Mi-Ja Kim

Antioxidant properties of ascorbic acid in bulk oils at different relative humidity.

The effects of relative humidity (RH) on the antioxidant properties of ascorbic acid (10, 20, 42, and 84ppm) were investigated in stripped corn oils stored at 60°C. The degree of oxidation in oils was determined by analysing headspace oxygen content and conjugated dienoic acids. The oxidative stability of bulk oils without addition of ascorbic acid was significantly different depending on the RH. As the concentration of ascorbic acid increased from 10 to 84ppm, oxidative stability increased significantly irrespective of RH (p<0.05). Generally, oils containing ascorbic acid at low RH had higher oxidative stability after storage at 60°C than those at high RH. The antioxidant properties of ascorbic acid were greatly influenced by both the moisture content in the oil and the ascorbic acid concentration.

Affordances in Interior Design: A Case Study of Affordances in Interior Design of Conference Room Using Enhanced Function and Task Interaction

Interior design of space is somewhat different from product design in view of followings: the space should afford the multiple users at the same time and afford appropriate interactions with human and objects which exist inside the space. This paper presents a case study of interior design of a conference room based on affordance concept. We analyzed all of users’ tasks in a conference room based on the human activities that are divided into human-object and human-human interactions. Function decomposition of an every object in conference room was conducted. The concept of a high-level function is used such as “configure the space” to satisfy the given condition of the number of humans, the types of conference, and so forth. The Function-Task Interaction (FTI) method was enhanced to analyze the interactions between functions and user tasks. Many low-level affordances were extracted, and high-level affordances such as enter/exitability, prepare-ability, present-ability, discuss-ability and conclude-ability were also extracted by grouping low-level affordances in the enhanced FTI matrix. In addition, the benchmarking simulation was conducted for several existing conference rooms and the results confirmed that the extracted affordances can be used for checklist and also for good guidance on interior design process.Copyright

Effects of deuterium oxide on formation of volatiles in linoleic acid model systems at different temperatures and oxygen limitation conditions

Effects of 30, 60, and 90°C treatments and oxygen limitation on formation of volatiles were determined for linoleic acid model systems containing deuterium oxide (D2O) and deuterium free water. The presence of D2O accelerated consumption of headspace oxygen, indicating that the rate of lipid oxidation increased in the presence of D2O. The presence of deuterium in headspace volatiles was indirectly determined based on comparison of the amount of the fragmented mass to charge ratio (m/z) (molecular weight, Mw), which was 73.1/72.1 for d1-pentane/pentane and 125.1/124.1 for d1-2,4 octadienal/2,4 octadienal. The ratio of 73.1/72.1 (m/z) for pentane was significantly (p<0.05) higher for samples containing D2O than for samples containing deuterium free water at 30, 60, and 90°C. Other volatiles did not follow the same pattern. 2,4-Octadienal in samples under unlimited oxygen conditions confirmed this trend, indicating that water was incorporated into volatiles during oxidation of linoleic acid under these conditions.

Evaluation of Antioxidant or Prooxidant Properties of Selected Amino Acids Using In Vitro Assays and in Oil-in-Water Emulsions Under Riboflavin Sensitization

The antioxidant properties of selected amino acids were tested using in vitro assays and oil-in-water (O/W) emulsions under riboflavin (RF) photosensitization. Headspace oxygen content, lipid hydroperoxides, and conjugated dienes were determined for the degree of oxidation. Riboflavin photosensitization was adapted as the oxidation driving force. In vitro assays showed that cysteine had the highest antioxidant properties followed by tryptophan and tyrosine. However, in O/W emulsions under RF photosensitization, tyrosine inhibited lipid oxidation whereas tryptophan acted as a prooxidant. Tryptophan accelerated the rates of oxidation in O/W emulsion without RF. The antioxidant properties of amino acids differed depending on the antioxidant determination methods, oxidation driving forces, and food matrices.

Analysis of Trans Fat in Edible Oils with Cooking Process

Trans fat is a unsaturated fatty acid with trans configuration and separated double bonds. Analytical methods have been introduced to analyze trans fat content in foods including infrared (IR) spectroscopy, gas chromatography (GC), Fourier transform-infrared (FT-IR) spectroscopy, reverses-phase silver ion high performance liquid chromatography, and silver nitrate thin layer chromatography. Currently, FT-IR spectroscopy and GC are mostly used methods. Trans fat content in 6 vegetable oils were analyzed and processing effects including baking, stir-frying, pan-frying, and frying on the formation of trans fat in corn oil was evaluated by GC. Among tested vegetable oils, corn oil has 0.25 g trans fat/100 g, whereas other oils including rapeseed, soybean, olive, perilla, and sesame oils did not have detectable amount of trans fat content. Among cooking methods, stir-frying increased trans fat in corn oil whereas baking, pan-frying, and frying procedures did not make changes in trans fat content compared to untreated corn oils. However, the trans fat content was so low and food label can be declared as ‘0’ trans based on the regulation of Ministry of Food ad Drug Safety (MFDS) (< 2 g/100 g edible oil).

β-Glucan from Aureobasidum species inhibits fat accumulation in 3T3-L1 adipocyte differentiation

The anti-fat accumulative effects of bacteria-derived β-glucan in 3T3-L1 adipocyte differentiation was investigated. 3T3-L1 preadipocytes were treated with β-glucan at 50 and 100 μg/mL during adipogenesis. Oil Red O staining was used to study expressions of the adipogenic genes PPARγ, ACC, and aP2. Adipogenesis of 3T3-L1 cells treated with β-glucan at 50 and 100 μg/mL was significantly (p<0.05) inhibited by 32.8 and 39.7%, respectively, compared with controls. Expressions of the PPARγ gene from 3T3-L1 cells treated with β-glucan at 50 and 100 μg/mL were significantly (p<0.05) decreased by 13.6 and 46.1%, respectively, ACC gene expression by 18.3 and 36.0%, respectively, and aP2 gene expression by 36.8 and 56.7%, respectively, compared to adipocyte controls. Bacteria-derived β-glucan inhibits fat accumulation at the cellular level that is mediated via decreases in expressions of the PPARγ, ACC, and aP2 genes.