Method for stabilizing hemp seed oil emulsion by using xanthan gum

Abstract

The invention provides a method for stabilizing hemp seed oil emulsion by using xanthan gum. As one of more functional components developed in hemp seeds, the hemp seed oil body plays an important role in enhancing the comprehensive utilization of hemp seed byproducts and developing and processing hemp seed oil body foods. The oil body extract tends to be similar to emulsions or creams, and is a natural oil-in-water (O / W) emulsion. However, during the storage period, due to the effects of factors such as emulsion concentration, emulsifying components, endogenous substances and the like, the stability of the oil emulsion is finally influenced. In order to improve the stability of the emulsion, polysaccharide plant components contained in food are researched and applied. At present, polysaccharide as a plant component has been widely applied to the food industry. The stability of the oil body emulsion is influenced on the basis of a mechanism that polysaccharide changes the surface charge quantity and surface tension of an oil body, forms a non-covalent bond, passivates the activity of lipoxygenase and the like. By adding the xanthan gum, the physicochemical properties of the hemp seed oil emulsion are influenced, so that the formed more stable hemp seed oil emulsion has important significance in the food industry.

Description

Technical Field

[0001] The present invention relates to a plant oil body processing technology, and in particular to a method for regulating the stability mechanism of hemp seed oil body emulsion by using xanthan gum. Background Art

[0002] Hemp (Cannabis sativa L.), also known as industrial hemp, is an ancient Asian crop that has been cultivated and grown for approximately 10,000 years. Its economic value is concentrated in the fiber-rich stems, which are mostly used to make fabrics, clothing and paper. Compared with the stems, the fruits or seeds of hemp are relatively underutilized. Hemp seeds are praised for their ability to provide sufficient nutrients to meet human dietary needs. Currently, hemp seeds are mainly processed through cold mechanical pressing or using organic solvents such as hexane to maximize the extraction of valuable oils, and the value of hemp seeds is enhanced by extracting and converting them from the cake into a powder component (hemp protein concentrate or isolate).

[0003] Oil bodies are considered to be special tissues that store oil in plant cells. They are mainly composed of triacylglycerols, phospholipids, proteins and other trace components. As one of the most developed functional components in hemp seeds, hemp seed oil bodies have played an important role in strengthening the comprehensive utilization of hemp seed by-products and the development and processing of hemp seed oil body foods. Oil body extracts tend to be emulsion-like or cream-like, and are a natural oil-in-water (O / W) emulsion. However, during storage, the stability of the oil body emulsion will eventually be affected by factors such as emulsion concentration, emulsifying components, and endogenous substances.

[0004] To improve the stability of emulsions, research and application of polysaccharides, a class of plant-based ingredients found in foods, has been conducted. Currently, polysaccharides are widely used as plant-based ingredients in the food industry. For example, surface modification with pectin, gum arabic, and gelatin has been shown to enhance the stability and application of plant oil emulsions. Furthermore, research has shown that the addition of certain concentrations of polysaccharides enhances their complexation with oil emulsion proteins by forming hydrogen bonds with the proteins in the emulsion, thereby stabilizing oil / water emulsions. Xanthan gum, a high-molecular-weight polysaccharide produced through microbial fermentation, belongs to the microbial exopolysaccharide class. It has a wide range of physiological effects, including improving the stability of emulsions by preventing lipid peroxidation and extending the shelf life of emulsions. This can control colloidal interactions, increase viscosity, and reduce droplet aggregation. Therefore, the use of xanthan gum to stabilize the aggregation of hemp seed oil emulsions, thereby improving their stability and extending their storage stability, has important guiding significance for practical production. Summary of the Invention

[0005] The present invention aims to provide a method for stabilizing hemp seed oil emulsion by using xanthan gum. The stability of the hemp seed oil emulsion is improved by adding xanthan gum, thereby directionally regulating the storage stability of the hemp seed oil emulsion.

[0006] A method for stabilizing hemp seed oil emulsion using xanthan gum is achieved by the following steps:

[0007] (1) Preparation of hemp seed oil bodies

[0008] Hemp seeds were cut with a knife to induce the release of hemp seed components in the aqueous phase. Hemp seeds were soaked in deionized water for 16 hours, the soaking medium was discarded, and impurities such as floating particles on the liquid surface were removed by suction filtration. Alkaline sodium bicarbonate-sodium carbonate buffer with a pH of 9.0 and a concentration of 0.1 mol / L was added, and the mixture was homogenized for 10 minutes using a homogenizer at a speed of 1000 rpm at 25°C. The homogenized mixture was filtered through three layers of gauze, and the filtrate was centrifuged for 0.5 hours. The upper suspension was collected and transferred to a centrifuge tube containing fresh sodium bicarbonate buffer with a pH of 9.0 and a concentration of 0.1 mol / L. The mixture was centrifuged at 5000×g for 0.5 hours and washed at 4°C for 3 times to adjust the pH value to 7. The upper cream containing hemp seed oil bodies was collected and stored in 0.01% sodium azide at 4°C.

