Microwave-assisted preparation method of corn starch phenolic acid compound

Abstract

The invention adopts a microwave-assisted mode, and provides a novel preparation method of a corn starch-phenolic acid compound, which comprises the following steps: gelatinizing corn starch under a certain high-temperature condition, mixing the cooled gelatinized starch with chlorogenic acid, treating a sample under a certain microwave power condition for a certain time, washing the sample with 50% ethanol after microwave treatment is finished, and drying to obtain the corn starch-phenolic acid compound. And freeze-drying, grinding and sieving. According to the preparation method disclosed by the invention, the binding stability of phenolic acid can be remarkably improved, and the phenolic acid content of the corn starch-phenolic acid compound after being washed for three times can reach 29.25 mg / g, which is remarkably higher than that of a traditional hydrothermal method. The method for preparing the corn starch phenolic acid compound is simple in process, low in time cost and high in phenolic acid combination stability.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a method for preparing a corn starch phenolic acid complex under the assistance of microwaves. Background Art

[0002] Phenolic acid is one of the main types of phenolic acid compounds. It not only has the benzene ring and hydroxyl group of phenolic acid compounds, but also has organic carboxylic acid functional groups. As a non-flavonoid polyphenol, phenolic acid contains only one aromatic ring. According to its benzene ring side chain structure, phenolic acid can be divided into two categories: benzoic acid derivatives and cinnamic acid derivatives. As a secondary metabolite of plants, phenolic acid is widely present in plants, vegetables and grains, and has a large raw material market. Common phenolic acids include chlorogenic acid, gallic acid, caffeic acid, ferulic acid, etc. Because phenolic acid has unique effects such as strong antioxidant properties and inhibitory effects on various glucose enzymes, it can be used as a dietary functional product; and many studies have confirmed that phenolic acid can help control cardiovascular diseases, nervous system diseases, diabetes, obesity and other diseases, which is of great significance for regulating human metabolism.

[0003] Phenolic acid, like most polyphenolic compounds, is sensitive to light and heat and has an extremely unstable structure. Therefore, it needs to be wrapped with a wall material to enhance the structural stability of phenolic acid. Starch is a natural macromolecular substance with mature production conditions. Some starch products such as natural starch, porous starch, maltodextrin, and resistant starch have been used as wall materials in the food industry. Starch can be used as a good wall material to maintain the stability of phenolic acid because of its wide distribution, low cost, non-toxicity, and easy digestion and degradation.

[0004] The preparation methods of starch-phenolic acid complexes are mainly divided into two categories: self-assembled starch-phenolic acid complexes are prepared by coprecipitation under high temperature conditions, and V-type inclusion starch-phenolic acid complexes are prepared by thermomechanical energy application. Phenolic acid can obtain enzyme inhibition effects on digestive enzymes such as α-amylase or α-glucosidase by occupying the binding sites of enzymes and substrates in various ways; the single helical structure generated during the formation of V-type inclusion starch-phenolic acid complexes can effectively increase the content of resistant starch and resist the digestion of various digestive enzymes; and the formation of the complex can regulate the expression of glucose transporters, thereby delaying the absorption of glucose by the matrix. In the context of rational use of natural resources and the pursuit of an environmentally friendly society, the preparation of starch-phenolic acid complexes by thermomechanical methods has gradually become a popular way to optimize food quality and safety. Microwave treatment is a thermomechanical method that utilizes the characteristics of natural starch materials with high resistivity and good wave transmission performance. The thermal effect of electromagnetic waves causes the starch chains to move violently in a short period of time to hydrolyze the starch chains, and then reshapes the starch structure through intermolecular hydrogen bonds and hydrophobic interactions, affecting its functional properties and thus complexing with phenolic acid. Compared with traditional methods, it has the necessary advantages of mechanized production such as low energy consumption and high efficiency.

[0005] By preparing starch-phenolic acid complexes under microwave-assisted conditions, the sample preparation efficiency can be improved, the functional properties of the phenolic acid structure itself can be effectively protected, and since no chemical reagents are added during the preparation process, the occurrence of food safety issues is greatly avoided. Summary of the invention

[0006] The purpose of the present invention is to improve production efficiency and reduce food safety hazards, and provides a novel method for preparing corn starch-phenolic acid complex under microwave assistance. The purpose of the present invention is achieved by the following technical means:

[0007] (1) Starch is mixed with distilled water to prepare a starch aqueous solution with a certain mass fraction.

[0008] (2) Gelatinize the starch aqueous solution in a water bath at high temperature.

[0009] (3) Cooling the gelatinized starch.

[0010] (4) Using microwave equipment, a certain amount of phenolic acid is added to the gelatinized liquid for microwave treatment under certain conditions of time and power.

[0011] (5) Slowly cool the microwaved sample.

[0012] (6) After cooling, the sample was washed several times with 50% ethanol.

[0013] (7) The washed product is freeze-dried, crushed and sieved to obtain a corn starch phenolic acid complex.

[0014] Preferably, the concentration of the starch aqueous solution in step (1) is 4 to 8% (w / v).

[0015] Preferably, the water bath temperature in step (2) is 80-90° C., and the water bath time is 20-40 min.

[0016] Preferably, the mass fraction of phenolic acid added in step (4) is 4-10% (w / w, based on the dry weight of starch).

[0017] Preferably, the microwave power of step (4) is 100-700 W, and the microwave time is 1-8 min.

[0018] Preferably, the washing times in step (6) are 3 to 5 times.

[0019] Preferably, the drying in step (7) is freeze drying, the drying temperature is ~60° C., and the vacuum degree is <20 Pa.

[0020] Preferably, the sieve used in step (7) has a mesh size of 100 to 200.

