Method for reducing flavor produced by thermal oxidative decomposition of unsaturated fatty acid by using phytic acid and application of method

Abstract

The invention discloses a method for reducing flavor produced by thermal oxidation decomposition of unsaturated fatty acid by using phytic acid and application thereof. The method comprises the following steps: mixing phytic acid and unsaturated fatty acid, and then carrying out heating oxidation treatment; wherein the unsaturated fatty acid comprises at least one of linoleic acid, oleic acid, linolenic acid and EPA. The optimal flavor control effect can be achieved under different processing conditions, and the content of bad flavor substances generated in the unsaturated fatty acid oxidation process is reduced; the oxidation reaction of unsaturated fatty acid can be effectively inhibited at a low temperature within a short heating time, so that the bad flavor generated by oxidation of unsaturated fatty acid is remarkably reduced, and the method has important significance for improving the quality of oil products. The method is not only suitable for the refining process of vegetable oil, but also can be widely applied to the field of processing of various foods containing unsaturated fatty acids, such as baking, cooking and production of instant products, and is beneficial to development of healthier and more delicious food products.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and more specifically to a method for utilizing phytic acid to reduce the thermal oxidation decomposition of unsaturated fatty acids to produce flavor and an application thereof. Background Art

[0002] Unsaturated fatty acids are very easy to undergo oxidation reactions with oxygen in the air at room temperature, thus causing rancidity. During this process, unsaturated fatty acids will gradually degrade to produce a series of complex compounds, such as alcohols, aldehydes, ketones, acids and furans. This oxidative deterioration will not only cause a significant decrease in the nutritional value of unsaturated fatty acids such as linoleic acid, but will also cause the flavor of the product to deteriorate and the color to deepen. What is more serious is that toxic compounds may be produced during the oxidation process, posing a potential threat to human health. Studies have shown that the oxidation products of unsaturated fatty acids are closely related to the occurrence of a variety of diseases, including tumors, cardiovascular and cerebrovascular diseases (such as atherosclerosis), abnormal accumulation of cholesterol in the liver, diabetes, and even different types of cancer.

[0003] Although existing technologies have developed a variety of methods to inhibit the oxidation of unsaturated fatty acids, these methods still have certain limitations and shortcomings. For example, most antioxidants themselves are very easy to oxidize, resulting in a short duration of inhibition.

[0004] Therefore, how to more efficiently and safely regulate the ability of unsaturated fatty acids to undergo thermal oxidation decomposition reactions and inhibit the generation of undesirable volatile flavor substances during the thermal oxidation process, thereby achieving the effect of inhibiting the oxidation of unsaturated fatty acids, remains an important issue that needs to be urgently addressed in current research and application fields. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects of the prior art, and to provide a method and application thereof for reducing the flavor produced by thermal oxidation decomposition of unsaturated fatty acids using phytic acid. The present invention creatively proposes a method for reducing the content of undesirable flavor substances produced during the oxidation of unsaturated fatty acids by adding phytic acid of different concentrations to an unsaturated fatty acid system. The method can effectively inhibit the oxidation reaction of unsaturated fatty acids at a lower temperature and a shorter heating time, thereby significantly reducing the undesirable flavor produced by the oxidation thereof.

[0006] In the experiment, the present invention selected common unsaturated fatty acids, including linoleic acid, oleic acid, linolenic acid and EPA, and conducted research under high temperature (180°C) and low temperature (60°C) conditions. By examining the regulatory ability of phytic acid on the thermal oxidation decomposition reaction of unsaturated fatty acids, the present invention revealed the significant inhibitory effect of phytic acid on the oxidation process of unsaturated fatty acids at different temperatures, providing an efficient and practical solution for improving the flavor stability of unsaturated fatty acids.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for reducing the flavor generated by thermal oxidative decomposition of unsaturated fatty acids using phytic acid, comprising: mixing phytic acid and unsaturated fatty acids and then performing heat oxidation treatment; wherein, the unsaturated fatty acids include at least one of linoleic acid, oleic acid, linolenic acid, and EPA.

[0009] Optionally, the volume ratio of the phytic acid to the unsaturated fatty acids is 4:1; the molar concentration of the phytic acid is 8.8 - 264 mmol / L.

[0010] Optionally, the temperature of the heat oxidation treatment is 60 - 180°C; the time of the heat oxidation treatment is 60 min.

[0011] Optionally, the temperature of the heat oxidation treatment is 60°C; the time of the heat oxidation treatment is 60 min.

[0012] Optionally, the temperature of the heat oxidation treatment is 180°C; the time of the heat oxidation treatment is 60 min.

[0013] The present invention also discloses an application of phytic acid in reducing the flavor generated by thermal oxidative decomposition of unsaturated fatty acids, and the application includes: mixing phytic acid and unsaturated fatty acids and then performing heat oxidation treatment; wherein, the unsaturated fatty acids include at least one of linoleic acid, oleic acid, linolenic acid, and EPA.

[0014] Optionally, the volume ratio of the phytic acid to the unsaturated fatty acids is 4:1; the molar concentration of the phytic acid is 8.8 - 264 mmol / L.

[0015] Optionally, the temperature of the heat oxidation treatment is 60 - 180°C; the time of the heat oxidation treatment is 30 - 60 min.

[0016] Optionally, the temperature of the heat oxidation treatment is 60°C; the time of the heat oxidation treatment is 60 min.

[0017] Optionally, the temperature of the heat oxidation treatment is 180°C; the time of the heat oxidation treatment is 60 min.

[0018] Implementing the embodiments of the present invention will have the following beneficial effects:

[0019] 1. The present invention creatively proposes a method of adding phytic acid to an unsaturated fatty acid system to inhibit the formation of undesirable volatile flavor substances during its thermal oxidation process, thereby achieving the effect of inhibiting the oxidation of unsaturated fatty acids. Under high-temperature and low-temperature conditions, the present invention studied the effects of different concentrations of phytic acid on the formation of undesirable volatile flavor substances during the thermal processing of unsaturated fatty acids. The results showed that phytic acid had a particularly significant inhibitory effect on linoleic acid, oleic acid, and linolenic acid, especially in reducing the formation of volatile aldehyde substances. It is worth noting that even adding a very low concentration of phytic acid can effectively inhibit the thermal oxidation reaction of unsaturated fatty acids. In addition, the addition of phytic acid mainly affects the content of volatile substances and has little effect on their composition. This discovery provides an efficient and practical solution for improving the flavor stability of unsaturated fatty acids during thermal processing.

