Method for preparing starch lipid compound by physical method

Abstract

The invention relates to the technical field of food processing, in particular to a method for preparing a starch lipid compound through a physical method. One or more of Lipu taro starch, corn starch and potato starch are adopted, the water content of the starch is adjusted to be 15%-35%, and a physical hydrothermal method is adopted for preparation. According to the preparation method, common starch and grease are not subjected to chemical treatment and enzymatic treatment, so that the preparation method is green and safe; the physical hydrothermal treatment experimental method is simple, and experimental equipment is easy to purchase; raw materials are simple to obtain and low in cost. According to the physical hydrothermal method, three kinds of starch from different sources are used for preparing experiments, the compounding effect is generated, the in-vitro digestion characteristic of the starch compound is also regulated, and the experimental method is simple and effective. In the preparation process, a proper amount of water is added, so that starch molecule recombination and compound formation are facilitated, and the structure of the compound is more stable.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and specifically relates to a method for preparing starch-lipid complex by a physical method. Background Art

[0002] Starch is a renewable and biodegradable natural polymer. Starch is the main source for the human body to obtain carbohydrates and is the main component of staple foods in our country. Different processing methods affect the texture, viscosity, shelf life and digestion characteristics of starch. When the human body intakes starch to obtain energy, it will also increase the blood sugar of the human body, which is not conducive to the health of diabetic patients.

[0003] According to the in vitro digestion simulation experiment of starch by Dr. Englyst, a British scholar, starch can be divided into three categories: rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS). Rapidly digestible starch (RDS) is starch that can be completely digested and absorbed in the mouth and small intestine (<20 min), belonging to high glycemic index (GI) foods; slowly digestible starch (SDS) is starch that can be slowly and completely absorbed in the small intestine (20 - 120 min), maintaining stable postprandial blood sugar; resistant starch (RS) cannot be digested and absorbed in the human small intestine (>120 min) and is fermented and utilized by microorganisms in the large intestine to promote intestinal health.

[0004] The preparation methods of starch-lipid complex can be divided into chemical method, physical method and enzymatic method. The chemical method for producing the complex uses toxic reagent products and cannot be eaten. The enzymatic method for production has high requirements for reaction conditions. The physical method for production is green and environmentally friendly, and the process is simple and convenient for enterprises to mass-produce. Therefore, finding a preparation method for starch-lipid complex with better effects, more safety and effectiveness is the current key research object. Summary of the Invention

[0005] In order to solve the above technical problems existing in the prior art, the present invention provides a method for preparing starch-lipid complex by a physical method, specifically as follows:

[0006] A method for preparing starch-lipid complex by a physical method includes the following steps:

[0007] (1) Drying of native starch: The native starch is dried at a low temperature to a water content of less than 10%.

[0008] (2) Adjust the moisture content of the starch: Detect the moisture content of the starch, adjust the moisture content of the starch to 15% - 35%, and seal it.

[0009] (3) Add lipids to the starch obtained in step (2).

[0010] (4) Seal the starch-lipid mixture with the obtained moisture content in step (3) and heat it.

[0011] (5) Dry all the samples prepared by heating at 40 °C, powder them, and store them sealed.

[0012] Further, the native starch is one or more of Lipu taro starch, corn starch, and potato starch mixed in any proportion.

[0013] Further, the drying in step (1) is drying at a low temperature of 40 °C.

[0014] Further, the detection of the moisture content of the starch is to detect the moisture content of the starch according to the national standard Determination of Moisture in Foods (GB / T 5009.3 - 2016).

[0015] Further, the sealing in step (2) is to seal at 4 °C and equilibrate for 48 hours.

[0016] Further, in step (2), adjust the moisture content of the starch to 25%.

[0017] Further, the lipid is palm oil, and the addition amount is 10%.

[0018] Further, the heating in step (4) is heating at 120 °C for 6 hours.

[0019] Further, the drying in step (5) is drying at 40 °C.

[0020] A starch-lipid complex is prepared by the above method.

[0021] Compared with the prior art, the technical effects of the present invention are embodied in:

[0022] (1) The preparation method of the present invention uses ordinary starch and oil without chemical treatment and enzymatic treatment, which is green and safe; the physical hydrothermal treatment experimental method is simple, and the experimental equipment is easy to purchase; the raw materials are easy to obtain and the cost is low.

