1.Qualitative and Quantitative Analysis of Phytochemicals and Antioxidant Activity in Stem Lettuce Peel Byproducts
Journal of the Korean Dietetic Association 2026;32(1):1-9
This study examined the phytochemical composition and antioxidant potential of the peel of stem lettuce (Lactuca sativa var. angustana), an agricultural byproduct that is typically discarded despite its potential as a functional material. The peel powder was prepared by freeze-drying and ethanol extraction, and ultra-high performance liquid chromatography–triple time of flight electrospray ionization mass spectrometry/ mass spectrometry was used for phytochemical profiling. The qualitative and quantitative analyses showed that the peel contained a wide range of phytochemicals, including phenolic acids, lignans, flavonoids, and sesquiterpene lactones. Among these, phenolic acids and sesquiterpene lactones were identified as the dominant groups contributing to the characteristic phytochemical composition of the peel. The antioxidant activity of the peel extract was evaluated using various in vitro assays, including radical scavenging and reducing power tests. The results revealed strong antioxidant capacity, suggesting that phenolic and flavonoid phytochemicals in the outer tissues of stem lettuce play a crucial role in protecting against oxidative stress. These findings confirm that the peel serves as a natural reservoir of functional phytochemicals with significant antioxidant potential. Collectively, these results highlight the potential of stem lettuce peel as a natural antioxidant source and functional food ingredient. The utilization of this plant byproduct aligns with sustainable food production and circular economy principles by promoting resource efficiency and reducing agricultural waste. Nevertheless, further research is needed to evaluate the bioavailability, stability, and practical applicability of peel-derived phytochemicals in food systems for their industrial application as natural functional materials.
2.Application of cooked meat codes to improve the validity of nutrient content estimation in a recipe-based food ingredient database
Seo-Young YUN ; Hee Joe LEE ; Taenam LEE ; Ga-Eun CHOI ; Minseo CHOI ; Mi-Kyeong CHOI ; Nami JOO ; Mi-Hyun KIM ; Cho-il KIM
Nutrition Research and Practice 2025;19(6):1002-1010
BACKGROUND/OBJECTIVES:
Accurate estimation of nutrient intake from food consumption requires reliable food composition data. However, since nutrient content changes during cooking, the application of raw ingredient composition may lead to overestimation, particularly for energy and fat in meat dishes. In this study, the suitability of applying cooked food codes for meat dishes to improve the validity of recipe-based nutrient content estimation was evaluated.MATERIALS/METHODS: Pork (thin-sliced and thick-cut belly and shoulder butt) and beef (tenderloin, loin, rib meat, and brisket point) were examined for cooking yield after grilling and their nutrient contents were estimated. Each cut was portioned to 100 g of raw meat and cooked in triplicate. Nutrient content was calculated using both raw and cooked meat codes from the Korean Standard Food Composition Table, and differences in energy, fat, and protein content were compared.
RESULTS:
When grilled under standardized conditions, the average cooking yield was approximately 65% for pork and 80% for beef (P < 0.0001). Thin slices of pork belly had a lower yield (62.6%) than thicker cuts (68.0%), while beef brisket point had the lowest yield among beef cuts (63.6%). Applying cooked meat codes and measured cooking yields resulted in overall decreases in energy (−10% to −50%) and fat (−20% to −60%) content, with slight increase in protein (up to +34%, P < 0.0001). For beef tenderloin, additional comparisons using matched raw and grilled data from the United States Department of Agriculture SR Legacy Database showed smaller percent differences in energy, fat, and protein than those obtained from the Korean database.
CONCLUSION
Incorporating measured cooking yields and corresponding cooked meat codes into recipe-based databases can improve the accuracy of nutrient intake estimation. The development of nutrient databases that reflect differences in cooking conditions—including temperature, duration, and doneness—should be prioritized to enhance the validity of national dietary surveys.
3.Relationship between Psychological and Physical Disability and Nutrient Intake in the Elderly -The 8th Korea National Health and Nutrition Examination Survey-
Jeong-Mi PARK ; Dah-Sol KIM ; Nami JOO
Journal of the Korean Dietetic Association 2023;29(4):248-260
This study provides basic data when planning nutrition support for healthy aging by revealing the relationship between various symptoms in the elderly and nutrient intake. From the 8th National Health and Nutrition Examination Survey, data from senior citizens aged 65 years or older in 2021 were used, and answers on the depression prevalence, activity restrictions, complaints of discomfort when chewing, and nutrient intake were analyzed through SPSS multiple logistic regression analysis. In the case of depression, there was a significant effect on the intake of four of the 20 nutrients (water, protein, cholesterol, and vitamin E). When experiencing activity restrictions, the intake of eight of the 20 nutrients (phosphorus, magnesium, vitamin A, vitamin D, beta-carotene, retinol, thiamine, and niacin) was affected. When experiencing chewing discomfort, the intake of three of the 20 nutrients (fat, magnesium, and vitamin E) was affected. Elderly people who suffer from depression, activity restrictions, and discomfort with chewing are at risk of various nutrient deficiencies, and related studies need to be conducted.
