Qualitative composition was determined by comparing peak retention times with corresponding fatty acid standards. Quantitative composition was performed using area normalization, expressed as a percentage by weight. Its value is directly affected by fat content and lean solids. Thus, milk with low or no fat content, such as skim milk, has more high density, and fat contributes to lower values ​​in whole milk. It was noted that there were no irregularities in the milk analysis in this study, but variations across seasons, which although significant, were small.

During autumn and winter the values ​​were intermediate. Dornic acidity varied significantly across seasons in organic milk. It was noted that during the summer the average acidity was higher than during other periods. This fact can be explained by an increase in temperature environment, which is directly related to the analyzed parameter. All components that can combine with basic ions contribute to the acidity of milk. This balance between the main components and acids determines the acidity of milk.

At high temperatures tricalcium phosphate may precipitate and increase acidity due to the dissociation of phosphate radicals. Heat can also break down lactose into various organic acids and neutralize the amino groups of protein. In regular milk, no statistical difference was found between samples. During hot periods, there is a decrease in food consumption by animals, accompanied by an increase in water consumption. Feeding is limited to pasture, which has a higher water content as there is more high frequency precipitation.

These factors cause the milk solids to dilute. On the other hand, during periods low temperatures higher energy requirements to maintain body temperature result in a reduction in the energy supply required for milk production, resulting in a subsequent decrease in production. Additionally, the association of low temperatures with the type of feed fed to cattle in this situation results in a relative increase in total solids.

Seasonal effects have been observed on organic milk in terms of fat content, which can be observed in Table 1. Animal diet can also be manipulated to cause changes in milk components, and fat content can vary by up to 3%. Animals raised in an organic system are fed primarily on pasture, while in a conventional system, feeding is also based on grains and soybean cakes. It was confirmed that in winter time organic milk represented 2.67% fat, the lowest in this study.

The organic milk evaluated in this study was obtained from small dairy products, typical of organic milk in Brazil, where there is virtually no homogenization process due to the cost of equipment. In refrigerated, non-homogenized milk, the fat, which has a lower density, is separated from the aqueous phase and a stable emulsion is difficult to form. However, it is worth noting that some samples were frozen for further analysis. A combination of these factors may explain the below values ​​observed in the winter samples.

Please note that regular milk has a higher fat content than organic milk, regardless of season. The opposite trend was observed for the protein content of the milk studied. It is observed that in milk from organic management, the proportion of protein varied significantly from 3.22% to 3.42%. These values ​​were higher than in regular milk. Protein and fat levels are lower during the summer due to changes in feed quality and availability. In the rumen, propionate production promotes protein synthesis, and the increase in propionate is increased by feeding ground feed.

No management or seasonal effects were observed on lactose content in organic and conventional samples. Lactose is the least variable component in bovine milk as shown in the present study. According to Harding, lactose content is not affected by diet except in excess or lack of food, but the percentage of lactose may be lower in warmer seasons, resulting in lower fiber intake by the animal.

Seasonality had little effect on ash content. Organic milk presented, at all times of the year, an ash content slightly higher than regular milk, however, only in winter there was a significant difference. Jennes also found excellent values ​​for ash in winter.

However, there was no effect of milk origin and seasonality on density, dry extract, protein and lactose content. The content of dry extract in milk was influenced by seasonality. The results were expressed as percentage fatty acids. The variant found among samples during the same season of the year is due to different brands of milk analyzed, explaining high values standard deviation.

Seasons and animal management did not reveal significant differences in the fatty acid content of milk. It is noted that the saturated fatty acid content of conventional milk was always higher than that of organic milk. Among saturated fatty acids, significant seasonal differences were found in capric acid content. The fatty acid profile of dairy products presented in this work is close to that described by Eifert et al for cow's milk.

These results are consistent with those found in the literature. The results of a study of seasonal changes in the physicochemical composition, fatty acid composition and conjugated linoleic acid content of organic and conventional dairy products sold in the city of São Paulo led to the conclusion that.

The choice of management system and seasonality influences the chemical composition of milk; The protein content of organic milk has always been higher high levels than in ordinary ones; The fat content of the milk was affected by the management system, and milk from the organic system contained lower fat content and a lower percentage of saturated fat than the conventional system; The conjugated linoleic acid content of milk from the organic system was higher than that of milk coming from conventional system. This applies to organic agriculture.

It officially approves official physicochemical analytical methods for the control of milk and dairy products in accordance with the annex to this regulatory instruction, specifying that they are used in national agricultural laboratories. Nutrition of dairy cows and milk composition.

Organic Livestock: Basic Procedures for Sustainable Farming. Biochemical composition of milk and lactation hormones. Milk production on pasture. Trans fatty acids: scientific progress and labeling. Bulletin of the International Dairy Federation, paragraph 393, pp. 1-25.

Organic livestock farming in Europe: goals, rules and trends with a focus on special attention animal health and welfare. Exemplary correspondent service. The dairy segment is among many sectors that have undergone an intensive reformulation process due to the profound structural transformation of the Brazilian economy throughout the 1990s. Overall, three factors were needed to explain these changes. The first of these was the process of economic opening during the Collora government.

The second is the implementation of the Plan in July. The economic opening has prompted Brazilians domestic producers modernize your production processes, improving the quality of their products under the threat of losing the market for imported products. The overthrow of chronic inflation caused by the implementation of the Real Plan also played an important role in reforming production and demand.

Because of high importance dairy segment, not only economically but also nutritionally, it sought to facilitate certain aspects of nutrition, and is also linked to the participation of these products in the market basket created monthly by the Institute of Agricultural Economics for the city of São Paulo. Nutritional aspects and importance of milk for human consumption.

The presence of milk in the diet is mainly due to the fact that this product is a source of proteins and minerals necessary to promote human growth and maintenance of life. In three periods of life, the role of milk is fundamental: in childhood it participates in the formation and development of the body as a source of protein, minerals and fat; V adolescence, provides conditions for rapid growth with good structure of muscles, bones and endocrine system; and for older people is a source of essential calcium for maintaining bone integrity 1.

The average percentage composition of milk is as follows: water, 85, 8; lactose, 4, 9; fat, 3, 9; proteins, 3, 5; and salt. Thus, it was found that 1 liter of milk provides 35 g of protein, 39 g of fat, 49 g of lactose and 9 g of salts. Add to these values ​​the value each component represents in the body's daily needs. 2. Fats contain fatty acids necessary for the body and act in the absorption of fat-soluble vitamins. One of the most noble components of milk - protein - has a recognized nutritional value both due to its high content of essential amino acids and its high digestibility.

The role of protein in food is essential for both the growth and maintenance of the human body; is the basic material of all cells and makes up ¾ of animal living matter. 3. Calcium, as the main constituent of bone mass, plays a fundamental role in public health as it has countless functions in the human body, such as the formation of bone structure and dental practice. It is also present in extracellular fluid, blood and muscle tissue, contributing to the processes of muscle contraction, transmission of nerve impulses, regulation of heart rate and blood pressure, blood clotting, stimulation of hormone secretion and activation of enzyme systems. The calcium available in milk is best found in nature because it is most easily absorbed by the body.