[0023] (2) The physical hydrothermal method of the present invention uses three different sources of starch for experiments, and all produce composite effects. The in vitro digestion characteristics of the starch complex are also regulated, and the experimental method is simple and effective.

[0024] (3) The addition of an appropriate amount of water during the preparation process of the present invention is beneficial to the recombination of starch molecules and the formation of the complex, making the structure of the complex more stable. Brief Description of the Drawings

[0025] Figure 1 It is the XRD pattern of taro starch and its composites.

[0026] Figure 2 It is the XRD pattern of corn starch and its composites.

[0027] Figure 3 It is the XRD pattern of potato starch and its composites.

[0028] Figure 1 , Figure 2 , Figure 3 In [, ], Anl represents the toughened composite sample; Gel represents the gelatinized sample; HMT15%, HMT25%, and HMT35% represent the hydrothermally treated composite samples.

[0029] Figure 4 It is the infrared spectrum of taro starch and its composites.

[0030] Figure 5 It is the infrared spectrum of corn starch and its composites.

[0031] Figure 6 It is the infrared spectrum of potato starch and its composites.

[0032] Figure 7 It is the microscopic morphology of raw taro starch sample particles.

[0033] Figure 8 It is the microscopic morphology of toughened composite sample particles of taro starch.

[0034] Figure 9 It is the microscopic morphology of gelatinized composite sample particles of taro starch.

[0035] Figure 10 It is the microscopic morphology of HMT15% composite sample particles of taro.

[0036] Figure 11 It is the microscopic morphology of HMT25% composite sample particles of taro.

[0037] Figure 12 It is the microscopic morphology of HMT35% composite sample particles of taro.

[0038] Figure 13 It is the microscopic morphology of raw corn starch sample particles.

[0039] Figure 14 It is the microscopic morphology of HMT15% composite sample particles of corn.

[0040] Figure 15 It is the microscopic morphology of HMT25% composite sample particles of corn.

[0041] Figure 16 It is the microscopic morphology of the corn HMT 35% composite sample particles.

[0042] Figure 17 It is the microscopic morphology of the composite sample particles prepared by gelatinizing corn.

[0043] Figure 18 It is the microscopic morphology of the composite sample particles prepared by toughening corn.

[0044] Figure 19 It is the microscopic morphology of the native potato starch sample particles.

[0045] Figure 20 It is the microscopic morphology of the composite sample particles prepared by toughening potato starch.

[0046] Figure 21 It is the microscopic morphology of the composite sample particles prepared by gelatinizing potato starch.

[0047] Figure 22 It is the microscopic morphology of the potato starch HMT 15% composite sample particles.

[0048] Figure 23 It is the microscopic morphology of the potato starch HMT 25% composite sample particles.

[0049] Figure 24 It is the microscopic morphology of the potato starch HMT 35% composite sample particles. Specific embodiments

[0050] The technical solution of the present invention will be further limited in combination with specific embodiments below, but the scope of protection required is not limited to the description made.

[0051] Examples

[0052] (1) Drying of native starch: Lipu taro starch, corn starch, and potato starch are dried at a low temperature of 40 °C until the water content is below 10%.

[0053] (2) Adjusting the water content of starch: The water content of starch is detected according to the national standard Determination of water in foods (GB / T 5009.3-2016). One portion of starch with water contents of 15%, 25%, and 35% is adjusted respectively by calculation, sealed at 4 °C, and equilibrated for 48 hours.

[0054] (3) 10% palm oil is added to Lipu taro starch, corn starch, potato starch with water contents below 10%, 15%, 25%, and 35% respectively.

[0055] (4) The starch-oil mixture of Lipu taro starch, corn starch, and potato starch (water content < 10%) is sealed and heated in a water bath at 50 °C for 14 hours.

[0056] (5) The starch-oil mixtures of Lipu taro starch, corn starch, and potato starch with water contents of 15%, 25%, and 35% were sealed and heated at 120 °C for 6 hours.

[0057] (6) All the samples prepared by heating were dried at 40 °C, powdered, and stored in sealed containers.

[0058] The test methods and results are as follows:

[0059] Composite index detection

[0060] Weigh 0.1 g of the composite sample into a 100 mL volumetric flask, add 1 mL of 95% ethanol, and then add 9 mL of NaOH (1 mol / L) and mix well. Place the volumetric flask in a boiling water bath, heat and stir for 20 min, and then make up the volume. Take 2.5 mL of the mixed solution into a 50 mL volumetric flask, add 2 mL of iodine solution (an aqueous solution containing 2.0% KI and 1.3% I2, w / v) and 1 mL of acetic acid (1 mol / L), then make up the volume, mix well and develop color. Measure the absorbance of the sample at 620 nm. The starch sample without FA is used as the control group.

