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Fruit Preserved in the Sun
Sun-preserved fruits are acknowledged to be better than those cooked in the ordinary way. Strawberries and raspberries may be preserved in this way, and, where one has access to a hot-bed, the labor is much lessened. Place the berries in a wire basket and plunge into a pan of cold water. Drain thoroughly, pick over, stem, being careful not to bruise the fruit. Weigh the berries and to each pound allow one pound of granulated sugar. Heat large earthenware plates in the oven, sprinkle with a layer of granulated sugar and over this place the berries. Cover with glass and stand in the sun's hottest rays. Shift the plates as the sun changes its position. About four o'clock bring the plates in and stand over night in a cool place. Bring them out again the next day into the hot sun, as before. By this time they will have a semi-transparent look and be tender, but perfectly preserved in form. With a fork lift each berry separately and place in a tumbler or jar. Boil the syrup for a few moments until it thickens somewhat, then strain, cool and pour over the berries.
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This is a solar preserve: fruit is never boiled, and nothing about the finished jar is sterile. The points below explain where the method breaks down rather than how to rescue it.
- Nothing reaches a killing temperatureFruit under glass in full sun reaches perhaps 120-150F, well short of anything that destroys mold spores, yeasts or the surface microflora of soft berries. Only the syrup is briefly boiled, and it is cooled before it goes over the fruit, so the berries themselves are effectively raw.
- No seal, no processingThe berries are lifted into "a tumbler or jar" and the syrup poured over. There is no water bath, no vacuum, and in the case of a tumbler no closure at all. A jar filled this way is a room-temperature culture vessel, not a preserve, and the book gives no storage instruction to compensate.
- The sugar concentration is not high enough to do the job aloneThe sugar concentration may not be high enough to do the job alone -- Preservation by sugar depends on driving the finished syrup to roughly 65 percent soluble solids, which is why conventional jams are boiled hard to a set. Here the syrup is thickened only "for a few moments," and then goes back onto fruit that is still giving up juice. The recipe offers no way to check the finished concentration, so there is no assurance it is high enough to prevent fermentation.
- Two days of open-air exposureThe plates stand outdoors from morning until four o'clock, twice, covered by a sheet of glass that is not airtight. Insects and airborne yeasts have access. Bringing the plates in overnight to "a cool place" in 1911 meant a cellar, larder or at best an icebox, not modern refrigeration.
- The spoilage risk is mold and fermentation, not botulismBerries are acidic enough that Clostridium botulinum is not the hazard; the realistic outcomes are surface mold, alcoholic fermentation and a blown jar. Some molds on stored fruit produce mycotoxins such as patulin, which is why skimming a fuzzy preserve and eating the rest was never as harmless as it was once thought.
- The hot-bedThe "hot-bed" mentioned in the first lines is a glazed garden frame heated from below by fermenting manure, used to force early seedlings. It is offered here as a ready-made solar oven, and it is also a reminder of how close this process sat to the barnyard.
- If you want the resultWhole berries suspended intact in a light syrup are worth having, and modern preserving books achieve it with short-boil methods, refrigerator jams or freezer jams that are properly measured and properly stored. Use a current tested recipe rather than this one.
Sun preserving was a genuine tradition rather than an eccentricity, practiced wherever there was reliable July heat, and prized for exactly the reason given here: gentle drying concentrates the syrup without the hard boil that collapses a strawberry into jam. Nineteenth-century American cookery writers printed versions of the method, and the semi-transparent whole fruit it produced was the mark of a skilled preserver. Its appearance in The Butterick Cook Book of 1911 sits at the end of that line. The same decade saw state agricultural extension services and the emerging science of home canning push households toward measured processing times, sealed jars and the boiling-water bath, and recipes that relied on sunshine and a pane of glass quietly disappeared from the canning chapters that followed.