa, $N_2$ gas substituted, was better in quality than absorbent treatment in sensory evaluation and no difference was detected in quality of 90 days storage Yukwa at $35^{\circ}C$ with 15 days. The main reason for lower sensory score of absorbent treatment was that the $O_2$ absorbent also absorbed the flavor component of Yukwa.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.69-74
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• 2000

Varietal difference in physicochemical characteristics of glutinous rice grain and interrelationships between these properties and the quality characteristics of Yukwa(fried rice cookie) were investigated on fourteen rice varieties, to obtained the basic informations for diversifying the utility of glutinous rice grain and for developing various glutinous rice cultivars adaptable to glutinous rice food processing. Among physicochemical properties of glutinous rice grain, the content of released reducing sugar during soaking treatment was the most positive correlation between the adaptability to Yukwa processing quality. CB243 and Sandong 71 were the most adaptable glutinous rice cultivars to make the Yukwa, because of its tested score in expansion volume, crispiness and sensory preference was higher than other glutinous rice cultivars.

• Korean journal of food and cookery science
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• v.19 no.1
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• pp.60-64
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• 2003

Yukwa is a popular Korean traditional fried rice snack. The high fat content and porous structure of Yukwa cause it to become rancid rapidly. For extending the shelf-life of Yukwa, the Bandegi was fried with palm oil and soybean oil. The stability of Yukwa in lipid oxidation was determined by acid value(AV), peroxide value(POV), composition of fatty acid and sensory evaluation during 8 weeks of storage at 20$^{\circ}C$ and 50$^{\circ}C$ As the storage time increased, the AVs of soybean oil and palm oil during storage at 50$^{\circ}C$ were increased up to 42.64 and 2.09 mg/g, respectively. The POV of soybean oil during storage at 50$^{\circ}C$ was increased up to 4 weeks and then decreased. And as the storage time increased, the contents of stearic and oleic acid were increased, while linoleic and linolenic acid were decreased.

• Korean journal of food and cookery science
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• v.24 no.4
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• pp.480-486
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• 2008

In this study, Yukwa(YU-G) was prepared by coating in syrup with water-soluble extracts of Gugija(Lycii fructus). The Yukwa samples were stored with PE film packing with air for 12 weeks at room temperature, after which the quality and shelf-life of the Yukwa were assessed. During storage, the moisture contents of YU-G were higher than those of the Yukwa due to being coated in syrup without water-soluble extracts of Gugija(YU-NG), whereas the instrumental textural hardness values of the YU-G were lower than those of the YU-NG. Color determination indicated that YU-NG and YU-G assumed a darker color after storage, becoming both redder and yellower. The peroxide and acid values increased abruptly in the YU-NG during storage, but increased slowly in the YU-G. During the 12 weeks of storage after preparation, the peroxide and acid values of YU-G remained at less than 40 meq/kg and 4 KOH mg/g, respectively. Thus, the experimental method of syrup coating with water-soluble extracts of Gugija rendered the YU-G fairly stable against fat rancidity. The YU-G evidenced generally higher overall acceptability than YU-NG when stored.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.818-823
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• 2002

Effects of pelleting, drying, conditioning, and additives on the characteristics of Yukwa (fried pellet) were determined. RVA maximum paste viscosity of Bandegi (waxy rice pellet) was the highest after 2 days of moisture conditioning process, and decreased 2 days later. Air bubbles in Bandegi were distributed uniformly but were not significantly affected by conditioning time. For higher expansion and softer texture of Yukwa, the optimum moisture content of dried and conditioned Bandegi was $14{\sim}17%$. The addition of soymilk and 25% alcohol (Soju) as additives was also effective for achieving higher expansion and soft texture of Yukwa, respectively. Larger air cells were distributed in the center and smaller ones on the edge of Yukwa.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.211-216
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• 2015

Yukwa was prepared with different amounts of curry powder (0, 5, 10, 15, and 20%) based on the amount of waxy rice flour used, and its physical, sensory, and antioxidant properties were measured. In terms of the textural properties, the hardness began to increase when ${\geq}15%$ curry powder content was used; however, the crispiness was unchanged by the amount of curry powder used. The expansion degree of yukwa significantly decreased when 20% curry powder was used. The internal microstructure was measured by scanning electron microscopy (SEM), which showed a more compact and homogeneous structure as the curry powder content increased. The use of increased curry powder in yukwa decreased the acid and hydroperoxide values, and this could have resulted from the antioxidant action of curcumin in the curry powder. Through sensory evaluation, yukwa containing 15% curry powder was chosen as the most acceptable by the elderly.

• Food Engineering Progress
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• v.14 no.3
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• pp.193-201
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• 2010

The aim of this study was to analyse the quality of Yukwa puffed by using a vacuum puffing machine and compare to deep-fried Yukwa. The effect of vacuum puffing condition including heating temperature(100-${160^{\circ}C}$), preheating time(0-8 min) and vacuum puffing time(5-20 min) on physical and microstructure characteristics of the Yukwa was investigated. Vacuum puffed Yukwa at ${100^{\circ}C}$ heating temperature, 6 min preheating time and 10 min puffing time had highest value in volumetric expansion ratio(10.04) and lowest value in bulk density(0.15 g/$cm^{3}$). The breaking strength showed the lowest value of 140 g/$cm^{3}$ in vacuum puffing Yukwa at ${100^{\circ}C}$ heating temperature, 6 min preheating time and 15 min puffing time. The Yukwa puffed with the vacuum puffing machine at ${100^{\circ}C}$ heating temperature, 6 min preheating time and 15 min puffing time had the higher value of bulk density and the lower value of volumetric expansion ratio than those of deep-fried Yukwa. Increasing preheating time and vacuum puffing time caused an increase in white and an decrease in yellowness. The vacuum-puffed Yukwa exhibited smaller and uniform cell structure, while deep-fried Yukwa exhibited apparently in larger pores inside and smaller pores near the surface layer. The optimum condition of vacuum puffing machine for the production of vacuum-puffing Yukwa was ${120^{\circ}C}$ heating temperature, 4 min preheating time and 5 min puffing time.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.6
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• pp.745-751
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• 2012

The purpose of this study was to investigate the quality characteristics and antioxidative effect of Yukwa prepared with Lycii fructus powder (LFP). The Yukwas were stored at $50^{\circ}C$ for 40 days. Yukwa dough prepared with 5% LFP demonstrated higher pH and density value compared to the other groups and control. For color values, as more LFP was added, the L-value decreased, whereas the a-value and b-value increased. The hardness of Yukwa made with 7% LFP was the highest among all samples. The results of a sensory evaluation test showed that Yukwas with 5% LFP was most preferable in terms of overall acceptability compared to the others. The acid, peroxide, and thiobarbituric acid values were lower in Yukwa prepared with 5% LFP compared to Yukwa prepared with 3% or 7% LFP, as well as control Yukwa.