[0021] The present invention promotes the unwinding of the natural crystal structure of starch by microwave treatment, generates a single helical structure under the induction of electromagnetic waves by adding phenolic acid, promotes the generation of V-type crystals, and effectively increases the enzyme resistance of the product to digestive enzymes such as α-amylase while protecting the original structural characteristics of phenolic acid, and has better anti-digestion function. The use of natural starch wall material enhances the structural stability of the complex and has a more sustained release effect.

[0022] The prepared starch-phenolic acid complex effectively protects the structural characteristics of phenolic acid and promotes the functional effects of phenolic acid. For patients with type 2 diabetes, obese patients and other groups, this product can control blood sugar and reduce the probability of obesity, and has broad application prospects. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically noted, conventional techniques can be used. Specific implementation method one:

[0025] The starch-phenolic acid complex of this embodiment is prepared according to the following steps: (1) high-amylose corn starch is mixed with distilled water to prepare a starch aqueous solution with a certain mass fraction. (2) the starch aqueous solution is gelatinized in a water bath at high temperature. (3) the gelatinized starch is cooled. (4) a microwave device is used to microwave the gelatinized solution to which a certain mass of chlorogenic acid is added under certain conditions of time and power. (5) the microwaved sample is slowly cooled. (6) the cooled sample is washed with 50% ethanol for multiple times. (7) the washed product is freeze-dried, crushed and sieved to obtain the corn starch-phenolic acid complex.

[0026] The starch-phenolic acid complex prepared in this embodiment has a chlorogenic acid content of up to 28.49±0.51 mg / g after hydrolysis, which effectively ensures the stability of the polyphenol structure. Specific implementation method 2:

[0028] (1) Mix ordinary corn starch with distilled water to prepare a starch aqueous solution with a certain mass fraction. (2) Gelatinize the starch aqueous solution in a water bath at high temperature. (3) Cool the gelatinized starch. (4) Use microwave equipment to microwave the gelatinized solution with a certain mass of chlorogenic acid added under certain conditions of time and power. (5) Slowly cool the microwaved sample. (6) Wash the cooled sample with 50% ethanol for multiple times. (7) The washed product is freeze-dried, crushed and sieved to obtain a corn starch phenolic acid complex.

[0029] The present embodiment is different from the first embodiment in that the raw material high-amylose corn starch is replaced with ordinary corn starch. The chlorogenic acid content in the starch-chlorogenic acid complex prepared in this embodiment is 13.41±0.14 mg / g. Specific implementation method three:

[0031] (1) Mix high-amylose corn starch with distilled water to prepare a starch aqueous solution with a certain mass fraction. (2) Gelatinize the starch aqueous solution in a water bath at high temperature. (3) Cool the gelatinized starch. (4) Use microwave equipment to microwave the gelatinized solution with a certain mass of gallic acid added under certain conditions of time and power. (5) Slowly cool the microwaved sample. (6) Wash the cooled sample with 50% ethanol for multiple times. (7) The washed product is freeze-dried, crushed and sieved to obtain a corn starch phenolic acid complex.

[0032] The present embodiment is different from the first embodiment in that the raw material chlorogenic acid is replaced with gallic acid, and the gallic acid content in the starch-gallic acid complex prepared in this embodiment is 19.39±0.45 mg / g. Specific implementation method four:

[0034] (1) Waxy corn starch is mixed with distilled water to prepare a starch aqueous solution with a certain mass fraction. (2) The starch aqueous solution is gelatinized in a water bath at high temperature. (3) The gelatinized starch is cooled. (4) A microwave device is used to microwave the gelatinized solution to which a certain mass of gallic acid is added under certain conditions of time and power. (5) The microwaved sample is slowly cooled. (6) The cooled sample is washed with 50% ethanol for multiple times. (7) The washed product is freeze-dried, crushed and sieved to obtain a corn starch phenolic acid complex.

[0035] The present embodiment is different from the first embodiment in that the raw material high-amylose corn starch is replaced with waxy corn starch, and the raw material chlorogenic acid is replaced with gallic acid. The gallic acid content in the starch-gallic acid complex prepared in this embodiment is 13.39±0.15 mg / g.

[0036] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a corn starch phenolic acid complex under microwave assistance, characterized in that: The steps include: (1) Mixing starch and distilled water to prepare a starch aqueous solution with a certain mass fraction; (2) gelatinizing the starch aqueous solution in a water bath at high temperature; (3) cooling the gelatinized starch; (4) using microwave equipment to perform microwave treatment on the gelatinized liquid to which a certain mass of phenolic acid is added under certain conditions of time and power; (5) Slowly cool the microwaved sample; (6) After cooling, the sample was washed several times with 50% ethanol; (7) The washed product is freeze-dried, crushed and sieved to obtain the corn starch phenolic acid complex.

2. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, characterized in that The corn starch is waxy corn starch, normal corn starch or high amylose corn starch.

3. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, characterized in that The phenolic acid is chlorogenic acid, gallic acid, ferulic acid or caffeic acid.

4. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The concentration of the starch aqueous solution in step (1) is 4 to 8% (w / v).

5. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The water bath temperature of step (2) is 80-90° C., and the water bath time is 20-40 min.

6. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The mass fraction of phenolic acid added in step (4) is 4-10% (w / w, based on the dry weight of starch).

7. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The microwave power of step (4) is 100-700 W, and the microwave time is 1-8 min.

8. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The step (6) is washed 3 to 5 times.

9. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The drying in step (7) is freeze drying, the drying temperature is ~60°C, and the vacuum degree is <20Pa.

10. The method for preparing a corn starch phenolic acid complex under microwave assistance according to claim 1, 2 or 3, characterized in that: The sieve used in step (7) has a mesh size of 100 to 200.

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