Welcome to Alluvium, a weekly newsletter about our fascinating world.
This week, we’re exploring the grocery store.
I like having some milk in the fridge for cereal and to put in my coffee. These days, I mostly prefer alternative plant-based ‘milk’ made from almonds, coconut, or soy. The other day I was at the grocery store buying some almond milk when I started wondering: why is most of the almond milk in the refrigerator at the back of the store, with the dairy milk, but some is on the bottom shelf of a normal aisle, next to the cereal?
Why does some almond milk need to be refrigerated, and some doesn’t?
My first thought was that the shelf-stable stuff must be full of preservatives to keep it from spoiling. But I know our food system is complex. So I looked a little closer.
First: the shelf-stable almond milk is more expensive than the refrigerated stuff. I did a little survey of the almond milk at my local grocery store, and the shelf-stable almond milks cost almost 40% more on average1.
Ok, so that’s kind of counterintuitive. I am used to having to pay more for fresh food at the grocery store, and the refrigerated almond milk definitely seems… fresher?
Let’s look at the back of the package. How do the ingredients differ?
I’m going to look at the Kroger store brand (Simple Truth) unsweetened almond milk, which comes in both refrigerated and shelf-stable varieties. The other big brands have very similar ingredients.
I’ve struck out the common ingredients to highlight the differences:
Shelf-stable:
Almond Blend (Filtered Water, Almonds),Tricalcium Phosphate,Sea Salt,Sunflower Lecithin,Gellan Gum,Locust Bean Gum,Vitamin A Palmitate,Ergocalciferol (Vitamin D2),Dl-alpha Tocopherol Acetate (Vitamin E).
Refrigerated:
Almondmilk (Water, Almonds),Calcium Carbonate,Salt,Potassium Citrate,Sunflower Lecithin,Gellan Gum,Mixed Tocopherols (Vitamin E),Vitamin A Palmitate,Vitamin D2.
Very interesting. Both share most of the same ingredients, including emulsifiers and nutritional additives (vitamins). There are only small differences, like which compound is used to add calcium2, the locust bean gum in the shelf-stable milk3, and the potassium citrate in the refrigerated milk4. None of these differences have anything to do with preserving the milk or making it more shelf-stable.
So both containers of almond milk contain basically the same thing, but the stuff in the refrigerator is cheaper.
Is the shelf-stable milk more expensive to produce?
I did a little bit of digging on industry websites to find out.
Refrigerated almond milk is processed like its dairy counterparts: after production, it is pasteurized and packed into containers in a clean environment.
Shelf-stable milk, on the other hand, is sterilized and packaged via the aseptic UHT (ultra high temperature) process, which kills pathogens to an even higher standard and packs the milk in special containers with no air inside.
Early aseptic packaging, 1960’s. TetraPak
The UHT process requires special pasteurization and filling equipment, and packaging that complies to a different standard. The entire process occurs in a rigorously sterilized workspace not unlike a cleanroom that might be used for scientific research or precision manufacturing.
It seems like this is where the cost difference comes from: all almond milk is produced using basically the same process and ingredients, with small differences between brands and varieties, but processing milk so it will be shelf stable adds cost.
So what?
Shelf stable milk lasts longer and can be stored in the pantry. It’s easier to buy in bulk and stock up. More importantly, it doesn’t need to be transported and stored in the ‘cold chain,’ which is much less costly from an environmental perspective. And because its shelf life is much longer, there is much less potential for wasting unsold product at the grocery store.
Throughout this post I’ve been talking about almond milk, because that’s what first caught my curiosity, but this applies to other alternative milks too, and to dairy milk as well5.
It might be time for Americans to get past our strong cultural association between refrigeration and freshness. For industrial food products (and yes, I’m including dairy milk in this category, considering that it must be pasteurized to be sold in US grocery stores) it makes sense to use modern technology to make our food last longer, especially when it doesn’t require any extra preservative ingredients. At a system-wide level, this has the potential to massively reduce energy cost and waste6. And with widespread adoption, the price differential between shelf-stable and refrigerated products would likely come down or even reverse.
For now, I think I’ll keep paying a bit extra for the convenience of shelf-stable milk.
Some quick hits:
A great single from the upcoming Mountain Goats album:
Some asthma inhalers are a meaningful source of greenhouse gas emissions.
This video of a bird bouncing a golf ball:
I hope you enjoyed this first edition of Alluvium. Have a great week. I’ll see you next Sunday!
At the City Market (Kroger) in Durango, CO.
Tricalcium phosphate is the form of calcium found in cow’s milk, while calcium carbonate (the primary constituent of limestone) is more commonly ingested as a standalone calcium supplement. Both are functionally interchangeable in this application, and are added to alternative milks for nutritional value.
The shelf-stable milk here has locust bean gum added, while the refrigerated milk does not. This is a thickening agent found in many processed food products, and in fact is found in some refrigerated almond milks (Silk) and not found in other shelf-stable almond milks (Almond Breeze). It doesn’t seem to have anything to do with making the product shelf stable.
Potassium citrate or ascorbic acid is an ingredient in many of the refrigerated almond milks, but in none of the shelf-stable ones. These are likely added to slightly lower the pH of the almond milk and more closely match the fresh taste of dairy milk. Ascorbic acid also has the nutritional benefit of adding some vitamin C. It is possible that the use of these acidic ingredients has something to do with some almond milks requiring refrigeration; perhaps a lower pH is less shelf-stable in this context?
While you can find shelf-stable dairy milk here, it is not very popular and is not always an option. It is much more common in other parts of the world.
There are some issues with the most common kind of UHT packaging, which is basically a gigantic juice box. This type of mixed material packaging is very costly to recycle and isn’t accepted by most domestic recycling programs. This might not be much of a differentiator considering that almost all of the milk sold in the US already comes in plastic or mixed-material packaging, very little of which is actually recycled in practice, but it does warrant consideration.