A Non-Destructive Method for Assessing Hair Interior and Surface Damage by Near Infrared Spectroscopy

This paper reports a non-destructive method for evaluating hair interior and surface damage based on near-infrared (NIR) diffuse reflectance (DR) spectroscopy. It is important to know the extent of chemical damage in the interior and surface proteins of the hair in order to choose an appropriate restoration agent or chemical treatment. Unfortunately, though there are many simple and non-destructive methods for evaluating the hair surface, the existing evaluation methods for monitoring chemical changes in the interior proteins are very complicated and destructive. Therefore, we have attempted to develop a new non-destructive method to evaluate the damage of the hair interior and surface simultaneously by using NIR-DR spectroscopy. The key to this study was the combined application of NIR-DR spectroscopy and principal component analysis to development of a method for the evaluation of hair damage and finding the most suitable wavenumber region (5060—4500 cm^-1) for this evaluation. In this study, we developed a new evaluation method that can indicate hair interior and surface damage conditions induced by chemical treatments in a simple, rapid, non-destructive manner based on NIR-DR using a fibre probe on hair
Paper presented at the IFSCC International Conference 2005, Florence, Italy.     

Effect of caffeic acid on haemoglobin‐mediated lipid and protein oxidation in washed cod mince during ice and frozen storage

BACKGROUND: Little is known about the relation between haemoglobin (Hb)‐mediated lipid and protein oxidation in muscle foods and how these two reactions can be inhibited by naturally occurring antioxidants. This study was aimed at evaluating (1) lipid oxidation and protein oxidation induced by 20 µmol L^?1 Hb during chilled and frozen storage of washed cod mince and (2) the efficiency of 10–1000 ppm (0.063–6.3 mmol L^?1) caffeic acid in preventing these reactions. RESULTS: Addition of 20 µmol L^?1 Hb increased peroxide value (PV), rancid odour, protein carbonylation, protein insolubilisation, redness loss and α‐tocopherol loss in ice‐stored washed cod mince. Since both lipid and protein oxidation developed at the same time, it was not possible to conclude which reaction initiated the other. All studied reactions were efficiently inhibited by ≥ 50 ppm caffeic acid, which could be a result of α‐tocopherol regeneration, general radical scavenging, reduced formation of oxidised Hb forms and/or conformational changes in Hb structure. During frozen storage the only clear effect of Hb was increased PV, and here caffeic acid was less efficient as an antioxidant. CONCLUSION: Hb‐induced lipid and protein oxidation occurred quickly in ice‐stored washed cod mince, and the two reactions could not be separated in time. During frozen storage, Hb caused only limited lipid oxidation. Caffeic acid (≥50 ppm) was an efficient antioxidant during ice storage. Copyright © 2010 Society of Chemical Industry     

No. 4Vol. 42, No. 4, pp. 305–312, 2008The Reaction of Oxidative Hair Dyes in Cuticle Layers

The mechanism of oxidative hair dyes (permanent hair color) in cuticle layers of human hair was studied. In general, it is considered that the oxidative hair dye deposits monomer into the cortex, and is polymerized with coloring in there. It was confirmed that not only cortex but also cuticle layers were dyed with the permanent hair color, through observation with the thin cross-section of the dyed hair. There were exogenous metals in the cuticle layers from tap water etc., and the transition metals increased the dyeing and decreased the bleaching. It was thought that the activity of oxidation reaction with hydrogen peroxide was increased in the cuticle layers, and permeability to the cortex was decreased. Furthermore, TEM findings suggested that the oxidation hair dyes mainly reacted in the β-layer/ δ-layer interface in the cuticle layers, unevenly distributing the metals in the β-layer of cuticular CMC.
Keywords:  hair, oxidative hair dye, hair color, bleach, cuticle, transition metal, ultrastructure, CMC, β-layer, oxidative reaction     

A highly sensitive method to determine the washing resistance of artificial hair colours