[0020] 2. In terms of food flavor, in the present invention, adding different concentrations of phytic acid at different temperatures can inhibit the thermal oxidation reaction of unsaturated fatty acids, reduce the concentration of volatile flavor substances, and slow down the formation of undesirable flavors due to the oxidation and rancidity of oleic acid. The specific results are as follows:

[0021] (1) At a lower oxidation temperature (60 °C), different concentrations of phytic acid were added to linoleic acid to study its effect on the concentration of volatile components. The results showed that when the concentration of phytic acid was 8.8 mmol / L, the concentration of most volatile components increased significantly; when the concentration of phytic acid increased to 44 mmol / L, the concentration of each substance began to decrease; when the concentration of phytic acid was further increased to 88 mmol / L, the concentration of most products reached the lowest level. For aldehyde substances, the reduction in concentration was particularly significant. When 88 mmol / L of phytic acid was added, the concentrations of aldehyde substances such as n-hexanal, trans-2-octenal, trans-2-nonenal, and trans-2-decenal all decreased to the lowest level. When 176 mmol / L of phytic acid was added, the concentration of trans,trans-2,4-nonadienal decreased from 35.62 mg / L to 11.79 mg / L, and the concentration of trans,trans-2,4-decadienal decreased from 175.58 mg / L to 91.90 mg / L. The concentration of 1-octen-3-ol increased when 8.8 mmol / L of phytic acid was added, but when the concentration of phytic acid increased to 88 mmol / L, its concentration decreased to the lowest level, from 4.34 mg / L in the control group to 0.65 mg / L. The concentration of 2-pentylfuran first increased and then decreased with the increase in the concentration of phytic acid, and the concentration in the control group was ten times the minimum concentration. The concentrations of ethyl octanoate, octanoic acid, and hexanoic acid also showed a similar trend: with the increase in the concentration of phytic acid, the concentrations of these substances first increased significantly and then decreased. Compared with the control group, the concentrations of these products decreased significantly after adding a high concentration of phytic acid.

[0022] (2) At a relatively high oxidation temperature (180 °C), phytic acid with different concentrations was added to linoleic acid to study its effect on the thermal oxidation reaction of linoleic acid. The results showed that low-concentration phytic acid had no obvious inhibitory effect on the oxidation reaction of linoleic acid, while high-concentration phytic acid showed a significant inhibitory effect. It is worth noting that for some substances, adding phytic acid at a concentration lower than 176 mmol / L may even promote the reaction. In terms of the formation of volatile aldehyde substances, the inhibitory effect of phytic acid was particularly significant. Among them, the concentration of trans,trans-2,4-decadienal decreased most significantly, and even adding low-concentration phytic acid could reduce its formation concentration. For other aldehyde substances (such as trans,trans-2,4-nonadienal, n-hexanal, trans-2-heptenal, and trans-2-octenal), when the phytic acid concentration was 8.8 mmol / L, the concentration of the products increased slightly; while when the phytic acid concentration increased to 176 mmol / L, the concentration of the products decreased to the lowest. In addition, when the phytic acid concentration was 8.8 mmol / L, the concentration of trans-2-hexenal decreased, but as the phytic acid concentration further increased, its concentration increased instead. The concentration of trans-2-nonenal increased with the increase in the phytic acid concentration, indicating that phytic acid had no obvious inhibitory effect on its formation. In terms of the formation of furan substances, phytic acid also showed a certain inhibitory effect. The concentrations of furfural, 2-pentylfuran, and 2-n-pentylfuranone decreased significantly, while the concentration of (E)-2-(1-pentenyl)-furan increased. For ketone substances, the inhibitory effect of phytic acid was not obvious, and the concentrations of most ketone substances did not decrease significantly. In contrast, phytic acid had a significant inhibitory effect on the formation of acid substances, and the concentration of acid substances decreased significantly compared with the control group. For ester substances, the concentrations of most ester substances did not decrease significantly. The concentrations of amyl hexanoate and ethyl hexanoate decreased when low-concentration phytic acid was added, while as the phytic acid concentration increased, the concentration of the products increased. This indicates that phytic acid can effectively inhibit the occurrence of various mechanisms during the oxidation process of linoleic acid.

[0023] (3) At a lower oxidation temperature (60 °C), phytic acid with different concentrations was added to oleic acid to study its effect on the formation of volatile substances during the thermal oxidation of oleic acid. The results showed that at 60 °C, adding phytic acid could reduce the concentration of volatile substances generated during the thermal oxidation of oleic acid. Among them, low-concentration phytic acid had a better inhibitory effect on the reaction. However, as the concentration of phytic acid increased, the concentration of the generated volatile substances would rise, and the concentration of some substances was even higher than that of the control group. For aldehydes, their concentration showed a trend of first decreasing and then increasing with the increase in the concentration of phytic acid. When the concentration of phytic acid was 8.8 mmol / L and 44 mmol / L, the concentration of the generated aldehydes was significantly lower than that of the control group. When the concentration of phytic acid was 8.8 mmol / L, the concentration of trans-2-octenal generated by the oxidation of oleic acid decreased the most, and the concentrations of nonanal, decanal, trans-2-decenal, and trans-2-undecenal all reached the lowest values. However, phytic acid had no obvious inhibitory effect on the formation of octanal and trans-2-nonenal. In terms of esters, after adding phytic acid, the concentration of esters generated by the oxidation of oleic acid also decreased significantly. Among them, the concentration of ethyl hexadecanoate decreased the most significantly, and the concentrations of ethyl nonanoate, ethyl octanoate, ethyl decanoate, and ethyl tetradecanoate also decreased significantly after adding phytic acid. In addition, the concentration of 2-n-octylfuran generated by the thermal oxidation of oleic acid reached the lowest value (0.26 mg / L) when 8.8 mmol / L of phytic acid was added, indicating that phytic acid had a significant promoting effect on the formation of 2-n-octylfuran.

