Study on the Change Characteristics of Fatty Acid Composition of the Recovery Oil of Range Hood in China University of Cereals and Oils, Su Delin, CHEN Chen, YAO Qinghua (Central Laboratory of Fujian Academy of Agricultural Sciences, Key Laboratory of Large Instruments, Fujian Province, Fuzhou 350003, China) Oil and blending oil, five different vegetable oils The cooking oil is subjected to a cooking test to collect the grease condensed by the range hood system. The change characteristics of the fatty acid composition of the recovered oil were analyzed by measuring the fatty acid recovered from the range hood and the corresponding uncooked oil. The results showed that the fatty acid type and content of the recovered oil were significantly different from the uncooked oil (P<0.05). The recovered oil increased the C14:0, C16:1n7c short-chain fatty acids, the content of saturated fatty acids increased, the content of unsaturated fatty acids decreased, and the fatty acid unsaturation decreased significantly, only 50% ~ 61% of uncooked oil. There is an increasing trend in the recovery of short-chain fatty acids in oils, a decrease in the content of long-chain fatty acids, and the addition of 8:3. and EPA fatty acids with little or no edible oil background. The quality of the recovered oil has also begun to change, and some of the recovered fatty acids have deviated significantly from the characteristic values ​​of normal vegetable oils. Therefore, the range hood recovery oil is no longer suitable for consumption, and the cooking temperature should be lowered during cooking to reduce the deterioration of the edible oil.
China is the world's largest producer and consumer of edible oil. Edible oil is used as a seasoning and is commonly used in cooking. Edible oils are prone to deterioration under high temperature stir frying or frying. Studies have shown that cooking will change the fatty acid composition of edible oils, for example, may cause the production of trans fatty acids under intense heating conditions. 2. Excessive intake of edible oils containing trans fatty acids will seriously threaten health 3-4. Range hoods It is widely used in the kitchen to absorb the fumes, and it can also cool the oil that is volatilized and cooked to facilitate the recovery of grease. Range hood recovery oil can reflect the degree of quality change of cooking oil in cooking. Some researchers have analyzed the quality of the range hood oil, and its peroxide value, acid value, moisture and other indicators seriously exceed the edible oil quality and health limit 5, and also contains the carcinogen benzopyrene 65-8. Recovering oil can easily cause intestinal diseases and even cause cancer and teratogenicity.
Vegetable oil is the most important edible oil. There are many varieties, and the fatty acid composition of each variety is different. However, the fatty acid composition ratio of the same vegetable oil is relatively fixed and has its characteristics. After cooking fatty acids, vegetable oil composition may change, at present, research on recycling hoods oil fatty acid composition features have not been Fund Project: National Science and Technology Support Program (2012BAD14B15307), Fujian Academy of Agricultural Sciences Youth Fund (2011QB19) Corresponding author: Lin Biao, male, born in 963, associate researcher, quality safety and reporting of agricultural products. In this study, five different vegetable oils, peanut oil, sunflower oil, tea seed oil, corn oil and blending oil, were used as cooking oils to conduct cooking tests, and the oils condensed by the range hood system were collected. By measuring the fatty acid composition of the oil recovered from the range hood and the uncooked oil, the variation characteristics of the fatty acid composition of the oil recovered from the range hood were analyzed to evaluate the changes in cooking quality of the edible oil. Designed to guide scientific cooking oil cooking and diet, while providing basic data for identifying waste oils.
1 Materials and methods 1.1 Materials peanut oil, sunflower oil, tea seed oil, corn oil and blending oil: commercially available. Petroleum ether, benzene, methanol, potassium hydroxide, sodium hydrogen sulfate, anhydrous sodium sulfate, sodium chloride: all analytically pure, Tianjin Kemiou Chemical Reagent Development Co., Ltd. 37 fatty acid methyl ester standards (Cat. No. 47885).
