Crash Course in Pectin Studies

With canning, you're always learning. This summer, I was the student and pectin was the teacher. 

It all started when I learned from three different sources (all very reliable) that you should use slightly under-ripe fruit for jam and jelly making. Slightly under-ripe fruit has higher pectin levels than fruit at its peak or over-ripe. For years, I had sought perfectly ripe fruit, and wasn't opposed to using fruit that was slightly dinged here and there -- I'd just cut those bruised pieces out. I think the "dinged fruit is fine fruit" theory was widespread -- even farmers would set aside these slightly imperfect fruits just for home canners at the farmers markets and charge a few cents less. You're going to cut it up, pour a bunch of sugar on it and cook the heck out of it, so it doesn't need it to be perfect, right? WRONG! 

I decided to conduct an experiment. I sliced and diced 5 cups of slightly under-ripe plums with the skin on (there's plenty of pectin in fruit skins, seeds and pits) and made my jam according to a Ball Blue Book recipe. The jam did its normal thing, but it seemed to set up faster -- took me by surprise! Before I knew it, my jam was sitting up straight on a spoon. When I opened my tester jar the next morning to have a taste, the knife didn't move through the jam as easily as I like it to. This jam was tasty and tart, but definitely FIRM! (I prefer a softer set, but have friends and family who like firm jam.) I still had loads of slightly under-ripe plums, so for the next batch, I peeled about half of the plums. The result was a nicely set up, but not too firm, batch of plum jam. My theory: If I was going to use fruit that had a higher level of pectin, I needed to remove some of the peel to get the texture I prefer. 

One of my sources at the UC Davis Department of Plant Sciences, Diane Beckles, pointed out that canners might have to make a trade-off between pectin content and sugar levels. Slightly under-ripe fruit may not be as sweet -- it depends on the fruit. 

There is a lot to consider when you're choosing your fruit! And, now it makes sense when I see tips that suggest using 3/4 firm-ripe and 1/4 under-ripe fruit in your recipes. (Not that you always have a choice when in comes to ratios of firm-ripe and under-ripe. This seems like splitting hairs, even to me.) I'll continue to mix it up and document the results, and of course, share with all of you!

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