4.A Study on the Meal Assistance and Nutrition Knowledge of Caregivers for the Elderly in Nursing Homes
Woo Jeong KIM ; Dah-Sol KIM ; Nami JOO
Journal of the Korean Dietetic Association 2021;27(4):232-247
This study attempted to examine the nutrition knowledge of caregivers for the elderly and the diet-related medical treatment and dietary assistance given by them. Thus, this research is a descriptive study focusing on the current nutritional knowledge of caregivers and the dietary assistance given by them. The survey included a questionnaire (nutritional knowledge level of digestive system diseases, diabetes, cardiovascular risk, brain disease, bone disease, and meal assistance performance status) for caregivers working in nursing homes for the elderly. Self-administered questionnaires were completed by 235 caregivers between February and March 2020. The results were analyzed using the SPSS 25.0, and the significance test of each question was verified by the Friedman test and the Chi-square independence test. The number of elderly people who needed meal assistance from caregivers was 4.4 more than the average. The most common types of meal assistance were partial assistance (59.20%) and the task of when to stop eating for the elderly (58.71%). Besides, the higher nutritional knowledge level of the caregivers, the more the time spent on services related to meal assistance (P<0.001), and the higher the meal assistance level. The disease state of the elderly was considered the most relevant (P<0.001). Caregivers with high levels of knowledge and offering significant meal assistance were found to have received nutrition education (P<0.001). Up to 80% of the respondents needed nutrition education, and most of them answered that they needed education on appropriate management methods for the specific disease state of the elderly (P<0.01). Accordingly, providing nutrition education for caregivers for the elderly should be a means to improve their ability to offer meal assistance.
5.Perception and Satisfaction of the Free School Meal Program for High School Students in Busan
Heesun YANG ; Young Il PARK ; Nami JOO
Journal of the Korean Dietetic Association 2021;27(1):26-34
This study investigates perception of the free school meal program, satisfaction of school meal, and eating habits of free and paid school meal program students in the Busan area. Between 20 to May 2020, a total of 350 students were researched, of which 177 belonged to the second grade of high school (free school meal program), and 173 were from the third grade of high school (paid school meal program). 96.0% free school meal program students and 89.0% paid school meal program students responded to the necessity of a free school meal program, which was significantly different between the two groups (P<0.05). All questions regarding the perception of the free school meal program, which were responded to by more than 3 points, were considered positive. ‘Decline of the school meal’s quality’ had the maximum response, from 64.4% and 76.4% free and paid school meal program students, respectively, and was significantly different between groups (P<0.05). Paid school meal program students wasted significantly more school food than the free school meal program students (P<0.001). ‘Not delicious’ was responded by 56.0% free school meal program students and 50.0% paid school meal program students. Evaluating satisfaction of the food quality and service categories was determined to be higher amongst free school meal program students than the paid school meal program students (P<0.05). Considering our study data, we propose that with the gradual expension of free school meal programs, inclusion as part of the education system will serve as a foundation for proper eating habits, and compulsory education will help improve students’ health and quality of life.
6.Effect of Application Service Quality Attributes on Perceived Value and Post-Purchase Behavior Intentions
Semi KIM ; Sanghyun PARK ; Nami JOO
Journal of the Korean Dietetic Association 2020;26(3):208-220
In modern society, the online to offline (O2O) market has become an emerging market. Based on socialand cultural phenomena, the importance of “FOODTECH” linked with mobile applications is growing in thefood and restaurant industry. This study examined subjective food application service quality, perceived value,and post-purchase behavior intentions. According to this study, of foodtech service quality attributes, only information,mobility, and reliability had positive (+) relationships with perceived value. However, foodtechservice quality attributes did not have a direct impact on behavior intentions. Perceived values had a positive(+) relationship with behavior intentions and showed full mediation effects between foodtech service qualityattributes and behavior intentions. Based on these results, future research on the relationship among food applicationservice quality, perceived value, and post-purchase behavior intentions is needed.
7.Efficiency of Purchase Management as Determined by the Adoption of School Meal Service Support Center in Gyeonggi Area
Ji-Hye LEE ; Boram KIM ; Nami JOO
Journal of the Korean Dietetic Association 2020;26(3):196-207
This study was undertaken to provide basic data for revitalizing the school meal support centers and improvingschool meals, by analyzing the purchase conditions and satisfaction of food according to an adoptionof a school meal service support center. Comparing the purchasing efficiency, convenience to purchase, andhigher overall satisfaction was achieved when a school meal service support center was adopted by the localgovernment, as compared to non-adopted school meal service support centers. Therefore, it is considered thatthe adaption of a school meal service support center is urgently required by non-adoption local governments.Moreover, the stability of food material supplies was also higher in the adopted rather than the non-adoptedcenters. Satisfaction with the quality of food ingredients was also found to be significantly higher in theadopted centers. These results indicate that if the local government adopts and introduces the school mealsupport center, inconsistencies observed in the return and exchange processes experienced by the non-adoptedcenters can be resolved, and food quality satisfaction can be improved. We, therefore, propose the necessityto implement a system for determining reasonable pricing by establishing systematic cooperation amongschools, manufacturing entities (suppliers), and the School Meal Service Support Center.
