CN107629480B

CN107629480B - Method for extracting natural pigment from corn gluten meal by using food-grade microemulsion

Info

Publication number: CN107629480B
Application number: CN201710205002.8A
Authority: CN
Inventors: 吴红艳; 孙长豹; 于晓丹
Original assignee: Qiqihar University
Current assignee: Qiqihar University
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2020-02-18
Anticipated expiration: 2037-03-31
Also published as: CN107629480A

Abstract

The invention relates to a method for extracting natural pigment from corn gluten meal by using oil-in-water food-grade microemulsion. The microemulsion is used as an extracting agent, and the corn gluten meal is used as a raw material to extract the edible pigment. The food-grade microemulsion comprises the following components in percentage by weight: 4% -8%, surfactant: 20 to 40 percent; the proportion of the microemulsion to the corn gluten meal is 30-50: 1; the extraction temperature is 45-70 ℃. The food-grade microemulsion is a novel green solvent and has the characteristics of no toxicity and no pollution. The microemulsion is used as a solvent for extraction, and water-soluble and fat-soluble pigments coexisting in the raw materials can be extracted simultaneously. Can increase the penetrability of active substances and improve the bioavailability. After the microemulsion extracts the pigment, the appearance shape of the microemulsion particle is still approximately spherical, the particle size of the microemulsion system is small, the distribution is uniform, and the stability is high.

Description

Method for extracting natural pigment from corn gluten meal by using food-grade microemulsion

Technical Field

The invention belongs to the field of food processing, and relates to a method for extracting natural pigment from corn gluten meal by using food-grade microemulsion.

Background

The micro-emulsion is an optically isotropic and thermodynamically stable system composed of water, oil, a surfactant and a cosurfactant, and is widely applied in many fields, more and more micro-emulsions are used as raw materials of food formulas in the food industry, as they can dissolve a large amount of hydrophilic and lipophilic food additives (functional nutritional factors), the reaction speed is improved, selective extraction and the like can also be carried out, edible pigments are divided into two major types of natural and artificially synthesized pigments, the natural pigments are not only high in safety and soft in color tone, but also have certain physiological activity, belong to functional natural food pigments, the components in animals and plants are complex, the polarity difference of different pigments is large, a single extraction solvent is usually aimed at one or a plurality of effective components, but cannot fully extract a plurality of micro-emulsion components, the micro-emulsion is one of important byproducts in the corn starch industry, the corn yellow powder contains abundant natural pigments, mainly the corn yellow pigments, but the corn yellow powder is sold as a single raw material or leftovers, no further deep processing is needed, the waste of the corn is caused by β -carotene, the micro-emulsion is one of the micro-emulsion, the micro-emulsion is not easy to be extracted, the micro-emulsion has a micro-emulsion, the micro-emulsion has a very high micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion has a very high micro-emulsion, the micro-emulsion is a very high micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion is a micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion has a micro-emulsion, the micro-emulsion.

Disclosure of Invention

The invention aims to develop a method for extracting natural pigment from corn gluten meal by using an oil-in-water food-grade microemulsion system, develop and produce the corn gluten meal which can be widely applied to the food industry, and simultaneously improve the additional value of the corn gluten meal. Another object of the present invention is to effectively prevent the oxidative decomposition of thermodynamically unstable pigments using milder extraction conditions; on the other hand, because a large amount of surfactants are arranged in the microemulsion system, the solubilization effect is good, and the particle size is small, the bioavailability of pigments with biological activity can be greatly improved.

The microemulsion is food-grade microemulsion, the oil phase in the microemulsion is edible oil, and the edible oil comprises evening primrose oil and sunflower seed oil.

The surfactant is an emulsifier which is allowed to be used in a national standard catalogue of food additives. Including tweens, spans, lauric acid, and the like.

The food-grade microemulsion comprises the following components in percentage by weight: edible oil and fat: 4% -8%; surfactant (b): 20 to 40 percent; the ratio of the microemulsion to the maize yellow powder is 30-50: 1.

The method for extracting the natural pigment from the corn gluten meal by using the microemulsion technology comprises the following steps:

(1) preparing an oil phase: mixing a surfactant and edible oil according to a ratio of 6-10: 1(m/m) on a constant-temperature magnetic stirrer to prepare an oil phase, wherein the mixing temperature is 20-45 ℃.

