It seems like we’re having a bit of a jam week around here.
I guess it’s only natural when the world around us blooms in an exponential kind of way. Here we’ve had a rather unusual month of May. Lots of sun. Lots of rain too. And because the temperatures rarely get above 20°C, once they will – perhaps after mid-summer – fruits will suddenly surround us.
I thought it would be nice to have a table to compare sugar, acid and pectin content of some of these fruits. Of course, those three factors will change depending on the degree of maturity of the fruits or their variety, but it’s a good starting point to adapt your favourite jam recipe for different fruits.
Should you add more sugar? Less pectin? More acid?
Hopefully this table here will help in answering your questions.
How to use the table?
Let’s take melon for example.
I currently don’t have a melon jam recipe. I do however have a killer strawberry jam one.
According to the table, I could make melon jam using my strawberry jam recipe, only I would need to add more citric acid at the end of the cooking process, as melon have an average pH of approximately 6, while strawberries’ pH is closer to 3.4.
Fruits with high pectin levels and low pH.
In the case of fruits with high pectin levels and low pH – like lemons, limes, cranberries, blackcurrants, oranges, gooseberries, grapefruits, mandarines or red currants – you probably don’t need to add much acid at all, and certainly don’t need to add extra pectin; as the fruits themselves offer the perfect conditions to form a gel (which for pectin are: sugar, acid, heat).
A quick note on citrus.
The flesh of citrus fruits isn’t high in pectin, while the zest and pips are.
What is pH anyway?
pH is a unit of acidity/alkalinity. A pH of 7 is considered neutral; above that it’s called alkaline or basic, and below that it’s called acidic.
It’s a bit of a shortcut, but what we fundamentally care about, here, is that the lower the pH the more acidic a fruit is. As you’ll notice in the table most fruits have an acidic pH, but only those with a pH ranging from 2-3.5 are empirically sharp.
Sugar, acid and pectin content of selected fruits
| %sugar | average pH | pectin level | |
|---|---|---|---|
| Apple | 13 | 3.5 | medium |
| Apricot | 9 | 4 | low |
| Blackberry | 8 | 4.2 | medium |
| Blackcurrant | 10 | 2.8 | high |
| Blueberry | 11 | 3.2 | low |
| Cherry | 14 | 4 | low |
| Cranberry | 4 | 2.5 | high |
| Fig | 15 | 4.8 | low |
| Gooseberry | 11 | 2.9 | high |
| Grape | 16 | 4 | medium |
| Grapefruit | 6 | 3 | high |
| Guava | 7 | 3.6 | very low |
| Kiwi | 14 | 3.5 | very low |
| Lemon | 2 | 2 | high |
| Lime | 1 | 2 | high |
| Litchi | 17 | 4.8 | very low |
| Mandarin | 13 | 3 | high |
| Mango | 11 | 4 | very low |
| Melon | 7 | 6 | low |
| Orange | 11 | 2.8 | high |
| Passion fruit | 11 | 3 | low |
| Peach | 9 | 3.8 | very low |
| Pear | 10 | 3.8 | low |
| Persimmon | 14 | 5.4 | high |
| Pineapple | 13 | 3.5 | low |
| Plum | 11 | 3.4 | low |
| Raspberry | 7 | 3.4 | low |
| Red currant | 6 | 3.2 | high |
| Rhubarb | 1 | 3.1 | low |
| Strawberry | 7 | 3.4 | low |
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