Detection of fraudulent addition of whey cheese in milk: Interference of bacterial proteases activity
Keywords:
caseinomacropeptide, protease, fraud, psychrotrophic.Abstract
One of the most common economic frauds applied to fluid milk is the addition of the cheese whey. The occurrence this fraud, in Brazil, is suggested by the analysis of the caseinomacropeptide (CMP) index, a portion of the ê-casein molecule soluble in the whey. However, the action of proteases produced by psychrotrophic microorganism can interfere with this test, leading to false-positive results, situation that started to have greater importance after the implementation of Normative Instruction 51 (2002). With the objective to evaluate this interference, Pseudomonas spp. was inoculated to a final concentration of ca 103 CFU/mL in milk, followed by incubation for 2 and 5 days at 7ºC. The microbial growth was monitored and, after these incubation periods, milk was submitted to thermal treatment (100 ºC/5 min) for elimination of the bacterial cells and the enzymatic extract was obtained for posterior analysis of proteases activity. After that, milk was submitted to incubation 30 ºC/30 d and the CMP index was analyzed at times zero and 30 days. The results of the proteases activity tests at the 2nd day incubation, using azocasein as substratum, not differed significantly (P > 0,05) from the 5th day. Differently, the CMP index at the zero time of the treatment 5d/ 7 ºC for the milk inoculated with P. fluorescens, were higher than the same milk frauded with 30% of cheese whey, denoting the necessity to control even more, this important spoilage organism. After 30 days there was a reduction of these indexes, possibly as a result of the CMP degradation by the same proteases produced by P. fluorescens.Downloads
Issue
Section
License
Term of Responsibility and Transference of Author Rights
The undersigned authors of the article entitled "INSERT TITLE" declare to have read and approved all the manuscript. The authors agree to submit it to the Journal of Candido Tostes Dairy Institute for evaluation and possible publication as true, authentic, and original results. This statement implies that the manuscript, regardless of language, was not submitted to other journals with the same purpose. The authors acknowledge that will be required to provide retractions or corrections of errors related to the article, if necessary. The authors are aware of the guidelines and editorial policy of the Journal and assign copyright to the Journal of Candido Tostes Dairy Institute with the exclusive right to print, publish and sell the product worldwide, in all languages and media. Therefore, it is forbidden to authors reproduce wholly or partially the submitted manuscript in any other part or media, print or electronic. Thus, the authors declare that accepts to transfer the rights of graphic reproduction to the Journal of Candido Tostes Dairy Institute in the case of the article with the above title (or title that later come to be adopted, to meet the suggestions of the editors and reviewers) will be published in the Journal of Candido Tostes Dairy Institute. In addition, the authors agree to appoint _(name)___________ as the corresponding author.
This term should be signed by all authors in the order of authorship, stating:
Date;
Authors name without abbreviation;
Document number;
Title/position of each author;
e-mail; and
the area for evaluation of the paper.
