Every August, when the summer squash starts piling up on my kitchen counter faster than I can fry it, roast it, or tuck it into casseroles, I get curious. That kind of curiosity is part thrift, part farm-country stubbornness, and part plain old kitchen habit from a life spent trying not to waste good produce. So when I had a basket of firm young yellow squash and zucchini that needed using, I decided to try an odd little experiment: no vinegar brine, no salt ferment, just cold prune juice, whole dried spearmint leaves, and a hearty squeeze of cod liver oil, with the squash spears kept fully submerged for 7 days.
I will tell you right up front that what happened was not a charming old-fashioned miracle in a jar. It was a lesson, and sometimes those are worth more than a recipe. In this piece, I’m walking you through exactly what I used, how it looked and smelled day by day, what changed in texture and flavor, why this mixture behaved the way it did, and most importantly, why this is not a safe preservation method for summer squash. If you enjoy kitchen experiments, stay with me. If you’re trying to put food by safely, I especially want you to read to the end.
1. Why I tried such a strange combination in the first place
Folks who have canned and pickled for decades will understand this: every now and then, you start wondering what happens if you step outside the usual rules. I had about 2 1/2 pounds of fresh-picked summer squash, mostly yellow crookneck with a few straight zucchini, all harvested within 24 hours. They were beautiful, 6 to 8 inches long, with glossy skin and no soft spots. Under ordinary circumstances, I would have made refrigerator pickles with a standard 5% acidity vinegar brine.
But that week, I had been thinking about old pantry habits, sweet-savory preserves, and how people once used whatever they had on hand. Prune juice is dense, sweet, and dark. Spearmint has a clean, cool scent that can flatter vegetables. Cod liver oil, though certainly not common in preserving, has long been one of those old-time household staples many of us remember from winter doses at the kitchen table. I wasn’t expecting it to make a proper pickle. I was trying to observe what happened when squash sat submerged in a low-acid, sugary liquid with herbs and oil.
2. Exactly what I used
Here are the quantities as close as I measured them. I sliced the squash into spears roughly 3/4 inch thick and 4 to 5 inches long, enough to pack into one clean 1-quart glass jar. The liquid mixture was 2 cups of chilled prune juice, 1 tablespoon whole dried spearmint leaves, and about 1 1/2 tablespoons cod liver oil. I pressed the squash down and added enough extra prune juice, about another 1/4 cup, to keep everything covered.
I used a wide-mouth quart jar, a nonreactive fermentation weight, and a lid screwed on loosely. I did not heat the liquid. I did not add vinegar. I did not add salt. I did not add sugar because prune juice already carries plenty; depending on brand, 8 ounces often contains around 24 to 30 grams of sugar. That matters, as I’ll explain later, because sugar feeds the wrong kind of activity if acidity and salt are not there to control it.
3. How I prepared the squash and the jar
I washed the squash under cool running water, trimmed both ends, and cut away one bruised patch no bigger than a quarter. The jar went through a hot, soapy wash and a very thorough rinse. That is good housekeeping, but let me be clear: a clean jar does not make an unsafe preserving method safe. Cleanliness reduces surface dirt and some microbes. It does not substitute for proper acidity, proper salt concentration, refrigeration rules, or tested canning methods.
I packed the spears upright as tightly as I could without crushing them. Summer squash contains a lot of water and has tender flesh, so I wanted to start with the freshest, firmest produce possible. If a vegetable is going to hold texture at all, freshness buys you time. Even so, summer squash is one of the softer vegetables, and unlike cucumbers, it does not stay crisp for long under adverse conditions.
4. What the mixture looked like on day 1
On the first day, the jar looked almost handsome in a rustic sort of way. The prune juice was a deep reddish brown, nearly opaque. The whole spearmint leaves floated at first, then some settled around the sides. The cod liver oil formed a pale golden sheen and a few rounded slicks across the top before I pressed the weight into place. The squash spears, bright yellow and green at the outset, looked dramatic against the dark liquid.
