Carbonyl Value Research Articles

함초(Salicornia herbacea)의 효소적 가수분해물이 고콜레스테롤 식이 흰쥐의 항산화방어계에 미치는 영향

The purpose of the present study was to investigate the effect of enzymatic hydrolysate (extract) of Salicomia herbacea L. (Korean name: Hamcho) on antioxidative defense system in rats fed high cholesterol diet. Rats were divided into six experimental groups which are composed of normal diet group, normal diet group supplemented with 2% Hamcho extract, high cholesterol diet group, high cholesterol diet groups supplemented with 1%, 2% and 4% Hamcho extracts. The activity of serum glutamate oxaloacetae transaminase in rats was not different among all experimental groups, while the activity of glutamate pyruvate transaminase in groups supplemented with Hamcho extract was significantly lower than that of high cholesterol control group. Supplementation of Hamcho extract (SHE) to the high cholesterol fed rats resulted in increased activities of hepatic superoxide dismutase and glutathione peioxidase. However, there was no significant difference in the activity of hepatic catalase among all experimental groups. SHE also resulted in decreased levels of hepatic thiobarbituric acid reactive substances and mitochondrial carbonyl values. Those effects were higher to some extent in 2% and 4% Hamcho extract groups than those of high cholesterol control group. These results suggest that enzymatic hydrolysate of Hamcho may reduce oxidative damage by activation of antioxidative defense system in rats fed high cholesterol diets.

DETERMINATION OF CARBONYL VALUE IN RANCID OILS: A CRITICAL RECONSIDERATION

ABSTRACT Different grades of 1‐butanol and 2‐propanol (2‐PrOH) with and without purification were reevaluated for preparation of blank solutions in a modified method for the determination of carbonyl value (CV) in rancid oils (soybean oil and a frying oil). Only purified 2‐PrOH with an absorbance lower than 0.35 at 420 nm was considered suitable as a solvent. Good correlations existed between the absorbance at 420 nm, and the molar concentration for 2‐decenal and 2,4‐decadienal solutions in 2‐PrOH reacted with 2,4‐dinitrophenylhydrazine. The sensitivity of the method in terms of 2‐decenal was higher than that of 2,4‐decadienal. The CVs calculated based on 2,4‐decadienal were higher than those of 2‐decenal, although differences between them were not statistically significant at low levels. Accordingly, the sensitivity of the measurement and the estimated CV content were dependent on the type of standard considered. Triphenylphosphine (TP) exerted a statistically significant effect on the CVs of the soybean oil, unless the peroxide content of the oil sample was very low or much higher than the amount of added TP. The addition of TP to the frying oil was not necessary because the conditions of the CV test did not lead to the production of excess carbonyl compounds caused by the degradation of peroxides.

Chemical Constituents, Antimicrobial Investigations, and Antioxidative Potentials of Anethum graveolens L. Essential Oil and Acetone Extract: Part 52

ABSTRACT: The antioxidant, antifungal, and antibacterial potentials of essential oil and acetone extract of Anethum graveolens L. were investigated in the present study. The extract has shown excellent activity for the inhibition of primary and secondary oxidation products for rapeseed oil in comparision with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), which were evaluated using peroxide, thiobarbituric acid, p-anisidine, and carbonyl values. The activity of extract was further confirmed using other antioxidant properties such as ferric thiocyanate method inlinoleic acid system, which reducing power and scavenging effect (%) on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Using inverted Petri plate method, the volatile oil completely inhibited the growth of Fusarium graminearum at 6 μL dose. Moreover, using poison food technique, the essential oil was found to be highly effective for controlling the growth of Penicillium citrinum and Aspergillus niger. In antibacterial investigations, using agar well diffusion method, the extract has shown better activity for Staphylococcus aureus and Bacillus cereus in comparison with commercial bactericide. However, essential oil has shown better activity for Pseudomonas aeruginosa. Gas chromatographic-mass spectroscopy studies on essential oil resulted in the identification of 35 components, which account for the 98.9% of the total amount. The major component was carvone (55.2%) followed bylimonene (16.6%), dillapiole (14.4%), andlinalool (3.7%). The analysis of acetone extract showed the presence of 25 components, which account for 94.5% of the total amount. The major components were dill apiole (43.2%), linoleic acid (23.1%), trans-anethole (11.0%), 2-propanone, 1-(4-methoxyphenyl) (4.6%), carvone (3.1%), p-anisaldehyde (2.7%), and myristicin (1.5%). In conclusion, the results presented here show that dill essential oil could be considered as a source for natural antimicrobial, whereas its extract could be considered as an alternative source of natural antioxidant.

