• Food Science and Preservation
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• v.13 no.4
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• pp.438-444
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• 2006

This study was carried out to obtain fundamental data such as peeling efficiency and quality of potatoes and sweet potatoes peeled by hand, machine and alkali(NaOH). The weight loss by peeling was influenced by peeling methods. Weight losses by rotational brushing-type peeler showed the lowest value, 7.9% in potato, and 7.3% in sweet potato. Any significant differences in moisture content were not found in potatoes and sweet potatoes by peeling methods. The pH of potatoes and sweet potatoes just after peeling were 5.8-6.8 and 6.23-6.63, and decreased somewhat until 3 hrs after peeling. Hardness of potatoes and sweet potatoes peeled by hand with fruit knife were better than that of others. Depending upon the peeling method used the color and color differences undergo some changes in their color and browning. Color difference value of peeled potatoes by hand with a technical tools, and by mechanical peeler such as rotational cutting-type peeler and rotational brushing-type peeler showed just slightly. In particular, changes of rotor differences value of potatoes and sweet potatoes peeled by dipping with 10% NaOH solution at $100^{\circ}C$ was the highest in the samples peeled by NaOH.

• Journal of the East Asian Society of Dietary Life
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• v.16 no.6
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• pp.655-662
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• 2006

This study was performed to investigate stress levels, dietary behaviors and food choices, and their correlations in college students. General characteristic stress scores, using a stress test, and the dietary behaviors and food choices of subjects under stress were measured in 358 subjects (185 males and 173 female). The mean total stress scores of the male and female students were $67.91{\pm}44.85$ and $85.62{\pm}48.91$, respectively. Female students were more stressed than males in relation to family, value, future, friends, and study related factors. There were gender differences in the food intake and frequency of eating sweet things when under stress. Stress increased the food intake and frequency of eating sweet things in female students. Especially, stress factors, such as value, economic, future, friends and study problems increased the food intake of female students. Female students preferred sweet tasting items; whereas, male students preferred hot tasting items when under stress. These results show the effect of life stresses on the dietary behaviors and food choices of college students. Stress not only increased energy consumption in certain individuals, but also changed their food choices. Therefore, education with regard to nutrition is necessary if college students are to practice good eating habits for the correct management of life stresses.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.218-222
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• 1997

Twelve varieties of yellow sweet potatoes were measured for carotenoids content to assess their potential as a source of natural food colorant. Benihayato variety had the highest content of carotenoids (20.2 mg/100 g fr wt) but other varieties ranged with $4.6{\sim}16.7\;mg/100\;g$ fr wt. Hunter's +a-values (redness) increased linearly $(R^{2}=0.826)$ with carotenoids content of yellow sweet potatoes. Absorption spectrum of carotenoids extracted from the Benihayato variety was similar to that of standard ${\beta}-carotene$ indicating that carotenoids in yellow sweet potato are mostly composed of ${\beta}-carotene$.

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.383-392
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• 2014

This study was implemented to understand the motivation factors for $2^{nd}$ grade schoolchildren that effect on their preference for the sweet taste. The subjects included were 118 children (59 boys and 59 girls) and 118 children's guardians, from one elementary school. Children participated in sweet preference test and questionnaire survey with researcher's guidance provided in the school. Children's guardians were asked to fill out the questionnaire via home-letters. The results were as follows: 59% of the children preferred the cocoa beverage with the highest concentration of sugar among five cocoa beverages (0%, 2.5%, 5%, 7.5%, and 10% of sucrose/milk volume). The variables consisted of affective attitude, cognitive attitude, self-efficacy, parenting style, and sweets frequency. According to the analysis, sweet preferences were correlated with children's affective attitude (r=-0.207, p<0.01), self-efficacy (r=-0.288, p<0.01), frequency of drinking carbonated beverage (r=0.272, p<0.01), preference for yogurt (r=0.184, p<0.05), and preference for sweet bread (r=0.226, p<0.05). These results indicated that children can be more affected by affective attitude than cognitive attitude, and self-efficacy can be an important motivation factor to control the eating behavior related to sweets. Therefore, nutrition educators need to focus on developing various methods related to increasing self-efficacy for encouraging and motivating healthy eating behavior in children.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.66-71
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• 2001

