Effect of Extended Storage on Microbiological Quality, Somatic Cell Count, and Composition of Raw Goat Milk on a Farm

Abstract

Dairy goat herds in the United States generally are small, widely scattered, and distant from processing facilities. Unlike the situation for cow milk, it is not cost-effective to collect goat milk everyday or every other day. In some areas, goat milk is collected only once each week, which is in violation of regulations specified in the Pasteurized Milk Ordinance for grade A milk. This study was conducted to determine the effect of up to 7 days of refrigerated bulk tank storage on composition, somatic cell count (SCC), pH, and microbiological quality of goat milk. Duplicate farm bulk tank samples were taken daily after the morning milking for seven consecutive days each month during the lactation season. Samples were analyzed immediately for all variables except free fatty acids. There were no significant changes (P > 0.05) detected in milk fat, protein, lactose, nonfat solids, SCC, or pH during extended storage, although significant effects of stage of lactation (P < 0.05) were observed. The mean standard plate count (SPC) increased to 1.8 x 10(5) CFU/ml after 6 days of storage, exceeding the grade A limit (i.e., 1.0 x 10(5) CFU/ml). The mean psychrotrophic bacteria count increased steadily to 1.5 x 10(4) CFU/ml after 6 days of storage, whereas the mean coliform count was approximately 500 CFU/ml for the first 3 days and less than 2500 CFU/ml throughout the 7 days of storage. No significant changes (P > 0.05) in the concentrations of free fatty acids, except for butyric and caprylic acids, were observed during milk storage. When stored under refrigerated and sanitary conditions, goat milk in farm bulk tanks met the grade A criteria for both SPC and SCC during 5 days of storage but was of low quality thereafter because of the growth of psychrotrophic bacteria.

Public Health Safety in Relation to Microbiological Quality of Freshly Drawn Cow’s Milk in Bangladesh

“…Present study show increase TVC than his bucket milk count, it may results from relatively poor hygienic condition or increase time in sample transportation and preparation process. Standard plate count (SPC) increased with increasing the storage period Zeng et al (2007). Present study strongly differ from the findings of Pandey et al (1996), who founded standard plate count of raw milk log 7.66 to log 9.15 per ml in area where sanitary quality of in approximately 45% raw milk was not acceptable.…”

“…In India, the raw milk and products were heavily contaminated by E. coli Soomro et al (2002). Present study findings strongly supports with the findings of Saharia et al (1997), Saitanu et al (1996) and Zeng et al (2007) who founded average coliform count of milk within 375 to 500 cfu/ml. In present study relatively lower TCC was found than Hempen (2006), Godefay and Molla (2000) and Uddin et al (2011) who found coliform counts above 1x 10 4 cfu/ml.…”

Monitoring bulk milk quality by an integral traceability system of milk

“…Nevertheless, at the same time there was a risk of psychrotolerant microorganism growth proliferating under these conditions (refrigeration time longer than 24 h), which can be a major cause of milk spoilage (Quigley et al 2013). If storage under refrigeration conditions goes from 25 to 48 h, it can lead to a marked increase in the total flora of small ruminants' milk (Zeng et al 2007;Yamazi et al 2013), particularly if the milk sample is not preserved with Azidiol (De Garnica et al 2011). This is because Tª and t periods need to be monitored since a period longer than 24 h at 8-10°C can lead to marked milk spoilage, and also to an impaired rennet coagulation aptitude when making cheese (De Garnica et al 2011;Malacarne et al 2013).…”

“…When the route finished (1.40 pm), the samples remained with the sensor at the dairy industry, where their Tª and t conditions continued to be monitored until they were taken to LILCAM two days after, at 8.10 am. In general, the analyses of all samples were done in an interval of 44.40-53.10 h. After the first milk sample had been collected, milk samples were kept at a Tª that neither exceeded 6°C nor went below 2°C, such conditions ensure the control of total flora developing (Zeng et al 2007;De Garnica et al 2011;Quigley et al 2013), and also prevents the risk of psychrotrophs developing or other technological parameters being altered (Malacarne et al 2013). Furthermore, it is considered that Azidiol-preserved sheep's milk kept at 4°C is suitable for maintaining the initial concentration for all the studied bacterial groups and species, particularly for mesophilic, psychotropic and coliform organisms for 96 h (De Garnica et al 2011).…”

“…To achieve this, it is essential to obtain good-quality milk from primary production and to maintain it until it is processed in the dairy industry by keeping any possible disruption to a minimum Zeng et al 2007;Franciosi et al 2011). In order to avoid risks, and to ensure hygiene-sanitary quality and raw cows', sheep's and goats' milk safety, in its Regulations (EC) Nos.…”