Analysis of dynamic chemical changes in Chinese cantonese sausage: Factors influencing content of nitrite and formation of flavor substances

Chinese cantonese sausage (CCS) is famous for its exotic flavors. This paper studied the dynamic chemical changes of sausages during oven-heating by using sodium nitrite, free amino acids (FAA), free fatty acids (FFA) and oxidation of fat as indicators. Sausages were prepared and hanged in an oven for heating, 3 h at 50 °C and then 69 h at 40 °C. Samples were taken for analysis during heating. N-1-naphthylethylenediamine dihydrochloride was analysed to determine the change of sodium nitrite in the sausage and ninhydrin colorimetry was used to determine FAA concentration (counted by cysteine). The peroxide value and carbonyl value were evaluated to determine the oxidation of fat. The chromogenic rate of sausage was determined as chromogenic rate = [ A 1 × 290/( A 2 × 680)] × 100%. There were three factors influencing nitrite content at different stages during the whole oven-heating process. During the first 6 h, the weight loss resulting from water evaporation mainly caused the increase of nitrite content from 10 mg/kg to 60 mg/kg. At the middle part between 6 and 50 h, nitrite content decreased from 60 mg/kg to 30 mg/kg, being consumed in the chromogenic reaction. After 50 h, the nitrite content decreased further from 30 mg/kg to 15 mg/kg as the pH value increased, which was related to the increase of precursors of flavor-forming reaction and oxygenolysis. The increase of pH did not correlate with the changes of content of FAA or FFA during the early period, which might be due to the relatively small amount of their content and FAA also had alkalescence. After 50 h, the pH value increased sharply, which resulted from FAA and FFA turning into precursors of flavor-forming reaction. The increase in the pH value accorded with the decrease of nitrite content. The amount of peroxide value and carbonyl value kept increasing, especially at the later part of the oven heating, which was the critical formation period of flavor substances. Therefore, it was concluded that consumption of FAA and FFA and the increase of oxidation of fat resulted in the formation of flavor substances.

Evaluation of Heat-deteriorated Oils. I. TLC-FID Method for Determining Polar Compounds Content

A simple and accurate method for determining polar compound (PC) content in heat-deteriorated oils was developed, since universal standards are necessary for assessing thermal rancidity in frying oil quality control. At present, the means used for standards differ according to countries. For instance, in Japan the upper limit of acid value (AV) is 2.5 and carbonyl value (CV) is 50, in the United States free fatty acid (FFA) content is less than 2.0%, and in EU countries PC content is below about 25% and smoke point is above 170°C. JOCS official method to determine PC content by column chromatography is complicated and time consuming, and thus in this study JOCS method was modified by TLC-FID, using soybean oil samples prepared under various heating conditions. TLC-FID method with hexane / diethyl ether (87/13 v/v) as developing solvent provided excellent linearity of y=1.02x + 0.53 with correlation coefficient (R2) of 0.9960, where y and x express PC content determined by JOCS and TLC-FID methods, respectively. Thermal rancidity of soybean oil samples heated under different air bubbling conditions was measured with PC content by TLC-FID, AV, CV, and anisidine value. PC content was clearly shown to be reflected in rancidity of sample oils with heating time. Correlation between PC content and AV displayed excellent linearity with correlation coefficient (R2) of 0.9310. The present TLC-FID method determining PC content may thus be concluded an effective means for evaluating the quality of heat-deteriorated oils.

Is the Frying Oil in Deep-Fried Foods Safe?