Kinetic parameters for the texture degradation of three varieties of sweet potato during heating were determined using two alternative methods, the biphasic model and the fractional conversion method. The texture degradation of sweet potatoes during heating could be expressed by two simultaneous first order reactions using the biphasic method, whose activation energies were ranged $71.0{\sim}75.1\;kJ/mol\;and\;48.4{\sim}59.6\;kJ/mol$ for the initial fast texture degradation reaction and the slow texture degradation reaction at a prolonged heating period, respectively. However, the whole texture degradation phenomena of sweet potatoes during heating could also be explained by a single first order reaction using the fractional conversion method. The activation energies were $67.5{\sim}75.3\;kJ/mol$, which were comparable with those of the first phase reaction for the texture degradation determined by the biphasic model. A kinetic compensation effect shown between the kinetic parameters determined by both methods indicates that both methods can be conveniently used to determine kinetic parameters for the texture degradation of sweet potatoes by heating.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.160-164
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• 1992

Cooking, texture and sensory properties of sweet potato Tangmyon (starch noodle), common Tangmyon (50% sweet potato starch+50% corn starch) and corn Tangmyon were evaluated. The weight gain of Tangmyon showed a linear relationship with the square root of cooking time, in which the common Tangmyon showed the highest value. The solid loss during cooking was the highest in common Tangmyon followed by corn Tangmyon. The sweet potato Tangmyon showed the highest value for compression strength and stretching ratio, but lowest value for elongation elastic modulus. At the same compression strength, corn Tangmyon had the highest tensile strength and sweet potato Tangmyon the lowest value. Sweet potato Tangmyon showed the highest sensory scores of gloss, clarity, adhesiveness, gumminess, extensibility and overall desirability, and corn Tangmyon the lowest scores. Except adhesiveness (by appearance) and the gumminess of common and corn Tangmyon, significant differences (p<0.05) were observed for other sensory properties among samples.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.24-29
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• 2002

The study was performed to investigate the degrees of gelatinization at various processing steps during the preparation of Dangmyuns using sweet potato, potato, corn and tapioca starches, and also determined the rehydration of the freeze dried sweet potato Dangmyun. The degrees of gelatinization after extrusion cooking showed higher value than other processing steps. The degrees of gelatinization after extrusion cooking were 63.5% in sweet potato, 80.0% in potato, 82.3% in corn, and 86.5% in tapioca Dangmyuns. The degree of gelatinization in Dangmyuns after extrusion cooking step decreased as the processing steps, such as cold storage, freezing, thawing, and sun drying, progressed. L values of color in Dangmyuns decreased in the order of corn>tapioca>potato>sweet potato Dangmyuns. The cooking loss decreased in the order of tapioca>corn>potato>sweet potato Dangmyuns. The percentage of weight gain was the highest in sweet potato Dangmyun followed by corn, potato, and tapioca Dangmyuns. The water absorption rate constant was the highest in sweet potato Dangmyun followed by corn, potato, and tapioca Dangmyuns. In the rehydration of freeze dried Dangmyuns, freeze dried sweet potato Dangmyun showed better than the others. An increase from 60% to 70% of the added amount of water in the mixing step resulted in an increase of the degrees of gelatinization after extrusion cooking from $63.4{\sim}70.7%$ to $73.8{\sim}75.0%$. An increase of the added water in the mixing step and a decrease of diameter in the extrusion cooking step slightly improved the rehydration in the boiled water of freeze dried sweet potato Dangmyun.