[0024] (4) At a relatively high oxidation temperature (180 °C), phytic acid with different concentrations was added to oleic acid to study its effect on the thermal oxidation reaction of oleic acid. The results showed that at 180 °C, after adding phytic acid, the concentrations of various substances generated during the oxidation of oleic acid decreased significantly, and the concentrations of most substances reached the minimum value when the phytic acid concentration was 88 mmol / L. Among them, the concentration of aldehyde substances decreased the most significantly. The concentration of trans-2-undecenal decreased significantly from 2519.55 mg / L in the control group to 1665.29 mg / L when the phytic acid concentration was 44 mmol / L. The concentrations of trans-2-decenal and nonanal also decreased significantly, reaching the minimum values when the phytic acid concentrations were 8.8 mmol / L and 44 mmol / L, respectively. In addition, the contents of 1-heptenol and 1-octenol generated decreased significantly. The concentrations of 1-nonen-3-ol and 1-nonenol showed a trend of first increasing and then decreasing with the increase of phytic acid concentration. At low phytic acid concentrations, the concentrations of some volatile substances were higher than those in the control group, and as the phytic acid concentration further increased, the concentrations of these substances gradually decreased. In terms of ester substances, when 88 mmol / L of phytic acid was added, the concentration of ethyl 9-decanoate decreased the most significantly, and the concentrations of ethyl octanoate, ethyl nonanoate, and ethyl 7-octanoate also decreased significantly. For furan substances, the inhibitory effect of phytic acid was relatively weak. Among them, the concentrations of 2-n-heptylfuranone, dihydro-5-propyl-2(3H)-furanone, and 5-ethoxydihydro-2(3H)-furanone decreased significantly, while the concentrations of other furan substances did not decrease significantly. Among the ketone substances, the content of 3-decanone was higher than that in the control group when low-concentration phytic acid was added, but started to show a downward trend when 88 mmol / L of phytic acid was added. The contents of octanoic acid and nonanoic acid decreased significantly with the increase of phytic acid concentration, indicating that phytic acid has an obvious inhibitory effect on the formation of acid substances.

[0025] (5) At a lower oxidation temperature (60 °C), different concentrations of phytic acid were added to linolenic acid to study its effect on the formation of volatile substances during the oxidation of linolenic acid. The results showed that at 60 °C, phytic acid could effectively inhibit the formation of volatile substances during the oxidation of linolenic acid, and the concentration of the generated volatile substances decreased significantly. For aldehydes, phytic acid showed an obvious inhibitory effect. Among them, the concentration of trans,trans-2,4-heptadienal decreased most significantly. With the increase in the concentration of phytic acid, the concentration of the generated trans,trans-2,4-heptadienal gradually decreased, from 132.92 mg / L in the control group to 67.92 mg / L when the concentration of phytic acid was 264 mmol / L. In terms of the formation of furans, phytic acid showed a significant inhibitory effect. The concentration of cis-2-(2-pentenyl)furan decreased most significantly and reached the lowest value when the concentration of phytic acid was 176 mmol / L. Phytic acid also had an obvious inhibitory effect on the formation of 2-n-butylfuran and 2-hexylfuran, and with the increase in the concentration of phytic acid, the concentration of these products gradually decreased. For esters, their concentration showed a trend of first decreasing and then increasing with the increase in the concentration of phytic acid. When the concentration of phytic acid was 8.8 mmol / L and 44 mmol / L, the concentration of the generated esters was lower than that in the control group, while when a high concentration of phytic acid was added, the concentration of esters was higher than that in the control group. Phytic acid also had an obvious inhibitory effect on the formation of ketones and alcohols, and when the concentration of phytic acid added was too high, the content of ketones and alcohols would increase to some extent.

[0026] (6) At a relatively high oxidation temperature (180 °C), phytic acid with different concentrations was added to linolenic acid to study its effect on the generation of volatile substances during the oxidation of linolenic acid. The results showed that at 180 °C, phytic acid could significantly inhibit the volatile substances generated by the oxidation of linolenic acid, causing a substantial decrease in the concentration of these substances. For aldehydes, phytic acid showed an obvious inhibitory effect. Among them, the concentration of trans,trans-2,4-heptadienal decreased most significantly, from 1788.81 mg / L in the control group to 77.78 mg / L when the phytic acid concentration was 264 mmol / L. Even when a low concentration of phytic acid was added, its concentration could be significantly reduced. The concentrations of trans,trans-2,4-hexadienal and trans-2-butenal also decreased significantly, reaching the minimum values when the phytic acid concentrations were 44 mmol / L and 88 mmol / L, respectively. In terms of furans, phytic acid also showed a significant inhibitory effect. The concentration of dihydro-3-methylene-5-methyl-2-furanone decreased the most, and the concentrations of 2-hexylfuran, 2-ethylfuran, and 5-ethyl-2-furfural also decreased significantly, reaching the lowest values when the phytic acid concentrations were 8.8 mmol / L, 88 mmol / L, and 88 mmol / L, respectively. After adding phytic acid, the concentration of octanoic acid generated by the thermal oxidation of linolenic acid decreased the most, from 841.81 mg / L in the control group to 35.46 mg / L when the phytic acid concentration was 88 mmol / L. The concentrations of 9-decenoic acid and n-hexadecanoic acid also decreased significantly after adding phytic acid, but the inhibitory effect on heptanoic acid was not very obvious. The inhibitory effect on esters was not as obvious as that on other substances. The concentration of esters reached the lowest when 88 mmol / L of phytic acid was added. When the concentration of phytic acid added was too high, there was no inhibitory effect on the concentration of the generated esters.