Citation: IFSCC Magazine, 11 (2008) (2) 139–142 Abstract: Due to the improved performance of modern hair colorants, the high natural variability in hair qualities and the individual influences of manual product applications, colour care effects of cosmetic treatments are very difficult to detect. A new, highly sensitive test method to study the colour fading behaviour of human hair was established for a large variety of cosmetic treatments. This method is based on an automatic multistage application of standard wool tissues combined with automatic colour evaluation by means of CIE L × a × b × measurements (DIN 5033). The delta E values are the main interest because they include all information regarding the L (black vs. white), a (red‐green) and b (blue‐yellow) axes defined in the Hunter Lab colour space. For validation of this new method, different permanent and non‐permanent hair colour shades were applied to undamaged light brown Caucasian hair strands. The hair strands were washed manually stepwise 30 times and the colour loss compared with the results obtained on wool tissues using an automatic application system. For most of the investigated hair colours, a coefficient of determination of r2 > 0.99 was achieved. Modern permanent hair colours show a high resistance to cosmetic treatments. Over 90% of the initial colour result was retained after 30 product applications. Shampoo and conditioner formulations induce different degrees of colour loss in hair. In basic formulas significant influences of single surfactants could be detected. The new method using wool tissues correlates very well with that using manually washed Caucasian hair strands. This automatic method is very time‐effective and offers an excellent reproducibility with a high sensitivity for assessing product influences on artificial hair colours. Keywords: Color fading, color protection, color retention, hair color resistance, hair wash simulation Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands     

Cuticular damage to African–American hair during relaxer treatments – A microfluorometric and SEM Study

Citation: IFSCC Magazine, 11 (2008) (2) 131–137 Abstract: In earlier publications [1,2,3 we discussed several in‐depth studies of characterization and quantification of damage done to European dark brown hair fibres by photochemical and cosmetic‐chemical oxidation (bleaching) and reduction (perming) processes. These earlier studies established considerable changes in surface chemistry such as an increase in acidity and hydrophilicity. We discussed in detail the breakdown of the lipid domains (delipidation) of the outer ^®‐layer of the exposed scale faces and generation of anionic (sulphonic acid) groups (acidification) on the hair surface caused by these oxidative and reduction processes. The goal of this current study is to characterize and quantify the level of chemical and physical changes in the surface of African–American hair caused by various »lye‐based« and »no‐lye« relaxer treatments [4]. This study attempts to establish which product delivers the best »hair straightening« performance while resulting in the least chemical and physical changes in the hair surface. We again use a microfluorometric technique with the help of the cationic fluorochrome Rhodamine B to detect, map and quantify relaxer‐induced changes in the surface chemistry of human hair fibre. In addition, we also use SEM at various magnifications to highlight relaxer‐induced changes in the physical nature of the hair surface. We attempt to associate the level of increase in fluorescence intensity, which represents an increased level of delipidation/acidification of the hair surface, with the damage level to the hair topography, and thus, determine the least damaging cosmetic chemical process. Damage to the physical nature of the hair topography as observed by SEM shows a clear difference between treatments involving lab‐made relaxer solutions and commercial relaxer systems. Keywords: African‐American hair, commercial relaxer systems, microfluorometry, relaxer‐induced surface changes/damage, physical nature, surface chemistry, relaxer solutions, SEM, +lye‐based1/2 and +no‐lye1/2 relaxers,     

Kinetic Study of the Quenching Reaction of Singlet Oxygen by Common Synthetic Antioxidants (tert-Butylhydroxyanisol, tert-di-Butylhydroxytoluene, and tert-Butylhydroquinone) as Compared with α-Tocopherol