But even at that stage, there were a few warning signs for anyone who has done much preserving. Proper pickling brine usually looks clean and purposeful. This looked unsettled. The oil wanted to separate. The dried mint wanted to trap air. The sugary juice clung thickly to the vegetable surfaces. It was not a stable system. It was simply ingredients sharing a jar.
5. Days 2 and 3: the first changes
By the second day, the squash had already started losing its fresh look. The green zucchini skins dulled first, then the yellow squash turned from sunny and vivid to a muted mustard shade. The prune juice had thinned slightly as water moved out of the squash tissue and into the surrounding liquid. That’s osmosis at work, though in this case not in a useful preserving way.
The smell when I cracked the lid for a cautious sniff was sweet, grassy, and a little fishy at the edges. The mint was noticeable but not strong enough to cover the cod liver oil. By the third day, the aroma was more confused than offensive: stewed fruit, damp herbs, green squash, and a marine note from the oil. Not rotten yet, but not appetizing either. The surface oil had broken into tiny globules, and a faint foamy ring had begun to appear around the inside of the jar near the top liquid line.
6. Days 4 and 5: texture started going downhill fast
Midway through the week, the real decline showed up in the texture. I lifted one spear with a fork on day 4, and instead of staying straight and crisp, it bent in the middle. The outside was still intact, but the inner flesh had gone from firm to sponge-like. Summer squash has delicate cell walls to begin with, and without salt or acid to shape the process, those tissues break down quickly.
By day 5, the prune juice had taken on a murkier look. The mint leaves were swollen and olive-brown instead of green. The squash surfaces looked slippery. That is a word home preservers learn to respect. Slippery can mean pectin breakdown, microbial growth, or both. Once produce starts turning slick in an untested preservation mixture, I no longer think in terms of “maybe it’s developing flavor.” I think in terms of “this is leaving the safe and sensible zone.”
7. Days 6 and 7: this is what happened in the end
At the 7-day mark, the jar did not contain pickles. It contained softened squash spears in a sweet, dark, separated liquid that smelled wrong for food storage. The pieces were fully saturated with prune juice and had turned brownish in spots, especially where the cut sides faced outward. When I pressed one spear gently against the side of a bowl, it yielded almost immediately. It was not crisp, not snappy, and not pleasantly marinated. It was soft enough that I would call it borderline mushy.
The smell was the deciding factor. The prune scent had become heavier and more fermented-smelling, though not in the clean, tangy way of a proper lacto-ferment. There was still an oily fish note from the cod liver oil, and the mint came across stale rather than fresh. I did not taste it. I discarded the contents. That was the correct choice.
8. Why this did not preserve the squash
Real preservation depends on control. A tested pickle uses acid, usually vinegar at 5% acidity, to push the pH low enough to inhibit dangerous microbes. A tested ferment uses a measured salt percentage, often 2% to 5% by weight, to favor beneficial lactic acid bacteria while suppressing spoilage organisms. Pressure canning uses high heat to destroy microbes in low-acid foods. This jar had none of those protections.
Prune juice is not an approved pickling medium. It is sweet and moderately acidic by beverage standards, but not reliably acidic enough, or formulated in a controlled enough way, to preserve low-acid vegetables like summer squash. The cod liver oil made matters worse by adding a separate fat layer. Oil in vegetable preservation can create oxygen-limited pockets and complicate spoilage patterns. The dried spearmint contributed aroma, but aroma is not preservation.
9. The food safety issue I want to be plain about
Low-acid vegetables such as summer squash need special care. The danger with improvised preservation is not just that the food may smell bad or turn mushy. The danger is that harmful bacteria can grow without obvious warning signs. Some unsafe foods do smell rotten. Others do not. You cannot judge safety by “looks okay to me.”
Because this mixture contained a low-acid vegetable, no tested vinegar brine, no proper salt fermentation ratio, and oil, it should not be considered safe preserved food at room temperature or as a casual experiment to taste later. Even under refrigeration, it would be an untested preparation I would not trust after several days. I say this as someone raised to use things up and not waste food: throwing out a bad experiment is cheaper than getting sick.