[0061] The calculation formula is as follows:

[0062] CI(%) = (Ac – As) × 100 / Ac

[0063] In the formula, Ac is the absorbance value of the control group, and As is the absorbance value of the sample.

[0064] In vitro digestion detection

[0065] Accurately weigh 200 mg of the sample into a 50 mL centrifuge tube, add 15 mL of sodium acetate buffer (0.1 mol / L, pH 5.2), mix well, and then place it in a boiling water bath for 20 min. Take it out and cool, then preheat it in a 37 °C water bath shaker for 5 min. Then add a mixed enzyme solution composed of porcine pancreatic α-amylase (14 U / mg) and amyloglucosidase (100 U / mg), and continue to oscillate in a 37 °C water bath (160 r / min). Take it out after digestion for 20 min and 120 min respectively, inactivate it in a boiling water bath, and use the 3,5-dinitrosalicylic acid (DNS) method to measure the absorbance at 540 nm. Calculate the hydrolysis rate of the sample at 20 min and 120 min according to the glucose content hydrolyzed from the sample measured by the analyzer. Calculate the contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) in the sample according to the formula.

[0066] RDS = (G 20 – G 0 ) × 0.9 / TS

[0067] SDS = (G 120 – G20 )×0.9 / TS

[0068] RS = 100 - RDS - SDS

[0069] Where: G 20 — Glucose content (mg) of the enzymatic hydrolysate of starch hydrolyzed for 20 min; G 120 — Glucose content (mg) of the enzymatic hydrolysate of starch hydrolyzed for 120 min; TS — Total starch content (mg) in the sample.

[0070] X-ray diffraction detection

[0071] Detected using the A24A10 model equipment produced by BRUKER AXS GMBH. Set parameters: voltage: 40 KV, current 40 / 15 mA, scanning range 5° - 50° (2θ), scanning rate 4° / min. Analyze the XRD pattern using the software MDIjade6.

[0072] Fourier transform infrared detection

[0073] Dry potassium bromide and the sample are mixed in a ratio of 100:1 and ground thoroughly until the mixed powder becomes matte, then pressed into a tablet. Background calibration is performed with a potassium bromide tablet in the scanning wavelength range of 400 - 4000 cm -1 、resolution of 4 cm -1 , and the sample tablet is scanned.

[0074] Microscopic morphology detection

[0075] Attach an appropriate amount of the sample to the conductive adhesive, sputter gold and purge for sample preparation. Observe the microscopic morphology of the sample using the scanning electron microscope of PHENOM company with the magnification factor for observation.

[0076] Table 1 Composite index and in vitro digestion test results

[0077]

[0078] It can be seen from the composite index and in vitro digestion test results in Table 1. The composite indices of the composites prepared from high-temperature samples are all higher than those of the composites prepared at toughening temperatures lower than the gelatinization temperature. High-temperature treatment promotes the opening of the starch structure and the formation of composites with oil under the influence of moisture. Gelatinization preparation completely gelatinizes the starch, enabling the starch and oil to be fully mixed and the oil to be more evenly dispersed in the gel. The composite indices of the three starches under high-temperature treatment at different moisture contents first increase and then decrease. During the hydrothermal treatment process, the double helix structure of the starch granules is destroyed under the action of moisture, the migration speed of starch molecules increases, promoting the formation of the composite structure and strengthening the amylose-lipid complex. As the moisture content increases, the migration speed of molecules accelerates, the degree of destruction of the starch lamellar structure stability increases, and the binding of amylose and lipid decreases.

[0079] According to the composite index and in vitro digestion test results in Table 1, it can be seen that the content of rapidly digestible starch in the starch-lipid complex is lower than that of the native starch, the content of resistant starch in the complex samples is higher than that of the native starch, and the content of slowly digestible starch first increases and then decreases with the severity of the hydrothermal conditions. The toughening treatment enhances the interaction between amylose and amylopectin in starch; the hydrothermal treatment with appropriate moisture content destroys and reorganizes the starch structure, and accelerates the molecular migration rate, which is beneficial to the combination of starch and fatty acids in oil. According to Figures 7 - 24 It can be seen from the morphology of the complex samples that the oil is wrapped on the surface of the sample particles, which limits the contact between enzymes and starch particles and reduces starch hydrolysis.