Long-used frying oil may pose health risks. In the last few decades, consumption of commercially deep-fried foods has increased drastically, thus drawing attention to the thermal deterioration of the frying oil used in their preparation. The purpose of this study was to collect basic information about deteriorated frying oil ingested through foods. We analyzed the acid value (AV), carbonyl value (COV), contents of polar compounds (PC) and triacylglycerol (TG) and Gardner color in oils used in the kitchen of a campus restaurant and in oils contained in batter coatings of commercially deep-fried foods purchased randomly in Kobe, Japan. The results of the restaurant investigation indicated that the properties of frying oil were almost within the safe limit when one batch of oil was used at 180°C for 3 hours a day for 5 consecutive days. Among oils extracted from the batter coatings, 4-22% samples, depending on the analytical items, showed properties worse than those of oil recovered from food manufacturing companies after use. It seems that deep-fried foods containing deteriorated frying oil were produced on some occasions but not others by certain companies and that deep-fried foods were sometimes prepared with long-used thermally deteriorated oil. Thus, to ensure the safety of deep-fried foods, measures should be taken to shorten the usage span of frying oil.

Effects of Vitamin E on Phospholipase A2 Activity and Oxidative Damage to the Liver in Streptozotocin-Induced Diabetic Rats

Background: The purpose of the present study was to investigate the effects of vitamin E on oxidative stress and cell membrane fluidity in the liver of streptozotocin (STZ)-induced diabetic rats. Methods: Sprague-Dawley male rats weighing 100 ± 10 g were fed a vitamin E-free diet (the DM-0E group), a 40 mg vitamin E/kg diet (the DM-40E group), or a 400 mg vitamin E/kg diet (the DM-400E group). Result: Dietary vitamin E reduced the increased concentration of lipid peroxides in the liver tissues of diabetic rats through decreasing their increased phospholipase A₂ (PLA₂) activity and phosphatidylethanolamine hydrolysis. However, vitamin E reduced the accumulation of superoxide radical and decreased the generation of oxidative damage substances, such as the carbonyl value, increased membrane fluidity and lowered oxidative damage. Conclusions: Vitamin E was found to be excellent for regulating the activity of PLA₂, reducing the generation of reactive oxygen species and damaging oxidative substances, and maintaining cell membrane fluidity in the liver of diabetic rats.

Inverse correlation between endogenous melatonin levels and oxidative damage in some tissues of SAM P8 mice

To assess whether oxidative damage in some tissues was related to their melatonin concentration, endogenous melatonin levels and the age-linked protein and lipid damage in spleen, thymus and liver in 5-month-old SAM P8 mice were examined. The results show that high levels of melatonin in spleen and thymus correlate with lower protein and lipid damage. The liver, which had much lower melatonin concentrations than the other two tissues, had much higher levels of oxidatively damaged protein, as measured by carbonyl values. These results add new evidence concerning the protective role of endogenous melatonin as an antioxidant agent, and suggest that a treatment with this molecule might help to reduce age-associated functional deficits in many organs, including those of the immune system.

Microwave roasting effects on the oxidative stability of oils and molecular species of triacylglycerols in the kernels of pumpkin ( Cucurbita spp.) seeds

Pumpkin ( Cucurbita spp.) seeds of the two cultivars were exposed to microwaves for 6, 12, 20 or 30 min at a frequency of 2450 MHz using a microwave oven. After the kernels were separated from the whole pumpkin seeds, the quality characteristics and composition of the oils, i.e., their tocopherol distributions and the molecular species of the triacylglycerols (TAGs) were investigated. These results were compared with those of an unroasted oil sample for the two cultivars. Only minor increases ( P < 0.05 ) in chemical changes of the oils, such as peroxide value, carbonyl value, p-anisidine value and thiobarbituric acid reactive substances (TBARS), occurred after a prolonged roasting period. Compared to the original level, more than 85% tocopherols remained after 20 min of roasting. Therefore, significant differences ( P < 0.05 ) in fatty acid distributions were observed in the pumpkin seeds roasted for 20 min or more. A modified AgNO3-TLC procedure provided 11 different groups of TAG, based on both the degrees of unsaturation and the total fatty acid chain-length. With a few exceptions, microwave roasting for 12 min caused no significant ( P > 0.05 ) loss or changes in the content of tocopherols and polyunsaturated fatty acids (PUFAs) in the kernels. These results contribute to further investigation of the functional properties of pumpkin seed products.