10. What surprised me most
The speed of the texture loss surprised me. In just 4 to 5 days, those firm squash spears had gone from garden-fresh to noticeably limp. Cucumbers can hold on a little longer under poor treatment. Summer squash really cannot. Its water content is high, its flesh is tender, and it simply does not have the natural staying power that makes a classic dill pickle possible.
The second surprise was how little the mint contributed. I expected the spearmint to bring brightness, but the prune juice dominated the scent profile, and the cod liver oil muddied everything further. If you’ve ever tried to freshen a room with a single mint sachet while something fishy is cooking, you know the principle. One note cannot rescue an unbalanced whole.
11. What each ingredient contributed after 7 days
The summer squash contributed water, enzymes, and a tender vegetable structure that broke down quickly. The prune juice contributed sugar, color, and a deep fruit aroma, but not the crisping or preserving effects you get from a proper pickling liquid. It also stained the squash enough that the pale interiors looked tea-brown by the end of the week.
The whole dried spearmint leaves contributed a gentle herbal smell in the first 48 hours, then seemed to flatten out. Dried leaves can also trap little air pockets when floating near the top. The cod liver oil contributed slickness, separation, and an unmistakable flavor note that did not belong with squash in any happy culinary sense. Of the three additions, it was by far the most disruptive.
12. If you want to experiment safely, here is how I would do it instead
If the appeal here is the sweetness and herbiness, I would move that idea into a refrigerator quick-pickle built on a tested acidic base. For 2 pounds of summer squash spears, I would use 2 cups white vinegar at 5% acidity, 2 cups water, 2 tablespoons pickling salt, and 2 to 4 tablespoons sugar. Then I would add 1 to 2 teaspoons dried spearmint, or better yet 2 to 3 small fresh sprigs, plus maybe a few peppercorns. Bring the brine to a boil, pour it hot over the packed squash, cool, and refrigerate. Eat within 1 week for best texture.
If you want prune flavor, I would use it in a cooked chutney or relish instead of a soaking liquid. For example, 4 cups diced summer squash, 1 cup chopped onion, 1 cup chopped prunes, 1 1/2 cups cider vinegar, 3/4 cup brown sugar, 1 tablespoon grated ginger, and 1 teaspoon salt can be simmered 35 to 45 minutes into a spoonable condiment. That gives you sweetness and depth in a form that makes culinary sense.
13. Better ways to preserve August summer squash
After all my years in the kitchen, I think summer squash is best preserved by methods that respect its softness. Freezing works better than canning for plain squash. I usually grate or slice it, blanch slices for 3 minutes, cool in ice water, drain very well, and freeze in 2-cup portions. For grated zucchini for baking, I often skip blanching, pack 2 cups per freezer bag, and squeeze out some moisture after thawing.
Pickling can work as a refrigerator item if you keep expectations realistic. Summer squash will not stay as crisp as cucumber, but it can still be tasty for 5 to 7 days chilled in a proper brine. Relish, chutney, and zucchini butter are also good choices. Around here, plenty of us shred overgrown squash into soups, spaghetti sauce, and quick breads, because not every harvest wants to be a pickle.
14. My final verdict after 7 days
What happened was simple: the squash softened, darkened, took on an unpleasant sweet-herbal-fishy smell, and failed as a preservation project. It did not become a safe pickle, a successful ferment, or a secret old-country delicacy. It became kitchen evidence that not every jarred idea deserves a second batch.
There’s no shame in that. Some of the best cooking wisdom I know came from seeing what did not work. My mother had a way of saying, “Well, now we know.” That’s exactly how I feel about this one. We know prune juice, dried spearmint, and cod liver oil are not a substitute for pickling brine. And if this little misadventure saves somebody else a basket of squash and a risky jar on the counter, then it was worth telling.
