Sung-Gil Choi

Textural and sensory properties of low fat pork sausages with added hydrated oatmeal and tofu as texture-modifying agents

Low fat sausages were prepared with added hydrated oatmeal or tofu as texture-modifying agents at levels of 10%, 15%, and 25% (w/w), respectively. The effects of the type and level of texture-modifying agents on the physical and sensory properties of low fat sausages were investigated. The water-holding capacity in sausage products increased by increasing the hydrated oatmeal level, but no significant differences was observed by the addition of tofu. The higher level of the agents produced a sausage product with less cooking loss and with a softer texture. The moisture absorption measurements suggest that the decrease in hardness of oatmeal-added sausage products may be due to the higher water-retention properties of oatmeal in response to heat treatment, while that of tofu-added sausage products may be associated with a weaker internal structure of tofu than the pork loin. The sensory evaluations indicated that the greatest overall acceptability in a low fat sausage was attained when the hydrated oatmeal or tofu were at their 15% addition level, respectively.

Zeatin Prevents Amyloid β-Induced Neurotoxicity and Scopolamine-Induced Cognitive Deficits

The antioxidative and protective effects of zeatin against amyloid beta-protein (Abeta)-induced neurotoxicity were investigated using PC12 cells. Zeatin showed antioxidative and cell protective effects against Abeta-induced neurotoxicity. In this study, we also evaluated the effect of zeatin on learning and memory capacity in vivo using ICR mice with amnesia induced by scopolamine (1 mg/kg of body weight). Zeatin, when administered to mice at 4.5 mg/kg of body weight, significantly ameliorated scopolamine-induced amnesia as measured in both the passive avoidance test and Y-maze test. Injecting mice with scopolamine impaired performance on the passive avoidance test (48 +/- 4.5% decrease) and on the Y-maze test (12 +/- 1.3% decrease). In contrast, mice treated with zeatin before scopolamine injections were protected from these changes (5-34% decrease in step-through latency; 1-4% decrease in alternation behavior). The present results suggest a possible chemopreventive role of zeatin in Alzheimers disease.

The effect of grinding at various vacuum levels on the color, phenolics, and antioxidant properties of apple.

The purpose of this study was to evaluate the effect of grinding at different vacuum levels (2.67, 6.67, 13.33, 19.99, and 101.33kPa) on key quality factors of apple. In the control apple, ground at atmospheric pressure of 101.33kPa, the antioxidant activities rapidly decreased within the first 30min, then plateaued thereafter, while enzymatic browning increased. When apples were ground and held under vacuum, changes in color and antioxidant activity were much less, and the least change was measured in samples prepared at the lowest pressure. Model fitting of the data showed that antioxidant activity decreased as a function of the logarithm of the absolute pressure. The results from analysis for key phenolic compounds including chlorogenic acid, procyanidin B2, and epicatechin indicated that these compounds were least changed at vacuum grinding at 2.67kPa, compared to atmospheric grinding.

Protective Effects of Black Soybean Seed Coat Extracts against Oxidative Stress-induced Neurotoxicity

Rat pheochromocytoma cells (PC12) and mice were utilized as in vitro and in vivo models to determine the neuroprotective effects of a 70% acetone extract of black soybean seed coat (BSSCE). BSSCE showed higher total phenolic contents than other extracts. Intracellular reactive oxygen species accumulation from H₂O₂ treatment of PC12 cells was significantly reduced when BSSCE was present in the media compared to PC12 cells treated with H₂O₂ only. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium-bromide (MTT) reduction assay and lactate dehydrogenase assay also showed significantly increased protective effects in PC12 cells. In addition, BSSCE improved the in vivo cognitive ability against amyloid beta peptide-induced neuronal deficits.

