大豆分离蛋白的实验方法及判断标准

Emulsion Soy Protein Isolate Testing Methods and Judgment Standard

一. Physical and chemical standard

1. Test methods

Methods of analysis of protein (N×6.25, dry base) and NSI content according to the standard of TJ-13-GL.

Methods of analysis of moisture and ash content based on standard GB/T5009.3-2003，GB/T5009.4-2003.

Microbiology analysis according to standard GB/T4789.1-35-2003.

Particle size: check 50g sample, put it in sievet of 100 meshes, then hand-vibration 2 minutes, weight the material left on screen.

Particle size= the left material weight/ sample weight.

PH: take the 5g sample, put it in the 50ml water; put the electrode of acidity instrument in the solution after stirring uniform, open the switches acidity instrument, measure and read the result directly.

Bulk density: pour 10ml soy protein isolate into 10ml cup, then check the weight of protein content.

Bulk density = sample weight / sample volume (g / l).

Brightness:

Viscosity: take 15g Samples, place in 150ml water, mixing evenly, then transfer to 150ml beaker, the liquid viscosity meter mark to the level of liquid solution. Open electrical switch by turning knob to the speed. After the pointer rotating 2 rings, press joystick pointer to a fixed number and count down, and then turn off the electrical, so that you can read from the reading window of pointer. When the number of indicator is too high or too low, you can transform the rotor and the speed, be sure to make read number between 30-90 mesh.

Viscosity (η) = coefficient (k) ×the indicator readings (а)

2. Judgment standard

Protein content ≥90% ，NSI≥90% ,water content ≤7.0 % , ash content ≤5.0%

PH:7.0-7.5 , particle size≤5% , bulk density whiteness viscosity

二．Function target

1. Test method

Water-holding capacity: check sample 10g, place in 40ml water, and 1.5 minutes mixing, and then put it out with a glass. Place it in the hands and forms a ball as well as observation, which determine the quality of its 胶性。

Oil-holding capacity：check 120ml water and place in a clean blender, add 30g sample; high-speed mixing for 2 minutes after low-speed mixing and blending; then add 120g of fat, low-speed mixing half a minute, and then three minutes of high-speed mixing; plus salt 5.4g, stirring1 minute, then remove and observe the emulsion status. 13% of centrifugal: take 13g sample and add 87ml (0.25%) saline, place it in 200ml beaker, stirring 2 minutes by hand later, then all solution be transferred to plastic centrifuge tube, control speed of 2000 r / min, centrifuge 2 minutes, remove and observe the 胶体均匀状态。

Penetration (16%): samples 16g add 84ml (0.25%) saline, placed in 200ml beaker, stirring by hand 2 minutes later, then all solution be transferred to plastic centrifuge tube, the control speed of 2000 r / 2 minutes, remove and place solution in 80 ℃water bath to maintain constant temperature for 30 minutes, then solution should be removed to cooling water for 30 minutes, pour out the middle paragraph about 3cm, testing its penetration.

2. Judgment standard

Water-holding capacity: If you cannot form a ball and get it out, the surface of ball without insoluble particles, any of bad situations happens; the product should be treated as a nonconforming product.

Oily-holding capacity: If the tested product was white, bright, good flexibility, it means the product has a good emulsification; if there is a bad, soft, oil spills and other phenomena, the product should be treated as a nonconforming product.

13% of centrifugal: if there was no water between the upper and middle part of the centrifugal colloidal, which means the gel of product is well; if there was water after centrifugation shows poor gel.

Penetration (16%): Penetration ≥24mm.