ABSTRACT: Effects of synthetic phenolic antioxidants (BHA, BHT, and TBHQ) on the methylene blue (MB) sensitized photooxidation of linoleic acid as compared with that of α‐tocopherol have been studied. Their antioxidative mechanism was studied by both ESR spectroscopy in a 2,2,6,6‐tetramethylpiperidone (TMPD)‐methylene blue (MB) system and spectroscopic analysis of rubrene oxidation induced by a chemical source of singlet oxygen. Total singlet oxygen quenching rate constants (k_ox?Q+k_q) were determined using a steady state kinetic equation. TBHQ showed the strongest protective activity against the MB sensitized photooxidation of linoleic acid, followed by BHA and BHT. TBHQ (1 × 10^?3 M) exhibited 86.5% and 71.4% inhibition of peroxide and conjugated diene formations, respectively, in linoleic acid photooxidation after 60‐min light illumination. The protective activity of TBHQ against the photosensitized oxidation of linoleic acid was almost comparable to that of α‐tocopherol. The data obtained from ESR and rubrene oxidation studies clearly showed the strong singlet oxygen quenching ability of TBHQ. The k_ox?Q+k_q of BHA, BHT, and TBHQ were determined to be 3.37 × 10⁷, 4.26 × 10⁶, and 1.67 × 10⁸ M^?1 s^?1, respectively. The k_ox?Q+k_q of TBHQ was within the same order of magnitude of that of α‐tocopherol, a known efficient singlet oxygen quencher. There was a high negative correlation (r² = ?0.991) between log (k_ox?Q+k_q) and reported oxidation potentials for the synthetic antioxidants, indicating their charge‐transfer mechanism for singlet oxygen quenching. This is the 1st report on the kinetic study on k_ox?Q+k_q of TBHQ in methanol as compared with other commonly used commercial synthetic antioxidants and α‐tocopherol.     

Isolation of a novel alkaline-induced laccase from Flammulina velutipes and its application for hair coloring

Laccase is a member of the multi-copper oxidase family and a promising for hair coloring. In this study, we isolated a novel alkaline-induced laccase from the white-rot fungus Flammulina velutipes and studied the possibility to apply the enzyme for hair coloring. Laccase activity detected in the culture supernatant of F. velutipes was found to significantly increase when exchanging the medium to laccase inducing one whose pH was adjusted to 9.0. Three isozymes were detected by activity staining on non-denaturing SDS-PAGE. The major isozyme, Flac1, was purified from the culture supernatant after being induced at pH 9.0 by ion-exchange column chromatography. The N-terminal peptide sequence of Flac1 was determined, revealing clear homology with laccases from other white-rot fungi. Optimum pH of oxidation was found to be around pH 5.0-6.5 regardless of several different substrates used. Oxidation activities of Flac1 to several hair dye agents as substrate showed the higher activity at pH 6.5 than that at pH 9.0. Oxidation activity was also detected at pH 9.0 which was suitable for hair coloring. When the purified Flac1 was applied for hair coloring system without using hydrogen peroxide, effective coloring was observed at the protein amount of 0.25mg/1g of hair used. These results indicated that this alkaline-induced novel laccase isolated from the culture supernatant of F. velutipes might be a useful enzyme for hair color.     

天然抗氧化剂对辣椒鸡油抗氧化性能的影响

为了筛选出适合辣椒鸡油的天然抗氧化剂,以延长其保质期,研究并比较了6种天然抗氧化剂（迷迭香提取物、维生素E、茶多酚、维生素C、槲皮素和硫辛酸）对辣椒鸡油酸值、过氧化值、DPPH自由基清除能力和总还原能力的影响。结果表明：6种天然抗氧化剂在辣椒鸡油中均具有一定的抗氧化能力;在抑制酸值方面,槲皮素效果最佳,维生素C最差;在抑制过氧化值方面,槲皮素效果最佳,维生素E最差;在DPPH自由基清除能力方面,迷迭香提取物效果最佳,硫辛酸最差;在总还原能力方面,槲皮素效果最佳,维生素E最差;槲皮素、迷迭香提取物和茶多酚在酸值、过氧化值、DPPH自由基清除能力和总还原能力方面均位于前三。综合考虑抗氧化效果、抗氧化剂稳定性、成本等因素,可优先选择迷迭香提取物和茶多酚作为辣椒鸡油的抗氧化剂以提高其储藏性能。     