1.2 Collection of recovered oil from range hoods Cooking with peanut oil, sunflower oil, tea seed oil, corn oil and blending oil 5 plant oils, respectively, collecting oil from the range hood of the range hood every 2 weeks. , collected a total of 3 times. The sample was filtered to obtain a clarified oil sample and used.
1.3 fatty acid methyl esterification method Weighed uncooked oil or range hood recovery oil sample 0. 1g in a plugged test tube, add 2mL petroleum ether, 2mL benzene, make the sample fully mixed, add 0.5mL 2mol / L potassium hydroxide Methanol solution, shaken for 1 min, placed for 20 min. Add about 2 g of sodium hydrogen sulfate to neutralize the remaining potassium hydroxide, add a saturated sodium chloride water bath, shake, and let stand for stratification.
The supernatant was taken, and an appropriate amount of anhydrous sodium sulfate was added to remove traces of water for gas chromatography analysis.
1.4 Gas chromatographic conditions - 2010 gas chromatograph (with flame ionization detector); DB-23 capillary column: 60mx0.25mmx0.25pm; carrier gas: nitrogen, constant current mode, flow rate: 1.0mL / min; split injection , split ratio: 50:1; injection volume: 1L; inlet temperature: 250C; detector temperature: 270 C; programmed temperature: 80 C retention rate rises to 175 ° C, then rises to 4 ° C / min 230 ° C, held for 5 min. Characterized by the relative retention time of the standard sample. Quantitative by area normalization.
1.5 Data Processing Each test sample was paralleled, the data was averaged, and the recovered fatty acid was expressed as X±s. The data were subjected to differential significance analysis using SPSS18.0 statistical software single-sample t-test. The uncooked oil was used as the test value, and the confidence probability was 95%. 2 Results and discussion Peanut oil, sunflower oil, tea seed oil, corn oil and The blended oils of five uncooked edible oil fatty acids are listed in Table 1. It can be seen from the table that the fatty acids of the five edible oils are mainly C16:0, C18:0, C18:1n9c and C18:2n6c, the sum of which accounts for more than 90% of the total fatty acids, but the fatty acid composition of different edible oils is different. . The fatty acid composition of the five types of range hoods collected after cooking is listed in Table 2. Compared to uncooked oils, there is an increasing trend in the types of recovered oil fatty acids. C14:0 was added to the five recovered oils. The recovery oil of peanut oil, tea seed oil and blended oil increased C16:1n7c. The recovered oil of peanut oil increased C18:1n9t, C18:3n3c, C20:5n3c3 fatty acids. The recovered oil of tea seed oil increased C18:1n9t, C20:1n9c2 fatty acids. However, the recovery oil of corn oil has been reduced by C22:0, C24:0. This may be related to the thermal degradation of edible oil during cooking. FrankelEN research found that the oil is prone to oxidative degradation of long-chain fatty acids when heated. Formation of short-chain fatty acids M. The fatty acid content of the oil recovered from the range hood has changed. Compared with the uncooked oil, the main fatty acid composition is significantly different (P < 0.05). The total amount of saturated fatty acids in the recovered oil of peanut oil, sunflower oil, tea seed oil, corn oil and blended oil is increased by the content of uncooked oil, and the content of C22:0 and C24:0 is decreased. The content of main fatty acids C16:0 and C18:0 increased significantly; the increase of C16:0 content was higher than that of C18:0, showing that the shorter the carbon chain length of fatty acids, the easier it is to increase; the long carbon chain fatty acids C20:0, C22:0, C24:0 accounted for a small proportion of the total fatty acid content, which did not change much, but the longer the fatty acid carbon chain length, the faster the content decreased. The oil is mixed with food and water during cooking, and under high temperature conditions, oxidative degradation reaction and hydrolysis reaction are apt to occur, resulting in the formation of fatty acids with low carbon chain-10. Table 1 Fatty acid composition of uncooked edible oil /% 6 Note: SFA represents the sum of saturated fatty acids; MUFA represents the sum of monounsaturated fatty acids; PUFA represents the sum of polyunsaturated fatty acids; - indicates no detectable, detection limit <0.05%, the following similar.