8.Study on Needs for Functional Candy (lozenges) Development for Oral Dryness
Kyoung Mi JOO ; Eunkyung JUNG ; Nami JOO
Journal of the Korean Dietetic Association 2020;26(1):30-41
As the morbidity of chronic diseases such as diabetes and high blood pressure has increased, the frequency of oral dryness upon taking drugs for a long time or several drugs at the same time has greatly increased. This study was conducted to investigate the status of oral dryness and utilize the data to develop treatment products. Surveys were assembled from October to December 2018, and a statistical analysis of the 144 responses was conducted. The surveyed consisted of 60 males and 84 females, with 31.3% of those in their 70s and older. Among them, 100 people took drugs for chronic diseases, while 27 people took drugs for more than 10 years and less than 20 years. Exactly 23 respondents who took drugs suffered from more than two types of chronic diseases, of which high blood pressure was the most cited, followed by hyperlipidemia and diabetes. Regarding complications, oral dryness (33.8%) was the most frequent, and there were significant differences in the degree of discomfort when taking medicine, especially for oral dryness depending on the age (P<0.05). Groups that took medicine showed severe symptoms of dry mouth, especially when waking up at night or in the morning (P<0.001) and eating food (P<0.01), and had difficulty in swallowing food (P<0.01) and speaking (P<0.01). Exactly 89.6% of the respondents didn’t take lozenges (candy) for improvement of oral dryness, and the type of the product that they wanted to purchase the most was candy (45.1%). Respondents worried about rising blood sugar, dental caries, and calories when eating candy for relieving dryness (P<0.01).
9.Quality Characteristics and Optimal Conditions for Sweet Rice Muffin Lotus (Nelumbo nucifera Gaertn) Seed Powder, Applying the Response Surface Method
Journal of the Korean Dietetic Association 2020;26(1):1-13
This study was undertaken to optimize preparation of sweet rice muffins using lotus (Nelumbo nucifera Gaertn) seed powder. The experimental conditions used in the preparation included lotus seed powder (X1) and soybean oil (X2). The muffin formulation was optimized using rheology. Lightness (P<0.01) displayed a quadratic model pattern, whereas yellowness (P<0.01) and redness (P<0.05) was presented a linear model. Texture properties significantly differed in cohesiveness (P<0.05). Evaluating the sensory characteristics of muffins, except for flavor and texture, the remaining properties of color (P<0.01), taste, overall quality, and appearance (P<0.05) were found to be significantly different. The overall quality was also affected by the proportion of lotus seed powder, rather than the amount of soybean oil. The optimal ratio for palatability of muffins was determined to be 47.80 g lotus seed powder and 95.28 g soybean oil. Taken together, our results indicate that sweet rice muffins prepared using lotus seed powder are sufficiently competitive in terms of function and quality.
10.Structural Relations of Convenience-Processed Food Purchasing Attitude and Selection Attribute according to Housewives' Stress: Focus on Housewives in Seoul and Gyeonggi Areas
Nanhee KIM ; Young Il PARK ; Nami JOO
Journal of the Korean Dietetic Association 2019;25(4):257-268
This study provides basic data on how stress impacts the processed convenience foods purchase attitudes and the selection attributes of housewives. The stress consists of 3 factors, which were housework stress, family relation stress and economic stress. The processed convenience food purchase attitude consisted of 2 factors, which were peripheral influence purchase and conviction purchase. The processed convenience food selection attribute consisted of 4 factors, which were quality, convenience, packaging and price. Factor loading confirmation and reliability test were conducted, and the reliability was confirmed with Cronbach's alpha coefficients for all the factors exceeding 0.5. The high stress levels showed significantly high stress factors of housework, family relations and economic stress (P<0.001). The high stress group was shown to make purchases by recognizing peripheral influences (P<0.01). When the selection properties of processed convenience foods depending on different stress levels were examined, it was revealed that among the three groups, the low stress group least considered the price aspect (P<0.01). After deducting the factors, AMOS (Analysis of Moment Structure) was used to conduct the confirmatory factor analysis for verifying validity. The structural equation model was used to determine the path coefficient. From the processed convenience foods purchase attitude, the peripheral influence purchase had significantly positive (+) effects on convenience (P<0.05). Also, conviction purchase was shown to have significantly positive (+) effects on quality (P<0.05). Housework and family relation stress were shown to have negative (−) effects on processed convenience foods selection attribute, and economic stress was shown to have positive (+) effects, although no significant relationships were revealed.
Family Relations
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Fast Foods
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Gyeonggi-do
;
Housekeeping
;
Product Packaging
;
Seoul

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