Well, you've asked a question that hits one of my "hot buttons:" I
have been an avid home cook/baker for years, and have recently
enrolled in a professional cooking program. So, between my recent
training in theory, and my "old school" East-coast upbringing, I think
I can give you all the information you'll need to do this
I'm going to start by briefly reviewing what *can* go wrong, and then
we can look at the recommended procedures. Hopefully, when we're
done, you'll have a good idea of what's been going wrong so far, and
how to successfully address it. If I cover points that you consider
to be blindingly obvious, please excuse me. I'm not being
patronizing; but we have no way here to judge your current level of
knowledge so thoroughness is the only real option.
To begin with:
Moulds, bacteria, and other pathogens need a few specific
environmental factors in order to grow. They need a relatively
neutral Ph (6.6 to 7.5 is optimal); they need a certain amount of
moisture; they need a source of food; they need a suitable temperature
to reproduce; they need to have a period of time at a suitable
temperature; and they need a suitable atmosphere...for some, that
means oxygen, for some, that means no oxygen.
There are several ways that pathogens and putrefactives (things that
spoil your food without making you reeeallly sick) get into your
canning. The first obvious way is on the food itself. Secondly, your
equipment must be sterile: your jars, lids, and utensils will need to
be cleaned carefully before every use, and sometimes during. Observe
good hygiene; wash your hands, work surfaces, and tools before moving
from one food to another. Keep a supply of fresh paper towels to dry
your newly-cleaned utensils with, since your kitchen towels will not
Assuming that the food has been properly handled and that the
equipment is sterile, the next point of vulnerability is with the jars
themselves. Are you using proper Mason-type jars (Bell, Kerr, etc) or
recycled supermarket jam jars? If you are using supermarket jars,
they will not produce an airtight seal, so you'll need to be creative.
Mason jars are infinitely preferable, as they'll handle the heat
better and will seal properly (they're also stronger glass...a factor
to consider, when you're shipping things). You'll still want to check
Mason jars carefully, since even a small chip along the rim will
prevent them from making a seal. You'll also want to use fresh lids
to ensure the best result.
If you have any doubt of a specific Mason jar, you may test it by
filling it 3/4 of the way with boiling water. Place a lid on the jar,
and tighten it finger-tight. When the water cools, the lid should be
depressed in the middle, forming a tight seal. That jar will be safe
to use. If it does not make a seal, however, it should be discarded
Once the food is placed in the cans, it must be cooked to an adequate
temperature; and for an adequate time. Failure in either regard will
leave viable spores and bacteria in your preserves, and cause them to
spoil more readily than they should.
So, having covered all of these variables, how does one go about it
In your instance, you would need to start by rinsing the cranberries,
picking the stems, and manually sorting out any that are moldy or
badly blemished (cutting off bad spots is okay). This is a tedious
job with cranberries - I get 5-10 lbs each year from my father, so I
know it all too well - but it is necessary. With the oranges, you'll
want to wash the rinds well with a gentle detergent (dish soap is a
good choice) and rinse them, before use. If you're peeling the apples
they'll need no special treatment; but if you're leaving the skins on
you'll treat them like the oranges. Toasting the nuts lightly in your
toaster oven will render them sterile, and also will improve their
flavour and texture.
Clean your utensils, jars, and cooking surfaces well. I'd recommend
using either a commercial sanitizing spray (quaternary ammonia, for
example) or a mild bleach solution on your counter, knives, and
cutting boards. One tablespoon of bleach per gallon of lukewarm water
makes an adequate sanitizing solution, and will not leave your
utensils smelling/tasting of chlorine.
The same solution may be used for your jars and lids. You may put
them through the dishwasher afterwards to remove any trace of
chlorine, but remember not to dry them with a towel. Let them airdry
in the dishwasher.
Now then, let's look at what sort of environment you're providing for
the pathogens to grow. Your cranberry relish will have a suitable
moisture level for micro-organisms (that's unavoidable); but because
of the berries, apples, and citrus the Ph will be rather low. That's
a good thing. Sealing the jars properly will eliminate aerobic
bacteria and molds; but several pathogens (including clostridium
botulinum, which causes botulism) are anaerobic. This means that an
oxygen-free environment is precisely what they require, which is why
botulism is such a threat to home canners. To beat botulism (and
other anaerobic pathogens) we need to look at temperatures.
