GB/T 8884-2017Edible potato starch (English PDF)

5.10 Conductivity test

The conductivity test shall be carried out in accordance with the method specified in Appendix B.

6.1 Batch

Products of the same variety and specification with intact packaging produced by the same batch of raw materials, the same shift and the same production line are considered a batch.

6.2 Sampling method, base and quantity

Randomly select products from the same batch. The base of the sample to be inspected shall be no less than 250kg, and shall be no less than 10 independent packages; the sampling personnel shall carry sampling tools and containers for samples. When sampling, 4 or more independent packages shall be randomly selected from 4 different parts of the same batch of samples, and the corresponding samples shall be taken out respectively; the total sampling quantity shall be no less than 2kg. The sampled samples shall be divided into four parts, and a part shall be taken out for inspection.

6.3 Exit-factory inspection

6.3.1 Each batch shall be inspected according to the exit-factory inspection items, and can only be shipped after passing the inspection.

6.3.2 Exit-factory inspection items include sensory requirements, moisture, ash, spots, fineness and whiteness.

6.4 Type inspection

6.4.1 Type inspection includes all items in the technical requirements specified in Clause 4.

6.4.2 Type inspection shall be carried out in any of the following cases:

a) When a new product is finalized and identified;

b) When there is a major change in the source of raw materials or the production process;

c) When the product is stopped for more than half a year and then resumed;

d) When the exit-factory inspection results are significantly different from the last type inspection;

e) When the national quality supervision agency or the competent department proposes a type inspection.

6.5 Judgment and re-inspection rules

6.5.1 Judgment and re-inspection of exit-factory inspection

6.5.1.1 All exit-factory inspection items meet the requirements of 4.1, 4.2 and 4.3 and are judged as qualified products.

6.5.1.2 If one of the exit-factory inspection items does not meet the requirements of this Standard, double random sampling can be used for re-inspection of the item. If it still does not meet the requirements of this Standard after re-inspection, the batch of products shall be judged as unqualified products.

6.5.2 Judgment and re-inspection of type inspection

6.5.2.1 All type inspection items meet the requirements of this Standard and are judged as qualified products.

6.5.2.2 If no more than two (including two) of the type inspection items do not meet the requirements of this Standard, double sampling and re-inspection may be carried out. If one item still does not meet the requirements of this Standard after re-inspection, the product shall be judged as an unqualified product.

7.1 Labels and marking

7.1.1 The labels of the products shall comply with the provisions of GB 7718 and clearly indicate the grades of the products.

7.1.2 The marking of the product shall comply with the provisions of GB/T 191.

7.2 Packaging

7.2.1 Packaging containers of the same specification shall be of the same size, dry, clean, firm and meet the relevant hygiene requirements.

7.2.2 Packaging materials shall be paper bags, woven bags, plastic bags, composite film bags, etc. that meet food requirements. The packaging shall be tight and firm, moisture-proof and pollution-proof.

7.3 Transportation

A.1 Principle

Measure the pH value of starch suspension with a pH meter.

A.2 Instrument

100mL beaker; pH meter.

A.3 Reagent

Distilled water or deionized water.

A.4 Operation procedures

A.4.1 Work before daily measurement

A.4.1.1 Check the glass electrode filled with salt.

A.4.1.2 Calibrate the pH meter with newly prepared standard buffer solutions with pH 4 and 7.

A.4.1.3 Record the correction results in the notebook.

A.4.2 Measurement

A.4.2.1 Take 25g of starch in a 100mL beaker.

A.4.2.2 Add 50mL of distilled water or deionized water.

A.4.2.3 Stir to make it a suspension.

A.4.2.4 Let the suspension stand for at least 5min and then stir again.

A.4.2.5 Wash the electrode with distilled or deionized water.

A.4.2.6 Measure the pH of the suspension before it settles.

A.4.2.7 Read the pH result on the display.

A.4.2.8 Wash the electrode placed in the sample with distilled or deionized water.

A.4.3 Work after measurement

B.1 Principle

Use a conductivity meter to determine the conductivity of a quantitative starch suspension.

B.2 Instrument

100mL beaker, conductivity meter.

B.3 Reagent

Distilled water.

B.4 Operation procedures

B.4.1 Measurement

B.4.1.1 Take 25g of starch in a 100mL beaker.

B.4.1.2 Add 50mL of distilled water or deionized water.

B.4.1.3 Stir the suspension evenly.

B.4.1.4 Before the starch settles, insert the electrode into the beaker and measure the conductivity immediately.

B.4.2 Work after measurement

B.4.2.1 Clean the electrode placed in the sample with distilled water or deionized water.

B.4.2.2 When not in use, the electrode shall be placed in a beaker filled with distilled or deionized water. If the displayed value exceeds 2.0µS/cm, the water shall be replaced every day.

B.4.2.3 Clean the electrode inserted in the sample with distilled or deionized water and store it in distilled or deionized water.

B.5 Analysis of results

B.5.1 The displayed value of conductivity is expressed in "µS/cm". If the allowable difference meets the requirements, the arithmetic mean of the two measurements is taken as the result.