Glass bottles are the best containers for pure Vermont maple syrup

Horse-drawn sleighs and buckets hanging from trees conjure up the nostalgia of crafting pure maple syrup. Those traditional processes are extremely rare in today’s maple syrup industry; however, the imagery endures. As the marketing message stayed the same over the years, the containers have changed. Metal tins of the old days have given way to the plastic jug, and to a lesser extent, glass bottles.

The shift in the industry, and the use of different materials raises some questions: does the packaging material for maple syrup matter? Which is better – metal, plastic or glass?

I’ve heard all sides of the debate. Some folks miss the traditional metal cans. They may have been messy to pour from, but that was part of what made real maple syrup real. Some customers want glass and will tolerate nothing else. Some maple farmers try to sell in glass, but all of their customers chose plastic jugs when glass and plastic were offered right next to each other.

As I investigated what type of container I wanted to use for my pure Vermont maple syrup, I had some concerns: preservation of maple syrup grade and flavor; environmental impact; ease of shipping, and presentation to the customer.

Preserving the Maple Grade

A startling revelation: oxygen can migrate through plastic. Seriously. Metal and glass block the oxygen, but plastic lets the oxygen slowly permeate through to reach the maple syrup inside. The effect is well documented, but it’s sort of a dirty little secret that most people don’t know about. The unfortunate result is that the oxygen turns the maple syrup a darker color. According to data from The University of Vermont in April 2020, light transmission, which is the quality used for grading maple syrup, dropped by 2.6% per month when the syrup is stored in commonly used HDPE plastic jugs.

Here’s what the light transmission needs to be for the different grades:

  • 'Golden' syrup’s light transmission is 75% or above
  • 'Amber' syrup is between 50% and 74.9%
  • 'Dark' syrup is between 25% and 49.9%
  • 'Very Dark' syrup is less than 25%

At a 2.6% loss per month, the maple syrup will drop a full grade in less than a year if stored in a standard plastic jug. That makes quality control difficult. An important note: the maple syrup packers typically pack when the light transmission is right at the low point of the scale. For example, Amber syrup is typically just barely above 50% when it is packed. The test samples in UVM’s experiment actually dropped out of the grade range before they even took the first measurements.

The State of Vermont does audit maple syrup sold in stores. When a product fails to meet the grade, or has other quality issues, then the entire lot must be removed from the shelves. The VAAFM inspector recently presented findings that 17% of the maple syrup on the shelves that they sampled were below the advertised grade. That’s more than one in six that violated the grading rules.

Internet sales are NOT inspected for grade. I recently bought a 'best seller' plastic jug of Vermont maple syrup online. I was curious about the low priced maple syrup sold through unregulated online storefronts. The expiration date on the jug was in 2022 so I assumed that the quality would be fine. I opened the jug, poured some into a sample jar, and checked with my 2021 grading kit.

The syrup was clearly not Amber color. In fact, it was only the slightest bit above Dark. To give it the benefit of the doubt, let’s say it was 30% light transmission. To be considered Amber grade, it should have been at least 50%! That’s a big delta! If the syrup sat in the jug until the expiration date, it would have been below the Dark range and into the Very Dark range.

The plastics companies have recently started applying a polyvinylidene chloride copolymer to the outside of the containers. This helps to slow the migration of the oxygen through the plastic maple syrup jugs to about 0.8% per month drop in light transmission. Those coatings add extra cost to the containers which many maple producers may not want to pay for. Plastic jugs are available with or without the coating so it may be difficult to know which type you are buying. In any case, odds are good that the syrup in any plastic jug is not the grade shown on the label.

It’s all About the Flavor

If infiltration of oxygen can change the color so drastically, it seems like it must have an impact on flavor. I don’t know of any experiments with storing the exact same syrup in different containers to evaluate long term impacts to flavor, but that would be fascinating. I do enjoy blind taste tests and those are the extent of my flavor research. My wife is often the guinea pig subjected to my line up of shot glasses.

After testing the color of the out-of-grade jug of syrup, I brought a sample along with three others to my wife. "Close your eyes. Here they are. Taste them all." Her face scrunched up when she tasted the out-of-grade syrup. She tried them again and the same result. “Something is off about this one. It has some sort of . . . . flavor to it.” I couldn’t help but fill in the blank: “plastic?” I asked. “YES! That’s it! I’m not eating that stuff.” This part of the evaluation was certainly qualitative, but one thing is clear: we would be ashamed to serve ‘that stuff’ to an unwelcome guest.

Metal cans have their issues too. They were used to pack maple syrup for decades, but not so much these days. There are recommendations to only store in tin cans for up to three months in order to avoid a metallic flavor in the syrup. About ten years ago there was a batch of cans from overseas that had some sort of contamination in them. That was certainly a wake up call to quality control.

Environmental Impact

I admit that until recently I didn’t have an appreciation for what ‘infinitely recyclable’ meant. I’ve always been an ardent recycler – pulling recyclables out of the garbage can whenever I noticed them in the wrong bin and washing the defiant peanut butter out of those plastic containers. Little did I know. The notion that plastic gets used over and over again is a myth promoted by the plastics industry to further the use of plastic. The reality is that most of those jugs we dutifully rinse and haul to the transfer station get recycled once, maybe twice.

Glass and metal, on the other hand, are infinitely recyclable. They can be used over and over again. All materials come with their cost to the environment. But when one can be reused forever, then that’s a really clear choice.


The shipping rules are really quite restrictive for liquids. There are three primary rules: screw top lids must be secured (this is why there is that annoying tape on lids), there must be enough absorbent material to soak up all of the liquid, and the liquid must be triple-wrapped (one of those must be water-proof). It seems like overkill, but I suppose that a gallon of maple syrup could make quite a mess of a USPS facility.

Metal cans need the lids secured, but they are exempt from the absorbent material and triple packing rules; glass and plastic containers are not exempt. That’s right: the rules are being violated when a plastic jug of syrup is rolling around in an over-sized cardboard box, even if there are a couple of those air bubble pillows floating in the box with it.

In order to obviate the need for the waterproof bag and absorbent material, the packaging can be certified to a shipping standard (ISTA Test Procedure 3A). This is a shock and vibration test. If the test is successful, then just tape the lid and you are good to go. The packaging of glass bottles shipped from Maple Farmers is certified to ISTA 3A, ensuring it meets the strict requirements, and (hopefully!) arrives safely.

The Beauty of Pure Maple Syrup

Maple syrup is beautiful! Why would you cover it up in a metal can or plastic jug? I spoke with a customer yesterday who said she leaves an unopened bottle on the counter because it looks like a golden jewel when the light shines through it. 

Enough said – I’m sticking with glass for my maple syrup.

Learn about Maple Syrup

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