Previously, we have shown that the fatty acid composition of Altay sheep tail fat is of reasonable value and is suitable for further development of possible commercial products. Changes in lipids of Altay sheep tail fat during 50 days of 4°C refrigerated storage were investigated. Lipid oxidation and lipolysis occurred during the storage. The pH showed a continually decreased from first day to the end of the storage (p < 0.05). The lipid oxidation was determined by peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS). The increase PV was observed in Altay sheep fat up to 24 days of storage and decreased from then to the day 30 (p < 0.05). The increase in TBARS was significantly throughout the refrigerated storage (p < 0.05). The changes of the fatty acids identified by GS-MS demonstrated that saturated fatty acids increased from 43.6% to 56.3% and that polyunsaturated fatty acids and monounsaturated fatty acids decreased form 51.2% to 43.7% and from 2.4% to 2.1%, respectively. The content of the functional fatty acids except (C18:2 n-9), started to decrease after 20 days of storage. Those changes indicated that lipid oxidation occurred in Altay sheep tail fat during a long time of low temperature storage. In addition, the good correlation between PV/TBARS values and changes of individual fatty acids could be used as an indicator to monitor the changes of the unsaturated fatty acid during the development process of Altay sheep tail fat-related commercial products.
The addition of more than about 1 ppm polydimethylsiloxane (PDMS) into oil results in PDMS forming both a layer at the oil-air interface and droplets suspended in the oil. It is widely accepted that the extraordinarily strong and stable antioxidative effects of PDMS are due to the PDMS layer. However, the PDMS layer showed no antioxidative effects when canola oil did not contain droplets but rather was covered with a layer of PDMS, then subjected to heating under high agitation to mimic deep-frying. Furthermore, no antioxidative effect was exhibited by oil-soluble methylphenylsiloxane (PMPS) in canola oil or by PDMS in PDMS-soluble canola oil fatty acid ester during heating, suggesting that PDMS must be insoluble and droplets in oil in order for PDMS to exhibit an antioxidative effect during deep-frying. The zeta potential of PDMS droplets suspended in canola oil was very high and thus the negatively charged PDMS droplets should attract nearby low molecular weight compounds. It was suggested that this attraction disturbed the motion of oxygen molecules and prevented their attack against unsaturated fatty acid moiety. This would be the reason in the deep-frying why PDMS suppressed the oxidation reaction of oil. PDMS droplets also attracted volatile compounds (molecular weight below 125 Da) generated by heating canola oil. Thus, adding PDMS to oil after heating the oil resulted in the heated oil smelling less than heated oil without PDMS.
The aim of this study was to discriminate the geographic origin of Korean, Chinese, and Indian sesame oils distributed in Korea using 1H NMR spectroscopy in combination with canonical discriminant analysis (CDA). 1H NMR spectra were obtained from 84 roasted oil samples prepared from 51 Korean, 19 Chinese, and 14 Indian sesame seeds. The integration values of 26 peaks observed in the NMR spectra were determined and normalized on the basis of the peak derived from the terminal CH3 of the fatty acids (0.7446–1.0445 ppm). The variables selected for the CDA include the integration value of one peak (2.7208–2.8533 ppm) that signifies the CH2 between two C=C bonds from linoleic acid and the integration values of three peaks (2.9811–3.1151 ppm, 3.5914–3.6819 ppm, and 5.9471–5.9625 ppm) attributed to the protons of sesamolin. The CDA results showed that 80 of the 84 oil samples and five of the six additional commercial sesame oil samples were correctly classified based on their production site. This study demonstrated that 1H NMR spectroscopy is a useful tool to simultaneously analyze the relative abundance of linoleic acid and sesamolin in the sesame oils and good discrimination between the three Asian sesame oils could be achieved when the 1H NMR analytical data were used in combination with CDA.
A flash extraction method was used to isolate Elaeagnus mollis oil (EMO). The optimal extraction parameters, sample/solvent ratio and extraction temperature, were determined to be 1:10 (g/mL) and 40°C, respectively. Especially, the extraction yield reached 49.30% when the extraction time was as short as 2 min. No obvious difference was observed in fatty acid composition, iodine value, saponification number, total phenolic content and tocopherol content between flash-extracted EMO and Soxhlet-extracted EMO, but their physicochemical values were lower than those of cold-pressed EMO. Cold-pressed EMO had higher oxidation stability, DPPH (1-diphenyl-2-picrylhydrazyl) and hydroxyl radical-scavenging activities than flash-extracted EMO and Soxlet extracted EMO. The flash extraction is demonstrated to be an alternative, efficient method for the vegetable oil production.
