The Kjeldahl's Method is named after the Danish chemist who developed it more then a century ago.
Today the method is widely used according to official methods to determine nitrogen and proteins in food, feed, soil ,wastewater, etc . VELP Scientifica's equipment allows to perform the Kjeldahl method easily, economically and with reproducible results on 4 levels of automation.

See product details Steam Distillation Unit UDK 152

See product details Steam Distillation Unit UDK 142

See product details Steam Distillation Unit UDK 132

See product details Steam Distillation Unit UDK 126


Published studies:

1. Changes in the fats in yellow cheese treated with surface antimold agents
Studied were the changes setting in with fats in the process of ripening of the ewe milk yellow cheese, kashkaval type, and cow milk yellow cheese Vitosha treated with the antimold preparations 'antiplessin' and 'potassium sorbate with movilit'. There were slightly expressed hydrolytic and oxidation processes involving the milk fat. On the 60th day fat acidity after Ketstorfer was 2.17 degrees K, resp., 2.25 degrees K, on an average, with ewe milk kashkaval, and 1.92 degrees K, resp., 2.03 degrees C, on an average, with Vitosha cheese. On the 60th day of ripening the peroxide number of milk fat in kashkaval was 0.1316, resp., 0.1335, on an average, and in Vitosha cheese it was within the range of 1.0298 to 0.1454, on an average. The average values of the iodine number of fats dropped up to the 60th day, however, remained within the normal value characteristic of quality fats.--32.77, resp., 32.97 for kashkaval, and 31.40, resp., 29.30 for cheese Vitosha. No epihydrin aldehyde was found in both types of cheese up to the 60th day of ripening with the use of the two preparations. For more details click here ... http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7168138&query_hl=8&itool=pubmed_docsum
2. Amino acid composition of kashkaval (cheese made of sheep milk) treated with antimold agents
Studied were 14 batches of ewe milk kashkaval and 13 batches of Vitosha yellow cheese treated with protective antimold agents, such as antiplessin and 'potassium sorbate with movilit'. Kjeldahl's method was employed to determine the total protein, and acid hydrolysis of proteins by means of an automatic amino acid analysis unit HD 1200 ERDG, CSSR to determine the amount of free amino acids. It was found that on the 60th day of the ripening of kashkaval treated with antiplessin the total protein averaged 25.16 per cent; with the use of 'potassium sorbate with movilit' it was 25.39 per cent, on an average. On the 60th day of ripening Vitosha yellow cheese contained 23.97, resp., 23.81 per cent total protein. With the employment of acid hydrolysis is protein in both types of kashkaval the following amino acids were produced: lysine, histidine, arginine, asparagic acid, treonine, serine, glutamic acid, proline, glycine, alanine, valine, methionine, tyrosine, isoleucine, leucine, and phenylalanine. It was also established that from the 30th up to the 60th day of ripening the amino acids were subjected to transformation. Highest were the amounts of lysine, asparagic acid, glutamic acid, proline, methionine, tyrosine, and leucine. During ripening no production of cystine was demonstrated. Both antiplessin and 'potassium sorbate with movilit' did not have any negative effect on the ripening of these types of kashkaval. For more details click here ... http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6892132&query_hl=8&itool=pubmed_docsum

3. Ampicillin tolerance and content in the mammary gland of lactating cows and sheep
Experiments were carried out with lactating cows and ewes consisting in the intramammary application of ampicillin-trihydrate with the use of syringe cannules, and with paraffin and vaselin as constituents. Cows were treated with 10 cm3 (500,000 IU) (in the respective quarter of the udder), and ewes--with one half of the syringe content. The milk of the treated animals was sampled prior to manipulation, at the 24th, the 48th, 72nd and 96th hour in order to follow up the time during which the antibiotic was retained in the milk as well as the changes in the cell content and the hydrogen ion concentration. It was found that ampicillin persisted in milk up to the 48th hour in therapeutic concentrations. At the 96th hour the milk proved free of the antibiotic in both cows and ewes and could be offered for consumption or technologic processing. For more details click here ...
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6892132&query_hl=3&itool=pubmed_docsum

4. Characteristics of the staphylococci isolated from the udder of cows with mastitis

A total of 175 strains of Staphylococcus aureus and 67 strains of Staphylococcus epidermidis were studied, isolated from 486 samples of milk secretion taken aceptically from the individual quarters of the udder of cows affected with subclinical and purulent (clinical) mastitis. The staphylococci were referred to as the causative agent of mastitis in case they were the only microflora in the seedings of the investigated material. Tests were applied as given in Fig. 1 to characterize the strains. It was found that mastitis in cows could be due to both plasma coagulating staphylococci (Staphylococcus aureus) and coagulase-negative Staphylococcus epidermidis organisms. The two Staphylococcus species were isolated from cows with clinical and subclinical mastitis. The division between pathogenic and nonpathogenic Staphylococcus strains by the plasma-coagulating symptom proved impossible, and this made it necessary to use other tests for pathogenicity. It became evident that the thing Staph. aureus and Staph. epidermidis had in common when isolated from cows with mastitis was the production of a gold-like pigment and delta hemolysin. Similarly to Staph. aureus isolated animals, the bovine Staph. epidermidis organisms did not possess fibrinolysin and rarely produced hemolysin. The isolated organisms belonging to the coagulase-positive staphylococci corresponded by their basic properties to Staphylococcus aureus var. bovis as described in the literature. The cultures of Staphylococcus epidermidis isolated under similar conditions showed in a considerable per cent of the cases somewhat different behaviour. For more details click here ...
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=960547&query_hl=8&itool=pubmed_docsum
5. Development and resistance of staphylococci in Bulgaricus milk
Studied was the dynamics of development of 9 strains of staphilococci isolated from humans and animals, kept in heat-treated milk, and their resistance in Bulgarian sour milk. It was established that the pathogenic Staph. aureus and Staph. epidermidis develop will in fresh milk kept up to 7 days at 2--6degreesC and 18--22degreesC. In the production of Bulgarian sour milk Staph, aureus was shown to be viable, remaining active for seven days at 2 to 6degreesC. At room temperature (18--22degreesC) the survival rate has been dependent on the dynamics of accumulating metabolite products in connection with the development of Lactobac. bulgaricum and Streptococcus thermophilus. When the total acidity value reaches 160degreesT the pathogenic staphylococci are destroyed. Staphylococcus epidermidis finds no favourable medium to develop in Bulgarian sour milk, and it perishes when the total acidity is 120degreesT and pH -- 3. For more details click here ...
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7875&query_hl=8&itool=pubmed_docsum

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