Several years ago I had a common blood test that showed that the HbA1c level was near the upper limit of what is currently regarded as acceptable. At that point I realized that I knew little about insulin and its function. I remedied that on a journey which eventually covered both nutrition and cell biology. On the way I discovered research by Robert Lustig, who now has a viral video, Sugar: The Bitter Truth, on YouTube. I had read the book Pure, White and Deadly published decades ago by nutritionist John Yudkin, and Robert Lustig was making the same point more forcefully. I had found most marmalade too sweet anyway so I experimented.
The recipe uses a 850 g can of cut Seville oranges. The can says to use 1.8 Kg of sugar. I reduced that to 1.3 Kg. Then noting that Lustig points out the different and less benign metabolism of fructose compared with glucose (especially for us non-athletic types), decided to try using glucose instead of sugar. This did not produce marmalade as we know it but some cloudy syrup.
The best result of experiments is:
850 g can of prepared Seville oranges. This can be fresh Seville oranges when available but then add pectin.
400 g water
650 g sugar
650 g dextrose
Boil for 10 to 15 minutes. You have to check for setting as it explains on the can, though I now keep all factors, quantities & heat, the same and find I don’t need to test.
This mix will give you about 1.5 g of fructose in two teaspoons of marmalade, and has the right bitter edge that is the point of having this conserve. If we go by what we used to consume before the days of cheap bulk sugar it looks like we had up to 15 g fructose a day; so this marmalade gives you space for other fruits. Friends to whom I have given a jar say they like it and don’t refuse more.