Chul Rhee

Selective Increase in Pinolenic Acid (all-cis-5,9,12-18:3) in Korean Pine Nut Oil by Crystallization and Its Effect on LDL-Receptor Activity

The aims of this study were to obtain concentrated pinolenic acid (5,9,12–18∶3) from dietary Korean pine (Pinus koraiensis) nut oil by urea complexation and to investigate its cholesteroi-lowering effect on the LDL-receptor activity of human hepatoma HepG2 cells. Pine nut oil was hydrolyzed to provide a low-pinolenic acid-containing FA extract (LPAFAE), followed by crystallization with different ratios of urea in ethanol (EtOH) or methanol (MeOH) as a solvent to produce a high-pinolenic acid-containing FA extract (HPAFAE). The profiles of HPAFAE obtained by urea complexation showed different FA compositions compared with LPAFAE. The long-chain saturated FA palmitic acid (16∶0) and stearic acid (18∶0) were decreased with urea/FA ratios (UFR) of 1∶1 (UFR1), 2∶1 (UFR2), and 3∶1 (UFR3). Linoleic acid (9,12–18∶2) was increased 1.3 times with UFR2 in EtOH, and linolenic acid (9,12,15–18∶3) was increased 1.5 times with UFR3 in MeOH after crystallization. The crystallization with UFR3 in EtOH provided the highest concentration of pinolenic acid, which was elevated by 3.2-fold from 14.1 to 45.1%, whereas that of linoleic acid (9,12–18∶2) was not changed, and that of oleic acid (9–18∶1) was decreased 7.2-fold. Treatment of HepG2 cells with HPAFE resulted in significantly higher internalization of 3,3′-dioctadecylindocarbocyanine-LDL (47.0±0.15) as compared with treatment with LPAFAE (25.6±0.36) (P<0.05). Thus, we demonstrate a method for the concentration of pinolenic acid and suggest that this concentrate may have LDL-lowering properties by enhancing hepatic LDL uptake.

Determination of rancidity of soybean oil by near infrared spectroscopy

The technique of near-infrared (NIR) reflectance spectroscopy was used in order to test its use as a potential method for determining the rancidity of soybean oils undergoing autoxidation. Commercial soybean oil was used as a substrate and was oxidized at 75°C until the oxidized oil reached the hydroperoxide decomposition stage. Peroxide values (POVs) and acid values (AVs) of the substrate determined by the chemical method were correlated with NIR spectral absorbances. Two wavelengths (2080 and 2020 nm) were selected for the POV calibration, and the resulting coefficient of multiple determination for regression was quite high (r = 0.9970, SEC = 9.10 meq / kg oil and SEP = 9.67 meq / kg oil). The prediction of oil rancidity by NIR using POV as a reference was found to be accurate in the early stages of oxidation. However, it was undesirable to use the POV calibration equation for the determination of rancidity in the hydroperoxide decomposition stages. Three wavelengths (2008, 1442 and 1752 nm) were used for AV calibration. High correlations were achieved between chemically analyzed AVs and NIR predicted AVs (r = 0.9987, SEC = 0.127 mg KOH / g oil, and SEP = 0.137 mg KOH / g oil). The AV represented a good indicator for the determination of rancidity of oil undergoing thermal oxidation, whereas evaluation of rancidity using the POV has proven to be difficult due to hydroperoxide decomposition. The result of this study suggested that prediction of rancidity by NIR using POV calibration equation was more precise than using an AV calibration equation in hydroperoxide accumulation stages, whereas the AV calibration equation was a better predictor of oil rancidity than the POV calibration equation at higher POV ranges.

Effect of heat treatment of digestion-resistant fraction from soybean on retarding of bile acid transport in vitro

In this study, we investigated the heat effect of digestion-resistant fraction (RF) from soybean on retarding bile acid transport in vitro. The RFs from soybean retarded bile acid transport. A raw, unheated RF of soybean (RRF-SOY) was significantly more effective than the heated RF of soybean (HRF-SOY). The RS1 which physically trapped in milled grains and inaccessible to digestive enzyme after 18 hrs incubation level of content in RRF-SOY was found to be as high as 24.1% and after heating the RS1 of HRF-SOY was significantly reduced to 16.8%. The X-ray diffraction pattern of RF from soybean was altered after heat treatment. The RFs from soybean were characterized by peak at diffraction angles of 12.0° and 20.0° corresponding to RS content. Cellulose contents of RRF-SOY was 5% higher than that of HRF-SOY and pentosan contents of RRF-SOY was 5% higher than that of HRF-SOY, too. Whereas the hemicellulose content of RRF-SOY was 13% lower than HRF-SOY.

Antioxidation activity of oil extracts prepared from various seeds

The anti-oxidative activity of ethanol and methanol extracts from various seed oils (perilla seed oil, camellia seed oil, pine seed oil, flaxseed oil, and olive oil) was investigated using DPPH free radical scavenging activity (DPPH-RSA), hydroxyl radical scavenging activity (Hydroxyl-RSA), fluorescent development, browning level development, microsomal lipid peroxidation (MLP), and t-BOOH-induced cytotoxicity assays. Both browning and fluorescence level were observed higher value in methanol extract of camellia seed oil (CSO-ME). This meant that CSO-ME had more available antioxidant matters. Radical scavenging activity of CSO-ME was the highest among all seed oil extracts, and was 61.1% in the DPPH-RSA and 64.5% in the Hydroxyl-RSA test. Based on in vitro tests, all extract treatments significantly reduced both thiobarbituric acid-reactive substrate formation and lactate dehydrogenase release, indicating high antioxidant activity. These results suggest that ethanol and methanol extracts from seed oils can be a potentially good dietary lipid supplement source against oxidative stress.

Determination of degree of retrogradation of cooked rice by near infrared reflectance spectroscopy

Near infrared (NIR) reflectance spectroscopy was used to determine the degree of retrogradation of cooked rice. Cooked rice samples were stored at 4°C for 120 hours, and the degree of retrogradation was measured every six hours during the storage time. Enzymatic method, using glucoamylase, was used as reference method for the determination of the degree of retrogradation. Spectral differences, due to retrogradation of cooked rice, were observed at 1434, 1700, 1928, 2100, 2284 and 2320 nm. 32 samples were used for calibration set and 16 samples were used for validation set. High correlations were achieved between degree of retrogradation determined by enzymatic method and by NIR with multiple correlation coefficient of 0.9753 and a standard error of calibration of 3.64%. Comparable results were obtained with 3.91% of standard error of prediction, when the calibration equation was applied to an independent group of samples. The moisture content of samples tested significantly affected the determination of degree of retrogradation by NIR. The critical moisture content for the determination of degree of retrogradation by NIR was found to be ca. 5% (W.B.). The results suggested that NIR spectroscopy might be used as a potential method for determining both the degree of retrogradation and gelatinization of cooked rice.