Brown rice has various health benefits; however, it is more difficult to cook and has a harder texture as compared to milled rice. In this study, the effect of the sous-vide cooking method on starch retrogradation and textural properties of brown rice was investigated by comparative analysis with conventionally cooked brown rice based on moisture content assay, evaluation of the textural property analysis, and differential scanning calorimetry (DSC). The results of the study are as follows: First, the moisture content of sous-vide cooked brown rice was higher than in the conventionally cooked brown rice. Second, the sous-vide cooked brown rice has lower hardness, higher adhesiveness, and lower retrogradation enthalpy during storage than conventionally cooked brown rice. Finally, the retrogradation properties of cooked brown rice during storage were analyzed by DSC. The enthalpy increased more rapidly in the case of conventional cooked brown rice, reaching 1.58 J/g after 3 days of storage. This indicated that sous-vide cooking is effective in preventing retrogradation of rice during storage.

In this study, baked rice donuts with added psyllium seed husk were manufactured and their quality and retrogradation characteristics were investigated. Control (Con) was made only with wheat flour; Psyllium seed husk in the amount of 8, 12, 16 and 20 grams was added to make rice donuts (P8, P12, P16 and P20). Higher amounts of psyllium seed husk reduced the moisture loss and baking loss, and increased the moisture content and water holding capacity of the donuts. The specific volume of Con was the highest of all the groups. As the amount of psyllium seed husk increased, the lightness and yellowness of the crumb decreased, and the redness of the crumb increased. Hardness also increased as the amount of psyllium seed husk increased. The hardness of P16 was the most similar to that of Con. The scanning electron microscopy images also identified that the structure of the donuts got denser as the amount of psyllium seed husk increased. Rate constant (k) of the rice donuts with psyllium seed husk were lower than that of Con. In conclusion, it is considered that P16 is the sample that is the most similar to Con in terms of texture, but the retrogradation was more retarded in P16 than Con.

An agricultural waste, pomegranate (Punica granatum L.) peel is known to be rich in total phenolics, which are flavonoids having strong antioxidant effects. In this study, pomegranate peel sponge cakes were prepared with varying ratios of freeze dried pomegranate peel powder (0, 1, 3, 5, 7% (w/w)) to examine their effect on quality characteristics, retrogradation and antioxidant activities. The specific gravity and moisture contents of 3, 5, and 7% pomegranate peel powder showed higher values than the control and 1% group. Addition of pomegranate peel powder increased the batter yield, while there was a significant decrease in baking loss. Increasing pomegranate peel powder content significantly decreased the lightness (L) (from 75.03 to 57.04) and pH values, whereas redness (a), yellowness (b) and ΔE were increased. Increasing concentration of the peel powder also increased the hardness and chewiness, while the springiness and cohesiveness decreased. Considering the Avrami equation, Avrami exponene (n) decreased from 1.8055 (control) to 0.9199 (7% pomegranate peel powder). Time constant (1/k) was lowest in control (at 17.64) and highest in the 7% group (39.84). Total polyphenol, flavonoid content, DPPH and ABTS radical scavenging activities significantly increased with increments in the content of pomegranate peel powder. A sensory evaluation by the 7-point scaling method showed that the sponge cake containing 7% pomegranate peel powder had the highest scores in color, flavor, sweetness, chewiness and overall acceptability. Hence, it is considered that sponge cake supplemented with 7% pomegranate peel powder is the most appropriate for quality characteristics, retrogradation and antioxidant activities.

This study investigated the quality characteristics, antioxidant activities, and retarding retrogradation of sponge cakes made with 0%, 1%, 3%, 5% and 7% pumpkin (Cucurbita moschata Duch.) leaf powder. Specific capacity significantly increased with the addition (0.33~0.38), but baking loss and dough yield were not significantly different (p<0.05). In color, there was a decrease in the L-value, a-value and b-value, but △E increased in proportion to the amount of pumpkin leaf powder. Moisture content increased in the 0~3% additions, from 27.90~31.68%, but decreased in 5% and 7% (22.37% and 28.15%, respectively). pH tended to decrease significantly according to the amount of pumpkin leaf powder (p<0.05). Hardness increased with the addition of pumpkin leaf powder, and pumpkin leaf groups presented higher springiness and cohesiveness than the control. Chewiness was not significantly differ (p<0.05). In retarding retrogradation, Avrami exponent (n) showed that addition of 5% (0.1329) had more retarding retrogradation effect than the control (0.4319), whereas time constant (1/k) showed both 3% (100.00) and 5% (70.42) addition had more effect than control (18.45). Total phenols and flavonoids content increased proportionate to the addition levels. ABTS radical scavenging activity tended to increase according to the level of pumpkin leaf powder. In sensory properties, 5% addition showed maximum color, and 3% addition had the highest scores in flavor, moistness, sweetness, chewiness and overall acceptability. These results suggested that pumpkin leaf was a good addition to improve the quality characteristics, health and sensory preferences. The most appropriate proportion to have the effect of retarding retrogradation in sponge cake is 3%.

