• Title/Summary/Keyword: degree of retrogradation

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Determination of Degree of Retrogradation of Cooked Rice by Near-Infrared Reflectance Spectroscopy (근적외 분광분석법에 의한 밥의 노화도측정)

  • Cho, Seung-Yong;Choi, Sung-Gil;Rhee, Chul
    • Korean Journal of Food Science and Technology
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    • v.26 no.5
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    • pp.579-584
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    • 1994
  • Near infrared reflectance(NIR) spectroscopy was used to determine the degree of retrogradation of cooked rice. Cooked rice samples were stored at $4^{\circ}C$ for 120 hours, and the degree of retrogradation was measured at every 6 hour during the storage time. Stored cooked rices were freeze-dried, milled and passed through a 100 mesh sieve. Enzymatic method using glucoamylase was used as reference method for the determination of the degree of retrogradation. Spectral differences due to retrogradation of cooked rice were observed at 1434, 1700, 1928, 2100, 2284 and 2320 nm. 32 samples of which moisture content were below 5% were used for calibration set, and 16 samples were used for validation set. High correlations were achieved between degree of retrogradation determined by conventional enzymatic method and by NIR with multiple correlation coefficient of 0.9753, and a standard error of calibration(SEC) of 3.64%. Comparable results were obtained with 3.91% of standard error of prediction(SEP), when the calibration equation was applied to independent group of samples of which moisture contents were in the range of calibration set. But when the calibration equation was applied to samples of which moisture contents were outer range of calibration set, SEP and bias were increased and correlation coefficient was decreased. The determination of degree of retrogradation was affected by sample moisture content. To determine degree of retrogradation of cooked rice by NIR using this calibration equation, it was suggested that sample moisture content should be controlled to below 5%.

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Comparative Degree of Gelatinization and Retrogradation on Gamkugsulgie with Added of Gamkug (감국 첨가에 의한 감국설기의 호화 및 노화도 비교)

  • 박금순;최미애;임정교
    • Journal of the East Asian Society of Dietary Life
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    • v.10 no.6
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    • pp.514-521
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    • 2000
  • This study was induced to compare retrogradation and gelatinization in sulgie with added powder and flower of gamkug, which had been stored in 4$^{\circ}C$, 1$0^{\circ}C$ and 3$0^{\circ}C$, respectively. The addition of 5% powdered gamkug showed the highest degree of gelatinization while the control did the lowest. The degree of hardness of gamkugsulgie was lower than control and the following order 4$^{\circ}C$>1$0^{\circ}C$>3$0^{\circ}C$. Gamkugsulgie showed a little lower degree of retrogradation than control group. The degree of retrogradation at 4$^{\circ}C$ was far greater comparing with the other group. The degree of retrogradation were delayed as the storing temperature rose tran 4$^{\circ}C$ to 3$0^{\circ}C$, temperature namely, gamkugsulgie retrogradation time constant of the test group was slower 1.18 times at 4$^{\circ}C$. 1.24 times at 1$0^{\circ}C$ and 2.58 times at 3$0^{\circ}C$ than that of the control group.

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Variation of Retrogradation and Preference of Bread with Added Flour of Angelica keiskei Koidz during the Storage (신선초가루를 첨가한 식빵의 저장 중 노화도와 기호도의 변화)

  • 최옥자;정현숙;고무석;김용두;강성두;이홍철
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.28 no.1
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    • pp.126-131
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    • 1999
  • We have got the following results from tests in the course of time retrogradation and taste change in bread with added flour of Angelica keiskei Koidz, which had been stored in room temperature (27±2oC), refrigerating(2±1oC) and freezing( 20±1oC), respectively. Bread with the added flour showed a little lower degree of retrogradation than control group, and every group in room temperature retrograded from the very first day. The degree of retrogradation of the group in refrigerating was far greater comparing with the group in room temperature. The longer bread was stored, the lower the degree of retrogradation was, and the higher the adding rate of the flour got, the later its retrogradation happened. Especially the flour of this vegetable's stem turned out to be the most effective in retarding its retrogradation. Group stored 30 days in freezing didn't show a wide difference in retrograde comparing with the group before storage. Preference for color and shape of the flour added bread stored in room temperatue, refrigerating and freezing did not change significantly from the group before storage. Although preference decreased for flavor, texture, mouth feel and overall quality with the lapse of time, flour added group improved in preference for these factors comparing with the control group. Above all, added flour of pretreated stem proved to be the most effective in the sensory tests. With respect to the storing method, the group stored in refrigerating showed greater preference for the texture and mouth feel over the groups in room temperature and freezing. Flavor preference of the group in freezing was the lowest of all.

