Characterization of quality of raw milk and pasteurized commercialized informally in Colorado do Oeste City, RO, Brazil

Milk quality can be characterized by physicochemical parameters indicating possible changes in the product properties. The poor quality of milk may affect human health and compromise the shelf life of the product. The objective of this study was to characterize the physicochemical quality of milk and to perform reductase testing of twenty four samples of raw milk and of twelve samples of pasteurized milk being informally commercialized in the city of Colorado do Oeste, RO. The density, the cryoscopic index, the fat (using the method of Gerber), the acidity (in Dornic degrees), and the defatted solids (SNG) (according to official methods) were evaluated accoring to the Normative Instruction 68. The results of cryoscopy and density, showed that 27% (n = 10) and 27% (n = 10) of the samples, respectively, do not comply with the IN-62 criteria. For the content of defatted solids, 19% of the samples were at odds with the legislation. The assessment of physicochemical parameters suggest that the informal trade of milk in the studied retail outlets can compromise the integrity of the product, a problem that might be solved by correcting and intensifying enforcement actions.


INTRODUCTION
Milk, due to its richness in nutrients, is considered one of the richest and most complete foods, presenting fundamental nutritional values for the human diet, besides occupying a prominent position on the children and elderly feeding. Its physicochemical and microbiological composition is determinant to ensure the food safety and adequacy to the human consumption, according to Tronco 1 .
One of the important aspects of food insecurity on the consumption of milk refers to the lack of treatments like pasteurization, making the sale of raw milk a probable vehicle of foodborne diseases and a carrier of pathogens, thus corroborating the researches of Dalzini et al. 2 that confirm that the transport of microorganisms by milk are related to foodborne diseases. Silveira and Bertagnoli 3 claim that consumers that unknow the basic principles about hygiene and milk quality may compromise their health when consuming raw milk. The obtainment, transport and trade of raw milk without inspection are prohibited in Brazil since 1980 4 . Nevertheless, researches by Montanhini and Hein 5 and Sovinsk et al. 6 indicate that this type of product is still informally commercialized. Consequently, there are frequent problems of public health that make necessary the submission of milk to thermal treatment in order to decrease the microbial load and to mainly eliminate pathogens. Bánkuti et al. 7 claim that the informality may be understood as a process through which the milk and/or milky products are not submitted to the pasteurization process and/or are not inspected by the competent agency (service of sanitary inspection). By doing so, informality also involve evading taxes.
The technical regulation of production, identity and quality of milk (RTIQ) recommended by the Normative Instruction 62 (IN-62) 8 , instituted by the Ministry of Agriculture, establishes some physicochemical requirements of milk: fat of until 3.0 g/100 g; titratable acidity between 14.0 and 18.0 g/100mL of lactic acid/100 mL; relative density between 1,028 and 1,034 g.mL; cryoscopic index of -0.530°H in -0.550°H; and at least 8.4 g/100 g of defatted solids.
Considering the great importance that milk has on the human feeding and the informal market of this product in Brazil, the present work was performed with the aim of investigating the physicochemical quality of raw and pasteurized milk informally commercialized in the municipality of Colorado do Oeste, RO.

MATERIAL AND METHODS
To carry out this study, three points of sale located in the town   (Table). Besides the arithmetic means, an analysis using graphs and descriptive measures was made. In order to verify the data behavior, a box diagram was used to provide an idea of position, dispersion and asymmetry.

RESULTS AND DISCUSSION
The results of cryoscopic index ( Figure 1) pointed values at odds with the legislation 8 .
The The mean values of milk density on Table ranged (Table). It is necessary to carry out restorative analyses for measuring density and chlorides and for evaluating evidence of possible fraud.

CONCLUSION
These results indicate a possible food insecurity, a problem that may be minimized by the supervision of competent agencies, monitoring the quality of the raw material obtainment and its trade.