• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.534-540
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• 2007

In this study, waxy rice starch was chemically modified using phosphorous oxychloride ($POCl_3$, 0.002-0.008%). Then the physicochemical properties of resulting cross-linked waxy rice starches were investigated in order to reduce the steeping time of Yukwa (a Korean oil-puffed rice snack) processing. The swelling powers of the cross-linked waxy rice starch samples were higher than the native waxy rice starch at temperatures above $60^{\circ}C$, and their increases were proportional to the $POCl_3$, concentration. The solubility of the cross-linked waxy rice starch was lower (1.6-3.4%) than the native waxy rice starch (2.7-6.1%). However, the moisture sorption isotherm of the cross-linked waxy rice starch was not significantly different from the native waxy rice starch. The rapid visco analyze. (RVA) pasting temperatures $(65.4-67^{\circ}C)$ of the cross-linked waxy rice starch were lower than those of the native starch $(67^{\circ}C)$. The RVA peak viscosities (287-337 RVU) of the cross-linked waxy rice starch were higher than that of native starch (179 rapid visco units (RVU)), and increased with increasing $POCl_3$ concentration. For the differential scornning calorimeter thermal characteristics, although Tc shifted toward higher temperatures with cross-linking, the To, Tp, and amylopectiin melting enthalpy of the cross-linked waxy rice starch showed no differences compared to the native waxy rice starch. The X-ray diffraction patterns of both the native and cross-linked waxy rice starches showed typical A-type crystal patterns, suggesting that cross-linking mainly occurs in the amorphous regions of starch granules. Therefore, the cross-linking reaction did not change the crystalline region, but altered the amorphous region of the waxy rice starch molecules, resulting in changes of solubility and RVA pasting properties in the cross-linked waxy rice starch. In summary, since cross-linked waxy rice starch has a high puffing efficiency and no browning reaction, it may be applicable for Yukwa processing without a long steeping process.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.5
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• pp.493-501
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• 1986

The present work aims to estimate the effect of heat treatment on the in vitro protein digestibility and formation of trypsin inhibitor or trypsin indigestible substrate(TIS) of raw and defatted flounder. It was also carried out to assess the formation of lipid-protein complexes under the conditions of different ratio of lipid addition. The in vitro protein digestibility increased when steamed for 5 min showing $88.09\%$ in raw and $90.56\%$ in defatted samples, respectively. After 40 min steaming, the digestibility decreased by $2{\sim}4\%$. As for microwaving, heating for 1 min resulted in slight increase of digestibility, however, heating for 7 min did decrease of digestibility by $3{\sim}4\%$ for both raw and defatted materials. There was no difference in fatty acid composition found with heat treatment. The major fatty acids of flounder meat were $C_{16:0},\;C_{16:1},\;C_{18:1},\;C_{20:5},\;C_{22:6}$ and the ratio of the unsaturated to saturated was 67.3:32.6. Fat oxidation and nonenzymatic browning were enhanced by heat treatment and protein solubility decreased necessarily as the brown pigment formation increased. On the other hand, the effects on the digestibility and TIS of the complexes formed from interaction of lipid and myofibrillar or meat protein of flounder were examined. The interaction of protein with lipid was considered to mostly contribute to the drop of digestibility of fish products. The digestibility of myofibrillar protein was $93.72\%$ for flounder, and it generally decreased as the amount of lipid added to protein and reaction time increased. Also mixed and heated samples were more active in digestibility decline than those mixed after heating. The result probably indicated that lipid-protein interaction was involved in the drop of digestibility which coincided with protein denaturation.

• Korean Journal of Agricultural Science
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• v.8 no.1
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• pp.117-125
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• 1981

The changes in chemical compositions of chestnuts were tested during processing in order to elucidate the effects of heat treatments such as boiling, steaming and roasting on the flesh compositions. The results obtained were as follows. 1. The chemical compositions of raw chestnuts were: moisture, 59-61%; total sugar, 24-27%; crude fat, 0.3%; crude fiber, 0.6-0.9%; ash, 1.0%; amino nitrogen, 0.3%; vitamin C, 20-22 mg%; and tannin, 40-48%. 2. The moisture contents were increased to 63.8% by the boiling and to 70.27% by the peeling and boiling from 59.41% of raw ones respectively, whereas decreased to 54.11% by the roasting. 3. Contents of crude protein were decreased to 8.04% by the peeling and boiling procedure from 8.72% of raw ones, and those of amino nitrogen also revealed a decreasing tendency by the heat treatments. However, no significant change was observed in crude fat content. 4. Total sugar contents were decreased by the peeling and boiling procedure approximately 3.0%, whereas reducing sugars were increased 2 to 3 times in the all treatments. 5. Vitamin C contents were decreased 72.0 to 78.0 % by the boiling procedure, 64.2% by the steaming, 51. 6% by the roasting as compared with the raw ones. Tannin contents were increased 11.0% by the boiling, and 46.0% by the roasting respectively, whereas decreased 22.0% by the peeling and boiling procedure. 6. The color was changed to brown with different degree, during the boiling, steaming and roasting procedure. The 0.1% solution of alum appeared to be effective in reducing the browning reaction during the heat treatments.

• Korean Journal of Food Science and Technology
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• v.41 no.4
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• pp.386-391
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• 2009

To verify the possibility of manufacturing a germinated rough rice tea, germinated rough rice was roasted at 200, 220, and $250^{\circ}C$ for 10, 20, and 30 min. The treated rice powder was then put into tea bags and leached for 1, 3, and 5 min, after which their antioxidant, physicochemical, and sensory characteristics were compared. The total polyphenol content and 2,2'-Azino-bis-(3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities of the germinated rough rice tea increased as the roasting temperature increased as well as in response to increased roasting and leaching times. Furthermore, the greater the roasting temperature, roasting time, and leaching time, the greater the increase in total soluble solid contents. Moreover, the turbidity and browning index of the germinated rice tea rose as the roasting temperature, roasting time, and leaching time increased. Additionally, the pH tended to decrease as the roasting temperature, roasting time, and leaching time increased. Evaluation of the sensory characteristics of the germinated rice tea revealed that the formation of a Maillard reaction product in the course of heating the rice added a unique flavor, which led to increase preference for the color, flavor, and taste, and therefore, the overall preference.

• Korean Journal of Food Science and Technology
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• v.6 no.1
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• pp.24-29
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• 1974

Deep fried instant noodles, biscuits, and cookies were prepared, using the same beef tallow as their fat ingredient. In addition to wheat flour and beef tallow, the common and major ingredients, the deep fried instant noodle contained 1.5% salt before frying, the biscuits 20.0% sucrose and 10.0% nonfat milk solid before baking, and the cookies 20.0% sucrose before baking. The three products and a portion of beef tallow, which was to be used as control, were stored in an incubator at $47.0{\pm}1.5^{\circ}C$. The peroxide value and the free fatty acid value of the control and the extracted fat were determined regularly during the storage period. The fat incorporated in the biscuits exhibited far greater stability to rancidity development than that of the control with regard to both peroxide value and free fatty acid value development. However, the fat incorporated in the deep fried instant noodles and the cookies showed much poorer stability than that of the control. Factors like a deep frying process and/or the presence of a significant amount of salt in the deep fried instant noodles appeared to promote the rancidity development of the fat incorporated in the product. On the other hand, Maillard type browning reaction products in the biscuits seemed to retard effectively the rancidity development of the fat incorporated in the product.