Soy protein is widely used in food because of its extremely high protein content and good functional properties. At present, industrial soybean protein products are usually prepared from defatted soybean meal. According to their protein content, they are divided into: soybean protein powder (SPF for short) with a protein content of about 50%, and soybean protein concentrate (SPC for short) with a protein content of 70% about, Soy protein isolate (SPI for short) has a protein content of about 90%.
Soy protein concentrate (SPC) is an environmentally friendly, light-flavored protein product made by removing non-protein components from defatted soybean meal. There are three preparation processes of soybean protein concentrate, including moist heat washing, dilute acid washing and alcohol extraction. At present, more than 90% of soybean protein concentrate is prepared by alcohol extraction, which has the advantages of high yield and no pollution. However, due to the strong protein denaturation and precipitation of soybean protein by alcohol solution, the NSI (Nitrogen Solubility Index) range of alcohol-processed soybean protein concentrate is lower than 10%, and the function is poor, which affects the concentration of soybean protein concentrate in food. Applications. Therefore, it is necessary to adopt a certain modification method to restore the functional properties of the protein.
The purpose is to overcome the above shortcomings and provide a preparation process of functional soy protein concentrate.
To achieve the above purpose, the implementation steps adopted are as follows:
A preparation technology of functional soybean protein concentrate, it is characterized in that implementing step comprises:
(1) The soybean protein concentrate curd that alcohol extraction process makes or commercially available cross 80 purpose soybean protein concentrate drop into the dissolving tank, add 6-15 times of water and mix and stir 10-20min, and the water temperature is controlled at 50-60℃;
(2) Adjust the pH value of protein liquid to 7.0-8.0 with sodium hydroxide, stir 10-20min;
(3) Protein liquid is pumped into ultra-high temperature sterilizer through centrifugal pump, and temperature reaches 120-155 ℃, insulation 1-240s, and feed liquid outlet temperature is set at 40-80 ℃;
(4) Feed liquid is pumped into spray-drying tower, conventionally carry out spray-drying, spray-drying inlet temperature 140-170 ℃, outlet temperature 75-90 ℃;
(5) Phospholipid is heated and added at different processing stages: join in feed liquid before 120-155 ℃ of heat treatment; Or join in feed liquid after 120-155 ℃ of heat treatment; Or after spray drying, be sprayed on protein by fluidized bed Surface; the addition of phospholipid is 0.1-1% of protein dry weight, and the HLB value of phospholipid is 4-10;
(6) Select to add one of sucrose ester and succinic acid monoglyceride, or both are added simultaneously; the additions of sucrose ester and succinic acid monoglyceride are each 0.1-0.5% of the dry weight of the protein.
In the process of alcohol treatment of soybean protein concentrate by alcohol method, the repulsive force between protein molecules is reduced because the dielectric constant of ethanol is lower than that of water, and the protein molecules are prone to aggregation; at the same time, the hydration of alcohol also weakens the protein-water The interaction of the protein reduces the solubility of the protein, and the reduction of the solubility leads to the decline of other functions. In the invention, the alcoholic soybean protein concentrate is dissolved in water, the pH is adjusted to an alkaline range, the surface charge of the protein molecule is increased, the repulsive force between the protein molecules is increased, the protein molecule chain is stretched, and the protein molecule is increased. Solubility. The protein molecules are subjected to 120-155°C ultra-high temperature heat treatment, and the protein molecules are rapidly dissolved and aggregated with each other to form soluble protein aggregates, so that the solubility of the protein, oil retention and water retention are significantly improved.
The protein raw material is heat treated by the ultra-high temperature sterilizer, and the protein liquid is cooled by the cooling equipment of the ultra-high temperature sterilizer, which is different from the traditional process of heating the protein liquid with steam and cooling the protein through the flash evaporation process. equipment. Using the ultra-high temperature sterilizer not only has a simple process and advanced equipment, but also the prepared functional protein has good performance.
Through the addition of various additives, the functional soybean protein concentrate has good properties.
Soy lecithin is a by-product of soybean production, has good surface properties, and can act as an emulsifier and dispersant. Methods of adding phospholipids include:
1. Fluidized bed drying method: Dissolve phospholipids in water to prepare a phospholipid solution with a certain concentration, and then spray the phospholipid solution on the surface of protein particles.
2. Spray drying method: add phospholipids to the protein feed solution, and then spray dry the slurry.
3. Dry mixing method: under 60 ℃-65 ℃ situation, phospholipid and protein powder raw material are mixed in dry form, and keep stirring, until phospholipid is uniformly dispersed on the surface of protein particle.
Phospholipids are generally described by HLB values. The HLB value, the hydrophilic-lipophilic balance value, is a value used to express the hydrophilic or lipophilic ability of a surfactant. The invention effectively improves the dispersibility, gelation, solubility and salt tolerance of the soybean protein concentrate by adding phospholipids in different processing stages of the soybean protein concentrate.
Meat products generally contain 2% -3% of salt. Due to the presence of salt, soluble soybean protein tends to become insoluble and precipitate, which makes meat products unfavorable in taste and reduces the gelling and emulsifying functions of the protein itself. Therefore, the applied functional soybean protein concentrate is required to have certain salt tolerance.