Preparation method of infrared synergistic microwave heat-treated sesame paste

Abstract

The application provides a preparation method of sesame paste by infrared and microwave heat treatment, and relates to the technical field of sesame paste processing. The content of benzopyrene in the sesame paste prepared by infrared and microwave heat treatment is significantly reduced by 13.73%, the content of PAH4 is significantly reduced by 20.5%, the content of Harman is reduced by 24.27%, the content of Norharman is reduced by 23.14%, the acid value is significantly reduced by 65.95%, and the peroxide value is significantly reduced by 37.93%. On the other hand, the infrared and microwave heat treatment produces flavor substances such as 2-ethyl-3,5,6-trimethylpyrazine, alpha-ethylene-benzene acetaldehyde, dihydro-jasmine ketone acid methyl ester, 2-butene-1-alcohol propionate and n-heptanol, so that the content of volatile compounds such as aldehydes, alcohols, esters and acids in the prepared sesame paste is increased by 31.54%, 3.72%, 42.39% and 16.95% respectively.

Description

Technical Field

[0001] This invention belongs to the field of sesame paste processing technology, specifically relating to a method for preparing sesame paste by infrared synergistic microwave heat treatment. Background Technology

[0002] Sesame paste is a product made from sesame seeds through processes such as washing, removing impurities, roasting, and grinding. Consuming sesame paste not only satisfies people's taste buds, but the grinding process also makes the nutrients and active ingredients in sesame seeds more easily absorbed by the body, maximizing their nutritional and health benefits.

[0003] Roasting is a key step in the production of sesame paste, which is essential for developing specific sensory qualities (aroma, flavor, and texture). However, in traditional roasting processes, the heat generated is transferred to the surface of the oilseeds via convection and then to the interior via heat conduction. During the heating process, the outer surface of the oilseeds may be over-roasted, and the heat may not be able to reach the core effectively. When oilseeds are improperly or over-roasted, the content of risk factors such as polycyclic aromatic hydrocarbons and heterocyclic amines increases, thereby affecting the safety and quality of the paste. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing sesame paste by infrared synergistic microwave heat treatment that meets the requirements for risk factors such as polycyclic aromatic hydrocarbons and heterocyclic amines and ensures the safety of the paste.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for preparing sesame paste by infrared-assisted microwave heat treatment includes the following steps:

[0007] S1 Material Selection: Select sesame seeds to obtain the raw materials;

[0008] S2 heating: The raw materials are first heated with infrared radiation, and then immediately heated with microwave radiation to obtain roasted sesame seeds.

[0009] S3 Smoke Removal: Cool the cooked sesame seeds and remove the debris to obtain the cooked sesame seeds to be ground;

[0010] S4 Grinding: Grind the cooked sesame seeds to obtain sesame paste;

[0011] S5 Bottling: Bottle the resulting sesame paste.

[0012] Preferably, in the S2 heating process, the infrared power is 600W-800W, and the heating time is 2-3.5min.

[0013] Preferably, in the S2 heating process, the microwave power is 650-750W and the heating time is 3-5 minutes.

[0014] Preferably, in the S2 heating, the stirring is once per 1.5-2 min.

[0015] Preferably, in the S3 fume generation, the roasted sesame is cooled to below 60 DEG C.

[0016] Preferably, in the S4 grinding, the grinding speed is 55-65 r / min, and the grinding time is 15-25 min.

[0017] Preferably, in the S5 bottling, the used bottling vessel is cleaned and high-temperature sterilized before use.

[0018] Preferably, in the S1 pretreatment, the sesame particles are full, free of mildew, and complete in appearance.

[0019] The sesame paste is prepared by the method for preparing sesame paste through infrared and microwave heat treatment.