(2) Preparing oil-in-water microemulsion: dropwise adding water into the oil phase while stirring at 20-45 ℃ until an oil-in-water type microemulsion is formed, wherein the water addition amount is 60-80%.

(3) Pre-treatment: and (3) crushing and sieving the corn gluten meal (60-100 meshes) for treatment.

(4) Extraction: mixing the corn gluten meal and the food-grade microemulsion according to the ratio of 1: 30-50 (m/v), and extracting for 1.5-3 hours in a constant-temperature water bath oscillator (45-70 ℃).

(5) And (3) filtering: and (4) carrying out suction filtration to remove solid impurities, and collecting filtrate to obtain the microemulsion rich in the maize yellow pigment.

(6) Refining: if pigment preparation with higher content is to be obtained, the emulsion can be broken by centrifugation and the water can be removed by evaporation.

After the microemulsion extracts the pigment, the color is deepened, and the phenomenon of layering and demulsification does not occur. The appearance of the microemulsion particle is still spherical, but is not round enough, and the particle distribution is more uniform. The microemulsion system has small grain diameter, uniform distribution and high stability.

Compared with the prior art, the invention has the following advantages: the food-grade microemulsion is a novel green solvent and has the characteristics of no toxicity and no pollution; the microemulsion is used as a solvent for extraction, so that water-soluble and fat-soluble pigments coexisting in the raw materials can be extracted simultaneously; the microemulsion has good solubilizing effect, small particle size and large interfacial area, and can easily pass through a hydration layer of a gastrointestinal wall to increase the penetrability of active substances, so that the bioavailability of some pigments with biological activity can be greatly improved.

Drawings

FIG. 1 shows appearance of microemulsion before and after extraction of sunflower seed oil microemulsion

FIG. 2 shows the particle size and polydispersity changes of the microemulsion before and after the extraction of pigment from the sunflower seed oil microemulsion

FIG. 3 is a transmission electron microscope image of the microemulsion after the pigment extraction from the sunflower seed oil microemulsion

Detailed Description

The invention will now be further described with reference to the following examples, but without thereby limiting the invention to the scope of the described embodiments.

Example 1:

weighing 5.5g of Tween 80 and 0.5g of span 80, uniformly mixing the Tween 80 and the span 80 to serve as a surfactant, adding 1g of sunflower seed oil, uniformly mixing the sunflower seed oil and the surfactant on a constant-temperature magnetic stirrer at 25 ℃, slowly dripping ultrapure water under magnetic stirring after uniformly mixing, firstly converting a clear and transparent system into turbid and viscous system, continuously dripping ultrapure water, converting the turbid and viscous system into clear and transparent system, and forming the O/W type sunflower seed oil microemulsion with the water content of 70%. Weighing 2g of maize yellow powder, crushing, sieving with a 80-mesh sieve, placing into a triangular flask, adding the sunflower seed oil microemulsion according to the mass ratio of 1:40, shaking uniformly, placing into a constant-temperature water bath oscillator at the temperature of 40 ℃, extracting for 1.5h, then carrying out suction filtration to remove solid impurities, and collecting filtrate to obtain the microemulsion rich in maize yellow pigment. The determination shows that the yield of the maize yellow pigment is 0.339mg/g, the content of the maize yellow pigment in the maize yellow powder is about 0.2-0.4 mg/g, and the pigment yield is higher. Under the condition, the extraction yield of the pigment in the corn gluten meal extracted by the absolute ethyl alcohol is 0.0350 percent, namely 0.35mg/g, and compared with the result of extraction by the micro-emulsion, the extraction yield of the food-grade micro-emulsion is slightly lower. But the microemulsion is an artificially designed green solvent, has the characteristics of no toxicity and no pollution, can make up the loss of a large amount of organic solvents to active substances, and simultaneously improves the bioavailability of pigments with biological activity.

Example 2:

uniformly mixing 5g of Tween 80 and 0.5g of span 80 on a magnetic stirrer to be used as a surfactant, then adding 1g of sunflower seed oil, uniformly mixing on the magnetic stirrer at a constant temperature of 25 ℃, slowly dripping ultrapure water under the magnetic stirring after uniformly mixing, firstly converting the system from clear and transparent to turbid and viscous, continuously dripping ultrapure water, converting the system from turbid and viscous to clear and transparent, thus forming O/W type sunflower seed oil microemulsion, and adding water for diluting to ensure that the water content is 75%. Weighing 2g of maize yellow powder, crushing, sieving with a 80-mesh sieve, placing in a triangular flask, adding 100ml of sunflower seed oil microemulsion, shaking uniformly, placing in a constant-temperature water bath oscillator at the temperature of 70 ℃, extracting for 2h, then carrying out suction filtration to remove solid impurities, and collecting filtrate to obtain the microemulsion rich in maize yellow pigment. The corn yellow pigment yield is determined to be 0.365 mg/g.