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Quality Characteristics of Bread Made with Brown Rice Flours of Different Preparations (제조방법을 달리하여 제조한 현미가루 첨가 식빵의 품질 특성)

  • 김명희;신말식
    • Korean journal of food and cookery science
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    • v.19 no.2
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    • pp.136-143
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    • 2003
  • This study was carried out to investigate the quality of bread made with different types of brown rice flours. 20% of the wheat flour from the bread recipe was substituted with the different types of brown rice flours, such as, raw brown rice flour (RBRF), soaked brown rice flour (SOBRF), and sprouted brown rice flour (SPBRF). The loaf volume of the bread: decreased by 3.2%∼7.4% with the addition of the brown rice flours. The "L" value of these breads decreased, while the "a" and "b" values increased. In terms of the texture, the SPBRF bread was the hardest on the 1st day of storage, but it was the least hard on the 5th day of storage. The RBRF bread was the least springy. The SPBRF bread was the most cohesive. The adhesiveness was not significantly different among the breads. In terms of the degree of retrogradation using the ${\alpha}$-amylase method, the SOBRF and SPBRF breads showed a little lesser degree of retrogradation than the control and the RBRF bread. In the sensory evaluation, the control bread obtained high score for crumb color and grain, while the brown rice flours breads obtained high scores for mouthfeel and taste. Overall acceptability, defined by a higher score, was higher for the SOBRF and SPBRF breads than the control bread, which was not significant. Thus, this study showed that processing rice flour was more effective than raw rice flour in substituting wheat flour.

Effects of Freezing Rate and Storage Temperature on the Degree of Retrogradation, Texture and Microstructure of Cooked Rice (동결속도 및 저장온도가 취반된 쌀의 노화도, 조직감 및 미세구조에 미치는 영향)

  • Choi, Sung-Gil;Rhee, Chul
    • Korean Journal of Food Science and Technology
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    • v.27 no.5
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    • pp.783-788
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    • 1995
  • Cooked rices were frozen at four different rates(3, 5, 7 and 12 hr) of maximum ice crystal formation zone and stored at $-20^{\circ}C\;and\;-70^{\circ}C$ for 3 months. Freezing rate, storage temperature and storage period all affected the degree of retrogradation of cooked rice. As the maximum ice crystal formation zone increased from 3 hrs to 12 hrs, the degree of retrogradation of cooked rice increased from 14.9% to 40.0%. Further retrogradation occurred during the freezing storage and cooked rice stored at $-20^{\circ}C$ retrograded faster than that held at $-70^{\circ}C$. The hardness and adhesiveness of frozen cooked rice thawed in $40^{\circ}C$ water were measured. Hardness of the frozen cooked rice was higher than that of non-frozen sample and was higher at lower freezing rate. However, the hardness of cooked rice decreased after 3 months of storage. On the other hand, the adhesiveness decreased during the freezing processing, and adhesiveness decreased more rapidly at a higher freezing rate. However, the adhesiveness of cooked rice increased after 3 months of the storage, and the level of decrease was higher at $-70^{\circ}C$ than at $-20^{\circ}C$. After 3 months of storage, ice crystal size of frozen cooked rice became larger by recrystalization than that of frozen sample prior to storage. Microstructure of cooked rice was damaged by ice crystal formation and its growth when observed by scanning electron microscope.

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Effect of Surfactants on the Characteristics of Cooked Rice During Storage (계면활성제가 저장 중의 밥의 특성에 미치는 영향)

  • 김수경;이신경;신말식
    • Korean journal of food and cookery science
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    • v.13 no.3
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    • pp.278-285
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    • 1997
  • The effects of three surfactants (SSL, Dimodan, and SE1670) on the properties of cooked nonwaxy and waxy rice during storage were investigated by sensory evaluation, instrumental test, and measurement of retrogradation degree. The results of sensory evaluation revealed that the overall quality of cooked rice was affected by textural characteristics. The addition of surfactant decreased the roughness and hardness of cooked rice, however, increased the stickiness and moistness during the storage in the order of SE, SSL, and Dimodan. In instron test, the hardness of surfactant-added cooked rice was significant lower than that of control. The addition of surfactant decreased the degree of retrogradation both in cooked nonwaxy and waxy rices.