[0027] (7) At a lower oxidation temperature (60 °C), phytic acid with different concentrations was added to EPA to study its effect on the thermal oxidation reaction of EPA. The results showed that at 60 °C, phytic acid could significantly inhibit the thermal oxidation reaction of EPA, resulting in a substantial decrease in the concentration of the generated volatile substances. For aldehydes, the addition of phytic acid generally decreased their concentration. Among them, the concentration of trans-4-oxo-2-hexenal decreased most significantly, from 1299.82 mg / L in the control group to 111.83 mg / L when 88 mmol / L of phytic acid was added. The concentration of 2,6-nonadien-1-ol also decreased significantly, from 712.30 mg / L in the control group to 25.15 mg / L when 8.8 mmol / L of phytic acid was added. In terms of esters, the concentration of ethyl octanoate decreased the most, from 1102.45 mg / L in the control group to 117.99 mg / L. The concentrations of pentanoic anhydride and methyl 3,6-dodecadienoate reached their lowest values when 88 mmol / L and 176 mmol / L of phytic acid were added, respectively. For furans, the concentration of the generated trans-2-(2-pentenyl)furan decreased from 3637.49 mg / L in the control group to 863.70 mg / L when 8.8 mmol / L of phytic acid was added. The concentration of volatile furans was generally the lowest when 8.8 mmol / L of phytic acid was added. The concentration of trans,trans-3,5-octadien-2-one also decreased significantly, from 820.92 mg / L in the control group to 36.53 mg / L when 8.8 mmol / L of phytic acid was added. In summary, at 60 °C, when 8.8 mmol / L of phytic acid was added, the overall concentration of the generated volatile flavor substances was relatively low, and the inhibitory effect was the most significant.

[0028] (8) At a relatively high oxidation temperature (180 °C), phytic acid with different concentrations was added to EPA to study its effect on the thermal oxidation reaction of EPA. The results showed that phytic acid could effectively inhibit the thermal oxidation reaction of EPA, and the concentrations of the generated volatile substances were significantly reduced. When 8.8 mmol / L phytic acid was added, the concentration of alcohols generated by the thermal oxidation of EPA did not decrease. As the concentration of phytic acid increased, the concentration of the generated alcohols decreased. Among them, the concentration of cis-3-octen-1-ol decreased the most, from 489.44 mg / L to 153.57 mg / L; for the generation of aldehydes, the concentration of trans,trans-2,4-heptadienal decreased the most, from 4030.64 mg / L to 202.61 mg / L, and the concentrations of 2,4-decadienal and trans-4-oxo-2-hexenal also reached the lowest values when 44 mmol / L phytic acid was added; adding phytic acid to the thermal oxidation reaction of EPA could reduce the concentrations of the generated furans, acids and ketones; the concentration of trans-2-(2-pentenyl)furan decreased significantly, from 3612.05 mg / L to 2183.08 mg / L. Adding phytic acid to the thermal oxidation reaction of EPA had a weaker inhibitory effect on the generation of volatile esters than other substances, and the concentration of the generated volatile esters was relatively low when 44 mmol / L phytic acid was added. To sum up, under the condition of 180 °C, when 44 mmol / L phytic acid was added, the overall concentration of the generated volatile flavor substances was relatively low, and the inhibitory effect was relatively significant.

[0029] 3. In terms of economic applications, adding phytic acid solutions with different concentrations to unsaturated fatty acids can inhibit the oxidation of unsaturated fatty acids, reduce the bad flavors generated due to oxidation, save time and costs, and at the same time can achieve high-temperature effects under low-temperature conditions, saving energy.

[0030] 4. Phytic acid is considered an antioxidant and preservative, and it is a natural plant compound. It exhibits properties such as being green and environmentally friendly and having rich flavors. At the same time, the chelating properties of phytic acid may promote the elimination of potential toxic heavy metal contents in organisms and help prevent cancer. Description of the Drawings

[0031] Figure 1 It is the effect of adding different concentrations of phytic acid on the concentration of volatile products of the thermal oxidation of linoleic acid at 60 °C in Example 1 (A) Other substances (B-C) Aldehydes.

[0032] Figure 2 It is the effect of adding different concentrations of phytic acid on the concentration of volatile products of the thermal oxidation of linoleic acid at 180 °C in Example 2 (A-B) Aldehydes (C-D) Esters (E) Alcohols and acids (F) Ketones (G) Furans.

[0033] Figure 3Effect of adding different concentrations of phytic acid on the product concentration of thermal oxidation of oleic acid at 60 °C (A) aldehydes (B) furans (C-D) esters.

[0034] Figure 4 Effect of adding different concentrations of phytic acid on the product concentration of thermal oxidation of oleic acid at 180 °C (A-B) aldehydes (C) alcohols (D-F) furans (G-H) esters.

[0035] Figure 5 Effect of adding different concentrations of phytic acid on the concentration of volatile products of thermal oxidation of linolenic acid at 60 °C (A) aldehydes (B) esters (C) furans (D) other substances.

[0036] Figure 6 Effect of adding different concentrations of phytic acid on the concentration of volatile products of thermal oxidation of linolenic acid at 180 °C (A) aldehydes (B-C) esters (D-E) furans (F) acids (G) other substances.

[0037] Figure 7 Effect of adding different concentrations of phytic acid on the concentration of volatile products of thermal oxidation of EPA at 60 °C (A) aldehydes (B) alcohols (C) esters (D) other substances.