[0009] (2) Preparation of xanthan gum-hemp seed oil emulsion

[0010] The oil bodies stored at 4° C. after extraction were added to deionized water to prepare a 10% (volume fraction) oil body emulsion, to which xanthan gum was added and dispersed uniformly with a high-speed disperser for 3 minutes to obtain a xanthan gum-hemp seed oil body emulsion.

[0011] Compared with natural hemp seed oil bodies and oil body emulsions, the effects of the present invention are:

[0012] (1) 1.5% xanthan gum has the strongest effect on reducing the average particle size of the emulsion. This is because 1.5% xanthan gum combines with oil body-associated proteins to generate electrostatic repulsion, causing the proteins to repel each other and then unfold, resulting in a smaller average particle size of the emulsion.

[0013] (2) When the concentration was 1.5%, the absolute value of the zeta potential of the oil body decreased significantly; this was because a certain concentration of xanthan gum could react with certain positively charged amino acids, thereby increasing the number of negative charges.

[0014] (3) When the xanthan gum concentration increased to 1.5%, the droplet distribution and particle size reached the best, indicating that the addition of xanthan gum can reduce the flocculation of hemp seed oil emulsion to a certain extent. This is because xanthan gum at a certain concentration will bind to proteins, causing intermolecular interactions to reduce the particle size and make the emulsion droplets evenly distributed. This shows that xanthan gum is beneficial to the preparation and stability of oil emulsions.

[0015] (4) The complexation of xanthan gum with hemp seed oil emulsion increased the intensity of the amide A band, indicating that the oil emulsion experienced a certain degree of OH stretching after the addition of xanthan gum. -1 The region has OH and NH extensions of the amide A band of the oil emulsion, from 3050 to 2800 cm -1 The region has stripes corresponding to CH stretches.

[0016] (5) Xanthan gum at different concentrations significantly increased the surface hydrophobicity of the oil bodies, and all showed a trend of increasing first and then stabilizing. This is because xanthan gum, as an anionic polysaccharide, can provide negatively charged groups, which repel the hydrophobic groups of proteins. As the surface hydrophobicity increases, the interfacial tension increases. As the concentration of xanthan gum increases, the chelation effect is enhanced, the protein denatures and inactivates, and the interface becomes unstable.

[0017] (6) When the xanthan gum concentration was 0.5%, the EAI and ESI of the oil bodies increased. The trend of changes in the emulsification properties of the oil body emulsion was highly similar to the surface hydrophobicity. This is because after the polysaccharide and protein are non-covalently bound, the more hydrophobic groups are exposed, the higher the interfacial strength. The unit mass of hemp seed oil bodies can emulsify a larger volume of oil, which is beneficial to maintaining the ESI of the emulsion to a certain extent.

[0018] (7) The inhibition rate was the highest at a concentration of 0.5% xanthan gum. In fact, the performance of antioxidants in emulsions is affected by many factors, including the distribution of compounds between the hydrophilic and hydrophobic phases, complex interfacial effects at the oil-water interface, the type and concentration of antioxidants, and free radical scavenging properties.

[0019] (8) The biopolymer formed by xanthan gum can build a dense interfacial layer around the droplets, which may have a synergistic effect on thermal stability. In addition, the transition temperature of the oil emulsion increases slightly with the increase of xanthan gum content. The change in enthalpy value indicates that the addition of xanthan gum can cause the formation of non-covalent bonds between the droplets, requiring more energy to destroy the oil emulsion structure. DETAILED DESCRIPTION Specific implementation method one:

[0021] (1) Hemp seeds were cut with a knife to induce the release of hemp seed components in the aqueous phase. Hemp seeds were added to deionized water at a ratio of 1:6-14 and soaked for 16 hours. The soaking medium was discarded and impurities such as floating particles on the surface of the liquid were removed by suction filtration. Alkaline sodium bicarbonate-sodium carbonate buffer with a pH of 9.0 and a concentration of 0.1 mol / L was added at a ratio of 1:2-11. The mixture was homogenized for 10 minutes using a homogenizer at a speed of 1000 rpm at 25°C. The homogenized mixture was filtered through three layers of gauze. The filtrate was centrifuged for 15-40 minutes. The upper suspension was collected and transferred to a centrifuge tube containing fresh sodium bicarbonate buffer with a pH of 9.0 and a concentration of 0.1 mol / L. The mixture was centrifuged at 5000×g for 0.5 hours at 4°C and washed three times to adjust the pH to 7. The upper cream containing hemp seed oil bodies was collected and stored in 0.01% sodium azide at 4°C.

