Proteins

Proteins are very important in living organisms and participate in almost all life activities. They are not only related to metabolism, immunity and biological evolution, but also provide a lot of information for human. Various proteins have different functions, giving products attractive commodity characteristics. When the functional properties of protein are applied to the composition of food, most of its functional properties affect the food quality, especially the structural characteristics, such as color, flavor, shape, texture, etc. It also plays an important role in the physical changes or chemical properties of food or food ingredients. For example, the sensory properties of baked foods are related to the viscoelasticity and dough formation of wheat gluten proteins, and the texture and juicy properties of meat products mainly depend on muscle proteins. The texture of dairy products and the formation of condensed milk depend on the unique colloidal structure of casein micelles, and the structure of cake and the foaming properties of sweet food depend on the properties of egg white protein. Protein content is often used as an important index to measure the nutritional value of food, so testing protein content is particularly important in food analysis.

As the world's leading food analysis services company, Alfa Chemistry provides incredible services and credible results. Alfa Chemistry is your one-stop-shop laboratory to test food for proteins according to ISO standards.

Samples tested by Alfa Chemistry include but are not limited to:

Alfa Chemistry's analysis methods:

• Kjeldahl Method

Proteins in food are decomposed under catalytic heating conditions, resulting in ammonia combined with sulfuric acid to form ammonium sulfate. The ammonia is dissociated by alkali distillation and titrated with the standard titration solution of sulfuric acid or hydrochloric acid after absorption of boric acid. The nitrogen content is calculated according to the consumption of acid and then multiplied by the conversion coefficient that is the content of protein.

• Spectrophotometry

The protein in the food is decomposed under catalytic heating conditions, and the ammonia produced by the decomposition combines with sulfuric acid to form ammonium sulfate, and reacts with acetylacetone and formaldehyde in a sodium acetate-acetate buffer solution of pH 4.8 to form a yellow 3,5-diacetyl -2,6-dimethyl-1,4-dihydropyridine compound. The absorbance value was measured at a wavelength of 400 nm, and compared with the standard series, and the result was multiplied by the conversion factor, which is the protein content.

• Dumas Method (Also Known as Combustion Method)

When the sample is burned at 900 ℃ ~ 1200 ℃, a mixture of gases is produced during combustion, in which the interference gases such as carbon, sulfur and salts are absorbed by absorption tubes, and the nitrogen oxides are reduced to nitrogen gas. The formed nitrogen gas flow is detected by the thermal conductivity detector (TCD).

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