Technique that uses mass spectrometry selectively identifies the fruit content in the product
Among the main components of chocolates are cocoa, sugars, fats and milk which, used in different proportions and in different processes, give rise to products ranging from the most bitter to the sweetest. The former are distinguished by a higher percentage of cocoa and, therefore, a greater quantity of phenolic compounds, bioactive substances considered important in the prevention of various diseases, including cardiovascular diseases. Very sweet foods have a lower cocoa content and are richer in sugar and fat. To guarantee consumers that the product actually has the cocoa content specified on the packaging, a study guided by professor Rodrigo Ramos Catharino, from the Faculty of Pharmaceutical Sciences (FCF) at Unicamp, proposes a methodology that uses image mass spectrometry.
This analytical processing uses catechin/epicatechin molecules as a marker, a mixture of isomers, which in the case of chocolate comes only from cocoa. By exclusively monitoring these molecules, it is possible to establish a linear correlation, ensuring that the higher the cocoa percentage, the greater the amount of catechin/epicatechin. The new analysis process even solves a technological problem faced by the chocolate industries: the effective control of cocoa levels in their products, which is also important to meet the demands of international markets.
As case studies, all products from an important and renowned national chocolate industry were analyzed. The advisor considers that the methodology, which uses a specific marker, is effective and makes it possible, through a simple approach, to selectively identify the cocoa content in chocolate, as well as being easily adaptable to each product to be evaluated.
The research, financed by Fapesp, which formed part of the doctoral project of student Diogo Noin de Oliveira, graduated in pharmacy, also had the participation of pharmacists Ana Carolina Camargo and Carlos Fernando Melo and was carried out at the Innovare Biomarkers Laboratory of the Faculty of Sciences Doctors (FCM) at Unicamp, affiliated to FCF and coordinated by the professor. It resulted in the article entitled "A fast semi-quantitative screening for coconut content in chocolates using MALDI-MSI" (A methodology for the rapid semi-quantitative assessment of cocoa content in chocolates using MALDI-MSI), published in the journal Food Research International.
The methodology
Diogo explains that, unlike chromatography, which is commonly used, he used image mass spectrometry, which allows the molecular composition of a solid sample, in this case chocolate, to be translated through images of various shades. As chocolate is made up of a variety of molecules, there is a need to select the images, the shades of a color, which derive only from the molecule of interest, in this case, the catechins chosen as markers. He explains: “Simply put, we can say that it is like taking a chemical photograph of each product, assigning a color to each of the types of molecules present. Depending on the quantity of these molecules, the color attributed to it ranges from the least intense to the most intense tone.” In the case of catechins, markers indicative of cocoa content, the shades vary and follow each other according to the concentrations of the respective molecules. This makes it possible to establish a curve, a template, in which each point refers to a certain concentration of catechin/epicatechin molecules and, therefore, to a certain cocoa content present in the chocolate.
The researcher explains that the adoption of this procedure was possible as a molecule was identified in cocoa that was effectively its expression in chocolate, and that did not also result from the presence of other components used in its manufacture, such as fats, sugars and The milk. And these molecules, the catechin isomers, are reliable representatives of cocoa in chocolate and can be considered its signature. To establish these markers, the researchers relied on statistical models and data available in the literature.
As the methodology developed uses a specific marker, recalls Catharino, other analytical techniques can be developed from it, different from image mass spectrometry, for its quantification, which contributes to resolving a technological problem faced by the food processing industries. chocolates.
