Review of the article by Dr. Piotr Kaczka entitled 'Assessment of the quality of high-protein supplements on the Polish market'

Dr. Paweł Przychodzen Krakow, 16.05.2013

Review of the article by Dr. Piotr Kaczka entitled 'Assessment of the quality of high-protein supplements on the Polish market'

Dr. Eng. Piotr Kaczka in the article 'Assessment of the quality of high-protein supplements on the Polish market' touches on an important problem from the point of view of modern consumers, so far treated very superficially. The author describes the specific properties of whey proteins that determine their importance for the human body, presents the Peptide Mass Fingerprinting method with tandem MALDI-TOF/TOF mass measurement used to identify individual types of proteins and presents an innovative application of this method in testing the quality of high-protein supplements using examples of commercial products.

In the first part of the article, as a general introduction, the Author compares the basic properties of whey proteins, such as biological value, content of exogenous amino acids, content of sulfur amino acids, with the properties of proteins from commonly available food products (Fig. 1). It should be noted that the presented data come from only one literature source, which seems to be insufficient, due to discrepancies in the values, e.g. BV given by other sources, e.g. JR Hoffman and MJ Falvo, Journal of Sports Science and Medicine (2004) 3 , 118-130. This is primarily due to different methodologies for describing BV, which the Author does not comment on. In addition, the Author uses keywords such as meat, egg, exogenous amino acids (mg/g), sulfur amino acids (mg/g), without any necessary commentary here. From the point of view of the presented numerical values, it is important to specify what type of meat they refer to (beef, pork, poultry or other), whether the whole egg or only the albumin was taken into account, and whether the given content of exogenous amino acids or sulfur refers to the raw product or the protein contained in it.

Next, the Author provides the most important property of whey protein concentrate and isolate, which is the typical content of beta-lactoglobulin, alpha-lactalbumin and serum albumin. Unfortunately, the Author has thoughtlessly copied the values ​​and units of molar masses for individual proteins directly from the apparatus database. The protein masses in the database, which the Author does not mention, are the result of theoretical prediction of the composition and sequence of a given protein based on the genome and modeling of the hydrolysis process to peptides. The actual mass of b-lactoglobulin is 18.3 kDa, a-lactalbumin is 14.2 kDa, and for BSA it is 66.4 kDa (HM Farrel, R. Jimenez-Flores Jr., GT Bleck, JE Butler, LK Creamer, CM Hicks, KF Ng-Kwai-Hang, HE Swaisgood, J. Dairy Sci. (2004) 87 , 1641–1674). In addition, it should be noted a gross error in the mass unit (rewritten from the apparatus database): the mass of b-lactoglobulin cannot be 20,269 kDa, at most Da. Moreover, determining the mass for a protein with an accuracy of 1 Da makes no physical sense.

In the further part of the article, the Author describes the general assumptions and method of protein identification using Peptide Mass Fingerprinting with tandem mass measurement MALDI-TOF/TOF. It should be noted that the Author focuses only on the advantages of this method, but does not mention its disadvantages and limitations. Additionally, the Author, comparing PMF to the Kjeldahl method, uses an abbreviation suggesting that the Kjeldahl method is a method of determining protein. In fact, it is a method of determining nitrogen content in the tested sample, and estimating protein content on this basis is only a consequence of the applicable regulation on labeling food with nutritional value.

In the experimental part, the Author discusses the practical application of PMF in assessing the quality of high-protein supplements using five proteomic analyses as an example, supplementing the research material with three determinations of protein amino acid content. The results of protein identification using the PMF method in individual commercial products include, among others, the measured protein mass, determination of its type and share in the protein pool, species origin. The Author provides a short commentary on the results of each product, without a broader analysis of the results obtained and discussion of possible causes of the observations made. Thus, in the case of the Whey C-6 product, the presence of caseins may be caused not only by the conscious action of the manufacturer, but it may also be a residue from milk processing. The Author, apart from stating the fact, leaves no comment on the detection of b-lactoglobulin from goat's milk in the 100% Whey Isolate product. Does this fact increase or decrease the value of the product and why? Does the manufacturer declare raw materials originating only from cow's milk? Could the observed reduced mass of b-lactoglobulin (the question is whether it is still b-lactoglobulin?) be the result of enzymatic preparation of the sample? And a general note: no or only small amounts of a-lactalbumin were found in the products tested. Could this also be the result of enzymatic preparation of the sample?

Significant differences between the actual content of protein amino acids and that declared by the manufacturers are clearly presented in Fig. 8. However, there is no comment by the Author regarding the possible reasons for such large discrepancies, reaching even 100%.

To sum up, Dr. Eng. Piotr Kaczka took up a difficult and innovative topic, which is the assessment of the quality of high-protein products. The author chose PMF as a method of protein identification and presented its practical application on examples of commercial products. However, despite the author's significant contribution to a strict, analytical approach to the composition of high-protein supplements, numerous methodological errors and poor literature mean that the article entitled 'Assessment of the quality of high-protein supplements on the Polish market' should rather be treated as the beginning of a discussion on the research of supplements for athletes and the search for other research methods that may be faster and cheaper to perform, than as a reliable basis for unambiguous conclusions.

We appreciate the work done by the author of the text, because it should always be in the interest of all producers of nutritional supplements, and especially consumers, to produce the highest quality supplements and nutritional supplements. However, because the topic is very broad and should not end with a one-time article, we cordially invite Dr. Piotr Kaczka to a discussion that will be broadcast live via the Internet.

At the same time, we took the liberty of sending an invitation by post to the editorial address of the magazine in which the article appeared and we are eagerly awaiting its receipt .

Update 24/07/2013 - Dr. Kaczka's response to Dr. Paweł Przychodzen's Review