무청이 고콜레스테롤 식이 흰쥐 간조직의 항산화계에 미치는 영향

본 연구에서는 무청의 생체 내 항산화작용을 규명하기 위하여 고콜레스테롤 식이 흰쥐 간조직의 항산화 방어계와 지질과산화에 미치는 영향을 관찰하였다. 실험동물은 체중 100 g내외의 Sprague Dawley 종 수컷 흰쥐를 이용하였으며, 정상군과 고콜레스테롤 식이 실험군으로 나눈 후 정상군은 다시 무청파우더를 공급하지 않은 군(N group), 무청파우더를 공급한 군(NR group)으로 나누고 고콜레스테롤 식이 실험군은 무청파우더를 공급하지 않은 군(HC group)과 무청파우더를 각각 2.5%(HRL group), 5%(HRM group), 10% (HRH group)씩 공급한 군으로 나누었다. 식이와 식수는 자유섭식시켰으며, 4주간 사육한 후 희생시켰다. 실험기간 동안의 체중증가량은 정상군에 비해 고콜레스테롤 식이군에서 유의적으로 증가하였으며, 무청파우더 공급군은 정상군 수준이었고, 식이효율 역시 유사한 경향이었다. 간조직 중의 항산화 효소 관찰에서 SOD는 실험군간의 유의적인 차이는 없었으나 무청파우더군에서 HC군에 비해 다소 증가한 경향이었다. GSH-px는 정상군에 비해 콜레스테롤 공급군 모두에서 감소되었으나 무청파우더를 5%와 10% 공급한 군에서는 HC군에 비해 유의적으로 증가되었다. 조직의 과산화적 손상의 지표가 되는 간조직의 TBARS 함량을 관찰한 결과 정상군에 비해 고콜레스테롤 식이군에서 유의적으로 증가하였고 HC군에 비해 무청파우더 5% 공급한 HRM군과 10%로 공급한 HRH군 두 군에서 유의적으로 감소되었다. 간조직의 cytosol에서 H₂O₂의 함량을 측정한 결과 정상군과 고콜레스테롤 군간의 유의적인 차이는 없었다. 간조직의 mitochondria에서 H₂O₂의 함량을 측정한 결과 정상군에 비해 고콜레스테롤군이 유의적으로 증가되었으나 무청파우더 5% 공급한 HRM군과 10% 공급한 HRH군은 정상군 수준이었다. 간조직의 microsome에서 O₂·- 함량을 측정한 결과 정상군에 비해 HC군에서 유의적으로 증가되었으나 무청파우더를 공급한 모든 군에서 유의적으로 감소되었다. 특히 무청파우더 10% 공급한 HRH군에서는 정상군 수준으로 감소되었다. 간조직의 mitochondria에서 O₂·- 함량을 측정한 결과 무청파우더를 5%, 10% 공급한 HRM, HRH군에서 정상군 수준으로 감소되었다. 이상과 같이 고콜레스테롤 식이 흰쥐에서 무청파우더 공급 수준에 따라 간조직의 항산화 방어 효소의 활성을 증가시켜 산화적 손상을 완화시키는 작용이 관찰되었다.

Chemical constituents, antimicrobial investigations and antioxidative potential of volatile oil and acetone extract of star anise fruits

AbstractGC and GC‐MS analysis of fruit volatile oil of star anise (Illicium verum Hook) showed the presence of 25 components which account for the 99.9% of the total amount. The major components were trans‐anethole (94.37%), methyl chevicol (1.82%) and cis‐anethole (1.59%). 15 Components were identified from its acetone extract accounting for 80.27% of the total amount. trans‐Anethole (51.81%) was found as a major component along with linoleic acid (11.6%), 1‐(4‐methoxyphenyl)‐prop‐2‐one (6.71%), foeniculin (5.29%) and palmitic acid (1.47%). Using an inverted petriplate method, the volatile oil completely inhibited the growth of Fusarium moniliforme at 6 µl dose. In case of extract, 50% mycelial zone inhibition was obtained for Penicillium citrinum and Penicillium viridicatum. Moreover, using food poison technique, the volatile oil was found to be effective for controlling the growth of F. moniliforme and Aspergillus niger whereas the extract has been found to be highly effective for Aspergillus flavus. In antibacterial investigations, using agar well diffusion method, the extract has shown better activity for Staphylococcus aureus and Bacillus cereus in comparison with volatile oil and commercial bactericide, ie Ampicillin. However, volatile oil has shown better activity for Salmonella aeruginosa and Bacillus subtilis. Moreover, the extract has shown excellent activity for the inhibition of primary and secondary oxidation products in rapeseed oil which were evaluated using peroxide, thiobarbituric acid, p‐anisidine and carbonyl values. The activity of extract was further confirmed using other antioxidant properties such as ferric thiocyanate method in linoleic acid system, reducing power and scavenging effect (%) on 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH) radical. Hence, the extract could be considered as natural antioxidant which may be used for chemoprevention of diseases occurring due to oxidative deterioration. Copyright © 2005 Society of Chemical Industry

