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Sep 2, 2009 01:27 AM

pH test strips to measure range of pH 3 to 6?

I posted on the Cookware board asking for a way to test pH for home canning purposes. Fritter suggested test strips for the mildly acidic range between pH 3 and 6.

Problem is I need them by friday morning. I've checked with a couple pharmacies and the type they stock are for pH 5 to 9 range.

Any ideas where I can get my hands on some NOW?

Cookware board:
pH test kits for home canning tomatoes?

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  1. The Master Food Preservers at your local Cooperative Extension Office could probably sell you a roll or "give" you a piece. There's one in Sacramento County - (916) 875-6913, and also one in El Dorado County.
    I would imagine grocery chain stores would have some, especially meat departments. Or, try food products vendors or culinary schools.

    1. Try calling Oak Barrel Winecraft in Berkeley. Rationale: vinegar pH about 3, they have supplies to make vinegar ergo perhaps they have testing equipment.

      Oak Barrel Winecraft
      1443 San Pablo Ave, Berkeley, CA

      1 Reply
      1. re: wolfe

        I spoke to the folks at Oak Barrel Winecraft. They have beer strips and wine strips, $6.50 per 100. The wine test strips measure from 2.8 to 4.4 and the beer strips measure from 4.6 to 6.2. For my range, I'd need to purchase a pack of each, but it could be a handy solution for someone nearby.

      2. Hydroponic supply stores sell pH meters which are more expensive but presumably would also supply a full range for other errr... projects.

        1 Reply
        1. re: little big al

          I wanted to report on what I've learned so far. The cheapest from hydroponics stores, about $7.50 for a kit, is General Hydroponics pH test indicator, which measures from 4.0 to 8.5. However, it does not have a fine gradation at the lower end that I need. Here's what it looks like.

        2. I canned some san marzanos from mariquita two weekends ago and I happen to have access to some pH paper (4 to 7, don't tell my boss) from work. If you're curious, the sauce ended up right at 4.4, which is the cutoff point for safe canning. I added 0.25tsp of citric acid/pint to a pint and conducted a taste test (see Well Preserved by Eugenia Bone). People really couldn't tell the citric acid was there, aside from one mildly positive comment about "brighter flavor." The strip said the sauce was about 4.3-4.4. So... to be on the safe side, I added the citric acid to all the jars. Some recipes say to add vinegar or bottled lemon juice, but I much prefer citric acid b/c it doesn't add any extra flavors.

          Anyhow, if you're desperate for some, I could give you some strips. I'm in SF, drop me a msg at the address in my profile.

          12 Replies
          1. re: sfbing

            Thanks so much for the info and your kind offer. Our San Marzanos from Mariquita are being delivered today. It will be very interesting to see what the numbers turn out to be for our batches compared to yours.

            Would I be able to buy citric acid at Rainbow or where did you purchase yours? You can tell I've never done this before . . .

            1. re: Melanie Wong

              I got my citric acid for cheesemaking at BBE in bulk section if Rainbow fails you but I doubt it.

              1. re: Melanie Wong

                Just in case Rainbow doesn't have it, I got my citric acid at 22nd and Irving on the bottom shelf where they have all their spices. (I tried Andronico's, Safeway, and Whole Foods but no dice.)

                I took the tomato canning class that happy girl kitchen offers, and Todd Champagne mentioned that different batches from the same farmer are usually very consistent with regard to pH but that batches from different farmers can differ.

                1. re: sfbing

                  Great, that works for me. I'll be in the Sunset tomorrow and can swing by.

                  Consistency from a single farm makes sense to me. It will be interesting to see if our later harvest date and presumably more ripeness after Saturday's heat wave makes much of a difference. I've asked one of my canning partners to get a lab notebook for us to record our info!

                  22nd & Irving Produce
                  2101 Irving St, San Francisco, CA

                  1. re: Melanie Wong

                    I have San Marzanos from Mariquita from last Saturday and am not canning them. But juice from the seeding is in the low 4's. My pH paper is full range so not as exact.

                    1. re: wally

                      I had emailed Julia to ask if she had a pH range for Mariquita's tomatoes. No data available, so I'm sure she'll be happy to get all this info.

                    2. re: Melanie Wong

                      Have fun! (I am also doing a canning party, hence my obsession with pH.)
                      I should also mention that I asked Andy of Mariquita about tomatoes for sauce. He said that the Early Girls are also popular for sauce, partially because they are more acid and therefore seem to taste more tomatoey to some people. However, the drawback is that they have a lot more water than the San Marzano, so take longer to cook down. Apparently some people also use his heirlooms to make sauce--the end result is orange rather than red. (I would definitely be concerned about pH with the heirlooms, though.) Like you, we went with the San Marzanos, but maybe we'll try another tomato in the future.

                      1. re: sfbing

                        I grew Big Rainbows this season which is a potato leaf heirloom. The fruit is orange. Very tasty but I'm not sure I would want to can an orange mater. I have some black from Tulas that might be an interesting option though.

                        1. re: Fritter

                          Where did you get the black from Tulas?

                          1. re: wally

                            I'm in greater Detroit and a local Organic farmer had the plants this spring.
                            A delicious tomato if you get a chance to try or grow them in the future.

                            1. re: Fritter

                              Oh ,well. I had them here a couple of years ago, but not lately.

                      2. re: Melanie Wong

                        Back in the City today, stopped by 22nd & Irving, no citric acid left. I even asked an employee to help me, and he was surprised that it was all gone, so must be a recent occurance. Not wanting to find an empty bin marked "citric acid" at Rainbow tomorrow morning, on my way down to Menlo Park, I stopped at Aladdin in San Mateo (on Hillsdale, just off 101) and bought some there.

