On Mar 21, 7:10 pm, "FarmI" <ask@itshall be given> wrote:
> "jmm1951" > wrote in message
> >I likeblackberrypreserves on toast for breakfast, but I'm not
> > terribly keen on the high fructose corn syrup, so yesterday I decided
> > to make someblackberrypreserves/jamat home for the first time. My
> > previous experience was limited to making grapefruit marmelade without
> > pectin, adding in a couple of lemons, then cooking until 218 degrees.
>
> > My marmelades have always set nicely, no problem.
>
> > Yesterday I looked up a recipe on the Internet forblackberry
> > preserves.
>
> > It said equal weight of fruit and sugar, a bit of lemon juice, simmer
> > for an hour, mix in 1 sachet of pectin, and away you go. This sounded
> > nice and simple so I got 2 lbs of frozen blackberries and made the
> > preserves.
>
> > However, I find today that it is not completely set. It is very nice,
> > but it runs a bit more than I would like.
>
> > I also made grapefruit marmelade yesterday in a slightly larger
> > quantity. I found that my candy thermometer was broken but boiled it
> > down until it looked right, then threw in a sachet of pectin for good
> > luck. The marmelade came out perfect. Positively orgasmic.
>
> > So why is theblackberryjamless set? I followed the recipe exactly.
>
> > The recipe seemed to suggest that if you used pectin there was no need
> > to cook to 218 degrees. Or is it because I used frozen blackberries
> > and not fresh? Or do I need more pectin? As pectin is rather
> > expensive, this would definitely add to the cost of a batch.
>
> > Of course thejamis perfectly good, as long as you don't mind it
> > running a bit, but I would like to know for next time.
>
> I've never used pectin in any of the various jams I make so I can't help you
> as to its effectiveness, I've also never used corn syrup (just sugar) and
> nor have I ever taken the temperature of thejamas I make it as I use the
> look and the feel and the 'cold saucer' treatment to see if it's reached
> setting point. However, I can make good prize winningjamand have the
> following comments which may or may not help.
>
> Set is helped by the addition of lemon juice, citric acid or tartaric acid
> which is why you have no trouble with achieving a set when you make
> marmalade - lots of acid. Blackberries in common with strawberries are low
> in acid content so that is why the recipe mentioned adding lemon juice - I'd
> add more or some citric acid rather than more pectin.
>
> I coulnd't recall off the top of my head what sort of pectin levels
> blackberries had so did a google and this site says all that I had planned
> to say so there is no point in my saying any mohttp://www.abc.net.au/tasmania/stories/s1349335.htm
Yes, that Web site is helpful.
Anyhow, I decided to do the following:
Reheat the jam, add one pureed lemon to the mix, and boil it down to
remove water and thus increase the percentage of sugar. As it tasted
rather sweet, I also figured that adding the lemon would add a bit of
sharpness to the flavor.
This worked quite well and the jam is now firmly set. However 2 lbs of
blackberries and 2 lbs of sugar has now given me about 3 lbs of jam.
I did a little bit more research, and the equation is quite complex,
but basically with blackberries you need about 65% sugar and a certain
degree of acidity to get a set. This proportion varies somewhat from
fruit to fruit.
The math is not quite as simple as it seems, because to know the
percentage of sugar, you will need to know the percentage of sugar in
the original fruit, and to know the acidity you will need to know the
original ph of the fruit, both of which may vary according to the
ripeness of the fruit.
However, if we are not involved in industrial production, we can use
empirical methods and get good results without getting into a lot of
theory.
Next time I will do better.