Monitoring the oxidation of docosahexaenoic acid in lipids

The oxidation of free DHA, DHA mixed with PC, and DHA incorporated into PC, PE, or TG was evaluated to determine which lipid provided DHA with the best protection against oxidation. DHA was either situated at the sn-1 position, sn-2 position, or both positions of the phospholipid, whereas the TG contained DHA at all positions. All lipids were incubated as bulk lipids, in chloroform, or as an emulsion in contact with air at 25-30 degrees C for 28 d. Since DHA, which is highly sensitive to oxidation, has a great impact on our health and is desired as a food additive, the stability of this FA is of great importance. This study was mainly focused on the primary oxidation products, which were monitored as eight monohydroperoxy-DHA isomer groups, the total amount of polyhydroperoxides, and the PV. However, a measure of secondary oxidation products, the carbonyl value, was also monitored. We found that DHA was most protected against hydroperoxide formation when it was incorporated at one position of either PC or PE. In these lipids, hydroperoxide formation at carbon atoms 4, 7, 8, and 11 was completely prevented. DHA mixed with PC was also protected, although to a lesser extent, and all hydroperoxide isomers were detected. In contrast, PC and TG containing DHA at all positions should be avoided, since they were highly oxidized.

Development of a Compound-Specific Isotope Analysis Method for Atmospheric Formaldehyde and Acetaldehyde

A novel method determining compound-specific carbon isotopic compositions for atmospheric formaldehyde and acetaldehyde in ppb or sub-ppb levels by gas chromatography/ combustion/isotope ratio mass spectrometry (GC/C/ IRMS) is presented. Atmospheric carbonyls are collected using the conventional 2,4-dinitrophenylhydrazine (DNPH) derivatization method, and their delta13C values are calculated based on stoichiometric mass balance after measuring the carbon isotopic compositions of the carbonyl-DNPH derivatives and DNPH, respectively. Using formaldehyde, acetaldehyde, and DNPH standards with their delta13C values predetermined, the delta13C fractionation is evaluated for derivatization processes both in solutions and in simulation experiment of atmospheric sampling. In these two derivatization systems, through reduplicate delta13C analysis, good reproducibility of the derivertization process is found with an average error of less than 0.5 per thousand, and the differences between the predicted and the measured delta13C values range from -0.18 to 0.49 per thousand, indicating that the derivatization process introduces no isotopic fractionation for both formaldehyde and acetaldehyde. Thus, the delta13C values of the original underivatized carbonyls can be accurately calculated through mass balance equation. Using the method developed, preliminary tests of atmospheric formaldehyde and acetaldehyde at two urban sites were conducted and revealed significant differences of their isotopic compositions, implying possible application of the method in helping us understand the primary emission, secondary formation, or removal processes of carbonyls in the atmosphere.