In order to obtain margarine free of trans-fatty acids, four interesterified basestocks were prepared by chemical interesterification (CIE) of oil blends. Different ratios of palm stearin, palm olein and soybean oil were mixed without and with 1) fully hydrogenated Acer truncatum oil (FHATO), 2) fully hydrogenated rapeseed oil or 3) palm kernel oil containing a similar amount of saturated, monounsaturated and polyunsaturated fatty acids, but different saturated fatty acid length for CIE. Compared to the physical blends, the CIE samples demonstrated lower slip melting points and decreased solid fat contents, especially at high temperatures, indicating that the CIE samples might have improved mouthfeel. In all CIE samples, the β crystal form disappeared and only the β’ crystal form was observed, except for sample 2, which contained a mixed β and β’ forms. Furthermore, in all CIE samples, except sample 1, the β' crystal forms began transforming to β form after only two cycles of higher temperature treatments indicating that the CIE sample with FHATO had the most resistance to temperature fluctuation during storage which may be attributed to its longer saturated chains. In conclusion, the CIE basestocks containing longer saturated fatty acids could be more suitable for margarine use.
n-3 Polyunsaturated fatty acids (PUFAs) are essential for the prevention and/or risk reduction of some diseases, including cardiovascular diseases and cancer. Therefore, PUFAs-rich marine microalgae have received considerable research attention. The diatom Phaeodactylum tricornutum, a rich source of lipids and fucoxanthin, has commercial applications in the food and pharmaceutical industries. In this study, the lipid class composition and fatty acid distribution in P. tricornutum under high-density and scale-up cultivation were investigated by thin-layer chromatography and gas chromatography. The fucoxanthin content was quantified by reverse-phase high-performance liquid chromatography. Both total lipid and fucoxanthin contents were high, accounting for 321.89 and 4.47 mg/g dry weight, respectively. Neutral lipids were the major lipids, and triacylglycerol was the predominant neutral lipids (33.63% of total lipids). The glycolipids (GLs) and phospholipids (PLs) represented 20.95% and 31.39% of total lipids, respectively. Sulfoquinovosyl diacylglycerol (SQDG) was the largest GLs fraction (9.81% of total lipids). Phosphatidylglycerol (PG) was the major PLs and accounted for 13.53% of total lipids. The main fatty acids were hexadecanoic acid (C16:0), palmitoleic acid (C16:1), and eicosapentaenoic acid. In addition, docosahexaenoic acid only accumulated in the PLs fraction. These findings provide new information on the lipid types, fatty acid composition of each lipid class, and the fucoxanthin content in P. tricornutum.
Mayonnaise, which is widely used in foods, is rich in lipids and therefore susceptible to oxidation during the manufacturing process, which can result in loss of quality. Herein, we detected and analyzed phosphatidylcholine hydroperoxide (PCOOH) isomers present in fresh mayonnaise using LC-MS/MS. The PCOOH isomer composition suggests that mayonnaise phospholipid peroxidation is predominantly initiated by radical-oxidation (i.e. upon autoxidation), rather than singlet oxygen-oxidation (e.g. upon light exposure), during manufacturing, packaging and/or storage. This LC-MS/MS method will be useful for elucidating the cause of lipid peroxidation in mayonnaise and related foods. Such information will be valuable to ensure maintenance of product quality.
Here, we report the results of thermodynamic analyses on the lamellar-vesicular transition for a cationic amphiphilic species, namely 2-hydroxyethyl di(alkanol)oxyethyl methylammonium methylsulfate (DEAE). Previously, we have shown that spontaneous vesicle formation from a Lα-lamellar liquid crystal (LC) phase only occurs on the addition of a quantitative amount of additives to the DEAE LC at certain temperatures and that this change occurs without the input of any extra mechanical energy. These lamellar-vesicular transitions occur in two steps: the first step is the formation of an excited state, caused by the solubilization of organic substances in the bilayer structure. The second step, induced by the addition of a small amount of inorganic salt to the excited LC state, is the transition from lamellar to vesicular phase. From our experimental data, the change in the Gibbs free energy was estimated by assuming an ideal electrical chemical potential. As a result, the thermodynamic parameters at 303 K for the lamellar-vesicular transition from the initial state (lamellar) to the final state (vesicle) were found to be approximately –2.7 kJ/mol for the Gibbs free energy, –14.6 kJ/mol for the enthalpy change, and –11.9 kJ/mol for the entropy change. Each state change was due to structural changes not only in the LC bilayers but also in the hydration structure of the surrounding water. Moreover, the most significant finding is that the free energy change in lamellar-vesicular transition is negative, which may be explained based on the stabilization of solubilized vesicles with respect to the unsolubilized lamellar phases.