[0020] Compared with the prior art, the method has the following beneficial effects:

[0021] The application provides a method for preparing sesame paste through infrared and microwave heat treatment. The sesame paste obtained has bright color, is yellow-brown in color, is good in smearing and flowing, and has the following advantages: the content of benzo(a)pyrene is reduced by 13.73% compared with that of sesame paste prepared through traditional baking, the content of PAH4 is reduced by 20.5%, the content of Harman is reduced by 24.27%, the content of Norharman is reduced by 23.14%, the acid value is reduced by 65.95%, and the peroxide value is reduced by 37.93%; on the other hand, the infrared and microwave heat treatment produces flavor substances such as 2-ethyl-3, 5, 6-trimethylpyrazine, alpha-ethylene-benzene acetaldehyde, dihydro-jasmine ketone acid methyl ester, 2-butene-1-alcohol propionate and n-heptanol, so that the contents of volatile compounds such as aldehydes, alcohols, esters and acids in the prepared sesame paste are increased by 31.54%, 3.72%, 42.39% and 16.95% respectively, the contents of 3, 5-dimethyl-2-pyrazine, 2-ethyl-3, 5, 6-trimethylpyrazine and other substances with roasted, bread, nut and cocoa aroma are significantly increased, the contents of isovaleraldehyde, 2-methylbutanal and benzene acetaldehyde related to umami and lipid aroma are significantly increased, and the contents of trimethylpentanol, n-hexanol and 1-octene-3-alcohol related to sweet, floral, waxy, green, citrus and fruit flavors are significantly increased. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1Fig. 1 is a photo of natural, pressed, and spread states of sesame paste.

[0023] Figure 2 Fig. 2 is a graph of acid value of sesame paste.

[0024] Figure 3 Fig. 3 is a graph of peroxide value of sesame paste.

[0025] Figure 4 Fig. 4 is a graph of polycyclic aromatic hydrocarbon content of sesame paste.

[0026] Figure 5 Fig. 5 is a graph of heterocyclic amine content of sesame paste.

[0027] Figure 6 Fig. 6 is a graph of volatile compound content of sesame paste.

[0028] Figure 7 Fig. 7 is a heat map of volatile compounds of sesame paste.

[0029] Figure 8 Fig. 8 is a principal component analysis graph of volatile compounds of sesame paste. DETAILED DESCRIPTION

[0030] The technical solutions and technical effects of the embodiments of the present application are further described in detail below in combination with the drawings of the present application.

[0031] A preparation method of infrared synergistic microwave heat (IR-MW) treated sesame paste, comprising the following steps:

[0032] S1 material selection: selecting sesame to obtain raw materials;

[0033] S2 heating: first heating the raw materials by infrared, and immediately heating by microwave after the infrared heating is completed to obtain cooked sesame;

[0034] S3 smoke raising: cooling and removing debris of the cooked sesame to obtain to-be-ground cooked sesame;

[0035] S4 grinding: grinding the to-be-ground cooked sesame to obtain sesame paste;

[0036] S5 bottling: bottling the obtained sesame paste.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] The application provides a preparation method of sesame paste by infrared and microwave heating, and the sesame is selected to obtain raw materials; the raw materials are first subjected to infrared heating, and then subjected to microwave heating immediately after the infrared heating is completed to obtain cooked sesame; the cooked sesame is cooled and the debris is removed to obtain to-be-ground cooked sesame; the to-be-ground cooked sesame is ground to obtain sesame paste; the obtained sesame paste is bright in color, yellow-brown in color, good in smearing and flowing, and the content of benzo(a)pyrene in the prepared sesame paste is significantly reduced by 13.73%, the content of PAH4 is significantly reduced by 20.5%, the content of Harman is reduced by 24.27%, the content of Norharman is reduced by 23.14%, the acid value is significantly reduced by 65.95%, and the peroxide value is significantly reduced by 37.93%; on the other hand, the infrared and microwave heating produces flavor substances such as 2-ethyl-3,5,6-trimethylpyrazine, alpha-ethylidene-benzene acetaldehyde, dihydro-jasmine ketone acid methyl ester, 2-butene-1-alcohol propionate and n-heptanol, so that the content of volatile compounds such as aldehydes, alcohols, esters and acids in the prepared sesame paste is increased by 31.54%, 3.72%, 42.39% and 16.95% respectively, among which, the content of 3,5-dimethyl-2-pyrazine, 2-ethyl-3,5,6-trimethylpyrazine and other roasted, bread, nut and cocoa aroma substances is significantly increased, the content of isovaleraldehyde, 2-methylbutanal and benzene acetaldehyde related to umami and lipid aroma is significantly increased, and the content of trimethylpentanol, n-hexanol and 1-octene-3-alcohol related to sweet, floral, waxy, green, citrus and fruit flavors is significantly increased.