Effect of Relative Humidity and Storage Temperature on the Quality of Green Tea Powder

After storing green tea powder for three months at three different temperatures (-20, 4, and 20 o C) with three different relative humidities (RHs) (23, 69, and 81%), the chemical quality was evaluated with green tea, which was prepared by soaking 1.5 g of the powder into 100 mL of distilled water at 70 o C for 5 min. Total phenolic contents, total flavanol contents, and ascorbic acid contents of green tea powder stored at 4 o C with 23% RH changed from 267.5, 49.4, and 24.2 mg/g to 287.1, 44.9, and 36.9 mg/g, respectively, compared to the powder before storage. EGC and EGCG, the main catechins of green tea, also changed from 16.9 and 27.3 mg/g to 24.3 and 36.5, g/g, respectively, after storage for 3 months at 4 o C with 23% RH. However, when the green tea powder was stored at -20 or 20 o C with higher RH such as 69 and 81%, the chemical compounds were significantly decreased. The results indicate that temperature and RH are important during storage of green tea powder, and low RH and refrigerated condition (-4 o C) are preferable to increase or preserve the chemical compounds of the tea.

Nutritional Composition and Cytoprotective Effect of Moringa oleifera Lam.

The cytoprotective effect of Moringa oleifera Lam. (drumstick tree) on neuronal cells was investigated to confirm the physiological benefits associated with this natural food resource. First, the drumstick tree extract was chemically analyzed to determine inherent nutritional constituents. Calcium and potassium were identified as the major mineral constituents, and palmitic acid (C16:0, 16.33%) and gadoleic acid (C20:01, 66.34%) were detected as the major fatty acids. Moreover, drumstick tree extract contained 94.78 mg/100 g vitamin E and 112.61 mg/100 g niacin. PC12 cells were used to study the cytoprotective effects of drumstick tree extract. Intracellular accumulation of reactive oxygen species was significantly reduced when H 2 O 2 treated-neuronal cells were cultured in a medium containing the methanolic extract of drumstick tree, compared to cells treated with only H 2 O 2 . Cell viability assay using MTT showed that the extract protected cells against H 2 O 2 -induced neurotoxicity and inhibited LDH leakage from the cell membrane. Caspase assay showed that the extract exerted cytoprotective effect against apoptosis. Consequently, these data suggest that drumstick tree is a useful natural resource with positive effects on human health.

Thermal and functional characteristics of defatted bovine heart using supercritical CO2 and organic solvent: Thermal and functional properties of SC-CO2 and hexane-treated bovine heart

BACKGROUND Consumer demand for low-fat foods has been increasing as a result of attempts to reduce obesity and chronic diseases. Bovine heart was defatted using supercritical CO2 (SC-CO2 ) at different pressures together with solvent extraction to produce a protein-based functional ingredient for low-fat food products. Thermal and functional characteristics of control and defatted samples were compared. RESULTS Supercritical CO2 treatment at high pressure results in more removal of fat, producing a protein-rich defatted bovine heart (DBH). The differential scanning calorimeter (DSC) thermograms and SDS-PAGE bands for SC-CO2 -treated DBHs were similar to those of the control sample, indicating high protein stability and better functionality. Hexane-treated DBH showed no major thermal peaks and very diffuse bands in SDS-PAGE, indicating denaturation of proteins during solvent extraction. No denaturation of proteins in SC-CO2 -treated DBHs resulted in significantly higher water/oil absorption capacities (3320.00 and 2630.00 g kg-1 , respectively), total soluble solids (822.20 and 208.71 g kg-1 at pH 3.5 and 6.5, respectively), foaming capacities (149.37%), and emulsion activity (66.89%) than the hexane-treated DBH. CONCLUSION Supercritical CO2 treatment of DBH led to higher thermal stability and functional properties than the control and hexane-treated DBH. Defatted bovine heart using SC-CO2 can be a functional ingredient for various low-fat and high-protein food products for health-conscious consumers.

