In ancient Russia, and even more recently, a single frog was placed in a milk bucket to keep the milk from going sour, and it worked. Scientists in Moscow who studied this preservation technique discovered several new antibiotics from the 76 peptides identified in secretions of common frogs (Rana temporaria). The peptides from the frog performed well against Salmonella and Staphylococcus bacteria that can be found in milk. A more traditional method of testing bacteria includes presumptive testing. ISO 11866-1:2005—Milk And Milk Products – Enumeration Of Presumptive Escherichia Coli – Part 1: Most Probable Number Technique Using 4-Methylumbelliferyl-Beta-D-Glucuronide (MUG) details methods for milk and milk products by the means of a combined method for the enumeration of presumptive Escherichia coli and of presumptive coliforms.
What Is a Presumptive Test in Coliform Count?
The Presumptive Coliform test is used as an indicator of possible fecal contamination of water supplies. The same test has been applied to milk. The test is called presumptive because the reaction observed may occasionally be due to the presence of some other organisms and the presumption that reaction is due to coliform organisms has to be confirmed. So, a presumptive coliform count gives an initial estimate of the concentration of coliforms. The completed test, used for quality-control purposes, establishes the presence of coliform bacteria. Milks of high coliform content tend to be regarded by Department of Health authorities as “not up to standard” and not suitable for marketing. Luckily, ISO 11866-1:2005 details a test method to examine presumptive coliform content in milk and milk products.
What Is ISO 11866-1?
ISO 11866-1:2005 specifies a combined method for the enumeration of presumptive Escherichia coli and of presumptive coliforms by means of a culture technique involving a liquid medium with MUG, and calculation of the number of presumptive Escherichia coli and/or coliforms per gram or per milliliter by the most probable number (MPN) technique after incubation at 30 °C. Presumptive Escherichia coli refers to “bacteria which at 30 °C cleave 4-methylumbelliferyl-β-D-glucuronide (MUG), with the production of fluorescence, and which produce indole from tryptophan.” The standard also specifies coliforms as “bacteria which at 30 °C cause fermentation of lactose with the production of gas.”
The method in ISO 11866-1:2005 is applicable to milk, liquid milk products, dried milk, dried sweet whey, dried buttermilk, lactose, acid casein, lactic casein and rennet casein, caseinate and dried acid whey, cheese and processed cheese, butter, frozen milk products (including edible ices), and custard, desserts, and cream. This method is preferred for samples in which comparatively low numbers of presumptive Escherichia coli and/or other presumptive coliforms (less than 100 per gram or 10 per milliliter) are suspected.
Dairy Vs Non-Dairy: What Is Healthier for You?
Cow’s milk is an excellent source of protein, providing a good mix of vital nutrients such as calcium, magnesium, potassium, riboflavin, folate, and Vitamin B12, and it is fortified with vitamin D. Dairy foods can play a key role in improving bone health, cognitive function and muscle growth, as well as facilitating weight loss. For instance, a Harvard study on dairy milk found that people who consume at least two servings of milk, yogurt, or cheese every day as part of their daily diet appear to have a significantly lower risk of heart disease and stroke than people who do not eat dairy foods.
At times, however, a high intake of full-fat dairy products has been linked to inflammation. In some cases, whey protein and casein found in milk can trigger or aggravate skin conditions like acne and rosacea. Consequently, for those who choose not to or are unable to consume dairy, non-dairy milks and other dairy-free substitutes can be a good option. Alternative non-dairy milks can vary in flavor (vanilla, chocolate, pumpkin, lavender, etc.) and sweetness (sweetened or unsweetened), and they can be categorized according to their plant base:
- Fruit: banana milk
- Grain: rice, quinoa, and oat
- Legume: pea protein and soy milk
- Nut: walnut, cashew, almond, macadamia, and coconut milks
- Seed: hemp, sesame and flaxseed milks
The dairy alternative that is closest to cow’s milk in terms of nutrition profile is soy milk. In fact, out of the non-dairy milks, soy milk has the most protein; it has much as cow’s milk. Most soy milk brands, as long as they are unsweetened, are pretty comparable to dairy milk for overall nutrition content. Almond milk, another popular dairy-free milk, is packed with key nutrients like Vitamin E, omega-6 fatty acids, iron, calcium, selenium, potassium, and zinc. Almond milk, however, often contains only a gram or two of protein per serving (since almond milk is usually mostly water), whereas dairy milk contains seven or eight grams per serving. Like almond milk, pea protein milk is low in carbs and is often fortified with vitamins and minerals and can have almost as much protein as cow’s milk or soy milk, although one should watch out for added sugars. Oat milk has more protein than almond milk (though not as much as soy milk) and also offers a small amount of fiber. Oat milk is also pretty sustainable, requiring way less water than almond milk and dairy milk and creating fewer emissions.
ISO 11866-1:2005—Milk And Milk Products – Enumeration Of Presumptive Escherichia Coli – Part 1: Most Probable Number Technique Using 4-Methylumbelliferyl-Beta-D-Glucuronide (MUG) is available on the ANSI Webstore.