Preparation of composite emulsion and application of composite emulsion in preservation of vegetarian meat

Abstract

The invention discloses preparation of a composite emulsion and application of the composite emulsion in preservation of vegetarian meat, and belongs to the field of food preservation. Soybean protein isolate and tea saponin are used as natural emulsifiers, vegetable oil and cinnamon essential oil are used as a mixed oil phase, and the cinnamon essential oil emulsion is formed after ultrasonic emulsification. The essential oil emulsion is used for soaking the vegetarian meat, so that the aim of prolonging the shelf life is fulfilled. Compared with a synthetic emulsifier, the natural emulsifier used in the emulsion is safer and more harmless to a human body, can overcome the defects of high volatility, poor water solubility, thermal instability, sensitivity to environmental change and the like of the cinnamon essential oil, and enables the cinnamon essential oil to play a maximum role in the vegetarian meat preservation process. The plant essential oil emulsion prepared by the invention is uniformly dispersed and has better physical stability, and the cinnamon essential oil emulsion has an obvious fresh-keeping effect on storage of vegetable protein meat, and can delay hardness and color change and inhibit growth of putrefying flora, so that the fresh-keeping period is prolonged. And the method is simple, easily available in material, low in cost and easy to popularize.

Description

Technical Field

[0001] The invention belongs to the field of food preservation, and specifically relates to the preparation of a soybean protein isolate-tea saponin cinnamon essential oil emulsion and the application of the emulsion in the preservation of vegetable vegetarian meat. Background Art

[0002] In recent years, plant-based meat products made from plants have been favored by consumers and have become a new direction for food research and development. Plant-based meat products are mainly composed of plant protein and are rich in nutrients. However, during storage, they are easily contaminated by bacteria, which poses a huge hidden danger to plant-based meat products. At present, my country's preservation of plant-based protein vegetarian meat mainly relies on chemically synthesized preservatives. Although chemical preservatives have the advantages of fast effect, broad bactericidal spectrum, and low price, long-term use of chemical preservatives will cause microorganisms to develop drug resistance, and will also have adverse effects on human health and the environment.

[0003] Essential oils are a large category of natural preservatives from plants. They are a kind of mixture with plant-specific aromatic odors, known as "liquid gold". Essential oils have the characteristics of high volatility, low residue in the matrix, and good biodegradability. In addition, it also has excellent antioxidant and antibacterial effects. Cinnamon essential oil is a volatile oil extracted from cinnamon. The main component includes cinnamaldehyde, which has strong antibacterial and antioxidant properties, which makes it very useful in the field of food preservation.

[0004] Tea saponin is a type of saponin and a natural nonionic surfactant. It consists of one or more hydrophilic sugar moieties covalently bound to a hydrophobic triterpenoid or steroid skeleton. This structure enables it to have good foaming, foam stabilization, dispersion, emulsification and other functions, and also has medical value such as antibacterial and anti-inflammatory. Studies have shown that tea saponin, as an effective surfactant, can be used to prepare nanoemulsions and commercial products. In addition, tea saponin has a certain inhibitory effect on Gram-positive bacteria such as Staphylococcus aureus and some Gram-negative bacteria.

[0005] Soy protein isolate is a rigid globular protein composed of glycinin and β-conglycinin. It is one of the most widely studied protein emulsifiers with high emulsifying activity and surface activity. Soy protein isolate can quickly adsorb to the surface of oil droplets, reduce interfacial tension and form a protective film around the oil droplets to prevent aggregation.

[0006] Nanoemulsions are widely used in the food industry and are often used as delivery systems for various fat-soluble, bioactive ingredients, and difficult-to-absorb substances. The use of soy protein isolate and tea saponin surfactants can enhance the performance of the emulsion and establish a new, green, low-cost, and highly stable nanoemulsification system, which provides a reference for the application of cinnamon essential oil nanoemulsion in food preservation. The use of this nanoemulsion to encapsulate cinnamon essential oil can improve the high volatility, poor water solubility, thermal instability, and sensitivity to environmental changes of cinnamon essential oil, so as to maximize the role of cinnamon essential oil in the preservation process of vegetarian meat. Summary of the invention

