I have 6 different types of grapes on 7 vines grown on a 2-story high trellis; so, I get way more grapes than our 3-person household can consume fresh. The surplus seedless grapes are all converted to grape juice and the juice is pressure canned to store it long term.
Something peculiar is that the juice of the Himrod grapes, the most productive variety, turns pink or red from its initial grey/green color during the canning process. The color seems to depend on the canning temperature; it’s usually pink when canned at 6 psi and dark red when canned at 7.5 psi (something that I discovered by mistake today). Does anyone know what is the chemical reaction that creates this color change? I could find nothing on the Web about this.
I’m also interested in processing the grapes by using a blender to chop the grape skins up and incorporate their nutrients into the juice. That would eliminate the need to run the grapes through a Victorio food strainer. I already force as much of the pulp as possible through the strainer, which takes some extra time and effort. Does anyone here have any experience with blending whole grapes? Is it best done before or after cooking them? Thanks.
Would be interesting to test pH of different colored juices from same batch at different psi.
Not that you want to buy another appliance (!), but using a steam canner is my very quick, alternate method of canning grape juice from both seeded and seedless grapes. If desired, you could add in some of the grape mash from the seedless batch at the end. No food strainer involved unless you wanted to add in a finely blended mash.
The process involves steaming the grapes over boiling water with an in-between spouted catchment pot. When the steamed grapes have reduced by 3/4, I drain the steamed juice into hot quart bottles and cap. They all seal from the hot juice cooling. Very quick!
I usually can about 24 quarts of grape juice plus apple and pear juice from surplus.
i have one as well. do you mash your fruit once they have softened? your juice is pretty clear so im guessing you dont. i like to crush mine a little to help the juice release but then you get more pulp in the juice.
I mash a bit with the grapes. With apples and pears I can the pomace separately as a thick apple/pear sauce. Aside from my dehydrator, I think the steam juicer is my best preserving appliance!
i made a bunch of cherry juice with my sour cherries and black currant juice. the chics get the pulp and seeds. black currant juice is so rich i have to cut it by half with water. tastes like a rich concord grape juice.
@lordkiwi, I’m not trying to protect the original color, which is an ugly gray/green. I like the pink or red colors that come with pressure cooking, but I’m curious about why the color changes. Also, grapes already contain a relatively large amount of antioxidants.
@cdamarjian, thanks for your comments about steam canners. I’ve tried steam-cannng by using my pressure canner without applying any pressure. It works fine, but, as mentioned above, I prefer the color of the pressure-canned juice. I also want to incorporate as much of the grape pulp and skin into the juice as possible. Many of the nutrients in grapes are located in the skin.
The pink/red/purple color in grapes is due to a class of chemicals called anthocyanins. These can also exist as a colorless form called leucoanthocyanins. Heating these compounds in an acidic environment like fruit juice can convert them to the colored form.
If you have ever cooked quince and had it turn pink, the same process was at work.
I have himrod and the vine has been building up, next year I’ll probably have enough to juice. I was planning to pressure can it, it would be nice if it was pink instead of grey!
I’ve noticed with other grape juices that if I don’t get all the skin out, it can make me nauseous to drink it later. I strain really well now, stems and pits I remove then I cook down in water the remaining flesh then strain well to get the skins and most pulp out. then can it.
I have a steam juicer. You put the fruit in (some put it in with the stems, etc. but I pick the grapes off) and it extracts the juice from the fruit as well as the skins. I know this because the inside of a Concord grape is green but the juice comes out a very deep purple. I don’t have to worry about seeds, skins or any of the debris and it really is no work. It even has a hose that makes filling the canning jars a breeze. I think I got it through Lehman’s, but price around as they aren’t always inexpensive. What is left in the colander part looks rather sickly. The fruit is grayish-beige and kind of shrivelled. This is how you know you’ve extracted all that there is to be extracted. I didn’t get any grapes last year because of a late spring freeze, but this year is making up for it. I am very excited to get going with them.
I agree…a steam juicer is the way to go! After years of water bath canning, this is so much simper. Pour hot juice into hot jars and they seal themselves. Plus if the fruit is seedless and the skins are tender you get fruit juice plus fruit puree. This is cherry juice and thick puree from Royal Anne cherries.
Written by Abigail Lambert under the direction and review of Hope Kleine, former SDSU Extension Health Education Field Specialist.
Steam Canning
Steam canning is a quick and simple method of preserving produce using steam. While steam canning was previously not an evidence-based practice, recently the University of Wisconsin published research indicating steam canning may be a safe home food preservation canning method for naturally acid and acidified foods.
Steam canners may look similar to water bath canners or they may have a shallow bottom, a wire rack that holds jars above the base and a dome-shaped lid (see below). Jars sit on a rack above the water-filled base. Processing is done by hot steam. The steam canner uses less water than a water bath canner. This helps speed up the processing time as there is less water to heat. It also makes it easier to remove from the heat after processing is complete.
A FEW THINGS TO CONSIDER WHEN USING A STEAM CANNER.
Foods must have a pH of 4.6 or lower in order to process safely.
Correct me if you are referring to something else, but my understanding is that steam canning is another way to heat the jars after they are filled, similar to a hot water bath.
It isn’t considered safe anymore. Probably it never was. I know it seems like a good idea, but,as a practical matter, it doesn’t really work. My Dad’s mother owned and operated a Conservo successfully — presumably canning tomato juice. My Mom inherited it, and we threw out a lot of canned green beans that went bad in storage. It may be good enough for acidic fluids, but for non-acidic solids … not so much. I think there’s just no way it gets hot enough and stays hot enough long enough. The door isn’t tight. Certainly canning meat — as the above promotional materials suggest you do — would amount to taking your family’s life in your hands.
Equipment and methods not recommended
Open-kettle canning and the processing of freshly filled jars in conventional ovens, microwave ovens, and dishwashers are not recommended, because these practices do not prevent all risks of spoilage. Steam canners are not currently recommended because processing times for use with current models are still being researched. It is not recommended that pressure processes in excess of 15 PSI be applied when using new pressure canning equipment. So-called canning powders are useless as preservatives and do not replace the need for proper heat processing. Jars with wire bails and glass caps make attractive antiques or storage containers for dry food ingredients but are not recommended for use in canning. Neither one-piece zinc porcelain-lined caps nor zinc caps that use flat rubber rings for sealing jars are recommended any longer.