[0038] Figure 8 Effect of adding different concentrations of phytic acid on the concentration of volatile products of thermal oxidation of EPA at 180 °C (A) alcohols (B) aldehydes (C) other substances (D) esters. Detailed implementation manners

[0039] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0040] Detection methods for various flavor substances:

[0041] The samples were treated by solid-phase microextraction. 10 μL of the diluted unsaturated fatty acid sample, 10 μL of the internal standard cyclohexanone sample at 1 mg / mL, and 40 μL of phytic acid solutions with different concentrations were mixed and added to a 20 ml headspace vial. They were heated and incubated at 180 °C and 60 °C for 60 min respectively, then transferred to a 60 °C water bath to stabilize the samples for 10 min, adsorbed by SPME for 40 min, inserted into the GC-MS for equilibration for 10 min. An Agilent 7890A GC-MS 5975C chromatograph and an Agilent HP-5MS (30 m × 0.25 mm i.d., μm) chromatographic column were used; the temperature programming was set as follows: the initial temperature was 30 °C, the retention time was 3 min, the temperature was increased to 280 °C at a rate of 5 °C / min, and a post-run was carried out at 320 °C for 5 min. The total running cycle time was 52 min. The inlet temperature was 250 °C; the detector temperature was 250 °C; the MSD temperature was 250 °C; the carrier gas was helium with a flow rate of 1 mL / min. The EI ionization source was used, the electron energy was 70 eV; the ion source temperature was 230 °C; the scanning range was 40 - 400 amu, and the Scan mode was selected. The temperature of the quadrupole detector was 150 °C. The n-alkanes (C7 - C30) were detected under the same gas chromatographic conditions, and the retention index was calculated. The NIST11 spectral library was used for retrieval and compared with the RI values reported in the literature. The components with a retention match greater than or equal to 800 were retained for the identification and analysis of the compounds, and then the types of the compounds were finally determined by comparison with the standard compounds.

[0042] Preparation of phytic acid: Phytic acid solutions with concentrations of 8.8 mmol / L, 44 mmol / L, 88 mmol / L, 176 mmol / L, and 264 mmol / L were prepared.

[0043] Source of raw materials: C7 - C30 n-alkanes were purchased from Sigma-Aldrich (Shanghai) Co., Ltd., cyclohexanone was purchased from Aladdin Co., Ltd., absolute ethanol was purchased from Sigma-Aldrich (Shanghai) Co., Ltd., phytic acid was purchased from Tianjin Damao Chemical Reagent Factory, ferric sulfate was purchased from Tianjin Damao Chemical Reagent Factory, NU-CHEK oleic acid standard, NU-CHEK linoleic acid standard, NU-CHEK linolenic acid standard, and NU-CHEK EPA standard were purchased from Sigma Aldrich Co., Ltd.

[0044] Example 1: Effect of adding different concentrations of phytic acid on the thermal oxidation of linoleic acid (60 °C)

[0045] A method for reducing the content of flavor substances generated during the oxidation of unsaturated fatty acids, comprising the following steps:

[0046] S1. Mix 10 μL of the diluted linoleic acid sample, 10 μL of the 1 mg / mL internal standard cyclohexanone sample, and 40 μL of phytic acid solutions with different concentrations, and then add the mixture into a 20 mL headspace vial.

[0047] S2. Phytic acid's effect on the thermal oxidation of linoleic acid: Keep the unsaturated fatty acid system prepared in step S1 at a constant temperature of 60 °C for 60 min to obtain the flavor substances generated by the oleic acid standard.

[0048] Example 2: Effect of adding different concentrations of phytic acid on the thermal oxidation of linoleic acid (180 °C)

[0049] This example is different from Example 1 only in that in step S2, it is kept at a constant temperature of 180 °C.

[0050] Example 3: Effect of adding different concentrations of phytic acid on the thermal oxidation of oleic acid (60 °C)

[0051] A method for reducing the content of flavor substances generated during the oxidation of unsaturated fatty acids, comprising the following steps:

[0052] S1. Mix 10 μL of the diluted oleic acid sample, 10 μL of the 1 mg / mL internal standard cyclohexanone sample, and 40 μL of phytic acid solutions with different concentrations, and then add the mixture into a 20 mL headspace vial;

[0053] S2. Phytic acid's effect on the thermal oxidation of oleic acid: Keep the unsaturated fatty acid system prepared in step S1 at a constant temperature of 60 °C for 60 min to obtain the flavor substances generated by the oleic acid standard.

[0054] Example 4: Effect of adding different concentrations of phytic acid on the thermal oxidation of oleic acid (180 °C)

[0055] This example is different from Example 3 only in that in step S2, it is kept at a constant temperature of 180 °C.

[0056] Example 5: Effect of adding different concentrations of phytic acid on the thermal oxidation of linolenic acid (60 °C)

[0057] A method for reducing the content of flavor substances generated during the oxidation of unsaturated fatty acids, specifically comprising the following steps:

[0058] S1. Mix 10 μL of the diluted linoleic acid sample, 10 μL of the 1 mg / mL internal standard cyclohexanone sample, and 40 μL of phytic acid solutions with different concentrations, and then add the mixture into a 20 mL headspace vial.

[0059] S2. Phytic acid's effect on the thermal oxidation of linolenic acid: Keep the unsaturated fatty acid system prepared in step S1 at a constant temperature of 60 °C for 60 min to obtain the flavor substances generated by the linolenic acid standard.

[0060] Example 6: Effect of adding different concentrations of phytic acid on the thermal oxidation of linolenic acid (180 °C)

[0061] This example is only different from Example 5 in that in step S2, it is treated at a constant temperature of 180 °C.

[0062] Example 7: Effect of adding different concentrations of phytic acid on the thermal oxidation of EPA (60 °C)

[0063] A method for reducing the content of flavor substances generated during the oxidation of unsaturated fatty acids specifically includes the following steps:

[0064] S1. Mix 10 μL of the diluted linoleic acid sample, 10 μL of the internal standard cyclohexanone sample at 1 mg / mL, and 40 μL of phytic acid solutions with different concentrations, and then add them to a 20 ml headspace vial.

[0065] S2. Thermal oxidation of linoleic acid by phytic acid: Keep the unsaturated fatty acid system prepared in step S1 at a constant temperature of 60 °C for 60 min to obtain the flavor substances generated from the EPA standard product.

[0066] Example 8: Effect of adding different concentrations of phytic acid on the thermal oxidation of EPA (180 °C)

[0067] This example is only different from Example 7 in that in step S2, it is treated at a constant temperature of 180 °C.

[0068] Performance comparative analysis:

[0069] 1. Add phytic acid with different concentrations to linoleic acid and study its effect on the concentration of volatile components.