Example 3:

weighing 804.69 g of Tween and 0.31g of lauric acid to prepare a mixed emulsifier, adding 1.25g of evening primrose oil, stirring on a constant-temperature magnetic stirrer at the temperature of 45 ℃, dropwise adding water after the emulsifier and the oil are fully mixed, and continuously stirring until a microemulsion is formed. The microemulsion was diluted and 50mL of water was added and the stirring was stopped. Weighing 2g of maize yellow powder, crushing, sieving with a 80-mesh sieve, placing in a triangular flask, shaking uniformly, placing in a constant-temperature water bath oscillator at the temperature of 45 ℃, extracting for 2h, then carrying out suction filtration to remove solid impurities, and collecting filtrate to obtain the microemulsion rich in maize yellow pigment. The corn yellow pigment yield is determined to be 0.321 mg/g.

Example 4: microemulsion particle size determination before and after extraction

The sunflower seed oil microemulsion obtained after the extraction of the zeaxanthin in the example 1 is still golden yellow in appearance, much darker in color and free from layering and demulsification, as shown in fig. 1. Diluting the microemulsion by 10 times with ultrapure water, after vortex oscillation is uniform, measuring the refractive index of the diluent, adding the diluent into a cuvette, and putting the cuvette into a Malvern particle size analyzer for particle size measurement. As is clear from FIG. 2, the particle diameter and PDI (Polymer dispersion index) value of the microemulsion increased before and after the extraction. The particle size is increased from the original 12.05nm to 37.76nm, the PDI value is increased from the original 0.164 to 0.218, and although the particle size is increased, the increase of the PDI value is relatively small, which shows that the particle size of the microemulsion system is increased, but the particle size distribution is uniform, and the system is relatively stable. During the extraction process, the collision among the particles is more violent due to the action of oscillation, aggregation occurs, and the oscillation plays a role of stirring to enable the aggregation to be more uniform. After extraction, the performance of the microemulsion is good.

Example 5: microemulsion transmission electron microscope morphology observation after pigment extraction

The sunflower seed oil microemulsion before and after the extraction of the zeaxanthin in the example 1 is diluted to 100 times with ultrapure water, a small amount of the diluted solution is absorbed and dripped on a copper mesh, negative dyeing is carried out with 1.5 percent of phosphotungstic acid, and the sunflower seed oil microemulsion is observed by a transmission electron microscope after being dried. As can be seen from fig. 3, the oil core of the microemulsion particles becomes opaque from original transparency, because most of the pigments in the zeaxanthin powder are fat-soluble pigments, and thus the zeaxanthin is dissolved in the oil phase after extraction, which results in the opaque microemulsion particles, and the microemulsion particles still have a substantially spherical appearance but are not round enough, and the particles are distributed uniformly.

Claims

1. A method for extracting natural pigment from corn gluten meal by using food-grade microemulsion comprises the following steps:

(1) placing a surfactant and edible oil on a constant-temperature magnetic stirrer according to the ratio of 6-10: 1(m/m) for mixing, dropwise adding water while stirring at the temperature of 20-45 ℃ until an oil-in-water type microemulsion is formed, wherein the water addition amount is 60-80%, crushing the corn gluten, sieving with a 60-100-mesh sieve, mixing with the microemulsion according to the ratio of 1: 30-50 (m/v), placing the mixture in a constant-temperature water bath oscillator for extraction at the temperature of 45-70 ℃ for 1.5-3 hours, performing suction filtration to remove solid impurities, collecting filtrate to obtain the microemulsion rich in the corn gluten, performing centrifugal demulsification on the filtrate, and evaporating to remove water;

(2) the food-grade microemulsion comprises the following components in percentage by weight: 4% -8%, surfactant: 20 to 40 percent; the edible oil is evening primrose oil and sunflower seed oil; the surfactant is Tween, span and lauric acid;

(3) the method is characterized in that no layering demulsification phenomenon occurs after the microemulsion extracts the pigment, and the microemulsion particles are still spherical in appearance and uniform in distribution.