[0022] (2) Add deionized water to the oil bodies stored at 4°C after extraction to prepare a 10% (volume fraction) oil body emulsion, add xanthan gum at a concentration of 0-2.0% to the oil bodies, and disperse them evenly with a high-speed disperser for 3 minutes to obtain a xanthan gum-hemp seed oil body emulsion. Specific implementation method 2:

[0024] The difference between this embodiment and the first embodiment is that the ratio of hemp seeds to deionized water is 1:7 to 13. The other steps of preparing the hemp seed oil emulsion under these conditions are the same as those in the first embodiment. Specific implementation method three:

[0026] The difference between this embodiment and the first embodiment is that the ratio of the added sodium carbonate-sodium bicarbonate buffer to the discarded soaking liquid hemp seeds is 1:4 to 10. The other steps of preparing the hemp seed oil emulsion under these conditions are the same as those in the first embodiment. Specific implementation method four:

[0028] The difference between this embodiment and the first embodiment is that the filtrate obtained by filtering the homogenized mixture through three layers of gauze is centrifuged for 20 to 30 minutes. The other steps for preparing the hemp seed oil emulsion under these conditions are the same as those in the first embodiment. Specific implementation method five:

[0030] The difference between this embodiment and the first embodiment is that the concentration of xanthan gum added to stabilize the hemp seed oil emulsion is 50-500 μmol / L. The other steps of preparing the hemp seed oil emulsion under these conditions are the same as those in the first embodiment.

Claims

1. A method for stabilizing hemp seed oil emulsion using xanthan gum, which is achieved by the following steps: Step 1: Preparation of hemp seed oil bodies: Hemp seeds are cut with a knife to induce the release of hemp seed components in the aqueous phase. Hemp seeds are added to deionized water at a ratio of 1:6-14 and soaked for 16 hours. The soaking medium is discarded and impurities such as floating particles on the surface of the liquid are removed by suction filtration. Alkaline sodium bicarbonate-sodium carbonate buffer with a pH of 9.0 and a concentration of 0.1 mol / L is added at a ratio of 1:2-11. The mixture is homogenized for 10 minutes using a homogenizer at a speed of 1000 rpm at 25°C. The homogenized mixture is filtered through three layers of gauze and the filtrate is centrifuged for 15-40 minutes. The upper suspension is collected and transferred to a centrifuge tube containing fresh sodium bicarbonate buffer with a pH of 9.0 and a concentration of 0.1 mol / L. The mixture is centrifuged at 5000×g for 0.5 hours and washed at 4°C for 3 times to adjust the pH value to 7. The upper cream containing hemp seed oil bodies is collected and stored in 0.01% sodium azide at 4°C. Step 2: Preparation of xanthan gum-hemp seed oil body emulsion: Add deionized water to the oil body stored at 4°C after extraction to prepare a 10% (volume fraction) oil body emulsion, add xanthan gum at a concentration of 0-2.0% (volume fraction) thereto, and disperse evenly with a high-speed disperser for 3 minutes to obtain a xanthan gum-hemp seed oil body emulsion.

2. A method for stabilizing hemp seed oil emulsion using xanthan gum according to claim 1, characterized in that In step 1, the ratio of hemp seeds to deionized water is 1:7-13.

3. A method for stabilizing hemp seed oil emulsion using xanthan gum according to claim 1, characterized in that The ratio of the sodium carbonate-sodium bicarbonate buffer added in step 1 to the hemp seeds from which the soaking liquid is discarded is 1:4-10.

4. A method for stabilizing hemp seed oil emulsion using xanthan gum according to claim 1, characterized in that The filtrate obtained by filtering the homogenized mixture through three layers of gauze in step 1 is centrifuged for 20 to 30 minutes.

5. A method for stabilizing hemp seed oil emulsion using xanthan gum according to claim 1, characterized in that The concentration of xanthan gum added in step 2 to stabilize the hemp seed oil emulsion is 0.5-2.0%.