The contribution of neurogenic inflammation to sensitive skin: concepts, mechanisms and cosmeceutical intervention

IFSCC Magazine , 11 (2008) (4) 317–320
Winner of the Poster Award at the IFSCC Congress 2008, Barcelona, Spain.
A new method was developed to study aging effects on human hair keratin caused by shampooing, blow drying and sunlight. An automatic multiple process allowed reproducible simulation of the stress of approximately 100 Central European summer days in only 5 working days. Stress-strain measurements showed a significant weakening of the hair structure due to simulated aging effects. A new keratin active containing peptides identical to those in human hair was developed. The new keratin active penetrates deeply into the cortex cells, which was demonstrated by means of fluorescence microscopy. Aging damage was successfully prevented by strengthening the hair structure.
Keywords: Hair keratin, hair strengthening, intermediate filament, keratin aging simulation, restructuring     

Change in surface chemistry of the cuticle of human hair by chemical and photochemical oxidation

This is a multifaceted study on the characterization and quantification of damage to the hair fiber surface caused by photochemical and cosmetic chemical oxidative processes. Unique techniques were used, including a microfluorometric method that had been adapted to characterize and quantify the delipidation and acidification of the human hair surface during light exposure and cosmetic chemical grooming processes such as bleaching. During photochemical and chemical oxidation, breakdown of the lipid domains (also called the F‐layer) of the outer b‐layer occurs on the exposed scale faces and cysteic acid groups are generated on the cuticle cell surface. The newly formed acid functionalities can be tagged with the cationic fluorochrome Rhodamine B, allowing not only quantification of the level of progressive acidification but also localization of the newly formed acid functionalities. On the other hand, the negative charges generated on the hair surface by oxidation can also bind low molecular weight quaternary cationic conditioning compounds such as cetyltrimethylammonium bromide. This process can be considered a relipidation by adsorption. We have shown that the entire process of delipidation/acid formation and subsequent relipidation by adsorption on the scale faces can be quantified by X‐ray photoelectron spectroscopy. Since X‐ray photoelectron spectroscopy analysis is highly sensitive and able to detect atomic species at the very surface of the hair fibers, receiving signals from an escape depth as shallow as 25 Å, it appeared ideal for the characterization of treatment‐induced changes in the hair surface. However, X‐ray photoelectron spectroscopy provides an average elemental composition of the hair surface including scale faces and scale edges. The microfluorometric technique, on the other hand, can distinguish progressive delipidation of the scale faces from changes occurring at the broken scale edges. This distinction was shown and characterized in detail by slow speed microfluorometric scanning of the hair surface. Chemical and photochemical oxidative processes at the hair surface result in certain collateral effects. Particularly changes in surface wettability and fiber friction are of significance to the cosmetic chemist because they affect the spreading and wicking of products in hair as well as the managability and the body of hair assemblies. Methods of characterizing these effects are discussed briefly.     

VE复合抗氧化剂在鸡油中的抗氧化性能研究

油脂是人们必需的食品和食品加工的主要原料之一,油脂氧化是影响油脂品质的一个重要因素.以VE、VE分别与茶多酚、迷迭香、硫辛酸、槲皮素的复合物为抗氧化剂,添加到鸡油中,比对研究抗氧化性能.结果表明:VE、茶多酚、迷迭香、硫辛酸、槲皮素都具有一定的抗氧化效果,相同添加量的情况下单品的抗氧化能力大小顺序为:迷迭香＞槲皮素＞茶多酚＞硫辛酸＞ VE;VE与4种天然的抗氧化剂1∶1进行复合以后与单一的抗氧化剂相比都具有一定的增效作用.     