Table 2 Fatty acid composition of recovered oil /% 742.6 Note: indicates significant difference P <0.05, indicating a very significant difference P <0.01 A total of C16 monounsaturated fatty acids were detected in the recovered oil and uncooked oil, of which C18:1n9c content highest. The total amount of monounsaturated fatty acids in the recovered oil of peanut oil, sunflower oil, tea seed oil, corn oil and blended oil is 0.90, 1.31, 0.94, 1.14, 1.29 times of uncooked oil, respectively, among which peanut oil and tea seed oil are single. The total amount of unsaturated fatty acids decreased, and the others increased. The content of C16 1n7c in the five recovered oils increased, and C16:1n7c was not detected in uncooked peanuts, teaseed oil and blended oil, while C16:1n7c was detected in the recovered oil; uncooked teaseed oil and C18:1n7c was not detected in corn oil, while C18: C18:1n9c in oil and teaseed oil was detected in the recovered oil; however, the content of C18:1n9c in sunflower oil, corn oil and blended oil was It has risen. This is similar to the study of Liu et al., under the heating conditions, the fatty acid of the same carbon chain length has a higher degree of unsaturation than the lower one. Although C18:1n9c degrades, its degradation rate is slower than that of polyunsaturated fatty acids, and C18:2n6c, C18:3n3c polyunsaturated fatty acids may be reduced to C18:1n9c. Therefore, the change of C18:1n9c content It is related to polyunsaturated fatty acids in edible oil background. When the content of polyunsaturated fatty acids is high, the content of C18:1n9c may increase. The recovered oil of peanut oil and tea seed oil was detected by trans fatty acid C18:1n9t; C18:1n9t was detected in uncooked sunflower oil, but C18 was not detected in the recovered oil: the formation and heating temperature of fatty acid, Cooking foods are all related to cooking oil. When the heating temperature is less than 200 C, there is very little production of trans fatty acids. 12. The content of C20:1n9c in uncooked and recovered oil does not change much.
C18:2n6c, C18:3n3c and C20:5n3c polyunsaturated fatty acids were detected in five edible oils of peanut oil, sunflower oil, tea seed oil, corn oil and blended oil, among which C18:2n6c was the highest. The total amount of polyunsaturated fatty acids in the recovered oil was 0.69, 0.76, 0.75, 0.81, and 0.74 times of the uncooked oil, respectively, which showed a downward trend. The content of C18:2n6c in the recovered oil decreased; the content of C18:3n3c in peanut oil, sunflower oil and corn oil increased, and the content of C18:3n3c in tea seed oil and blended oil decreased. In these edible oils, the fatty acid content of carbon chain length greater than 18 carbons is less, so the longer note: U / S represents the ratio of unsaturated fatty acids to saturated fatty acids, M / S means monounsaturated fatty acids and saturation The ratio of fatty acids, P/S, represents the ratio of polyunsaturated fatty acids to saturated fatty acids.
The unsaturation of fatty acids in edible oils before and after cooking has a lower probability of producing C18:3n3c. However, the increase in C18:3n3c in peanut oil, sunflower oil and corn oil may be related to the production of linolenic acid rich in cooking purslane, spinach, soybean, flaxseed, walnut, etc. 13. In addition, it was detected in peanut oil. C20: 5n3c (EPA). EPA is a characteristic fatty acid in fish oils and is widely found in fish and its products, but these five test edible oils do not contain this fatty acid, which may be related to the EPA-rich fish food used in cooking. related.