[0039] Further, in the S2 heating, the power of the infrared is 600W-800W, and the heating time is 2-3.5min.

[0040] Further, in the S2 heating, the microwave power is 650-750W, and the heating time is 3-5min.

[0041] Further, in the S2 heating, the stirring is performed once every 1.5-2min.

[0042] Further, in the S3 smoke raising, the cooked sesame is cooled to below 60℃.

[0043] Further, in the S4 grinding, the grinding speed is 55r / min-65r / min, and the grinding time is 15min-25min.

[0044] Further, in the S5 bottling, the used bottling vessels need to be cleaned and sterilized at high temperature before use. The high-temperature sterilization is specifically as follows: the used vessels are cleaned and sterilized at high temperature steam at 121℃ for 20min.

[0045] Further, in the S1 pretreatment, the sesame particles are full, free of mold, and have a complete appearance.

[0046] The sesame paste is prepared by the method for preparing sesame paste through infrared and microwave synergistic heat treatment.

[0047] The following is a specific preparation example:

[0048] The sesame is from Zhumadian, Henan, and is placed at dry and room temperature. The sesame is oval-shaped, about 3*1.5*0.5 mm, and the full and mature sesame without mold and decay is selected.

[0049] Example 1-3:

[0050] S1 material selection: select sesame to obtain raw materials;

[0051] S2 heating: 600 g of selected sesame is weighed, 100 g per batch is placed in the middle of the two infrared heating plates placed horizontally on the electric roller, the infrared power is set to 600 W, 700 W and 800 W respectively, heating for 3 min, the roller speed is set to 400 rpm, and the heated sesame is immediately taken out and placed in a microwave oven special ceramic plate, heated at a microwave power of 700 W for 4 min, and stirred every 2 min during the heating;

[0052] S3 smoke raising: the cooked sesame is repeatedly poured in a container, and after the smoke is raised, it is cooled to room temperature to obtain the sesame to be ground;

[0053] S4 grinding: the sesame to be ground is added to the graphite at a uniform feeding speed, the graphite speed is 60 r / min, the sample mass is 600 g, and the grinding time is 20 min.

[0054] S5 bottling: the ground sesame paste is collected in a sealed glass jar and stored at 4℃ for grinding to obtain the sesame paste.

[0055] Comparative Example 1

[0056] S2 heating: the oven is preheated at 170℃ for 10 min before use, 600 g of selected sesame is weighed, 100 g per batch is placed in a single layer on the oven tray, the oven temperature is set to 170℃ and baked for 20 min. Immediately after baking, the tray is taken out of the oven and the sesame is placed in a container. Except for the S2 step, the other steps are the same as Example 1.

[0057] The quality of the sesame paste is evaluated by the following method.

[0058] I. Appearance and color of sesame paste

[0059] The original, pressed and smeared forms of the sesame paste are photographed, and the results are as followsFigure 1 The sesame paste obtained after IR-MW heating treatment and oven heating all showed a sticky texture and yellow-brown color, with good flowability and spreadability. Among them, the sesame paste prepared by oven heating had the deepest color, and the color gradually deepened from IR-MW600 to IR-MW800 and approached the oven treatment.

[0060] The color of the sesame paste was determined by a colorimeter, and the results are shown in Table 1. After heat treatment, the L* value of the sesame paste sample was between 52.52-54.89, with no significant difference, and had similar heating endpoints. The a* value was between 7.25-7.88, and the roasting treatment increased the a* value, which may be due to the Maillard reaction, leading to non-enzymatic browning and phospholipid degradation to form brown pigments.

