Cooking For Engineers Forum Index Cooking For Engineers
Analytical cooking discussed.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Jelly, jam and candy
Goto page Previous  1, 2
 
Post new topic   Reply to topic    Cooking For Engineers Forum Index -> Engineer Speak
View previous topic :: View next topic  
Author Message
Dilbert



Joined: 19 Oct 2007
Posts: 1304
Location: central PA

PostPosted: Fri Jun 27, 2014 7:40 pm    Post subject: Reply with quote

all true - but it still leaves the issue of "I followed the directions exactly and it turned out runny!"

a lot of recipes / directions just don't bother with a temperature thing - they rely on just 'continue to cook for x minutes'

but, if the magic temp - which is in the range of 221-225'F - can be slightly higher for (thick) jams/marmalade with low pectin fruits - is not reached 'accidentally on purpose' - it does not set up.

those temps don't really require a candy thermometer. the candy thermometer thing came into the discussion elsewise.....

as pointed out, there's a lot of variables. to make the magic work, the pectin, sugar and acid needs to be 'in proportion' - altho there is quite some latitude in the proportions. added (powered) pectin requires more sugar - people are trying to use less...

sticking a thermometer in the pot is not exactly burdensome - but it can give more reliable results that guessimating.

Jack's wife's notes: just add pectin and bring it to a boil can in fact work peachy keen.
if there was not excess water in the fruit
if it's left at a boil long enough to kick-over
if and if and if.

I prefer a thermometer (g)
Back to top
View user's profile Send private message
Jim Cooley



Joined: 09 Oct 2008
Posts: 377
Location: Seattle

PostPosted: Sat Jun 28, 2014 1:43 pm    Post subject: Reply with quote

Quote:
Extremely ripe fruit can also be a challenge as the ripening process breaks down pectin naturally,


Okay, that's a very plausible explanation for why my jams don't set very well. I use really ripe blackberries, and just the recommended amount of either liquid or dried pectin. (which leads me to ask, does that stuff have an expiration date?) I also use smallest amount of sugar in the recipe, because the riper the blackberry, the more sugar it contains.



Quote:
Some acid typically helps though.

Can you elaborate on this? How important is the acidity to set a jam or preserve? I do have citric acid powder sitting around and the increased tartness would not be objectionable. (too sweet IS objectionable, though)

Appreciate the thoughtful reply.

Jim
Back to top
View user's profile Send private message
Jim Cooley



Joined: 09 Oct 2008
Posts: 377
Location: Seattle

PostPosted: Sat Jun 28, 2014 1:50 pm    Post subject: Reply with quote

Quote:
but, if the magic temp - which is in the range of 221-225'F - can be slightly higher for (thick) jams/marmalade with low pectin fruits - is not reached 'accidentally on purpose' - it does not set up.


Duly noted. Thanks Dilbert!

Still curious about the chemistry of pectin. Any difference between the powdered and liquid varieties? Does it have an expiration date? Should I keep the stuff in the freezer because constant exposure to room temp will make it "break down"?

Jim
Back to top
View user's profile Send private message
Dilbert



Joined: 19 Oct 2007
Posts: 1304
Location: central PA

PostPosted: Sat Jun 28, 2014 2:40 pm    Post subject: Reply with quote

the basics of pectin:
http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/pectin.asp

typically I buy the smallest amount possible - if it's not in the store section with the other canning stuff, the health food store has it.

I don't keep it after the 'season' - at the cost of fresh fruits around here, a batch of jam/preserves - four to six jars worth - runs pretty close to $20 and I'm not going to risk the time and effort using stale stuff.
Back to top
View user's profile Send private message
Jim Cooley



Joined: 09 Oct 2008
Posts: 377
Location: Seattle

PostPosted: Sat Jun 28, 2014 4:26 pm    Post subject: Reply with quote

Dilbert,

More than I ever wanted to know about pectin. Thanks.


Mera naam Jeem
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Cooking For Engineers Forum Index -> Engineer Speak All times are GMT
Goto page Previous  1, 2
Page 2 of 2

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group