Unicamp researchers map production in five regions of the country
Artisanal cheeses produced by small, medium or large producers, established in several Brazilian states, are safe for consumption and have an important diversity of microorganisms, responsible for their physical, chemical and sensorial characteristics. Researchers from the Quantitative Food Microbiology Laboratory at the Faculty of Food Engineering (FEA) at Unicamp, in partnership with the University of Naples Federico II, verified the microbial diversity of a series of samples of the product and, with the data, developed a map . The cartographic survey was published in the scientific journal Food Microbiology, last December. Its content can be accessed here: https://www.sciencedirect.com/science/article/pii/S074000201831027X.
“It is the first work that shows the characterization of these microorganisms in artisanal cheeses from Brazil. This is important not only for economic reasons, but also in relation to the cultural heritage that these cheeses represent. Their manufacture and consumption are linked to society and the history of the regions where they are produced”, highlights Professor Anderson de Souza Sant'Ana, advisor and coordinator of the research.
An important fact is that, in none of the 582 samples of 11 types of cheese from different regions of Brazil, did the researchers isolate pathogens, including the bacteria Listeria monocytogenes ou Salmonella, responsible for outbreaks of food poisoning around the world. The study of pathogens is nearing completion and is also part of the doctoral thesis defended by Bruna Akie Kamimura at FEA. The work was supported by Fapesp through a doctoral scholarship in Brazil and abroad (BEPE) and also with funding from CNPq. Bruna signed the article published in the magazine, together with Francesca De Filippis and professors Sant'Ana and Danilo Ercolini.
In Italy, Bruna developed part of her doctorate, carrying out the genetic sequencing of selected samples. The methodology that the researcher used is different from the traditional analysis carried out using culture media, in which bacteria are isolated. In this case, researchers extract the DNA of microorganisms directly from the sample, managing to detect all the microbial diversity present.
According to Professor Sant'Ana, unlike expected, the map shows that cheeses made with raw milk, such as those from Canastra, Araxá and Campo das Vertentes, in the State of Minas Gerais, have less microbial diversity than those made from of pasteurized milk. They are also rich in lactic acid bacteria such as Lactococcus e lactobacillus, and some strains are already widely used in the production of dairy products.
“These microorganisms can have beneficial effects on the product. This diversity may reflect differences related to the ingredients used, the method of manufacturing and also the manufacturing environment, including climatic aspects”, highlights the professor. Minas Gerais cheeses made with raw milk incorporate what producers call “pingo”, which corresponds to a “yeast” used to inoculate the cheese with microorganisms. The drippings were also analyzed by the researchers, in addition to the cheese itself.
“Each drop carries the microorganisms that have adapted to the place and that prevail in that product. For some reason, whether related to the climate, the product itself or the practice employed, that microorganism is more abundant and ends up giving the product a specific characteristic”, adds the professor.
Cheeses made from pasteurized milk, such as those from Marajó Island, butter cheese or coalho, from the Northeast, showed greater microbial diversity. “When you pasteurize milk, pathogens are inactivated, but also a series of microorganisms that are already adapted to that environment and that could lead to beneficial characteristics of flavor, odor, and even texture of the product”, he states. In this case, contamination can occur after the finished product, during handling, for example.
Samples were collected by researchers who went to the places where the cheeses were produced or sold. Professor Anderson visited places in the south of the country that still maintain traditions brought from Italy to make colonial cheese. “If we know what's behind these cheeses, it becomes easier to think of actions to maintain traditions and their characteristics, but at the same time guarantee their safety. In France, the issue of microbiological safety was overcome not by ending cheese produced with raw milk, but by hygiene procedures and veterinary care”, he explained.
The next stage of the work is to understand the influence of the processing environment on the microbiota of artisanal cheeses. Bruna has already collected environmental samples in three manufacturing units in the city of Medeiros (MG), where Canastra cheese is produced.
The study of artisanal cheeses is comprehensive and includes other researchers from the laboratory (see the article). The mapping of the diversity of microorganisms points, according to the professor, to the need to understand the historical issues related to the production of artisanal cheese. “Because if this is changed by arbitrary measures that do not consider the cultural aspect, the microbial composition of the product and, consequently, its flavor and texture may also be altered.”