VE复合抗氧化剂在猪油中的抗氧化性能研究

以VE,VE分别与茶多酚、迷迭香、硫辛酸、槲皮素的复合物为抗氧化剂,添加到猪油中,比对其抗氧化性能。结果表明:VE、茶多酚、迷迭香、硫辛酸、槲皮素都具有一定的抗氧化效果,相同添加量的情况下单品的抗氧化能力大小顺序为:槲皮素>茶多酚>迷迭香>硫辛酸>VE;VE与四种天然的抗氧化剂1∶1进行复合以后与单一的抗氧化剂相比都具有一定的增效作用。     

Antioxidative Properties and Ability of Phenolic Compounds of Myrtus communis Leaves to Counteract In Vitro LDL and Phospholipid Aqueous Dispersion Oxidation

Antioxidant activities of Myrtus communis leaf phenolic compounds (McPCs) were investigated on 2,2′‐9‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS⁺?) and oxygen radical absorbance capacity (ORAC) tests or on oxidation of biological models, human low‐density lipoprotein (LDL) and phospholipid aqueous dispersion (l ‐α‐phosphatidylcholine stabilized by bile salts). Two extraction techniques, microwave‐assisted (MAE) and conventional (CE), were used to isolate McPCs, producing similar results of phenolic compound content. ABTS⁺? assay showed clearly that myrtle extracts exhibited a stronger scavenging effect than butylated hydroxyanisole and α‐tocopherol, with a slight advantage for myrtle CE extract. In ORAC assay, the both McPC extracts were similarly less effective than the pure compounds as caffeic acid and myricitrin (myricetin 3‐O‐rhamnoside) but stronger than butylated hydroxytoluene. Moreover, myrtle CE and MAE extracts, and myricitrin were able to inhibit similarly the production of conjugated dienes and to prolong the lag phase (Tlag) during Cu²⁺‐induced LDL oxidation with a dose‐response effect. The cryo‐electron microscopy observations on studied phospholipid dispersion stabilized by bile salts (BS) revealed the presence of bilayer vesicles and micelles. In 2,2′‐azobis (2‐amidinopropane) hydrochloride–induced phospholipid/BS oxidation, myrtle CE and MAE extracts gave similar effects to α‐tocopherol and caffeic acid but myricitrin showed a higher protective effect than myrtle extracts. We showed also that no synergic or additive effect between α‐tocopherol and myrtle extracts or caffeic acid in α‐tocopherol–enriched phospholipid/BS dispersion, but myricitrin showed an additive effect and thus promoted the total antioxidant activity. These data showed that myrtle extract could be used as potential natural antioxidants, food stabilizers, or natural health products.     

The role of chelants in controlling Cu(II)‐induced radical chemistry in oxidative hair colouring products

The catalytic formation of hydroxyl radicals in oxidative hair colourant systems in the presence of added copper ions was measured and quantified using a colorimetric probe N,N′‐(5‐nitro‐1,3‐phenylene)bisglutaramide. Also monitored in the same experiments was the decomposition of hydrogen peroxide. The first set of experiments was performed using aqueous model solutions containing the key oxidant actives in a hair colourant, ammonium hydroxide and hydrogen peroxide at pH 10, with added copper and calcium ions. The second set of experiments was performed in the presence of hair containing different levels of copper in conditions very close to those found during hair colouring. Both sets of experiments demonstrate the ability of copper ions to trigger the formation of hydroxyl radicals and catalyse the decomposition of hydrogen peroxide. The ability of chelants ethylenediamine tetraacetic acid (EDTA) and N,N′‐ethylenediamine disuccinic acid (EDDS) to moderate the flux of hydroxyl radicals formed in solution systems was demonstrated in the presence of copper ions alone. However, only EDDS was successful in the presence of both calcium and copper ions. This was confirmed in the hair experiments where again only EDDS was successful at preventing hydroxyl radical formation where hair is added as the source of copper and calcium ions. These results are explained using metal speciation modelling and demonstrate the importance of the chelant to be able to specifically bind and prevent the one‐electron redox chemistry of copper in the presence of high levels of calcium ions as found in hair. The formation of hydroxyl radicals during the colouring process was shown to lead to hair structure damage as measured by protein loss. EDDS was demonstrated to significantly reduce cuticle damage by suppressing the formation of the hydroxyl radicals in systems with realistic concentrations of calcium and copper.     