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Retrogradaion of Rice Flour Gels with Different Storage Temperature (저장온도에 따른 쌀가루 겔의 노화)

  • Kim, Jeong-Ok;Shin, Mal-Shick
    • Applied Biological Chemistry
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    • v.39 no.1
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    • pp.44-48
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    • 1996
  • Effects of storage temperature on the retrogradation of 50% nonwaxy rice flour gels stored at $20^{\circ}C,\;4^{\circ}C\;and\;-18^{\circ}C$ for 6 days were investigated by ${\alpha}-amylase-iodine$ method, differential scanning calorimetry(DSC) and x-ray diffractometry. The retrogradation of gels increased with increasing storage time and the initial retrogradation rate was higher. The degree of retrogradation gels stored at different temperature increased as following order, $-18^{\circ}C>20^{\circ}C>4^{\circ}C$. The enthalpy of retrograded rice flour by DSC showed similar as the degree of retrogradation by ${\alpha}-amylase-iodine$ method, but the differences between storage temperatures were clear in using ${\alpha}-amylase-iodine$ method. X-ray diffraction patterns of gels stored at $4^{\circ}C\;and\;20^{\circ}C$ showed small peaks at $2{\theta}=17^{\circ}\;and\;20^{\circ}$, but the difference was not detected.

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The Effect of Water Activity and Temperature on the Retrogradation Rate of Gelatinized Corn Starch (호화 옥수수전분의 노화속도에 미치는 온도 및 수분활성도의 영향)

  • Lee, Seog-Weon;Rhee, Chul
    • Korean Journal of Food Science and Technology
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    • v.26 no.4
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    • pp.370-374
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    • 1994
  • The effect of water activity(Aw) and storage temperature on retrogradation of pregelatinized corn starch was investigated at various temperature of $4^{\circ}C$, $20^{\circ}C$ and $30^{\circ}C$. Samples stored at different water activity, i.e., 0.43, 0.52, 0.75, 0.83, 0.88 and 0.93 by means of saturated salt solutions. The rate of retrogradation was determines. by enzymic digestibility, and evaluated by Avrami equation. The degree of retrogradation during storage showed a great difference around Aw 0.8. At Aw 0.52 and 0.75 at all temperatures, retrogradation occurred slightly. The effect of water activity on retrogradation was much greater at $4^{\circ}C$ than 300. And at Aw 0.43, the degree of retrogradation after 3-week storage was smaller than 3.9%. The critical water activity of retrogradation was inferred as Aw 0.43. At each temperature, the degrees of retrogradation of gelatinized corn starch after 24-day storage were 30% at Aw 0.8 and Aw 0.9, and greater than 50% at the Aw above 0.9. At Aw below 0.8 the degree of retrogradation was about 20%. The rate constants of retrogradation according to Aw showed small differences at $20^{\circ}C$ and $30^{\circ}C$, but showed a great difference at $4^{\circ}C$. The value of exponent of Avrami was 1.0 regardless of temperature and water activity. And the rate constants of retrogradation increased with increasing Aw, but decreased with increasing temperature.

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Varietal Difference in Retrogradation of Cooked Rice and Its Association with Physicochemical Properties of Rice Grain

  • Choi, Hae Chune;Hong, Ha Cheal;Cho, Soo Yeon
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.44 no.4
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    • pp.355-363
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    • 1999
  • 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 $\alpha$-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.

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Processibility aptitude of Dobyeong with pigmented rice bran extract (유색미 미강층 추출물을 첨가하여 제조한 도병의 제병 적성 검정)

  • Kim, Joo-Hee;Kim, Mi-Hyun;Kang, Mi-Young
    • Korean journal of food and cookery science
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    • v.22 no.6
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    • pp.898-904
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    • 2006
  • This study was performed to examine the processibility aptitude for the addition of Dobyeong to pigmented rice bran extract. Dobyeong from pigmented rice was less bulky and coarser than Dobyeong-added pigmented bran extract. The viscosity and degree of retrogradation in Dobyeong-added Pigmented bran extract were lower than Dobyeong from pigmented rice, indicating that the inhibitory action of retrogradation was higher in Dobyeong-added pigmented bran extract. The scores for springiness, adhesiveness, cohesiveness, gumminess, and chewiness were increased in Dobyeong-added pigmented bran extract. Dobyeong-added pigmented bran extract showed a decreased natural flavor of pigmented rice and degree of retrogradation, but had higher scores in color values. Dobyeong-added pigmented bran extract was more acceptable in sensory evaluation. Based on these results, the use of rice-added pigmented bran extract instead of pigmented rice in rice-processed food has advantageous effects in terms of the palatability of polished rice and phytochemicals of pigmented non-polished rice. This study will help develop new health-promoting rice products.