[0007] Cinnamon essential oil is used instead of chemical preservatives, and natural emulsifiers are used instead of synthetic emulsifiers to prepare a safe and effective preservative that can preserve plant-based meat without causing any harmful substances to remain and endanger human health. To achieve this purpose, the present invention provides the following technical solutions: (1) Tea saponin and soybean protein isolate were dispersed in deionized water at a ratio of 1: (1-2) to obtain a (2-3)% (w / v) dispersion, and then the dispersion was adjusted to pH 12, stirred continuously at room temperature for 1 h to form a uniform system, and then the dispersion was adjusted to pH 7, stirred for 1 h and placed in a 4 °C refrigerator for standby use as the water phase of the nanoemulsion. Cinnamon essential oil and soybean oil were mixed in a volume ratio of 1: 1 and stirred overnight at 25 °C to serve as the oil phase of the nanoemulsion. The aqueous phase and oil phase obtained above were mixed in a ratio of 1: (15-19) and homogenized at a high-speed disperser at 10000 r / min for 2 min to prepare a cinnamon essential oil crude emulsion. The crude emulsion was ultrasonically emulsified using an ultrasonic cell disruptor at an ultrasonic power of (200-300 W) to obtain a soybean protein isolate-tea saponin-cinnamon essential oil nanoemulsion; (2) Sterilize the vacuum packaging bag at 121°C for 10 min and set aside; (3) Divide the plant protein meat prepared by high-moisture extrusion into vegetarian meats of uniform size and quality. (4) Adjust the ratio of soybean oil to cinnamon essential oil, and keep the overall proportion unchanged. Prepare a cinnamon essential oil emulsion with a concentration of 1-4%, and place the prepared plant vegetarian meat in the cinnamon essential oil emulsions of different concentrations, soak for 5 minutes, and drain. Pack it in sterilized vacuum packaging bags, store it in a 4°C refrigerator, and measure the changes in the indicators of the plant vegetarian meat products during storage.

[0008] Compared with the prior art, the present invention has the following advantages:

[0009] The main effective antibacterial component of cinnamon essential oil is cinnamaldehyde. Compared with traditional chemical preservatives, cinnamon essential oil has low residue in the matrix, good biodegradability, broad-spectrum antibacterial and antioxidant capacity, and has inhibitory effects on meat spoilage bacteria such as Escherichia coli and Staphylococcus. As an antibacterial agent, it has the advantages of being safer and healthier. Compared with synthetic emulsifiers, soy protein isolate and tea saponin as natural emulsifiers have high emulsifying activity and surface activity. And some triterpenoid saponins in tea saponin can play an antioxidant role in inhibiting lipid oxidation. The two natural emulsifiers have more sustainable sources, are safer and more environmentally friendly. Compared with single use, the combined use of soy protein isolate and tea saponin can give full play to their emulsifying activity and surface activity, and the prepared emulsion has better stability. Cinnamon essential oil emulsion combined with vacuum preservation can reduce the growth of microorganisms, increase the shelf life of products, and avoid the potential harm of various chemical synthetic preservatives and preservatives to humans and the environment. DETAILED DESCRIPTION

[0010] Embodiment 1:

[0011] Soy protein isolate (SPI) and tea saponin (TS) were dispersed in deionized water at a ratio of 2:1 to obtain a 2% (w / v) dispersion. The dispersion was then adjusted to pH 12 with 1 M NaOH and stirred continuously at room temperature for 2 h to form a uniform system. The dispersion was then adjusted to pH 7 with 1 M HCl and placed in a 4°C refrigerator for use as the aqueous phase. The mixed oil phase with a mass fraction of 5% was slowly added to the aqueous phase and homogenized for 2 min at a high-speed disperser of 10000 r / min to prepare a crude cinnamon essential oil emulsion. The crude emulsion was ultrasonically emulsified using an ultrasonic cell disruptor. The emulsion was ultrasonically treated with a titanium probe with a diameter of 6.36 mm at a frequency of 20 kHz and 200 W (amplitude: 31%). Each power output lasted for 10 min (timing pulse duration: 3 s; interval: 2 s) to obtain a soy protein isolate-tea saponin cinnamon essential oil nanoemulsion.

[0012] With the addition of tea saponin, the average particle size of the nanoemulsion decreased. This reduction may be attributed to the interaction between soy protein isolate and tea saponin, which promotes the adsorption of soy protein isolate and tea saponin at the oil-water interface, thereby forming a dense interfacial layer and preventing the coalescence of droplets. When the ratio of soy protein isolate: tea saponin is 2:1, the minimum average particle size is 264.3 nm. The smaller the particle size of the nanoemulsion, the higher the stability of the emulsion. In summary, adding an appropriate amount of tea saponin can effectively reduce the interfacial tension of the emulsion and thus stabilize the nanoemulsion well.

[0013] Embodiment 2:

[0014] Soy protein isolate (SPI) and tea saponin (TS) were dispersed in deionized water at a ratio of 1:2 to obtain a 2% (w / v) dispersion. The dispersion was then adjusted to pH 12 with 1 M NaOH and stirred continuously at room temperature for 2 h to form a uniform system. The dispersion was then adjusted to pH 7 with 1 M HCl and placed in a 4°C refrigerator for use as the aqueous phase. The mixed oil phase with a mass fraction of 5% was slowly added to the aqueous phase and homogenized for 2 min at a high-speed disperser of 10000 r / min to prepare a crude cinnamon essential oil emulsion. The crude emulsion was ultrasonically emulsified using an ultrasonic cell disruptor. The emulsion was ultrasonically treated with a titanium probe with a diameter of 6.36 mm at a frequency of 20 kHz and 200 W (amplitude: 31%). Each power output lasted for 10 min (timing pulse duration: 3 s; interval: 2 s) to obtain a soy protein isolate-tea saponin cinnamon essential oil nanoemulsion.