                        Aladdin Deli & Market
                        224 E Hillsdale Blvd, San Mateo, CA 94403

                2. Depends where you are. I'm 95% certain the ph strips I buy from SF Brewcraft on Clement street cover the mildly acidic range you mention; they're always around and would answer the phone. I think they come out around $0.25 each, sold as how ever many you want.

                  Oak Barrel also probably carries them. I think there are also home brew stores up in Santa Rosa.

                  Places is cranky, so here's the info:
                  1555 Clement St.
                  San Francisco

                  12 Replies
                  1. re: SteveG

                    Yeah, I feel really dumb that I didn't know this when I was in wine country two days ago, would have been so easy.

                    The guy at San Francisco Brewcraft answered the phone even though the store doesn't open until noon. The beer or wine test strips, for the range I noted above, are 50¢ each.

                    I also called More Wine (aka Fermentation Frenzy) in Los Altos. There's a second local store in Concord. It has test paper to measure the 3.0 to 6.0 range, 10 sheets for $1.80. One of our canners is coming from Palo Alto, so I'll have her pick it up for us.


                    95 Detroit Ave. Unit G
                    Concord, CA 94518
                    Phone: 925-671-4958
                    Fax: 925-671-4978
                    Mon - Fri 9am to 6pm
                    Sat & Sun 10am to 5pm

                    991 N. San Antonio Road
                    Los Altos, CA 94022
                    Phone: (650) 949-BREW (2739
                    )Mon - Fri 10am to 6pm
                    Sat & Sun 10am to 5pm

                    San Francisco Brewcraft
                    1555 Clement Street, San Francisco, CA

                    1. re: Melanie Wong

                      I have a PH meter for soil which measures from 3 to 8, its new so not dirtied up. Can you use this????

                      1. re: celeryroot

                        You're a gem! But I won't be back to Healdsburg to get it until after the canning party in SF. I had checked garden supply places and the range the simple kits measured bottomed out at 5.0. Thanks for the offer.

                        1. re: Melanie Wong

                          Melanie, I've been reading all your posts..I assume you got the citric acid by now at Rainbow. I also picked up SM's today. I was curious if you are using a pressure canner or a water bath. Acidity is more a concern with a water bath as more bacteria survives a water bath method. Are you doing hot pack or raw?

                          1. re: cakebaker

                            With a pressure canner you usually don't have to worry about acidity, if you follow directions.

                            1. re: cakebaker

                              I'm not back in the City yet. The plan is to cook sauce then process it in a water bath. We are descending on a friend's new condo on friday for the project. I've not canned before and will show up with a borrowed food mill and tomato press, plus 10.875 qts worth of canning jars I scrounged from various households this week. Others are more experienced than I, fortunately, but the Italians are aghast at the thought of adding acid. I was happy to read sfbing's finding with Mariquita's product and look forward to hearing about yours.

                              Here's a thread on the Home Cooking board about pressure canning tomatoes that might be the more appropriate place to comment.

                              Here are the guidelines for home canning that raised the acidity concerns for us.
                              The section on acidity says: "Researchers at USDA and at the University of Minnesota have found that most underripe to ripe, cooked tomatoes have a pH below 4.6. Unfortunately, a few varieties may have a pH above or close to 4.6. These include Ace, Ace 55VF, Beefmaster Hybrid, Big Early Hybrid, Big Girl, Big Set, Burpee VF Hybrid, Cal Ace, Delicious, Fireball, Garden State, Royal Chico, and **SAN MARZANO**. Some of these are grown for commercial purposes and are not found in home gardens. However, safely canning these varieties requires additional acid for water bath processing or a pressure canning process similar to low acid vegetables." (emphasis added


                              P.S. would you believe that I'm roasting my last 2#s of raw Hatch chiles now?

                              1. re: Melanie Wong

                                How about new canning jar lids? The rubber seals aren't intended for reuse, and while they're fine a time or two, I find they pick up odors and it's best to use new. My noccino has a subtle but present fermented garlic pickle note...

                                1. re: SteveG

                                  De rigueur at the kitchen where I volunteer and jar food weekly. A new lid for every jar.

                                  1. re: SteveG

                                    Yep, I've got new canning jar lids, both sizes. Bought them at Ace hardware, marked down a little (~10¢) until 9/7. Also have quart-size freezer bags and some squarish containers to freeze sauce.

                          2. re: Melanie Wong

                            I'll be waiting to see your results. An excellent expiriment.
                            Will you be testing different methods? Lime Juice Vs Vinegar Vs Citric acid Vs Au natural?

                            1. re: Melanie Wong

                              Cool, thanks for researching everything! I'll check out the place in Los Altos, that's a better price than SF Brewcraft. The nerd in me wants to check the PH of my grain mash constantly at different temperature rests, but it seems wasteful at $0.50 a shot, especially if I have to adjust the ph and retest.

                              You can definitely buy citric acid at Rainbow Grocery. It's near the bulk refrigerator with the individual mason jars above the bulk nut butters/behind the bulk oil spigots. Comes in a small jar that looks like a vitamin jar, from the same vendor as some of their vitamins and supplements.

                              1. re: SteveG

                                You might want to get a pH meter, then you can take as many measurements as you want. I think I remember the description saying that it would calculate the effects of temperature on pH. The place in Los Altos has a handheld one for $90. My canning partner bought the only two pH 3 to 6 strips in stock. They measure in 0.5 increments.

                                To nerd out myself, I did pick up a few strips from SF Brewcraft today. The ones for wine measure 2.8 3.1 3.4 3.6 3.8 4.0 4.3 4.6