Leather Hydrolysates Contamination Analysis

Leather hydrolysates are hydrolyzed proteins produced from the leather waste after chemical treatment.

Figure 1. Examples of food products associated with leather hydrolysates contamination

Leather hydrolyzed protein is produced through the hydrolysis of leather waste which is made of animal fur. The hydrolyzed protein produced from the leather can have high content of protein. With the addition of pigment and fragrances, the leather hydrolysates are used as an illegal adulterant like melamine added into the foods to enhance the level of amino acids.

The major source for leather hydrolysates getting into the foods is through illegal addition. Currently no approved regulations exist on the use of leather hydrolysates in foods. Some illegal merchants found the adulteration of leather hydrolysates or related compounds in infant formula and dairy products could increase the protein content of the food products due to their high level of amino acids. The addition of leather hydrolysates can reduce the cost of products by the manufactures.

The hydrolyzed protein is protein and may not have adverse effect on the human health. But during the production and process of leather products, a number of chemicals are used to make the final products. The step of the harmful chemical removal increases the expense and cost a lot of money for the manufacturer. Most manufacturers do not include this important step to produce leather hydrolysates. So the protein hydrolyzed from the leather without removing the chemical hazard residuals can have serve health impacts on humans. The heavy metals and harmful chemicals remained in the leather hydrolyzed protein can cause damage to the human's organs.

No established regulations have approved the addition of leather hydrolysates in the foods to enhance the content of protein. China has listed leather hydrolyzed protein as illegal food adulterants in 2009. The illegal addition of leather hydrolysates in the dairy products was monitored and regulated strictly by regulatory agencies.

The analysis of leather hydrolyzed protein is usually more difficult and complex than the detection of melamine. Because hydrolyzed protein is still protein and we need to have methods to distinguish it from other food natural proteins.

Leather hydrolyzed protein is animal protein which has two specific amino acids, L-hydroxyproline and L-hydroxylysine, and the content of L-hydroxyproline is higher (>10%). While the milk protein and soy protein do not have these amino acids. Therefore, the detection of the presence of L-hydroxyproline can determine if the leather hydrolysates are illegal added into the dairy products. The procedure for the analysis of leather hydrolyzed protein in foods includes sample preparation and extraction, and detection/quantification. We have expertise in the sample preparation of a variety types of food matrices. The sample preparation has significant effect on the accuracy of the level measured in the food samples.

We offer accurate and validated analytical methods that have been widely applied in the determination of leather hydrolysates in food samples and animal feed to meet customers' needs.

UV-spectroscopy is an easy and simple method to determine the level of L-hydroxyproline in order to analyze the leather hydrolysates.

We also maintain high quality assurance for the analysis. The recovery of internal standard, the use of blanks and spikes is monitored for each batch of analysis.