[0015] When the SPI:TS ratio is 1:2, the average particle size of the nanoemulsion becomes larger, and the average particle size is 283.5 nm. This may be due to the excessive addition of tea saponin. A part of the tea saponin is combined with soy protein isolate and adsorbed together at the oil-water interface, and a part of the tea saponin forms a large micellar structure in the water phase. The large micellar structure makes the nanoemulsion system very unstable. The nanoemulsion droplets are easily aggregated due to the electrostatic repulsion and reduction of steric hindrance between the oil droplets, resulting in an increase in the average particle size of the emulsion. In summary, excessive TS has been proven to be unfavorable for the formation of stable nanoemulsions.

[0016] Embodiment 3:

[0017] Prepare a 2% cinnamon essential oil emulsion, place the prepared plant-based meat in different concentrations of cinnamon essential oil emulsions, soak for 5 minutes, and drain. Pack it in the above vacuum packaging bags, store it in a 4°C refrigerator, and measure the changes in the indicators of the plant-based meat products. (The total number of colonies is determined in accordance with the national standard GB 4789. 2-2016)

[0018] The blank sample was not treated with cinnamon essential oil emulsion, and the shelf life of the blank sample was 21 days. Compared with the blank group, the shelf life of the plant-based meat treated with 2% cinnamon essential oil emulsion was significantly extended to 28 days. This shows that cinnamon essential oil treatment can significantly inhibit the growth of spoilage bacteria in plant-based meat and extend the shelf life of plant-based meat.

[0019] Embodiment 4: Prepare a 4% cinnamon essential oil emulsion, put the prepared plant-based meat into different concentrations of cinnamon essential oil emulsions, soak for 5 minutes, and drain. Pack it in the above vacuum packaging bags, store it in a 4°C refrigerator, and measure the changes in the indicators of the plant-based meat products. (The total number of colonies is determined in accordance with the national standard GB 4789. 2-2016)

[0020] The blank sample was not treated with cinnamon essential oil emulsion, and the shelf life of the blank sample was 21 days. Compared with the blank group, the shelf life of the plant-based meat treated with 4% cinnamon essential oil emulsion was significantly extended to 35 days. This shows that cinnamon essential oil treatment can significantly inhibit the growth of spoilage bacteria in plant-based meat and extend the shelf life of plant-based meat. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Effect of the ratio of tea saponin to soy protein isolate on the average particle size of the emulsion Figure 2 Changes in the total colony count of plant-based meat treated with cinnamon essential oil emulsions of different concentrations during storage.

Claims

1. A preparation method of a soybean protein-tea saponin cinnamon essential oil emulsion and a method for preserving high-moisture extruded vegetable vegetarian meat. The preparation method comprises the following steps: (1) Disperse soy protein isolate and tea saponin in deionized water in different proportions to obtain a dispersion, then adjust the dispersion to a pH of 12, stir continuously for 1 h at room temperature to form a uniform system, then adjust the dispersion to a pH of 7, stir for 1 h and place in a 4°C refrigerator for standby use as the aqueous phase. Mix cinnamon essential oil and soybean oil in a volume ratio of 1:1 and stir overnight at 25°C to obtain the oil phase of the soy protein isolate-tea saponin cinnamon essential oil nanoemulsion; (2) mixing the aqueous phase and the oil phase obtained above in a certain proportion, and homogenizing them in a high-speed disperser at 10,000 r / min for 2 min to prepare a cinnamon essential oil crude emulsion; (3) The crude emulsion was ultrasonically emulsified using an ultrasonic cell disruptor to obtain a soy protein isolate-tea saponin cinnamon essential oil nanoemulsion, and the stability of the emulsion was measured.

2. The cinnamon essential oil emulsion according to claim 1, characterized in that: The ratio of tea saponin to soy protein isolate is 1:(1-2) to obtain a (2-3)% (w / v) dispersion.

3. The cinnamon essential oil emulsion as claimed in claim 1, wherein the ratio of the oil phase to the water phase is 1:(15-19).

4. The cinnamon essential oil emulsion as claimed in claim 1, wherein the crude emulsion is ultrasonically emulsified using an ultrasonic cell disruptor, and the emulsion is ultrasonically treated using a titanium probe with a diameter of 6.36 mm at a frequency of 200-300 W, and each power output lasts for 10 minutes (timing pulse duration: 3 s; interval: 2 s).

5. A method for preserving protein-based vegetarian meat by increasing the moisture content by using the cinnamon essential oil emulsion according to claim 1, comprising the following steps: (1) Sterilize the vacuum packaging bag at 121°C for 10 min and set aside; (2) Dividing the plant-based meat prepared by high-moisture extrusion into meat-based meats of uniform size and quality; (3) Adjust the ratio of soybean oil to cinnamon essential oil, and keep the overall proportion unchanged. Prepare cinnamon essential oil emulsions with a concentration of 1-4%, and place the prepared plant-based meat in cinnamon essential oil emulsions of different concentrations, soak for 5 minutes, and drain. Use the above-mentioned vacuum packaging bags to pack them, store them in a refrigerator at 4°C, and measure the changes in the indicators of the plant-based meat products.

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