The effects of breed and other factors on the composition and freezing point of cow’s milk in Poland

Abstract

The milk obtained from six cow breeds (Polish Holstein‐Friesian Black‐White and Red‐White, Simmental, Jersey, Polish Red and Polish Black‐White) managed in the Lubelskie region and the Bieszczady Mountains was analysed. A total of 3618 milk samples collected between 2005 and 2008 were evaluated for the total solids content, percentage concentrations of fat, protein and lactose, and the freezing point: the mean milk freezing point was −0.538°C. The freezing point of milk was influenced by breed, successive lactations, lactation stage and the geographic region. In milk with a high urea concentration (over 300 mg/L), the increased apparent protein level caused a decrease in the milk freezing point values. The combined influence of geographic region and production season showed significant interactions for daily milk yield and total solids content (P < 0.01) and the milk freezing point (P < 0.05).

The effect of season and production systems on qualitative and quantitative properties of milk produced in dairy farms of Yazd province

“…The freezing points of milk produced in industrial and traditional systems determined at present study showed no significant differences, being -0.579 and -0.576 ºC respectively (p>0.05) but the highest and the lowest values occurred in winter and summer respectively (p<0.01, table 1). Freezing point is determined by proportion of components which by itself is affected by some factors such as breed, stage of lactation, consumed water, climatic conditions, seasonal effects, heat stress etc [10,12,13]. Freezing point is applied to recognize the milk quality that might be deliberately diluted with water.…”

“…Freezing point is also an important qualifying specification because it is used to determine the probable addition of water to milk that increases melting point [11]. It is affected by many factors such as breed, milking stage, consumed water, climatic condition, season effects, heat stress etc [10,12,13]. The microbial load is a very important criterion to evaluate the quality status of milk that is an indication of freshness, mainly affected by ambient temperature and the primitive microbial load.…”

Desenvolvimento e validação de método para extração e ­quantificação através de HPLC com índice de refração para ­lactose em leite pasteurizado

“…pelo rearranjo de Lobry de Bruyn-Alberda van Ekenstein [12] , ou pela isomerização alcalina [5,21] .…”

“…Em leite pasteurizado, a concentração de lactulose é de cerca de 0,3 g L -1 [5,10,23] , observada no cromatograma da amostra, no tempo de reten- …”

“…O leite é considerado o mais nobre dos alimentos, como uma importante fonte nutritiva para o ser humano, devido a sua composição rica em proteínas, gorduras, carboidratos, sais minerais e vitaminas [2,3] . Essa composição pode variar em função da fisiologia, raça, estado de saúde e alimentação dos animais [3][4][5] . Todavia, nos últimos anos têm-se verificado alterações por constantes adulterações, com adição de água ou neutralizantes ou substâncias que ameaçam a segurança alimentar como: melaminas, ureia, nitrato de amônia, urina e peróxido de hidrogê-nio [4,6] .…”