From the unsaturation of fatty acids (the ratio of unsaturated fatty acids to saturated fatty acids, U/S), it can be seen that the unsaturation of the recovered oil is significantly reduced, peanut oil, sunflower oil, tea seed oil, corn oil, blended oil The degree of unsaturation decreased from 3.6, 7.5, 10.4, 6.0, and 5.3 of cooking to 1.8, 3.8, 6.4, 3.6, and 3.1 of recovered oil. The recovered oil is only 50% to 61% of uncooked oil. The ratio of polyunsaturated fatty acids to saturated fatty acids, P/S) is greater than the single unsaturation (ratio of monounsaturated fatty acids to saturated fatty acids, M/S). The multiple unsaturations are from 1.6.
4,. 8,. 9,. 7 changes to 0.7. 2,. 4,. 1,. 8. The single unsaturation is never 2.0 of the cooking oil. 2,. 7,. 1, 1.6 changes to 1.1, 1.5, 6.0, 1.5, 1.4. This shows that after cooking oil, its fatty acid saturation has an increasing trend. Therefore, when using cooking oil, residents should consider the ratio of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids in edible oils, and rationally mix nutrition.
Affected by planting area, time and individual differences, the proportion of certain fatty acids in vegetable oil has a certain range of variation, but the fatty acid composition ratio of the same vegetable oil is relatively fixed, with 6.5%, 14.0%~39.4%, 48.3%. ~74.0% M. Analysis of the comparison of recovered oil and uncooked oil found that the fatty acid composition of some recovered oils has deviated from the characteristic value of vegetable oil. For example, the recovery oil of sunflower oil is 8:2.6. The mass fraction is 42.5%, which is lower than the characteristic index value; the C18:2n6c mass fraction of the tea seed oil recovery oil is 4.7%, which is 7.0% higher than its characteristic index value. 14.0%M is low, the saturated fatty acid mass fraction is 13.2%, which is higher than its characteristic index value of 7.0%~11.0%; the mass fraction of C16:0 of ​​peanut oil and corn oil is 25.1% and 17.7%, respectively, which is 8.0. %~14.0%, 8.6%~16.5% high 6-17; the C18:3n3c characteristic index values ​​of peanut oil and sunflower oil are 0% ~0.3%, and the C18:3n3c mass fraction of the recovered oil is 1.2%, 3.6%, higher than its characteristic index. Explain that cooking can change the fatty acid composition of edible oils and even affect their quality. Therefore, in the actual cooking process, the cooking temperature should be lowered or the cooking time should be shortened to avoid deterioration of the cooking oil.
3 Conclusions The main fatty acid composition of peanut oil, sunflower oil, tea seed oil, corn oil and blended oil was significantly changed (P<0.05). First, compared with uncooked oil, the fatty acid type of the recovered oil changes, mainly adding low-carbon chain saturated fatty acids such as C14:0, C16:1n7c. Second, the content of various fatty acids in the recovered oil has also changed. The increase of saturated fatty acid content, the decrease of unsaturated fatty acid content, the unsaturation degree is obviously reduced, only 50%~61% of uncooked oil, and the degree of unsaturation is greater than that of single unsaturation. In terms of fatty acid composition, there is an increasing trend of short-chain fatty acids, a decrease in long-chain fatty acid content, and the addition of fatty acids with little or no edible oil background, such as C18:3n3c and EPA. The quality of the oil has also begun to change, and some of the recovered fatty acids have seriously deviated from the characteristic values ​​of normal vegetable oils.
(Finish)
Wear your hair straight one day and wavy the next with our collection of flat irons and hair curlers. Hair Curler insists you use only the best in order to achieve enviable locks. Our professional-grade tools will last you for years, won`t damage your mane into a frizzy and fried mess, and will ensure that your hair stays beautiful all day long. Hair Curler Once you try our styling tools, you`ll wonder how you ever lived without them.
Hair Curler Price,Hair Dryer Curler,Hair Curling Tools,Hair Curling Machine
Ningbo Meirou Electric Appliance Co.,Ltd. , https://www.mrhaircurler.com