[0061] Table 1 Effect of heating treatment on the color of sesame paste

[0062]

[0063] II. Determination of acid value and peroxide value of sesame paste

[0064] The acid value and peroxide value of the sesame paste were determined according to GB 5009.229-2016 and GB 5009.227-2016, and the results are shown in Table 2 and Table 3. Figure 2 and Figure 3 The acid value of the sesame paste prepared by oven heating at 170°C for 20 min reached 1.85 mg / g. After IR-MW heating treatment, the acid value of IR-MW600 was 0.64 mg / g, and with increasing infrared power, the acid value of IR-MW800 increased to 0.70 mg / g. The peroxide value of the control group sesame paste was 0.05 g / 100g, and after IR-MW heating treatment, it decreased to 0.03 g / 100g, 0.03 g / 100g, and 0.04 g / 100g, respectively. Compared with the traditional roasting method, the IR-MW new type of heat treatment significantly reduced the acid value and peroxide value of the sesame paste.

[0065] III. Determination of polycyclic aromatic hydrocarbons in sesame paste

[0066] Take 1 g ± 0.01 g of sesame paste and mix with 5 mL of acetonitrile (HPLC pure) in a vortex mixer for 1 min, and then centrifuge at 4000 r / min for 5 min after ultrasonic-assisted extraction for 8 min. The supernatant was transferred to a glass tube, and the whole extraction process was repeated twice. The three extracts were mixed completely in a sealed glass bottle, frozen overnight at -18℃, and then the sample was rotary evaporated at 60℃, and the separated supernatant was concentrated to substantially no solvent. The residue was redissolved in 2 ml of n-hexane, passed through a PCX solid phase extraction column previously activated with n-hexane, repeated twice with a loading speed of 1 mL / min, and then the solid phase extraction column was eluted with 4 mL of n-hexane-dichloromethane (1:1, v / v). The collected eluent was blown dry with nitrogen at 45℃, redissolved with 1 ml of acetonitrile, filtered through a 0.22 μm organic filter membrane, and then injected. About 1 ml of the solution was added to the e2695 high performance liquid chromatograph, using an automatic injector, a C18 column (250.0 m x 4.6 mm x 5 μm) from Waters, and a fluorescence detector from Agilent. In the pulse undivided mode, the injection amount was 10 μL. The mobile phase was A: acetonitrile B: ultrapure water, and the flow rate was 1.0 mL / min. The HPLC gradient elution program was as follows: 0-8 min, 60% acetonitrile; 8-28 min, acetonitrile increased from 60% to 100%; 29-35 min, acetonitrile decreased from 100% to 60%, and the column temperature was maintained at 35℃.

[0067] The contents of benzene[a]pyrene, benzene[a]anthracene, benzene[b]fluoranthene and chrysene in the sesame paste after heat treatment were determined, respectively, and the results are shown in Table 1. Figure 4 As shown in Table 1, the contents of benzene[a]pyrene and PAH4 in the sesame paste reached the maximum after heating in the oven at 170℃ for 20 min, which were 1.45 μg / kg and 4.99 μg / kg, respectively. When the infrared power increased from 600 W to 800 W, the content of benzene[a]pyrene increased from 1.25 μg / kg to 1.26 μg / kg, and the content of PAH4 increased from 3.97 μg / kg to 4.22 μg / kg. Therefore, compared with traditional roasting, the content of polycyclic aromatic hydrocarbons in the sesame paste obtained by the new IR-MW heating method was significantly reduced, and the safety of the sesame paste was improved.

