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Ice Cream – weight vs volume

In several of my previous blogs I had adjusted by weight (expressed in grams) when comparing across ice cream products. While the amount of weight per serving is an important value and in comparing using it gives useful information, in reality we eat ice cream by volume, not weight. When you scoop up some ice cream the real limiting factor is volume, in other words size, because ice cream will never be heavy enough for you to care about a spoonfuls worth of weight.

For this reason I’ll try to stick to comparing against volume in future posts. Originally I had started comparing using weight because I noticed this different across ice cream producers and thought it translated to different volumes, so it would be the most fair way to compare. However I was wrong – most ice cream/frozen dessert companies use a standard serving size of 1/2 cup, which yields 4 per pint.

Here is a sample of average weight per 1/2 cup serving for a few ice cream companies:

  • Talenti: 100 grams
  • Haagen Dazs: 100 grams
  • So Delicious Coconut Milk: 85 grams
  • Bryers: 66 grams

So how can the weight be almost double for the same volume? The basic ingredients, coconut/cow milk and sugar, shouldn’t differ too much in weight and the minor ingredients are in a lower proportion and have only a small effect on the total weight. The answer may be a little surprising to those who haven’t researched how ice cream is made:

Air.

Believe it or not air bubbles are actually a necessary component of (tasty) ice cream. If you want to see what I mean, you can try an experiment which I accidentally did the other day. Move a small portion of ice cream into your refrigerator and wait a few hours until it melts into liquid. Then transfer it back to the freezer and wait a few more hours. It will re-freeze but much of the air (and ice crystals) will be gone, so the texture will be ruined. Also you will see the volume is reduced. If you own an ice cream machine you’ll know that its primary purpose is to continually spin the cream so that these air bubbles form.

If you go back and look at the table above again, you might be upset since Bryer’s is essentially filling their ice cream with air. I found a great post which discusses this practice and does some research to discover the cheaper the ice cream the more air is puffed in. You can find it here.

Some might declare we need to stand up to ice cream producers and force them to stop saving money by giving us air-filled ice cream, but I would disagree. At least for a company like Bryer’s that produces great-tasting ice cream, I don’t think there is any reason for them to change. Personally, I have gravitated to more dense ice creams in the last few years, but I have no problem eating some Bryer’s now and then, albeit in small portions.

Besides a cheaper price to the consumer, there are other advantages to adding air – less calories and sugar content. But be careful, since a much larger container size (gallon vs a pint) means you are likely to gobble up more per sitting. You could also argue there is less nutrition, but most people don’t eat ice cream primarily for nutrition.

Regardless on how you judge things, I believe in transparency – consumers knowing what is really in the products they buy. This includes air, which is not listed on the label as an ingredient.

Ingredient Math – estimating worst (or best) case for ingredient proportions

Have you ever wondered how much of a certain ingredient is really present in a sweet, or any food product?

You probably know that ingredients are listed on food labels in order or prevalence, with the most predominant ingredient first. You may have even known this was determined by weight. But in this article I will discuss a method to get an estimate for the maximum of each ingredient’s percentage of total weight – just by using the ordered ingredient list.

To derive this formula, lets start with a very simple example, a product with just “coffee and sugar”. Since coffee is listed first we know it has higher or equal amount of total weight when compared to sugar.

Is there anything we can do to determine about how much the first ingredient, coffee, is really in the product? The answer is no because coffee could be almost 100% to almost 0% of the total weight, with sugar filling in the remaining space. (Actually, there is a trick to determine the amount here since the second ingredient is sugar, which I’ll discuss later in this article).

But what about the sugar?

Well, if you think about it, there can’t be more than 50% sugar, by weight, since any more of that would mean there was more sugar than coffee, which we know is not the case.

So we’ve learned something important – that there is no more than 50% sugar in the product. This would apply to another second ingredient when there are two total ingredients.

What if there were three or more total ingredients? We would get the same result, because the other ingredients could be in trace amounts (practically 0%), so the “50% maximum for the second ingredient” rule would still apply.

What about the maximum amount of the third ingredient? Using the same logic you will see it cannot be above 33.3%, since any more of that would mean it is in greater proportion than the first and second ingredients. And for the forth ingredient you get a maximum, by weight, of 25%.

Turning this into a simple formula we get the following:

Maximum percentage of the Nth ingredient = (100 / N)

So for the 5th ingredient, you would get (100 / 5) = 20% maximum weight of that ingredient.

If you use formula along with the serving size you can determine the maximum weight of any of the ingredients per serving. Pretty handy if you want to minimize your intake of certain things.

If you want to take this to the next step, you can infer more information when one more more ingredients are a type of sugar. For example, if a product contains “coffee, sugar” and has 3 grams of sugar per 15 gram serving, then you know right away there is 20% sugar and 80% coffee in this product. Keep in mind that the grams of sugar listed includes any type of sugar, so if you have multiple ingredients which contain some type of sugar (even fruits) then the calculation gets a little trickier.

Besides knowing there is a certain percentage of sugar, you can use that to deduce information about other ingredients.

For example, if the imaginary product I just described had a third ingredient, say “coffee, sugar, vanilla”, then you would know that there is 20% or less vanilla because sugar is 20% or less. This assumes that there is no sugar in the vanilla, otherwise it would be harder to make any definitive conclusions.

Similarly, if you know how much protein is in each ingredient, you can figure out even more using the supplied protein in grams.

You can also leverage information about other ingredients to deduce additional information about the other ingredients. For example if a product had “milk, sugar, guar gum, vanilla”, you would know that the proportion of vanilla is much less than 25% since guar gum is typically used in relatively small doses. (I’ve tried overusing guar gum in homemade ice cream – its not pretty!)

I love thinking about food and ingredients from a methodical, logical point of view since it allows me to apply science to my everyday life.

References

http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm064880.htm