Concentration‐dependent antioxidant activities of conjugated linoleic acid and α‐tocopherol in corn oil

BACKGROUND: Antioxidants prevent rancidity (lipid peroxidation) and natural antioxidants, e.g., α‐tocopherol, likely provide additional value to oil‐based food products because of their health benefits. Conjugated linoleic acid (CLA) has potential health benefits and may exhibit antioxidant properties. The main aim of this study was to compare the antioxidant efficacy of α‐tocopherol, trans‐10, cis‐12‐CLA and cis‐9, trans‐11‐CLA (in graded concentrations) added to antioxidant‐stripped corn oil. RESULTS: As compared to α‐tocopherol, both CLA isomers displayed significant inhibition of corn oil lipid peroxidation induced by copper. Inhibition of thiobarbituric acid reactive substances (TBARS) were CLA concentration dependent for both isomers but with significant inhibition occurring at 0.1 and 1 ppm of CLA isomers or α‐tocopherol, respectively (P < 0.05). Graded concentrations of α‐tocopherol, and for both CLA isomers and time, had significant effects on TBARS formation (P < 0.0001). There were significant effects in interactions between graded concentrations and time for both CLA isomers (P < 0.0001) but not for α‐tocopherol (P > 0.05). CONCLUSION: CLA compounds could serve as useful food antioxidants and provide additional value because of their potential bioactivity in disease prevention. Copyright © 2007 Society of Chemical Industry     

Production of the Tissue Inhibitor of Metalloproteinase-2 (TIMP-2) and Evaluation of Its Potential as Anti-Aging Active

Oxidative hair color, the most commonly used for coloring hair, is characterized by its bleaching effect. This effect enables dark hair to be dyed in various bright colors. In order to enhance this bleaching effect, the concentration of either the alkalizing or oxidizing agent in the hair color base is generally increased. However, this method causes chemical damage to the hair. With the aim of finding methods to obtain an improved bleaching effect without increasing the amount of bleaching ingredients, the authors investigated the permeation mechanism. Cationic bases showed the highest bleaching effect and allowed greater penetration, permitting bleaching ingredients to enter the cortex of the hair more easily and diffuse more quickly. In addition, the molar ratios of higher alcohol (A) to cationic surfactant (C) as a function of the bleaching effect were also evaluated. The results showed an optimum range for this A/C ratio. The smoothness of the hair was also evaluated, revealing an optimum range for the A/C ratio. Based on these findings, a product with an A/C ratio that maximizes the bleaching effect and the smoothness of the hair was successfully developed. Comparison of this newly developed product with a conventional product verified that the new product has a greater bleaching effect and gives a beautiful depth of color while maintaining the silky smoothness of the texture of the hair.
Part of this study was presented at the 23rd IFSCC Congress 2004, Orlando, Florida USA.     

Light effects on lipid oxidation,antioxidants, and pigments in dried laver (Porphyra) during storage

Effects of light on lipid oxidation, antioxidants, and pigments in dried laver (Porphyra) were studied during storage at 40°C and at a water activity of 0.75 for 15 days. Lipid oxidation was evaluated by measuring peroxide value (POV) and conjugated dienoic acid (CDA) contents, whereas fatty acid composition was analyzed by gas chromatography. Contents of polyphenols, tocopherols, porphyran, chlorophylls, carotenoids, and phycobilins were also monitored. The POV and CDA contents of dried laver lipids increased during storage, whereas contents of eicosapentaenoic acid, pigments, and antioxidants decreased. Light accelerated lipid oxidation as well as degradation of antioxidants and pigments during storage of dried laver. Chlorophyll and polyphenols were the most rapidly degraded among all pigments and antioxidants, respectively, and light had the strongest effect on their degradation. Lipid oxidation of dried laver due to light was highly dependent on the content of a-tocopherol among all minor compounds.     