• Culinary science and hospitality research
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• v.18 no.1
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• pp.54-64
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• 2012

The purpose of this study is to develop $Sulgidduk$ which meets the consumers' taste by using cooked purple sweet potato. The samples of $Sulgidduk$ were prepared with different ratios of cooked purple sweet potato(0, 10, 20, 30, 40%) and analyzed for moisture content, Hunter's color value and texture characteristics and sensory evaluation. The moisture contents of the samples ranged 40.83% to 44.91% The L-value and b-value decreased, while a-value increased, with increasing amounts of cooked purple sweet potato. In the mechanical evaluation of physical properties, hardness, adhesiveness, springiness, gumminess and cohesiveness showed no significant difference with the increasing amount of cooked purple sweet potato. However, chewiness decreased significantly with the increasing amount of cooked purple sweet potato. Based on the quantitative descriptive sensory evaluations on $Sulgidduk$ samples, purple color, sweet potato flavor and taste, sweetness, and moistness significantly increased, while hardness decreased significantly with the increasing amount of cooked purple sweet potato. $Sulgidduk$ added 40% cooked purple sweet potato showed the highest in overall acceptability and the slowest hardening in the textural changes during storage.

• Korean journal of food and cookery science
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• v.24 no.4
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• pp.501-510
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• 2008

In this study, we evaluated the quality characteristics of sweet potato Sulgidduk produced with varying amounts of fresh sweet potato, after three days of storage. The more fresh sweet potato was added, the higher were the levels of crude protein and crude lipid; however, crude ash contents were lowest in the control sample, and no significant differences in this value were detected among the samples to which fresh sweet potatoes were added. Moisture contents evidenced a tendency to decrease with increases in the amount of added fresh sweet potato and increased storage time, but pH rose with increases in the amount of added sweet potato. Total cell counts showed a tendency toward decrease with increases in the amount of added fresh sweet potato. L values tended to be low with increases in the amount of added fresh sweet potato and a values were lowest immediately after its production, although no consistent tendencies were noted in correlation with the amount of added fresh sweet potato. b values tended to increase directly with the amount of added sweet potato . With increasing storage time, the L and a values decreased, whereas the b value tended to increase. Upon textural assessment, it was observed that hardness, adhesiveness, springiness, gumminess, and chewiness(all textural components except for cohesiveness) increased with increasing quantities of added fresh sweet potato, and these factors also tended to increase with the progression of storage time. After observation via scanning electron microscopy(SEM), it was noted that the cohesiveness also increased with increasing amounts of added sweet potato. With regard to the sensory evaluation, the samples to which 15% fresh sweet potato had been added evidenced the highest acceptability in terms of color, flavor, and s0weetness, and softness and moistness in these samples decreased with increasing percentages of added sweet potato. It has been previously demonstrated that the addition of 15% fresh sweet potato resulted in optimal overall acceptability. In accordance with the aforementioned results, it has been verified that the use of fresh sweet potato in Sulgidduk is possible and probably desirable, and an addition of 15% sweet potato appears to be the optimal approach in terms of overall quality and functionality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1668-1674
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• 2011

We investigated the physical characteristics and changes in the functional components of red pepper paste, or gochujang, during fermentation at $20^{\circ}C$ for 90 days with different amounts of sweet persimmon powder. The viscosity of the paste decreased a little with increasing fermentation time. There was no significant difference (p<0.05) in all the treatments during fermentation. The L value, a value, and b value showed a tendency to gradually decrease with increasing fermentation time. And the samples with sweet persimmon powder showed a lower values compared to the control during fermentation. The phenolic compound content of the paste with sweet persimmon powder ranged from 13.72 mg% to 16.13 mg% at an early stage of fermentation, showing a significantly higher value (p<0.05) when increasing the amount of the powder. The content was in the range of 13.72~16.09 mg% on the 90th day in the final stage of fermentation, showing no significant difference (p<0.05) compared to those content at an initial stage of fermentation. The carotenoid content showed significantly higher values (p<0.05) when increasing the amount of sweet persimmon powder. In conclusion, sweet persimmon powder in the red pepper paste would gives a more functional effect which could be from bioactive components, such as phenolic compounds and carotenoids. But, it did not positively affect the color of the red pepper paste.