[0080] Table 2 Detection results of the crystallinity of the complex

[0081]

[0082] According to Figure 1 , Figure 2 , Figure 3 As shown, the native taro starch and native corn starch have an A-type crystalline structure, and potato starch has a B-type crystalline structure. According to the detection results in Table 1, it can be seen that with the increase of water content and temperature, the intensity of the diffraction peak of the complex gradually decreases. Except for the toughening treatment, the crystallinity of the samples treated by other methods decreases, and the integrity of the starch crystal form decreases. Compared with the native starch, the diffraction peaks of the complexes prepared by hydrothermal and toughening treatments are sharper at a diffraction angle of 2θ = 20°, and the crystal forms of the completely gelatinized sample complexes are transformed into A + V type and B + V type respectively. Compared with the toughening results, at high temperatures, starch undergoes a gelatinization reaction with water, and with the increase of water content, the degree of destruction of the starch crystal structure increases.

[0083] FTIR spectroscopy can reflect the intermolecular interaction between starch and FA and characterize the short-range order of the complex. According to Figure 4 , Figure 5 , Figure 6 It can be seen that the absorption peak located near 3425.0 cm -1 corresponds to the stretching vibration peak of the hydroxyl group; the absorption peak located near 2920.0 cm -1 corresponds to the stretching vibration peak of the methylene group in starch. The characteristic peak of the methylene group in the starch-lipid complex shifts to a lower wavenumber, and the addition of oil enhances the intermolecular interaction between methylene groups, thereby restricting the intermolecular interaction between hydroxyl groups in starch.

[0084] The peak intensities at 2934 cm -1 and 2851 cm -1 show an increasing trend with the increase of the moisture content in the hydrothermal treatment. The complex has peaks at 1740.0 cm -1 and 2850.0 cm -1Two absorption peaks were found near 1747cm, which were caused by the stretching vibration of the carbonyl group and the methylene group in the oil. -1 The infrared spectrum of the sample shows a peak for the ester carbonyl group. -1 The presence of the peaks is related to the formation of starch-lipid complexes in the starch and palm oil blends and the presence of free palm oil in the blends.

[0085] according to Figures 7 - 24 The microscopic morphology of the sample particles showed that the surfaces of the composite samples were all coated with oil and the starch particles were adhered by the oil and multiple particles were aggregated. The gelatinized sample composite starch was broken into pieces and no complete starch particles could be observed. The toughened composite sample starch particles were intact and aggregated under the adhesion of oil. The intact particles of the HMT15% sample of the three starch wet-heat prepared composite samples were obviously broken; the HMT25% sample was more tightly aggregated, and there was slight damage on the surface of the starch particles; the HMT35% sample was a mixed aggregate of gel fragments and starch particles, and the edges of the starch particle samples were observable to be damaged, and the surface of the particles was obviously damaged. The degree of starch damage increased with the increase of moisture content.

[0086] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A method for preparing starch lipid complex by physical method, characterized in that: The steps include: (1) Drying of raw starch: Dry the raw starch at low temperature to a moisture content below 10%; (2) Adjusting the moisture content of starch: Detecting the moisture content of starch, adjusting the moisture content of starch to 15% to 35%, and sealing; (3) adding lipid to the starch obtained in step (2); (4) sealing and heating the starch-oil mixture with a water content obtained in step (3); (5) All samples prepared by heating were dried at 40°C, powdered, and sealed for storage.

2. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: The native starch is one or more of taro starch, corn starch and potato starch mixed in any proportion.

3. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: The drying in step (1) is performed at a low temperature of 40°C.

4. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: The detection of starch moisture content is carried out according to the national standard for determination of moisture in food (GB / T 5009.3-2016).

5. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: The sealing in step (2) is to seal and equilibrate at 4° C. for 48 hours.

6. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: In the step (2), the moisture content of starch is adjusted to 25%.

7. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: The lipid is palm oil, added at 10%.

8. The method for preparing starch lipid complex by physical method according to claim 1, characterized in that: The heating in step (4) is performed at 120° C. for 6 hours.

9. The method for preparing starch-lipid complex by physical method according to claim 1, characterized in that: The drying in step (5) is performed at 40°C.

10. A starch-lipid complex, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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