Influence of Storage and Preservation on Fossomatic Cell Count and Composition of Goat Milk

Abstract

This study was designed to evaluate the effects of different test conditions on the somatic cell count (SCC) and composition of goat milk. To this end, 3600 tests were performed on 1800 aliquots taken from 40 goat milk samples using a combined instrument set-up based on flow cytometry for SCC and Fourier transform infrared analysis for fat, total protein, lactose, total solids, and freezing point determinations. The conditions tested were storage temperature (refrigeration and freezing), use of a preservative [no preservative (NP), azidiol (AZ), and bronopol (BR)], and age of the milk samples at each storage temperature (24 h to 42 d at refrigeration temperature and 21 to 105 d at freezing temperature). Significant effects on logSCC variation were shown by the storage temperature, the preservation treatment, the interaction of storage temperature x preservation treatment, and milk age within the interaction of storage temperature x preservative. Highest counts were recorded in the BR-preserved milk samples (logSCC = 5.877), and lowest counts were recorded in milk samples preserved using AZ (logSCC = 5.803). The use of frozen/thawed samples led to a significantly decreased logSCC for the treatments AZ and NP; the logSCC was not modified when BR-preserved frozen/thawed samples were analyzed. During storage, variations in the SCC observed for BR-preserved samples stored at refrigeration temperature for up to 25 d and at freezing temperature for all times tested were always < 10%. The preservation treatment was the main factor affecting the milk composition variables examined. Highest values of most variables were obtained in the BR-preserved samples, and the lowest values were obtained in the AZ-preserved samples. The freezing point was lower in the preserved samples than in the NP samples. The levels of milk constituents recorded in the BR-preserved samples were independent of both the storage temperature and age of milk sample. Our findings indicate that the freezing point of goat milk must be interpreted according to the preservative used.

Efeito da temperatura e do tempo de armazenamento de amostras de leite cru nos resultados das análises eletrônicas

“…Outros autores também obtiveram resultados diferentes, como Sánchez et al (2005), que armazenaram amostras de leite de cabra sob refrigeração a 4°C e observaram decréscimo de 5% na CCS nas amostras com 10 dias de armazenamento. Gonzalo et al (2003) armazenaram amostras de leite de ovelha sob refrigeração a 4°C e observaram decréscimo de 2,8% na CCS nas amostras com nove dias de armazenamento.…”

“…De acordo com Sánchez et al (2005) Médias seguidas de letras minúsculas diferentes nas linhas diferem entre si pelo teste de Duncan (P<0,05). Médias seguidas de letras maiúsculas diferentes nas colunas diferem entre si pelo teste de Duncan (P<0,05).…”

Comparação de metodologias para a determinação do pH e do ponto de congelamento do leite bovino cru sob diferentes características de conservação

“…Por isso, os laboratórios têm buscado novas metodologias por meio de equipamentos mais rápidos e precisos. Uma delas é a espectroscopia de infravermelho (Bertrand, 1996;Gonzalo et al, 2004;Sánchez et al, 2005). Esta metodologia ganhou novo impulso, com o surgimento dos equipamentos interferométricos e a utilização da operação matemática conhecida como Transformada de Fourier (Araújo, 2007).…”

“…Como estratégias de conservação tem-se utilizado, principalmente, a adição de conservantes químicos associados ao resfriamento da amostra. Estudos têm sido conduzidos para análise desses efeitos, porém a maioria contempla somente os parâmetros de composição e de CCS (Bertrand, 1996;Sánchez et al, 2005). Existem poucos trabalhos na literatura que investigam os efeitos da conservação das amostras sobre os resultados de pH e ponto de congelamento (Oliveira et al, 2006;Sánchez et al, 2007).…”

Effects of HACCP system implementation on reproduction, milk quality, and milk sanitation on dairy farms in Korea

“…Samples were stored at 4°C in a cold storage box and delivered to the lab within a day. Each milk sample was analyzed by an automatic milk analyzer (Automatic IR 4000/5000 Milk Analyzer, Foss Electric) for somatic cell count, number of bacteria, and fat and protein content (Sánchez et al, 2005).…”