Jam & Science

Nerd alert! I love science! So an opportunity to include science with jam is very exciting for me. It turns out, there is a science to making jam.


First, the obvious…great jam requires precise measuring. Read the instructions in any box of store-bought pectin and the tips start out with something about measuring ingredients exactly. For those of you like my sister Rachel, who live by the “ish” system when cooking and baking, jam probably isn’t your thing. Jam, like baking, is about chemistry. Adding baking powder to biscuits makes them plump up perfectly in the oven. Checking the temperature of milk or water before adding it to yeast ensures the yeast will be activated and bread will rise correctly. The same principles apply to jam. The correct amount of fruit, sugar and pectin combined with the proper cooking temperature produces the desired jammy consistently. The proper water bath canning time ensures that your jam is shelf-stable, sterile and safe.

Second, the lesser known…jam labeling requires science. The Food and Drug Adminstration specifies different types of fruit that can be used to make jam or preserves and fruit butter. Further, the FDA designates the classification of jams or preserves and fruit butters. The FDA’s classifications are based on the amount of fruit and sugar in each product. Well, you may be asking, how does one go about measuring the amount of fruit and sugar in each product? That’s easy, you use a digital refractometer. A what? A refractometer measures the concentraction or mixture ratio of water soluble fluids. The denser the liquid, the slower the light will travel through it, and the higher its reading will be on the refractometer. The refractometer reflects the Degrees Brix which indicates the sugar content of a liquid solution.

This little beauty is an example of a digital refractometer.

digital refractometer pic

To use, first zero the scale using distilled water. Then, add a tiny bit of jam or fruit butter and the refractometer calculates a number, the Degrees Brix. The Degress Brix indicates the FDA’s classification, over 43 for fruit butters and over 65 for jams or preserves. Aunt Becky’s measures the Brix number for each batch of special jam and fruit buttter to confirm consistency and accurate product labeling.

Finally, the best part…great jam must be sampled to determine, scientifically of course, its level of deliciousness. My niece Lily measures the tastiness of jam based on how many times she wants to lick a layer of jam off a piece of toast and ask for more. It reminds me of the Children’s book “If You Give a Mouse a Cookie” by Laura Numeroff.  If you give a girl toast with jam, she’s going to want to lick off the toast. Then she’s going to ask for more jam. And, frankly, how can I say no to this face?

easy bake oven


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