"jmm1951" > wrote in message
>I like blackberry preserves on toast for breakfast, but I'm not
> terribly keen on the high fructose corn syrup, so yesterday I decided
> to make some blackberry preserves/jam at 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 for blackberry
> 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 the blackberry jam less 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 the jam is 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 the jam as 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 winning jam and 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 mo
http://www.abc.net.au/tasmania/stories/s1349335.htm