This is a series of posts in which I share
snippets of what it's like to be a food scientist. As a product
developer for dry powder shakes, there are some lessons I never learned in school and some challenges I never saw coming.
Green-Eyed Insight on Stability Studies
Have you ever looked at an expiration date and wondered,
"How do they know?" Determining or confirming the shelf-life of a
product is important for several reasons, but the process itself can be a bit
mind-numbing. Here's what I didn't learn in school.
Why It's Important
Expiration dates are based on the answers to several
different questions. When does the product become unpalatable? When do the
vitamins and minerals degrade below the amounts on the label? When does the
product become unsafe to eat? To sell a product that meets consumer sensory
expectations, label claims and food safety requirements, you have to know the
answers to all three questions.
Side-note: Why It's Confusing
This would be a great time to note that expiration dates can
be perplexing. An expiration date is not quite the same as the "sell
by", "use by" or "best by" date. For example, "use
by" is meant to help consumers know when a product is no longer good to
eat whereas "best by" and "sell by" are meant to help those
selling the product manage their stock (think of those racks of discounted
"Manager's Special" items in back of the grocery store).
Misinterpretation of these dates leads to as much as $165 billion in food waste
PER YEAR according to a report by
the Harvard Food Law and Policy Clinic and the National Resources Defense
Council [1, 2].
Why It's Complicated
As a product developer, I work on a dry powder shake that's supposed to last one year. Our products don't use the "best
by" or "use by" terms; our packages say "EXP
MM/DD/YYYY". Up until that date, our product is expected to taste as
delicious as the day it was made, and must provide all the vitamins/mineral and
nutrient contents on the label. This is harder than it seems because flavors,
proteins, vitamins/minerals and oxidation-prone (air-sensitive) ingredients
like fish oil, chia and flax all have different rates of degradation. In some
cases, products start out with vitamin/mineral overages so there's enough left
at the end of shelf-life to meet the label claims. Instead of using overages,
you might shorten the shelf-life or slow the degradation of certain nutrients with
encapsulation [3].
How We Do It Here
In order to continuously improve the food safety and quality
of our finished product, my team and I are always looking at alternate
ingredients. For example, say blueberry powder A is great, but blueberry powder
B is cheaper and has lower heavy metal contents. We can't just switch from one
to another; what if blueberry powder B makes the product taste funny after 6
months? Our product is supposed to be delicious and nutritious for a whole
year. We've got to test this.
 |
| 500 servings x 35g each x 4 variants |
Step One: Make your blends.
For your control and all your variants you need to make a big enough batch to put a few servings into the freezer ("time
zero"), a few servings into room temperature storage, and a few servings into
accelerated storage (where 1 week at 40* Celsius is equivalent to 2 months at
room temp). Accelerated storage is a marvelous tool because it only takes six
weeks to determine how the product will taste after one year in real time. Plus,
since my office is always freezing cold, I rather enjoy fetching samples from
accelerated storage and feeling the hot air hit my face.
 |
| break big tasks into small steps | | | |
|
Step Two: Divvy your blends up into single pouches.
Warning
– this may take a while, depending on the size of your batches and number of
variants. Unless you have Audible or music or some metaphysical question to
ponder you may feel your mind slipping a little. Fight the urge to listen to
podcasts because you need to pay attention to what you're doing. I swore off
listening to Baseball Tonight and "Wait Wait …Don't Tell Me" because
once I lost track of what sample I was working on and had to start
over. Rookie mistake.
Step Three: Seal your pouches.
Make darn sure they're
sealed. There's nothing worse than putting all the time and energy into
preparing samples then seeing random powder piles on the shelves inside the
stability chamber.
 |
| Plastic bags and small boxes come in handy! |
Step Four: Set calendar reminders.
Include specifics on what
samples to pull, from what location (freezer, room temp, accelerated) on which
days. Even though you've put all this work into setting up the stability study,
it's not uncommon to set it and forget it. Putting the samples in the Hot Box
mentally feels like the job is done – no more Open Loops. Since one week in the
40*C chamber is the equivalent of two months, it's important not to miss the
days you're supposed to pull a sample.
Step Five: Taste.
This might be a mentally exhausting
exercise based on the number of samples you have to pull. Unlike Pavlov's
dogs you might grow to dread the sound of the calendar reminder, especially if there's a lot of samples or if
they're not aging well. This is where oyster crackers and carbonated water
come in handy –
see previous post.
Bottom Line
Shelf-life and stability studies can be mind-numbing, tedious,
time-consuming experiments, but you'll learn more about your ingredients and
your product than you could possibly anticipate. It's kind of exciting to have
that knowledge that others aren't privy to, and that knowledge improves your
product and your skill set as a product developer. That is the silver lining.
Resources:
Related Posts:
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