[0068] Four, determination of heterocyclic amines in sesame paste

[0069] Take 1 g ± 0.01 g of sesame paste and mix with 5 mL of acetonitrile (HPLC pure) in a vortex mixer for 1 min, and then extract with ultrasonic assistance for 8 min. Centrifuge at 4000 r / min for 5 min, and then transfer the supernatant to a glass tube. Repeat the entire extraction process twice. Purification: load the collected supernatant onto a PCX solid-phase extraction column that has been activated with 3 mL of methanol and 3 mL of ultrapure water, and control the flow rate at 1 mL / min. Then sequentially wash the solid-phase extraction column with 3 mL of 0.1 mol / L hydrochloric acid solution and 3 mL of methanol, and then use a vacuum pump to dry the remaining solution in the extraction column. Then elute with 3 mL of methanol-ammonia solution (95:5 v / v), and collect all the eluate under nitrogen blowing at 45°C until dry. Then redissolve the dried material with 1 mL of methanol, pass it through a 0.22 μm organic filter membrane, and then inject it. HPLC conditions: the chromatographic column is a Waters C18 column (250.0 m x 4.6 mm x 5 μm), the column temperature is 30°C, and the injection volume is 10 μL. The mobile phase A is 10 mmol / L ammonium formate solution with pH = 6.8, and the B is acetonitrile, with a volume ratio of 85:15. The time is 15 min, and the flow rate is 1 mL / min. The fluorescence detector conditions are: excitation wavelength / emission wavelength 300 nm / 440 nm.

[0070] The contents of Harman and Norharman in the sesame paste after heat treatment were determined, and the results are shown in Table 1. Figure 5 Compared with the oven 170°C roasting for 20 min, the Harman content in the sesame paste after IR-MW roasting decreased significantly by 24.27% (from 144.36 μg / kg to 109.33 μg / kg), and the Norharman content decreased significantly by 23.14% (from 235.04 μg / kg to 180.65 μg / kg). When the infrared power increased from 600 W to 800 W, the Harman content increased from 109.33 μg / kg to 122.26 μg / kg, and the Norharman content increased from 180.65 μg / kg to 185.56 μg / kg. Therefore, compared with traditional roasting, the content of heterocyclic amines in the sesame paste obtained by the new IR-MW heating method decreased significantly.

[0071] Comparative Example 2

[0072] S2 heating: After selecting, 600 g of sesame was weighed, and each batch of 100 g was placed in the middle of the two infrared heating plates placed in parallel on the upper and lower parts of the electric roller, and heated at an infrared power of 700 W for 7 min. The other conditions were the same as in Example 1.

[0073] Comparative Example 3

[0074] S2 heating: 600g of selected sesame seeds were placed in a microwave oven special ceramic plate, heated under the power of 700W for 7min, and stirred every 2min during the heating. The other conditions were the same as in Example 1.

[0075] V. Determination of volatile compounds in sesame paste

[0076] The volatile components of sesame paste were determined by HS-SPME. First, 4g ± 0.01g of treated sesame paste sample was weighed in a 25mL headspace bottle and immediately sealed with a silica gel septum. The sample bottle was equilibrated in a 65℃ water bath for 25min, and stirred with a magnetic stirrer at 80r / min. Then, an activated divinylbenzene / carbonoxy / polydimethylsiloxane (DVB / CAR / PDMS) fiber extraction needle (length: 2cm; thickness: 50 / 30μm) was inserted for extraction for 40min. For the first use, the fiber needle was aged at 250℃ for 90min, and for subsequent use, only 30min was needed. Then the extracted SPME fiber head was inserted into the GC injection port (250℃), and the analysis time was 5min, and the collection program was started. The gas chromatography conditions were as follows: HP-5MS capillary column (30m x 0.25mm x 0.25μm); the initial temperature was 35℃, then increased to 220℃ at a rate of 5℃ / min, maintained for 10min, and finally increased to 250℃ at a rate of 15℃ / min, then maintained for 8min. The mass spectrometry conditions were as follows: ion source temperature 230℃; interface temperature 250℃; electron energy 70eV. By matching the peak time of each compound in the sample with the spectral library, components with a matching degree greater than 80% were selected.