[0070] As Figure 1-2The results in Table 1-2 show that at a lower oxidation temperature (60 °C), when the phytic acid concentration is 8.8 mmol / L, the concentrations of most volatile components increase significantly; while when the phytic acid concentration rises to 44 mmol / L, the concentrations of various substances start to decline; when the phytic acid concentration is further increased to 88 mmol / L, the concentrations of most products reach the lowest level. For aldehydes, the decrease in concentration is particularly significant. When 88 mmol / L of phytic acid is added, the concentrations of aldehydes such as n-hexanal, (E)-2-octenal, (E)-2-nonenal, and (E)-2-decenal all drop to the lowest level. Among them, the concentration of (E,E)-2,4-nonadienal decreases from 35.62 mg / L to 11.79 mg / L, and the concentration of (E,E)-2,4-decadienal decreases from 175.58 mg / L to 91.90 mg / L. The concentration of 1-octen-3-ol increases when 8.8 mmol / L of phytic acid is added, but when the phytic acid concentration rises to 88 mmol / L, its concentration drops to the lowest level, from 4.34 mg / L in the control group to 0.65 mg / L. The concentration of 2-pentylfuran first increases and then decreases with the increase in phytic acid concentration, and the concentration in the control group is ten times the minimum concentration. The concentrations of ethyl octanoate, octanoic acid, and hexanoic acid also show a similar trend: with the increase in phytic acid concentration, the concentrations of these substances first increase significantly and then decrease. Compared with the control group, after adding a high concentration of phytic acid, the concentrations of these products decrease significantly.

[0071] At a relatively high oxidation temperature (180 °C), the results showed that low-concentration phytic acid had no obvious inhibitory effect on the oxidation reaction of linoleic acid, while high-concentration phytic acid showed a significant inhibitory effect. It should be noted that for some substances, adding phytic acid at a concentration lower than 176 mmol / L may even promote the reaction. In terms of the formation of volatile aldehyde substances, the inhibitory effect of phytic acid was particularly significant. Among them, the concentration of trans,trans-2,4-decadienal decreased most significantly, and even adding low-concentration phytic acid could reduce its formation concentration. For other aldehyde substances (such as trans,trans-2,4-nonadienal, n-hexanal, trans-2-heptenal, and trans-2-octenal), when the phytic acid concentration was 8.8 mmol / L, the concentration of the products increased slightly; while when the phytic acid concentration increased to 176 mmol / L, the concentration of the products decreased to the lowest. In addition, when the phytic acid concentration was 8.8 mmol / L, the concentration of trans-2-hexenal decreased, but as the phytic acid concentration further increased, its concentration increased instead. The concentration of trans-2-nonenal increased with the increase of the phytic acid concentration, indicating that phytic acid had no obvious inhibitory effect on its formation. In terms of the formation of furan substances, phytic acid also showed a certain inhibitory effect. The concentrations of furfural, 2-pentylfuran, and 2-n-pentylfuranone decreased significantly, while the concentration of (E)-2-(1-pentenyl)-furan increased. For ketone substances, the inhibitory effect of phytic acid was not obvious, and the concentrations of most ketone substances did not decrease significantly. In contrast, phytic acid had a significant inhibitory effect on the formation of acid substances, and the concentration of acid substances decreased significantly compared with the control group. For ester substances, the concentrations of most ester substances did not decrease significantly. The concentrations of amyl hexanoate and ethyl hexanoate decreased when low-concentration phytic acid was added, while as the phytic acid concentration increased, the concentration of the products increased. This indicates that phytic acid can effectively inhibit the occurrence of various mechanisms during the oxidation of linoleic acid.

[0072] 2. Different concentrations of phytic acid were added to oleic acid to study its effect on the concentration of volatile components.

[0073] Such as Figure 3-4The results in Table 3-4 show that at a relatively low oxidation temperature (60 °C), adding phytic acid can reduce the concentration of volatile substances generated during the thermal oxidation of oleic acid at 60 °C. Among them, a low concentration of phytic acid has a better inhibitory effect on the reaction. However, as the concentration of phytic acid increases, the concentration of the generated volatile substances will rise, and the concentration of some substances is even higher than that of the control group. For aldehydes, their concentration shows a trend of first decreasing and then increasing with the increase in the concentration of phytic acid. When the concentration of phytic acid is 8.8 mmol / L and 44 mmol / L, the concentration of the generated aldehydes is significantly lower than that of the control group. When the concentration of phytic acid is 8.8 mmol / L, the concentration reduction of trans-2-octenal generated by the oxidation of oleic acid is the largest, and the concentrations of nonanal, decanal, trans-2-decenal, and trans-2-undecenal all reach the lowest values. However, phytic acid has no obvious inhibitory effect on the formation of octanal and trans-2-nonenal. In terms of esters, after adding phytic acid, the concentration of esters generated by the oxidation of oleic acid also decreases significantly. Among them, the concentration reduction of ethyl hexadecanoate is the most significant, and the concentrations of ethyl nonanoate, ethyl octanoate, ethyl decanoate, and ethyl myristate also decrease significantly after adding phytic acid. In addition, the concentration of 2-n-octylfuran generated by the thermal oxidation of oleic acid reaches the lowest value (0.26 mg / L) when 8.8 mmol / L of phytic acid is added, indicating that phytic acid has a significant promoting effect on the formation of 2-n-octylfuran.

