In this study, when manufacturing Yakgwa, 0, 25, or 50% of embryonic rice flour (ERF) was substituted for wheat flour (WF) to make the dough. After making Yakgwa by hot air frying (HF) or deep-fat frying (DF) methods, physicochemical characterization and acceptance tests were conducted. ERF had a higher water-binding capacity and a lower fat-binding capacity than WF (p<0.05). Yakgwa prepared by HF had lower crude fat contents, peroxide values, and expansion rates, but higher hardnesses, lightnesses, and rednesses (p<0.05) than that prepared by DF. Higher ERF substitution ratios reduced acid values and expansion rates and increased hardness (p<0.05). Acceptance testing showed 0% ERF Yakgwa prepared by HF had a significantly higher acceptance than Yakgwa prepared by DF. HF was found to have a positive effect on product acceptability. Yakgwa prepared with the DF method by substituting WF with ERF resulted in better flavor and overall acceptability than Yakgwa prepared with WF alone (p<0.05).

This study was undertaken to examine the quality characteristics of glutinous barley flour (GBF) Yakgwa produced by air frying. To achieve this, the pH of the dough as well as expansion ratio, color, texture, and sensory evaluation of Yakgwa were measured. The pH of the Yakgwa dough significantly decreases with increasing amount of GBF, over the range 5.35-5.45. Lightness (L), redness (a), and yellowness (b) also decrease with increasing amount of GBF. Furthermore, significant decrease was observed in the hardness, proportionate to the ratio of GBF added (p<0.001). Generic descriptive sensory evaluation results reveal that samples with high ratio of GBF show increased grain aroma, burnt aroma, grain flavor, nutty flavor, astringency, chalky taste, and hardness. The acceptance test determined the GBF-20 sample group to be high in flavor and texture (p<0.05). Therefore, it would be appropriate to apply to 20% GBF for alternative and the addition of GBF would be considered to have positive effects on the quality characteristics of Yakgwa using air fryer.

For the purpose of promoting the consumption of rice powder, 5 cultivars were applied differently to establish the optimal manufacturing conditions and measured Hunter color values, hardness and expansion rate of Yakgwa for the optimal conditions. Looking into the optimal manufacturing conditions of Yakgwa, the commercial flour-facilitating Yakgwa is shown to have a great shape when the mold is made with a thick paste for C-2 manufacturing method, Hangaru 100 mesh for H100-2 manufacturing method, Hangaru 200 mesh for H200-2 manufacturing method, Shingil 100 mesh for S100-2 manufacturing method, and Shingil 200 mesh for S200-1 manufacturing method. It also showed a trend of chewy taste after frying without cracks. Hunter color values (L) and red chromaticity and value b of yellow chromaticity indicated a lower value for the commercial flour and Hangaru 200 mesh in its entirety. The hardness of Yakgwa is within the range of 1,981.41~3,756.45 g and the degree of hardness is shown differently for each rice powder exclusive cultivars. Rice flour developed as rice powder 5 cultivars, and as a result of measuring chromaticity, hardness and expansion rate of Yakgwa for the quality characteristics, the item of hangaru 200 mesh had outstanding quality characteristics for Yakgwa.

Quality changes in yakgwa (such as color, moisture contents, acid value, rheological properties, and viable cells) using different types of frying oils was examined for 5 weeks. During the storage period, the lightness and yellowness of all samples were increased and there was no significant difference in redness. After 5 weeks of storage, rice bran oil showed the least color difference. There was no difference in the moisture contents of all samples except for grape seed oil, while the moisture contents of yakgwa fried with grape seed oil was decreased. The acid value increased as the storage period increased regardless of the type of frying oil, and yakgwa fried with rice bran oil and grape seed oil showed a low acid value. The hardness was increased as the storage period increased, but there was no difference in the hardness between the samples. The adhesiveness and resilience were decreased and the chewiness was increased. The total cell count did not increase significantly as the storage period, and there was also no difference in the total cell count between the samples. There was a high level of yeast and mold in comparison to total cell count, and the colony of bacteria was not detected.

The purpose of this study was to examine the effect of different types of frying oil on the quality of yakgwa such as expansion rate, color, moisture content and rheological properties. Yakgwa fried with corn oil showed the highest expansion in width and length, and rice bran oil in height. With regard to the overall expansion rate, yakgwa fried with rice bran had the highest value. As for lightness and yellowness, yakgwa fried with soybean oil had the highest lightness (34.74), while yakgwa fried with grape seed oil had the lowest lightness (29.82). As for redness, however, no significant difference was found. Regarding fat content, yakgwa fried with rice bran oil showed the highest value with 18.91%, while yakgwa fried with corn oil and canola oil showed the lowest value. No difference was found in moisture content according to the type of frying oil. In relation to the acid value, yagkwa with soybean oil showed the lowest value of 0.24±0.66; as for peroxide value, yagkwa fried with rice bran oil showed the lowest value of 3.59±1.74 meq/kg. No difference was found in hardness, cohesiveness and resilience according to the type of frying oil. Yagkwa fried with corn oil and canola oil showed the lowest value in terms of adhesiveness and chewiness, respectively. The results of the sensory evaluation showed not significance difference in overall preference, but yakgwa fried with rice bran oil had the highest value of 5.93±1.87.