Effect of Grinding at Modified Atmosphere or Vacuum on Browning, Antioxidant Capacities, and Oxidative Enzyme Activities of Apple: Effect of grinding at MA or vacuum…

This study evaluated the effects of grinding at atmospheric pressure (control), under vacuum (∼2.67 kPa), or with modified atmosphere (N2 and CO2 ) on the browning, antioxidant activity, phenolics, and oxidative enzyme activity of apples as a function of time. The control group was affected most, showing distinct browning and losing most of the antioxidant activity and concentrations of the main phenolic compounds. The modified atmosphere groups retained color, antioxidant activity, and phenolic compounds better than the control group. Least changes were obtained with vacuum grinding, particularly in terms of preventing enzymatic browning and oxidation of antioxidants apples. At 12 h after grinding, vacuum-ground apples retained total phenolic contents 5.32, 1.54, and 1.49 times higher than control, nitrogen gas, and carbon dioxide gas-ground samples, respectively. The oxidative enzyme activity, including that of polyphenol oxidase and peroxidase, decreased in the control and modified atmosphere group, but they were maintained in the samples ground under the vacuum. PRACTICAL APPLICATION In this study, we found that grinding with modified atmosphere or vacuum conditions could effectively prevent browning as well as loss of phenolic compounds and antioxidant activity of ground apples. These results can help scientists and engineers build better grinding systems for retaining nutrient and quality factors of ground apples. In addition, these results may be useful to other fruit and vegetable industries that wish to retain fresh-like quality and nutritional value during grinding and storage.

Variations in vitamin E, phenolic content, and antioxidant properties of different wheat cultivars of South Korea

ABSTRACT The vitamin E, total phenolic content (TPC), and antioxidant activity (AA) profiles of 32 whole wheat cultivars were investigated. Samples were classified based on its hardness (HW: hard wheat, MW: medium wheat, and SW: soft wheat) for easy identification. Total vitamin E content ranged from 64.38SW2 to 111.83MW9 mg/kg; α-tocopherol (6.03MW13 to 21.98MW2 mg/kg), β-T (2.14MW8 to 21.01MW9 mg/kg), α-tocotrienol (4.28MW12 to 9.34MW9 mg/kg), and β-T3 (38.71MW16 to 61.07MW9 mg/kg) were the predominant homologs, with β-T3 as the highest. AA ranged from 334.40MW4 to 584.80HW4 μmol gallic acid equivalent/kg while TPC varied from 1139.70SW6 to 2772.60MW1 μmol GAE/kg. Significant differences in the vitamin E content, TPC, and AA were found among the cultivars regardless of its hardness index. A very weak correlation was found between TPC and AA while a moderate negative correlation was observed between vitamin E content and AA. Results from this study can serve as basis of further studies on the bioactive profiles of Korean wheat cultivars.

Onion Beverages Improve Amyloid β Peptide-Induced Cognitive Defects via Up-Regulation of Cholinergic Activity and Neuroprotection

To examine the cognitive function of onion (Allium cepa L.) beverages (odourless and fortified), we analyzed in vitro neuronal cell protection against H2O2-induced cytotoxicity and performed in vivo tests on amyloid beta (Aβ)-induced cognitive dysfunction. Cellular oxidative stress and cell viability were evaluated by DCF-DA assay and MTT assay. These results show that fortified beverage resulted in better neuronal cell protection than odourless beverage at lower concentration (0∼100 μg/mL). Fortified beverage also showed more excellent acetylcholinesterase (AChE) inhibitory activity (IC50: 4.20 mg/mL) than odourless beverage. The cognitive functions of odourless beverage and fortified beverage in Aβ-induced neurotoxicity were assessed by Y-maze, passive avoidance, and Morris water maze tests. The results show improved cognitive function in both groups treated with beverages. After in vivo tests, cholinergic activities were determined based on AChE inhibition and acetylcholine levels, and antioxidant activities were measured as SOD, oxidized glutathione (GSH)/total GSH ratio, and MDA levels in mouse brain tissue. In a Q-TOF UPLC/MS system, main compounds were analyzed as follows: odourless beverage (five types of sugars and three types of phenolics) and fortified beverages (six types of phenolics and two types of steroidal saponins).