0.8%(w/w) 밀가루를 첨가 시 증자 쌀가루 내부온도를 달리하여 제조한 가래떡을 4oC에서 28일간 저장하면서 노화억제효과를 분석하였다. 저장 기간에 따른 가래떡 전분의 표면미세구조는 처리구의 경우 저장 초기나 대조구에 비하여 표면에 작은 구멍이 보였으며 이는 저장 중 밀가루의 가수분해효소작용에 의한 것으로 판단된다. 저장 기간에 따른 blue value를 측정한 결과 대조구는 감소한 반면에 처리구는 증가하였다. 결정구조에서는 대조구와 첨가온도 95oC의 경우 저장 28일 후 B-type과 V-type이 혼합된 형태의 XRD pattern의 peak가 날카로워지면서 크기가 커지는 것을 관찰되었고 첨가온도 55oC와 75oC의 경우는 단일 피크의 XRD pattern을 그대로 유지하고 있었다. 저장기간에 따른 대조구의 용융엔탈피(ΔE)는 처리구보다 높게 나타났고 첨가온도 55oC가 가장 적은 용융엔탈피 값을 보였다. 저장 28일 후의 경도와 씹힘성은 첨가온도 55oC가 가장 낮았으며 각각 대조구의 0.7과 0.5% 수준이었다.

This study was performed to analyze the degree in the reduction of retrogradation in Garaetteok during 3 days at4oC with the addition of 0.8% wheat flour. The water holding capacity of the control (CO) and Garaetteok with0.8% wheat flour added (TR) after storage for 3 days was 45.8% and 76.0% respectively compared with that inthe initial storage stage. The water solubility of TR showed higher values than that of CO throughout the storageperiod, and the difference between CO and TR increased as the storage period increased. For the X-ray diffraction(XRD) pattern, CO showed an A-type pattern and the peak was sharp with the peak size increasing as the storageperiod increased, whereas TR showed a single peak throughout the storage period. Enthalpy changes (∆E) by dif-ferential scanning calorimeter (DSC) of CO and TR after storage for 3 days were 851.8 and 16.1J/kg respectivelywith hardness of 96.3 and 4.0N respectively, which were significantly different at the 0.1% level.

본 연구에서는 떡 굳음방지기술의 적용하여 저장성이 개선된 건강지향형 잡곡 떡을 제조하기 위하여 멥쌀의 일부를 보리 분말 0, 15, 30, 45%로 대체한 가래떡을 제조한 후 4oC에서 3일간 저장하면서 수분, 색도, 텍스처 및 기호도 검사를 수행하였고, 이들간의 상관성을 분석하였다. 떡굳음방지기술을 적용하여 제조한 가래떡의 경도는 보리 분말로 45% 대체한 가래떡을 제외하고 저장 기간이 경과하였음에도 경도 증가가 억제되었다. 색도는 보리 분말 대체량이 증가할수록 명도(L값)는 감소하고, 적색도(a값) 및 황색도(b값)는 증가하였다. 떡 굳음방지기술을 적용한 가래떡의 전반적인 기호도는 제조 직후에는 보리 분말을 함유하지 않은 가래떡이 가장 높은 결과를 보였으며, 보리 분말 대체량이 증가할수록 전반적 기호도는 저하되었으나, 보리분말 0, 15% 대체 가래떡은 저장 3일 후 유의적 차이가 없었다. 가래떡의 기계적 및 관능적 품질 특성 간의 상관관계를 분석한 결과, 가래떡의 전반적인 기호도는 수분 함량과 높은 양의 상관관계를 보였고, 제조 직후와 저장 3일 후 기호도 평가에서는 각각 경도와 점착성이 높은 음의 상관성을 나타내었다(p < 0.01). 이상과 같이, 굳음방지기술을 적용한 보리 분말 대체 가래떡의 저장 후 노화지연, 기계적 텍스처 및 관능적인 기호도를 고려할 때 보리 분말 대체량 15%가 적합한 것으로 사료된다.