Hierarchical structures, also known as fractal structures, exhibit advantageous material properties, such as water- and oil-repellency as well as other useful optical characteristics, owing to its self-similarity. Various methods have been developed for producing hierarchical geometrical structures. Recently, fractal structures have been manufactured using a 3D printing technique that involves computer-aided design data. In this study, we confirmed the accuracy of geometrical structures when Koch curve-like fractal structures with zero to three generations were printed using a 3D printer. The fractal dimension was analyzed using a box-counting method. This analysis indicated that the fractal dimension of the third generation hierarchical structure was approximately the same as that of the ideal Koch curve. These findings demonstrate that the design and production of fractal structures can be controlled using a 3D printer. Although the interior angle deviated from the ideal value, the side length could be precisely controlled.
The present study showed unique properties of an alkaline, thermophilic lipase of Geobacillus sp. which was isolated from soil of hot spring. The study was aimed to investigate the optimum immobilization conditions of lipase onto silica gel matrix (100-200 mesh) by surface adsorption method and its application in the synthesis of methyl salicylate. Lipase immobilized by surface adsorption onto silica pretreated with 4% glutaraldehyde showed 74.67% binding of protein and the optimum binding time for glutaraldehyde was found to be 2 h. The enzyme showed maximum activity at temperature 55°C, incubation time of 10 min at pH 9.5 of Tris buffer (0.1 M). Free as well as immobilized lipase was more specific to p-NPP (20 mM). All the metal ions and detergents used had inhibitory effect on free as well as immobilized enzyme. The silica immobilized enzyme was reused for hydrolysis and it retained almost 40.78% of its original activity up to 4th cycle. On optimizing different parameters such as molar ratio, incubation time, temperature, amount of enzyme, amount of molecular sieve, the % yield of methyl salicylate was found to be 82.94.
The contact toxicity and repellent activities of the essential oil extracted from the rhizomes of Zingiber zerumbet (L.) Smith (Zingiberaceae) was evaluated against cigarette beetles (Lasioderma serricorne). The essential oil obtained by hydrodistillation was investigated by GC-FID and GC-MS. The main constituents of the essential oil were zerumbone (40.2%), α-caryophyllene (8.6%), humulene epoxide II (7.3%), camphene (5.9%) and fenchene (4.7%). Zerumbone and its analogues totally are accounting for 60.3% of the essential oil. It was found that the essential oil possessed contact toxicity against L. serricorne adults with a LD50 value of 48.3 µg/adult. α-Caryophyllene (LD50 = 13.1 µg/adult) exhibited stronger contact toxicity against L. serricorne than humulene oxide (LD50 = 31.2 µg/adult), β-caryophyllene (LD50 = 35.5 µg/adult) and zerumbone (LD50 = 42.4 µg/adult). Moreover, α-caryophyllene possessed strong repellent activity (Class IV and V, respectively) against the beetles at 78.63 nL/cm2, after 2 and 4 h treatment. The results indicate that zerumbone and its analogues might be developed into natural insecticides or repellents for control of cigarette beetles, but their bioactivities are affected by their structures.
The purpose of the present study is to bear our hypothesis and to make a profound discussion on the theoretical aspects of triacylglycerin (TG) positional isomer separation on reverse phase high performance liquid chromatography (HPLC). Authentic triacid TG positional isomers and authentic diacid TG positional isomers were injected to a monomeric and polymeric HPLC. Relationship between TG molecular structure and those elution profiles were carefully analyzed. In polymeric column, thickness of the ODS chain is high compared to monomeric column. And for this reason, clearances between the ODS stationary phase chains are considered to be very limited compared to those of monomeric column, thus limiting the TG molecule transformations and rotations to only a “longest stem direction” which gives the smallest resistance in passing through the ODS chains. The longest stem direction of the TG molecule was considered to be the crucial factor for the interaction between the stationary phase. And under this condition, interference occurring between the fatty acid moieties must be the main contributing factor for positional isomer separation in polymeric column. These aspects were considered to explain why they are not consistent with the addition theorem of A.J.P. Martin in partition chromatography.
Synthetic receptors possessing two complexing chromophores connected by a single spacer are referred to as molecular tweezers. We report an electrochemically triggered molecular tweezers, which is a calixarene-bis-porphyrin conjugate, that acts as a proof-of-concept demonstration system showing an electro-statically induced approach to guest release. The electrochemical behavior represents that 1,4-diazabicyclo[2.2.2]octane (DABCO) is released from the complex formed between calixarene-bis-porphyrin conjugate and DABCO, just after cooperative two-oxidation occurs at 0.41 V.