The effectiveness of butylated hydroxyanisole and α‐tocopherol in inhibiting oxidant‐induced chemical and structural changes of whey protein

The objective of the study was to investigate the role of butylated hydroxyanisole (BHA) and α‐tocopherol in protecting whey protein isolate (WPI) from oxidative modification. The results showed that oxidation increased protein carbonyls and decreased total sulfhydryls, and led to higher dityrosine and surface hydrophobicity (P < 0.05) than nonoxidised WPI. The presence of BHA and α‐tocopherol significantly reduced (P < 0.05) the extent of WPI oxidation, thus limiting the oxidation‐induced protein aggregates and structural changes. Therefore, BHA and α‐tocopherol may be used as potential antioxidants in WPI and WPI‐containing foods.     

Singlet Oxygen‐Related Photooxidative Stability and Antioxidant Changes of Diacylglycerol‐Rich Oil Derived from Mixture of Olive and Perilla Oil

Abstract: This study investigated the oxidative stability and antioxidants changes in diacylglycerol (DAG)‐rich oil under singlet oxygen. DAG‐rich oil was derived from triacylglycerol (TAG) oil of extra virgin olive and perilla oil mixture by hydrolysis and re‐esterification using lipases. The oxidation of oils was performed at 25 °C for 48 h under singlet oxygen produced with chlorophyll b under light, and was evaluated by headspace oxygen consumption and peroxide value (POV). The oxidation of DAG‐rich oil was higher and faster in the co‐presence of light and chlorophyll than in their single presence. DAG‐rich oil was more oxidation‐susceptible than TAG oil. There was no significant change in fatty acid and lipid subclass compositions in DAG‐rich oil during the photooxidation. Tocopherols were degraded, whereas polyphenols weren't during phootooxidation of DAG‐rich oil. The oxidation of DAG‐rich oil was well‐correlated with tocopherol contents, not with polyphenol contents, indicating that tocopherols were effective antioxidants in the singlet oxygen‐related phootooxidation of DAG‐rich oil. The results suggested that the oxidative stability of DAG‐rich oil under singlet oxygen be improved by a precise control through retention of tocopherols. Practical Application: The results of this study can be applied to the utilization of diacylglycerol oils to the area of functional edible oils with good oxidative stability.     

Extraction Efficiency of Hydrophilic and Lipophilic Antioxidants from Lyophilized Foods Using Pressurized Liquid Extraction and Manual Extraction

The efficient extraction of antioxidants from food samples is necessary in order to accurately measure their antioxidant capacities. α‐Tocopherol and gallic acid were spiked into samples of 5 lyophilized and pulverized vegetables and fruits (onion, cabbage, Satsuma mandarin orange, pumpkin, and spinach). The lipophilic and hydrophilic antioxidants in the samples were sequentially extracted with a mixed solvent of n‐hexane and dichloromethane, and then with acetic acid–acidified aqueous methanol. Duplicate samples were extracted: one set was extracted using an automated pressurized liquid extraction apparatus, and the other set was extracted manually. Spiked α‐tocopherol and gallic acid were recovered almost quantitatively in the extracted lipophilic and hydrophilic fractions, respectively, especially when pressurized liquid extraction was used. The expected increase in lipophilic oxygen radical absorbance capacity (L‐ORAC) due to spiking with α‐tocopherol, and the expected increase in 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activities and total polyphenol content due to spiking with gallic acid, were all recovered in high yield. Relatively low recoveries, as reflected in the hydrophilic ORAC (H‐ORAC) value, were obtained following spiking with gallic acid, suggesting an interaction between gallic acid and endogenous antioxidants. The H‐ORAC values of gallic acid–spiked samples were almost the same as those of postadded (spiked) samples. These results clearly indicate that lipophilic and hydrophilic antioxidants are effectively extracted from lyophilized food, especially when pressurized liquid extraction is used.