[0074] At a relatively high oxidation temperature (180 °C), the results showed that at 180 °C, after adding phytic acid, the concentrations of various substances generated during the oxidation of oleic acid decreased significantly, and the concentrations of most substances reached the minimum value when the phytic acid concentration was 88 mmol / L. Among them, the concentration of aldehyde substances decreased most significantly. The concentration of trans-2-undecenal decreased significantly from 2515.55 mg / L in the control group to 16.15 mg / L when the phytic acid concentration was 44 mmol / L. The concentrations of trans-2-decenal and nonanal also decreased significantly and reached the minimum values when the phytic acid concentrations were 8.8 mmol / L and 44 mmol / L, respectively. In addition, the contents of 1-heptenol and 1-octenol generated decreased significantly. The concentrations of 1-nonen-3-ol and 1-nonenol first increased and then decreased with the increase of phytic acid concentration. At low phytic acid concentrations, the concentrations of some volatile substances were higher than those in the control group, and as the phytic acid concentration further increased, the concentrations of these substances gradually decreased. In terms of ester substances, when 88 mmol / L phytic acid was added, the concentration of ethyl 9-decanoate decreased most significantly, and the concentrations of ethyl octanoate, ethyl nonanoate, and ethyl 7-octanoate also decreased significantly. For furan substances, the inhibitory effect of phytic acid was relatively weak. Among them, the concentrations of 2-n-heptylfuranone, dihydro-5-propyl-2(3H)-furanone, and 5-ethoxydihydro-2(3H)-furanone decreased significantly, while the concentrations of other furan substances did not decrease significantly. Among the ketone substances, the content of 3-decanone was higher than that in the control group when low-concentration phytic acid was added, but showed a downward trend when 88 mmol / L phytic acid was added. The contents of octanoic acid and nonanoic acid decreased significantly with the increase of phytic acid concentration, indicating that phytic acid has an obvious inhibitory effect on the formation of acid substances.

[0075] 3. Different concentrations of phytic acid were added to linolenic acid to study its effect on the concentration of volatile components.

[0076] Such as Figure 5-6The results in Table 5-6 show that at a relatively low oxidation temperature (60 °C), it is indicated that under the condition of 60 °C, phytic acid can effectively inhibit the oxidation of linolenic acid to generate volatile substances, and the concentrations of the generated volatile substances are significantly reduced. For aldehydes, phytic acid shows an obvious inhibitory effect. Among them, the concentration reduction of trans,trans-2,4-heptadienal is the most significant. With the increase of phytic acid concentration, the concentration of generated trans,trans-2,4-heptadienal gradually decreases, from 132.92 mg / L in the control group to 67.92 mg / L when the phytic acid concentration is 264 mmol / L. In terms of the generation of furans, phytic acid shows a significant inhibitory effect. The concentration reduction of cis-2-(2-pentenyl)furan is the most obvious, reaching the lowest value when the phytic acid concentration is 176 mmol / L. Phytic acid also has an obvious inhibitory effect on the generation of 2-n-butylfuran and 2-hexylfuran. With the increase of phytic acid concentration, the concentrations of these products gradually decrease. For esters, their concentrations show a trend of first decreasing and then increasing with the increase of phytic acid concentration. When the phytic acid concentrations are 8.8 mmol / L and 44 mmol / L, the concentrations of the generated esters are lower than those in the control group, while when high-concentration phytic acid is added, the ester concentrations are higher than those in the control group. Phytic acid also has an obvious inhibitory effect on the generation of ketones and alcohols. When the added phytic acid concentration is too high, the ketones and alcohols will increase to some extent.

[0077] At a relatively high oxidation temperature (180 °C), the results showed that at 180 °C, phytic acid could significantly inhibit the volatile substances generated by the oxidation of linolenic acid, causing a substantial decrease in the concentration of these substances. For aldehydes, phytic acid showed an obvious inhibitory effect. Among them, the concentration of trans,trans-2,4-heptadienal decreased most significantly, from 1788.81 mg / L in the control group to 77.78 mg / L when the phytic acid concentration was 264 mmol / L. Even when a low concentration of phytic acid was added, its concentration could be significantly reduced. The concentrations of trans,trans-2,4-hexadienal and trans-2-butenal also decreased significantly, reaching the minimum values when the phytic acid concentrations were 44 mmol / L and 88 mmol / L, respectively. In terms of furans, phytic acid also showed a significant inhibitory effect. The concentration of dihydro-3-methylene-5-methyl-2-furanone decreased the most, and the concentrations of 2-hexylfuran, 2-ethylfuran, and 5-ethyl-2-furfural also decreased significantly, reaching the lowest values when the phytic acid concentrations were 8.8 mmol / L, 88 mmol / L, and 88 mmol / L, respectively. The concentration of octanoic acid generated by the thermal oxidation of linolenic acid decreased the most after adding phytic acid, from 841.81 mg / L in the control group to 35.46 mg / L when the phytic acid concentration was 88 mmol / L. The concentrations of 9-decenoic acid and n-hexadecanoic acid also decreased significantly after adding phytic acid, but the inhibitory effect on heptanoic acid was not very obvious. The inhibitory effect on esters was not as obvious as that on other substances. The concentration of esters reached the lowest when 88 mmol / L of phytic acid was added. When the concentration of phytic acid added was too high, there was no inhibitory effect on the concentration of the generated esters.

[0078] 4. Different concentrations of phytic acid were added to EPA to study its effect on the concentration of volatile components.

[0079] Such as Figure 7-8The results in Table 7-8 show that at a relatively low oxidation temperature (60 °C), it is indicated that under the condition of 60 °C, phytic acid can significantly inhibit the thermal oxidation reaction of EPA, resulting in a substantial decrease in the concentration of the generated volatile substances. For aldehydes, the addition of phytic acid generally reduces their concentration. Among them, the concentration of trans-4-oxo-2-hexenal decreases most significantly, from 1299.82 mg / L in the control group to 111.83 mg / L when 88 mmol / L of phytic acid is added. The concentration of 2,6-nonadien-1-ol also decreases significantly, from 712.30 mg / L in the control group to 25.15 mg / L when 8.8 mmol / L of phytic acid is added. In terms of esters, the concentration of ethyl octanoate decreases the most, from 1102.45 mg / L in the control group to 117.99 mg / L. The concentrations of pentanoic anhydride and methyl 3,6-dodecadienoate reach their lowest values when 88 mmol / L and 176 mmol / L of phytic acid are added, respectively. For furans, the concentration of the generated trans-2-(2-pentenyl)furan decreases from 3637.49 mg / L in the control group to 863.70 mg / L when 8.8 mmol / L of phytic acid is added. The concentration of volatile furans is generally the lowest when 8.8 mmol / L of phytic acid is added. The concentration of trans,trans-3,5-octadien-2-one also decreases significantly, from 820.92 mg / L in the control group to 36.53 mg / L when 8.8 mmol / L of phytic acid is added. In summary, under the condition of 60 °C, when 8.8 mmol / L of phytic acid is added, the overall concentration of the generated volatile flavor substances is relatively low, and the inhibitory effect is the most significant.