As mentioned above, pathogens thrive in a specific range of
temperatures: 40 degrees Fahrenheit, to 140 degrees (4-60 degrees
Celsius). Below that range, they will be dormant and will multiply
slowly if at all; if held at higher temperatures for a sufficient
length of time, they will be killed. The trick, then, is to heat your
relish hot enough - for long enough - to kill the pathogens, then to
seal the jars while the contents are still too hot for pathogens to
Temperatures of 170 degrees Fahrenheit, maintained for two minutes,
will kill any bacteria present in your foods. The trick is to achieve
that temperature right through to the middle of your jar! If you are
using the water bath method with your jars (sitting the jars in a pot
of boiling water) leave them in the bath for 15 minutes to ensure
proper heat. With a relish, you may also use a candy or meat
thermometer to monitor the temperature as you cook it; when it's been
at the correct temperature long enough, pour it immediately into
sterile jars and seal at once.
Never let your cooked relish drop back to room temperature before
canning, as this will give micro-organisms a chance to re-establish a
If you are using supermarket jam jars, sealing them properly can be
problematic. The traditional method has been to pour melted paraffin
into the tops of the jars to make the seal. This usually works well
enough, but there are a couple of things to be aware of. One is that
paraffin is brittle. It will break easily in shipping. A second is
that paraffin may shrink from the sides of the jar, allowing air in.
Placing a piece of clean cheesecloth in the still-liquid paraffin will
help with both of those problems.
Some favour beeswax to seal their jars, as it is not quite as rigid
and brittle as paraffin. This is reasonable, as long as the beeswax
is heated to the same temperatures discussed above. Some also use
honey or olive oil to seal their jars, but this is not generally
If, on the other hand, you're using Mason jars, life is much simpler.
Tighten the rings just finger-tight on the lids while the contents are
still hot. Once they've cooled and sealed themselves, tighten the
rings the rest of the way. Now you're ready to store or ship your
jars of relish.
A note on cooling: place your jars, well spaced, in a well-ventilated
(but not too breezy) location. Don't put your jars in too chilly a
place to cool...a refrigerator, say, or a wintertime windowsill.
There's just a chance that the change in temperature will cause a jar
to shatter, especially if you're not using Mason jars. It doesn't
happen often, but it's very messy...and a lot of work down the drain.
So, to recapitulate:
+ Sterilize your tools, work surfaces, and utensils (including jars)
+ Clean your ingredients as best you can.
+ Heat your relish to the correct temperature, for an adequate time.
+ Seal the jars while still hot.
+ Seal the jars adequately.
+ Cool them gently, when done.
"Vacuum-sealing" the jars themselves, after they're packed, will be of
no benefit. If the contents are properly sterile, it's
unnecessary...and if they're not, it's ineffective. As for adding
preservatives, that should not be necessary if you carefully follow
the steps above.
This answer was prepared primarily with the use of three printed
Rodale's Organic Gardening Harvest Book (Rodale Press, Emmaus PA,
The Joy of Cooking, Irma S. Rombauer & Marion Rombauer Becker (my
personal copy is the two-volume paperback Signet edition, 1974)
On Cooking: A Textbook of Culinary Fundamentals, Second Canadian
Edition (Labensky et al, Prentice-Hall, New Jersey, 1999)
All of these works make reference to USDA data. The USDA, in turn,
publishes a booklet called the "USDA Complete Guide to Home Canning."
This is the best resource I know of for a private individual to work
from. A quick search on Google, using the keywords
USDA "home canning"
revealed several sites which made the text of the current (1994)
revision available online. One such text, nicely formatted as a .pdf
file (Adobe Acrobat reader required) is available at Utah State
I believe the above will provide you with all the information you need
to successfully pursue this project in future.
If I have been in any way unclear, by all means let me know.