Chemical constituents and antimicrobial and antioxidant potentials of essential oil and acetone extract of Nigella sativa seeds

AbstractThe antifungal, antibacterial and antioxidant potentials of essential oil and acetone extract of black cumin were investigated by different techniques. In the inverted petriplate method, the essential oil showed complete zones of inhibition against Penicillium citrinum at a 6 µl dose. Essential oil showed complete growth inhibition against Bacillus cereus, Bacillus subtilis and Staphylococcus aureus, Pseudomonas aeruginosa at 2000 and 3000 ppm, respectively, by the agar well diffusion method. The antioxidant activity was evaluated by measuring peroxide, TBA and total carbonyl values of rapeseed oil at fixed time intervals. Both the extract and essential oil showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, their inhibitory action in the linoleic acid system was studied by monitoring the accumulation of peroxide concentration. Their radical scavenging capacity was carried out on 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) radical and they showed excellent scavenging activity in comparison with synthetic antioxidants. Their reducing power was also determined, demonstrating strong antioxidant capacity of both the essential oil and extract. Gas chromatographic and gas chromatographic–mass spectrometric studies on the essential oil resulted in the identification of 38 components representing 84.65% of the total amount. The major component was p‐cymene (36.2%) followed by thymoquinone (11.27%), α‐thujene (10.03%), longifolene (6.32%), β‐pinene (3.78%), α‐pinene (3.33%) and carvacrol (2.12%), whereas extract showed the presence of 16 components representing 97.9% of the total amount. The major components were linoleic acid (53.6%), thymoquinone (11.8%), palmitic acid (10%), p‐cymene (8.6%), longifolene (5.8%) and carvacrol (3.7%). Copyright © 2005 Society of Chemical Industry

QUALITY CHANGES IN SELECTED FRYING FATS DURING HEATING IN A MODEL SYSTEM

ABSTRACT The quality changes in rapeseed and soybean oils and hardened frying fat during heating were investigated. Two kilograms of samples were heated at 180 ± 2C in an open deep‐fat fryer during six consecutive days (2 × 2 h per day) until the total time of heat treatment was 24 h. The samples were evaluated after every 2 h of heating. The indices used for evaluation of quality changes in fat and oils were: acid value (AV), peroxide value (PV), carbonyl value (CV) and 2‐thiobarbituric acid (TBA) value. The fatty acid compositions of oils and fat before heating were also determined. The lower intensity of hydrolytic and oxidative changes during heating, as measured by selected indices of quality, suggests wider use of hardened frying fat for food frying.

Deterioration of diacylglycerol‐ and triacylglycerol‐rich oils during frying of potatoes

The stabilities of a commercial diacylglycerol-rich oil (DAG) and a salad oil (TAG) that had been prepared from a mixture of rapeseed and soybean oils were compared while frying potatoes at 180 °C for 3 h. The representative chemical and physical characteristics of the oils were assessed before and after frying, together with the amount of volatile aldehydes in the exhaust of frying. Among the deterioration indications, the carbonyl value, polymer content, and residual polyunsaturated fatty acid content were similar and not significantly different between the TAG and DAG. On the other hand, the characteristics relating to free fatty acids, i.e. the acid value and emission of chemiluminescence at 100 °C, were greater and the smoke and flash points were lower in the DAG than in the TAG. An irritating odor was generated from the DAG after 1 h of frying and got stronger as frying continued. These results suggested that DAG more easily forms free fatty acids under frying conditions than TAG.

Antimicrobial and Antioxidant Potentials of Essential Oil and Acetone Extract ofMyristica fragransHoutt. (Aril Part)

ABSTRACT: The antifungal, antibacterial, and antioxidant potentials of essential oil and acetone extract were carried out by different techniques. In poison food medium method, the essential oil showed complete zones of inhibition against Fusarium graminearum at the all tested doses. For other tested fungi and bacteria, they gave good to moderate zone inhibition. The antioxidant activity was evaluated by measuring peroxide, thiobarbituric acid and total carbonyl values of rapeseed oil at fixed time intervals. Both the extract and essential oil showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, their inhibitory action in linoleic acid system was studied by monitoring peroxide concentration in emulsion during incubation. The results were well correlated with above values. Their radical scavenging capacity was carried out on 2,2′-diphenyl-1-picrylhydracyl (DPPH) radicalm, and they showed strong scavenging activity in comparison with synthetic antioxidants. Their reducing power was also determined, which also proved strong antioxidant capacity of essential oil and extract. Gas chromatographic-mass spectroscopy studies on essential oil resulted in the identification of 49 components representing 96.49% of the total amount, and the major component was sabinene (20.22%), followed by terpinen-4-ol (12.08%), safrole (10.32%), αpinene (9.7%), β-phellandrene (6.56%), and γ-terpinene (5.93%). The acetone extract showed the presence of 23 components representing 71.66% of the total amount. The major components were isocroweacin (18.92%), elemicin (17.68%), methoxyeugenol (8.13%), linoleic acid (4.12%), dehydrodiisoeugenol (4.06%), palmitic acid (2.8%), and trans-isoeugenol (2.76%).