[0080] At a relatively high oxidation temperature (180 °C), the results showed that phytic acid could effectively inhibit the thermal oxidation reaction of EPA, and the concentrations of the generated volatile substances were significantly reduced. When adding 8.8 mmol / L phytic acid, the concentration of alcohols generated by the thermal oxidation of EPA did not decrease. As the concentration of phytic acid increased, the concentration of the generated alcohols decreased. Among them, the concentration of cis-3-octen-1-ol decreased the most, from 489.44 mg / L to 153.57 mg / L. For the generation of aldehydes, the concentration of trans,trans-2,4-heptadienal decreased the most, from 4030.64 mg / L to 202.61 mg / L. The concentrations of 2,4-decadienal and trans-4-oxo-2-hexenal also reached the lowest values when adding 44 mmol / L phytic acid. Adding phytic acid to the thermal oxidation reaction of EPA could reduce the concentrations of the generated furans, acids and ketones. The concentration of trans-2-(2-pentenyl)furan decreased significantly, from 3612.05 mg / L to 2183.08 mg / L. Adding phytic acid to the thermal oxidation reaction of EPA had a weaker inhibitory effect on the generation of volatile esters than other substances. When adding 44 mmol / L phytic acid, the concentration of the generated volatile esters was relatively low. To sum up, under the condition of 180 °C, when adding 44 mmol / L phytic acid, the overall concentration of the generated volatile flavor substances was relatively low, and the inhibitory effect was relatively significant.

[0081] Table 1 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of linoleic acid thermal oxidation at 66 °C (Identification method: RI, MS)

[0082]

[0083] Note: The content is the average value ± standard error obtained from three repeated experiments: "a, b, c" represent significant differences (p < 0.05).

[0084] Table 2 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of linoleic acid thermal oxidation at 186 °C (Identification method: RI, MS)

[0085]

[0086]

[0087] Note: The content is the average value ± standard error obtained from three repeated experiments: "a, b, c" represent significant differences (p < 0.05).

[0088] Table 3 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of oleic acid thermal oxidation at 66 °C (Identification method: RI, MS)

[0089]

[0090]

[0091] Note: The content is the average value ± standard error obtained from three repeated experiments. "a, b, c" indicate significant differences (p < 0.05).

[0092] Table 4 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of oleic acid thermal oxidation at 186°C (Identification method: RI, MS)

[0093]

[0094]

[0095]

[0096] Note: The content is the average value ± standard error obtained from three repeated experiments. "a, b, c" indicate significant differences (p < 0.05).

[0097] Table 5 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of linolenic acid thermal oxidation at 66°C (Identification method: RI, MS)

[0098]

[0099]

[0100] Note: The content is the average value ± standard error of three repetitions. "a, b, c" indicate significant differences (p < 0.05).

[0101] Table 6 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of linolenic acid thermal oxidation at 186°C (Identification method: RI, MS)

[0102]

[0103]

[0104] Note: The content is the average value ± standard error of three repetitions. "a, b, c" indicate significant differences (p < 0.05).

[0105] Table 7 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of EPA acid thermal oxidation at 66°C (Identification method: RI, MS)

[0106]

[0107]

[0108] Note: The content is the average value ± standard error of three repetitions. "a, b, c" indicate significant differences (p < 0.05).

[0109] Table 8 Effects of adding different concentrations of phytic acid on the concentrations of volatile products of EPA thermal oxidation at 186 °C (identification methods: RI, MS)

[0110]

[0111]

[0112] Note: The content is the average value of three repetitions ± standard error; "a, b, c" indicate significant differences (p < 0.05).

[0113] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A method for reducing the thermal oxidation decomposition of unsaturated fatty acids to produce flavor by using phytic acid, characterized in that: include: Phytic acid is mixed with unsaturated fatty acids and then subjected to heating and oxidation treatment; wherein the unsaturated fatty acids include at least one of linoleic acid, oleic acid, linolenic acid and EPA.

2. The method for reducing the thermal oxidation decomposition of unsaturated fatty acids to produce flavor by using phytic acid according to claim 1, characterized in that: The volume ratio of the phytic acid to the unsaturated fatty acid is 4:1; The molar concentration of the phytic acid is 8.8-264 mmol / L.

3. The method for reducing the thermal oxidation decomposition of unsaturated fatty acids to produce flavor by using phytic acid according to claim 1, characterized in that: The temperature of the heating oxidation treatment is 60 to 180° C.; the time of the heating oxidation treatment is 30 to 60 minutes.

4. The method for reducing the thermal oxidation decomposition of unsaturated fatty acids to produce flavor by using phytic acid according to claim 3, characterized in that: The temperature of the heating oxidation treatment is 60° C.; the time of the heating oxidation treatment is 60 minutes.

5. The method for reducing the thermal oxidation decomposition of unsaturated fatty acids to produce flavor by using phytic acid according to claim 3, characterized in that: The temperature of the heating oxidation treatment is 180° C.; the time of the heating oxidation treatment is 60 minutes.

6. An application of phytic acid in reducing the flavor produced by thermal oxidation decomposition of unsaturated fatty acids, characterized in that: The application comprises: mixing phytic acid and unsaturated fatty acids and then performing heating oxidation treatment; wherein the unsaturated fatty acids comprise at least one of linoleic acid, oleic acid, linolenic acid and EPA.

7. The use according to claim 6, characterized in that: The volume ratio of the phytic acid to the unsaturated fatty acid is 4:1; the molar concentration of the phytic acid is 8.8-264 mmol / L.

8. The use according to claim 6, characterized in that: The temperature of the heating oxidation treatment is 60-180° C.; the time of the heating oxidation treatment is 60 minutes.

9. The use according to claim 6, characterized in that: The temperature of the heating oxidation treatment is 60° C.; the time of the heating oxidation treatment is 60 minutes.

10. The use according to claim 6, characterized in that: The temperature of the heating oxidation treatment is 180° C.; the time of the heating oxidation treatment is 60 minutes.

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