Ever since I met Vivien Lloyd last summer I have been thinking about how sugar works in preserves and continuing to experiment with recipes. I don’t pretend to be a food scientist but I can share what I’ve learnt from her, from reading and from my own experiments.
One of the things I knew about Vivien well before I met her was that she was a passionate advocate for traditional preserving methods. A preserver of preserves, if you like. However you shouldn’t mistake this as nostalgia for a golden age of jam when our grandmothers stirred copper pots on the range. Oh no: she is talking about science.
The traditional level of sugar in preserves is 60%+, which is the level at which they have a wobbly, gelled consistency and a bright colour. If you were to experiment by progressively lowering the amount of sugar in a recipe it would become progressively more difficult to achieve a set (especially if not using commercial pectin) and, for many fruits, the colour will start to take on the look of faded curtains. High levels of sugar also ensure that the resulting preserve actually does what it was originally designed to do – preserve – by preventing the growth of microbes. This action starts to fail at levels below around 60% which explains why, once open, you need to keep reduced sugar preserves in the fridge and eat them relatively quickly.
But surely we should be trying to reduce our intake of sugar for health reasons? This is quite likely true of the average diet but we should not kid ourselves that eating reduced sugar preserves will make a big difference. Take jam, for example: a traditional jam will be 60-65% sugar, a reduced sugar fruit preserve maybe 45-50%. So if you are in the habit of spreading a generous layer on your toast every morning, switching from one to the other will reduce your sugar intake by around half a teaspoon a time – not terrible, but hardly a statistic to impress your dentist.
Personally, I’m much more interested in how sugar relates to flavour. Logically, a higher fruit to sugar ratio should dictate a better flavour and indeed it often does, yet things are a little more complex than that. The variety of fruit, how it has been grown, when it was picked and how (and how quickly) it is processed all have a big impact on flavour. I was recently fascinated by this Guardian article about the celebrated American chef Dan Barber, a passionate advocate of sustainability; where he states his belief (if I read this right) that flavour starts with the quality of the soil. (But I digress – maybe a topic for another blog!)
Fruit cheese differs from other preserves in that it is more concentrated, with a lower water content as a result of a longer cooking time. Sugar levels are therefore correspondingly high but I have long been fascinated with how to achieve the strongest, most true flavour of the fruit, not too sweet, whilst still maintaining a good set, texture and colour. Not asking much, then!
Unsurprisingly this has led to a long trail of failed experiments, but these have gradually failed less as I learn more and become better at understanding the process. My method is to start with an existing trusted recipe, where one exists, then to pull it and stretch it until I identify the minimum amount of added sugar needed to make the recipe work. This is not an exact science as there are other factors at play such as batch size, temperature, speed of cooking etc but I now finally have a set of recipes that I am more or less happy with. Some fruits have stubbornly refused to co-operate: I have had to admit defeat with the medlar as lowering the sugar even a fairly small amount caused the ‘cheese’ to set at the surface but remain unset beneath. (By the way, if anyone can tell me why then I’d love to hear from you!)
So in summary? Sugar levels in preserves will determine some of their properties quite reliably but are far from being the only factor when it comes to flavour. The only real way to know that is to trust your taste buds!