MadSci Network: Biochemistry
Query:

Re: simply would organic milk spoil faster or would regular?

Date: Thu Dec 6 08:41:28 2007
Posted By: Rafael Garcia, Faculty, Fats, oils and Animal Co-Products, USDA-ARS
Area of science: Biochemistry
ID: 1195946685.Bc
Message:

In the US, typically very little is added to conventional OR organic milk. Some varieties of milk have vitamins A and D added. All else being equal, the main factors determining how fast the milk spoils are 1) The concentration of bacteria in the milk to begin with 2) the severity of the bacteria-killing pasteurization the milk receives.

The severity of the pasteurization given to different milk products varies, but to my knowledge, organic and conventional varieties of the same milk product receive exactly the same pasteurization.

It is possible that conventional and organic milk differ in the amount of bacteria they start out with before pasteurization. Many conventional dairy cows are given antibiotics which kill bacteria, so conventional cows may have less bacteria. On the other hand, some would argue that organically raised cows are healthier, and thus have stronger immune systems and less bacteria. It is possible that research has already been done to find out which of these two views is correct. It is also possible that some antibiotic from the conventionally raised cows gets into the milk which could kill bacteria and inhibit spoiling. I am sure that studies have been done on whether the antibiotics end up in the milk but I am unsure of the results of these studies. Some people are concerned about other substances given to conventional cows, such as growth hormones, which may possibly get into the milk. This is a legitimate concern, but probably has no effect on the rate of spoilage.

Overall, my intuition is that if all other factors were kept exactly the same, the difference in rate of spoilage would be very small. You could do experiments to check this, but you would want to be very careful to keep everything the same- for example try to get milk that was packed on the same day and keep it in exactly the same conditions.

**Note! The author is answering on his own behalf and his comments do not represent a statement from the USDA.

Rafael A. Garcia

[Moderator's note: This paper by Bailón-Pérez et al. (cited below) discusses their method for detecting beta-lactam antibiotics such as nafcillin, cloxacillin, oxacillin, dicloxacillin, ampicillin, amoxicillin, and penicillin G in milk, in an effort to determine if the levels of such antibiotics are below the level acceptable under European Union (EU) guidelines. In the EU, the maximum levels for these antibiotics in foods of animal origin (including milk) are (in micrograms per liter) 4 ug/L for ampicillin, amoxicillin, and penicillin G, and 30 ug/L for dicloxacillin, cloxacillin, and nafcillin.

The authors tested raw bovine (cow) milk purchased from a Spanish biotech company, bovine skimmed milk porchased at a local (to Granada, Spain) market, and raw goat milk purchased from a local (again to Granada, Spain) farm, all of which the authors describe as being antibiotic free. So, we can conclude that there are some milk products in Europe that are not-antibiotic free, which is why the authors are describing this detection method.

Bailón-Pérez MI, García-Campaña AM, Cruces-Blanco C, Del Olmo Iruela M. Large-volume sample stacking for the analysis of seven beta-lactam antibiotics in milk samples of different origins by CZE. Electrophoresis. 2007 Nov;28(22):4082-90.

--SM]


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