Storage indicator detection

This standard specifies the method for determining protein in food. The first method and the second method of this standard are applicable to the determination of protein in various foods, and the third method is applicable to the determination of solid samples of grains, bean milk powder, Rice noodles, protein powder, etc. with protein content above 10 g/100 g. This standard is not applicable to the determination of foods containing inorganic nitrogen-containing substances or organic non protein nitrogen-containing substances. The protein in food is decomposed under catalytic heating conditions, and the resulting ammonia combines with sulfuric acid to form ammonium sulfate. Alkalization distillation frees ammonia, absorbs it with boric acid, and titrates it with a standard titration solution of sulfuric acid or hydrochloric acid. The nitrogen content is calculated based on the consumption of acid, and then multiplied by the conversion coefficient to obtain the protein content. 3 Reagents and Materials 3.1 Reagents Unless otherwise specified, all reagents used in this method are analytical pure, and the water is Grade III water as specified in GB/T 6682. 3.1.1 Copper sulfate (CuSO: · 5HgO). 3.1.2 Potassium sulfate (KSOR). 3.1.3.3- Sulfuric acid (H SO,). 3.1.4 Boric acid (H, BO,). 3.1.5 Methyl red indicator (C, Hj: N, O:). 3.1.6 Bromocresol green indicator (CHy; Br, O, S). 3.1.7 Methylene blue indicator (C. Hy, CIN, S -, HO). 3.1.8 Sodium hydroxide (NaOH). 3.1.995% ethanol (CH; OH). 3.2 Reagent Preparation 3.2.1 Boric Acid Solution (20 g/L): Weigh 20 g of boric acid, dissolve in water, and dilute to 1000 mL. 3.2.2 Sodium hydroxide solution (400 g/1): Weigh 40 g of sodium hydroxide and dissolve it in water. Cool and dilute to 100 ml. 3.2.3 Sulfuric acid standard titration solution [e (, H, SO,)] 0.050 0 mol/L. or hydrochloric acid standard titration solution [c (HCl)] 0.050 0 mol/L. 3.2.4 Methyl red ethanol solution (l g/L): Weigh 0.1g of methyl red, dissolve in 95% ethanol, dilute with 95% ethanol to 100 mL, and 3.2.5 Methylene blue ethanol solution (1 g/L); Weigh 0.1 g of methylene blue, dissolve in 95% ethanol, and dilute to 100 mLe with 95% ethanol

Function of testing report:

1. Project bidding: Issue authoritative third-party CMA/CNAS qualification report

2. Online e-commerce platform entry: Quality inspection report recognized by major e-commerce platforms

3. Used as a sales report: issuing legally effective testing reports to make consumers more confident

4. Papers and research: Provide professional personalized testing needs

5. Judicial services: providing scientific, fair, and accurate testing data

6. Industrial problem diagnosis: Verify the troubleshooting and correction of industrial production problems

BAIJIAN testing process:

1. Telephone communication and confirmation of requirements

2. Recommend solutions and confirm quotations

3. Mail samples and arrange testing

4. Progress tracking and result feedback

5. Provide reports and after-sales service

6. If urgent or priority processing is required

Our Competitive Edge:

1. The testing industry is fully covered, meeting different testing needs

2. Fully cover the laboratory and allocate localized testing nearby

3. Engineers provide one-on-one services to make testing more accurate

4. Free initial testing, with no testing fees charged

5. Self service order delivery for free on-site sampling

6. Short cycle, low cost, and attentive service

7. Possess authoritative qualifications such as CMA, CNAS, CAL, etc

8. The testing report is authoritative and effective, and is generally used in China