Retardation of lipid oxidation in blue sprat by hot water tea extracts

AbstractThe blue sprat is a small fish belonging to the family Clupeidae. Deterioration of its freshness after catching is so rapid that the fish is cooked in simple ways and consumed locally. The prooxidant activity of the skin, dark meat and ordinary meat was much higher than that of other fishes such jack mackerel. Suppression of lipid peroxidation in blue sprat was attempted using hot‐water extracts of five types of Taiwanese tea with different degrees of fermentation, ie Longjing‐type green tea, Shy Jih Chuen oolong tea, Tungting oolong tea, Pouchong tea and black tea. All the tea extracts showed antioxidant activity on oxidation of linoleic acid induced by the extracts of blue sprat's tissues. The antioxidant activity of each tea extract showed a positive correlation with the contents of total catechins, especially with that of epigallocatechin gallate, but a poor correlation with the contents of total polyphenols. The Tungting oolong tea together with Chinese green tea effectively suppressed the prooxidant activities of the dark meat and skin of blue sprat. Impregnation of blue sprat in the extract of the Tungting oolong tea retarded the lipid oxidation in fish meat assessed by peroxide value and carbonyl value during refrigeration. Copyright © 2005 Society of Chemical Industry

Stability of Edible Oils Containing Triacylglycerol and Diacylglycerol in the Presence of Tocopherol and/or Vitamin C

Autoxidation of triacylglycerol (TG) oil occurred most rapidly, whereas oils containing tocopherol (Toc) showed a slower increase compared to the ordinary TG oil. Autoxidation of oils was apparently delayed by addition of Toc and vitamin C (VC), and the effect of these antioxidants was greater in diacylglycerol (DG) oil than in TG oil. On the other hand, there was no apparent difference between DG and TG oils in the presence of Toc only. The ΔE values (color difference) of TG oils were higher than those of DG oils, and the values were lower in the oils containing both Toc and VC than in those containing only Toc. The carbonyl value (COV) of TG oil increased with aeration time and tended to be lower without Toc than with Toc. The peroxide value (POV) of DG oil did not change with aeration time, whereas POV of TG oil increased with aeration time and the amount of Toc. COV and the p-anisidin value (ANV) increased with the number of uses, however, the values of DG oils containing Toc tended to be lower than those of the other samples. The dehydration rate, weight decrease and moisture content tended to decrease with the number of uses, which might contribute to the oily or greasy taste of fried food. COV, ANV and the acid value (AV) showed significant correlation with each other, but not with oil absorption, dehydration rate, weight decrease or moisture content.

Temporal relationship between lens protein oxidation and cataract development in streptozotocin-induced diabetic rats

We compared the progression of lens opacification with the time course of oxidation of lens proteins under conditions of streptozotocin-induced experimental diabetes in rats. By the end of the 17th week, approx. 50% of the diabetic animals developed mature cataracts. During the following month, 95% of the eyes in the diabetic group became cataractous. In the course of lens opacification we observed a time-dependent increase in the content of protein carbonyls and decrease in the concentration of protein sulfhydryls in the lenses of diabetic animals. Significantly higher protein carbonyl (p<0.01) and lower protein sulfhydryl (p<0.001) content was found in lenses with the advanced stage of cataract when compared with the diabetic lenses still transparent. We showed that the values of protein carbonyls exceeding 1.2 nmol/mg protein and of sulfhydryls falling below 60 nmol/mg protein corresponded to an approximately 50% incidence of mature cataract development. At the end of the 34th week, when all lenses of diabetic rats became cataractous, the corresponding values of protein carbonyls and sulfhydryls were 2.5 nmol/mg protein and 27 nmol/mg protein, respectively. The main finding of this study is the disclosure of quantitative relationship between the degree of protein oxidation and the rate of advanced cataract development in the widely used model of streptozotocin-induced experimental diabetes in rats.