[0077] The content of volatile compounds in sesame paste was determined by Figure 5 、 Figure 6 、 Figure 7and Table 2, a total of 81 volatile compounds were detected in the sesame paste, including pyrazines (11), pyrroles (1), pyridines (2), furans (4), aldehydes (10), ketones (4), alcohols (11), esters (9), acids (2), hydrocarbons (19), and other compounds (8). Compared with Comparative Examples 1-3, the contents of aldehydes, alcohols, esters, and acids in the sesame paste prepared by IR-MW heating were increased by 31.54%, 3.72%, 42.39%, and 16.95%, respectively. After heating treatment, pyrazine compounds were the most abundant volatile compounds in the sesame paste, which usually presented roasted, bread, nut, and cocoa flavor aroma. Compared with the sesame paste treated by oven, the content of 3,5-dimethyl-2-pyrazine in IR-MW800 was increased (from 1923.95 μg / kg to 1973.65 μg / kg), and 2-ethyl-3,5,6-trimethylpyrazine was produced; the contents of isovaleraldehyde, 2-methylbutanal, and phenylacetaldehyde associated with umami and lipid aroma were significantly increased; the contents of trimethylpentanol, n-hexanol, 1-octen-3-ol, and the like associated with sweet, floral, waxy, green, citrus, and fruity flavors were significantly increased. IR-MW heat treatment produced 2-ethyl-3,5,6-trimethylpyrazine, a-ethylidene-phenylacetaldehyde, dihydrojasmonic acid methyl ester, 2-buten-1-ol propionate, n-heptanol, and other volatile substances. In Comparative Example 2, infrared (IR) radiation is a non-ionizing electromagnetic spectrum with a wavelength range of 0.75-1000 μm, located between the ultraviolet and microwave regions. In the heating of oilseeds, the energy emitted by the infrared heater is absorbed by the internal components (water molecules and ions) of the oilseeds and converted into heat energy, which is conducted in the form of electromagnetic waves throughout the oilseeds, but long-term exposure to IR radiation can cause changes in the structure of the material itself; in Comparative Example 3, microwave (MW) energy enters the oil in the form of electromagnetic radiation, and a large amount of water vapor is produced from the inside out, forming an effective vapor pressure gradient that drives water migration to the surface. The polar structure of the internal water molecules undergoes high-frequency vibration under the action of microwaves, resulting in a large friction effect and thermal motion, which causes the water to rapidly flow out, but during microwave heating, uneven heating is easy to occur, and the formation of oxygen-containing compounds and fatty acid conjugates can also reduce the stability of the oil and accelerate the rancidity of the oil.

[0078] Table 2 Effect of heating treatment on the content of volatile compounds in sesame paste

[0079]

[0080]

[0081] The above disclosure is merely the preferred embodiments of the present application, and of course cannot be used to limit the scope of the present application, and those skilled in the art can understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made according to the claims of the present application, still belong to the scope covered by the present application.

Claims

1. A method for preparing sesame paste by infrared synergistic microwave heat treatment, characterized in that, It comprises the following steps: S1 selecting material: selecting sesame to obtain raw material; S2 heating: first heating the raw material by infrared, and then immediately heating it by microwave to obtain cooked sesame; Wherein, the power of the infrared heating is 800 W, and the heating time is 2-3.5 min; the power of the microwave heating is 650-750 W, and the heating time is 3-5 min; in the heating process, stirring is carried out once every 1.5-2 min; S3 fumigating: cooling the cooked sesame and removing the debris to obtain the to-be-ground cooked sesame; S4 grinding: grinding the to-be-ground cooked sesame to obtain sesame paste; S5 bottling: bottling the obtained sesame paste.

2. A process for the preparation of sesame paste by infrared synergistic microwave heat treatment as claimed in claim 1 wherein: In the S3 fumigating, the cooked sesame is cooled to below 60℃.

3. A process for the preparation of sesame paste by infrared synergistic microwave heating as claimed in claim 1 wherein: In the S4 grinding, the grinding speed is 55 r / min-65 r / min, and the grinding time is 15 min-25 min.

4. A process for the preparation of sesame paste by infrared synergistic microwave heating as claimed in claim 1 wherein, In the S5 bottling, the used bottling vessel needs to be cleaned and sterilized at high temperature before use.

5. A process for the preparation of sesame paste by infrared synergistic microwave heating as claimed in claim 1 wherein, In the S1 selecting material, the sesame particles are full, without mildew, and the appearance is complete.

6. A tahini, characterized in that: It is prepared by the method of claim 1-5.

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