This study was performed to analyze the retarded degree of Garaetteok retrogradation added with different ratios 0-15% (w/w) of apple pomace dietary fiber powder (DFP). SEM (×500) showed that air cell size on the Garaetteok surface increased as DFP content increased, whereas control had a compact structure without air cells. The degrees of Garaetteok retrogradation after 3 days at 4 and 25℃ by α-amylase iodine method were 57.44 and 41.55% for control, respectively. On the other hand, those of 15% DFP Garaetteok were 28.38 and 15.05%, respectively. Enthalpy changes (δE) by DSC of control, 10 and 20% DFP Garaetteok after 3 days of storage at 4℃ were 4.41, 4.17, and 3.80 J/g, respectively, whereas those at 25℃ were 2.14, 1.04, and 0.72 J/g. Hardness of 15% DFP Garaetteok was around 48% compared to that of control after 3 days of storage at 25℃. Increasing DFP content from 0 to 15% decreased L color value from 86.2 to 55.1, whereas a and b values increased from -1.9 to 8.9 and from 5.3 to 20.8, respectively. In a sensory intensity test, hardnesses of 15% DEP Garaetteok were significantly different at 1 and 0.1% compared to those of control after production and followed by storage for 3 days at 4℃, respectively.

DSC를 이용하여 acom starch와 com starch 및 starch-saccharide-water system 의 겔화와 노화에 관한 열적 메카니즘을 알아보았다. 전분에 fructose와 maltose를 첨가한 starch-saccharide-water 계의 엔탈피를 측정한 결과, 당을 첨가하지 않은 경우의 엔탈피 값보다 컸으며 겔화 온도 역시 증가하였는데 이는 당이 물과 상호 작용하여 비결정성 영역에 흡수된 자유수가 감소하고 결정부분이

The experiments were carried out to elucidate the varietal variation of retrogradation in aged cooked rice and its association with some physicochemical properties of milled rice. The fifteen rice materials were selected from forty-three low-amylose japonica and Tongil-type rice cultivars based on palatability and retrogradation of cooked rice stratified by preliminary sensory evaluation of warm and cooled cooked rice. One japonica glutinous rice variety was included for comparison of retrogradation of cooked rice. The α -amylase-iodine method was adopted for checking the varietal difference in retrogradation of cooked rice. The desirable checking time for evaluating the varietal difference in deterioration of aged cooked rice was four hours after storing in room temperature and two hours after preserving in refrigerator based on the largest coefficients of variations in degree of retrogradation of cooked rice. The rice cultivars revealing the relatively slow retrogradation in aged cooked rice were Ilpumbyeo, Chucheongbyeo, Sasanishiki, Jinbubyeo and Koshihikari. A Tongil-type rice, Taebaegbyeo, and a japonica cultivar, Seomjinbyeo, showed the relatively fast deterioration of cooked rice. The retrogadation index represented by the percentage of retrogradation difference between warm and cooled cooked rice to original estimates of warm cooked rice was significantly affected by the degree of retrogradation of cooled cooked rice. Generally, the better rice cultivars in eating quality of cooked rice showed less retrogradation and much sponginess in cooled cooked rice. Also, the rice varieties exhibiting less retrogradation in cooled cooked rice revealed higher hot viscosity and lower cool viscosity of rice flour in amylogram. The sponginess of cooled cooked rice was closely associated with magnesium content and volume expansion of cooked rice. The hardness-changed ratio of cooked rice by cooling was negatively correlated with solids amount extracted during boiling and volume expansion of cooked rice. The major physicochemical properties of rice grain closely related to the palatability of cooked rice may be directly or indirectly associated with the retrogradation characteristics of cooked nce. The varietal difference in retrogradation of cooked rice can be effectively classified by scatter diagram on the plane of upper two principal components based on some retrogradation properties of cooked rice. The deteriorated structural change in cooled cooked rice by observing through the scanning electron microscope was more conspicuous in the fastly retrograded cooked rice than in the slower one.