We use Walmart milk but I notice the freshness dates vary widely by store location. Unfortunately our closest one always has poor dates. Since Walmart has stated the milk is hormone free, I am surprised at the long expire dates. I think the milk I bought on Thursday expires Dec 19.
No. Milk shelf life mostly a function of how it is pasteurized. UHT(ultra high temp) will last longer. More likely to see it used for creams than milk in the US. Parmalat and Costco's organic milk use UHT. Sealed UHT milk can be stored at room temp, but that weirds out US consumers. HT-ST(high temp, short) is how most milk is pasteurized in the US. Or it was, I haven't kept track of what the biz does. For completeness, LT-LT(low temp, long time) is the pasteurization method you can do on the stove top. It's a batch process that can take up to an hour. The others are continuous. Microfiltered milk might last longer than pasteurized. There are naturally occurring preservatives in milk that pasteurization destroys. It alone isn't allowed by US law.
I think the homogenisation affects shelf life, non homogenised doesn't last as long because there are all sorts of stuff that come out of the milk when sent through the high speed centrifuge that evenly mixes the cream through the milk. More moons ago than I care to remember, I worked at a milk processing and bottling factory where the tankers came in and dumped the milk into huge tanks and from there it went through the processing ...... cleaning out the centrifuge drum after a homogenisation batching required a strong stomach, but I always drank homogenised milk after that The lactose free process releases the milk sugars and makes it plenty sweet enough for my coffee, doesn't need sugar, we go through a lot of milk and the UHT cartoons last a lot longer than the 1 ltr cartons or plastic bottles, even though they are stored in the fridge (UHT lives in the cupboard until opened). We go through 2 ltr/day, but storing two x 1ltr cartons/bottles in the fridge for the following day risks the second days milk developing that turning smell and wrecks a good cup of coffee ..... can't handle the taste/texture of powered milk, so, no milk, no coffee and a rather unpleasant Terry to be around until that situation is rectified T1 Terry
The homogenizers I've used(only small bench or pilot scale) were a set of pistons than beat the fat globules into smaller ones. Other methods can do the job, but you are describing the skimmer. That will also take out dirt and blood that ended up in the milk. Larger operations use a clarifier, which is a skimmer that doesn't change fat content, before the skimmer. These are all set up in a line with the pasteurizer for a continuous operation. Of course getting the crud out will help shelf life. The only lactose free milk I've had is Fair Life. It's good, but it also undergoes ultra filtration to concentrate the protein. That will effect the flavor too.
Our farm's dairy operation ended and the centrifuge stored away in the attic before my time, so my very limited dairy experience came from staying over with the neighbors while our parents were away. I got to run their centrifuge numerous times. But it was a cream separator, not a homogenizer. I can't speak for your country, but here it seems that centrifuges are used commercially as cream separators (first stage), and as clarifiers (second stage). Then different types of equipment are used for homogenization. Here is an overview: Diary Equipment & Utilities The Role of Homogenizers and Centrifuges in Milk Processing In youth, I was never proficient at hand milking their several dairy cows. Proficiency greatly increased after retirement from engineering and spending increased time helping dad, and occasionally needing to act as a lactation coach for newborn beef (not dairy) calves that didn't naturally catch on quickly enough. We hand-milk the cow, then bottle-feed the calf, until they are able to do it themselves.
Remember feeding the lambs and poddy calves at the uncle's wheat property that was miles (2 hr drive) from any shops, so hand milked the house cows, some was left over for the lambs and calves. From memory, the centrifuge before the homogeniser was for filtering out the blood and other foreign bodies before it went into the high pressure pumps and nozzles to avoid blockages ..... but the memory is not what it once was .... and even then it wasn't brilliant ..... remember running the bottle washer for 3 hrs, until the lady chemist stormed in and asked if I'd put in any detergent at all 4,000 bottles of milk emptied down the drain ..... but they didn't put me on the bottle washing machine again, so that was a plus ..... what a mindless job that was ..... T1 Terry
Was that each What weight? The wife is into the chook butt breaker extra large eggs, 800g marked on the 12 egg carton T1 Terry
In the typical American flow described in my link, that would be the #2 centrifuge. The #1 centrifuge did the cream separation. That would be the homogenizer. I can identify with those ... I figured out early that there were greener pastures well away from the actual green pastures (and crop fields). All of us kids figured that out, and each did better than the farm-ranch ever had. Now that our generation owns it, it is essentially a retirement hobby for one sibling, with the rest of us helping out and keeping our connections there.
Mine was more a break from brain straining motorcycle mechanics to a mind numbing job for a while, but the money was so bad I went back to being a mechanic, just not on motorcycles again ..... building miniature mechanical things that were expected to rev to a zillion rpm without flying apart, yet all the parts were so small I was worried that if I dropped one I'd never find it Went back to plant mechanics for a hire company, but worked on the back hoe and bigger equipment side ..... T1 Terry
