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Partial Dehydration as a Technique to Control Fermentation and Yeast Inhibited Fruit Ferments

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In a world where everything seems to have been done before, I have not seen reference to this technique anywhere, so would like to share it for others to try.

Three years ago, I harvested 10 pounds of sweet cherries. I was drying some and trying to think of extra things to do with them besides obvious go-tos like pies. I swear, every time that I forage fruit in town, I get asked if I am making a pie. I had crushed the cherries with the side of a knife for easy pit removal. This released the juices somewhat in the process. I laid them out on silicone baking sheets atop sheet pans on a speed rack in my closet dehydrator. The low temp, but quick dry, was leading to something delicious on its own. The sweet cherries were turning tart, while the sweetness was also increasing. The cool temps didn't cause the flavor to flatten like most heated dehydrators. Each cherry developed a small syrupy juice puddle under it. As they began to develop a touch of chewy gumminess, I began to wonder what the outcome of fermenting them after dehydrating them would be. At that time, there was robust cherry flavor, a sweetness that tempered the now concentrated malic, citric, tartaric, succinic, quinic, shikimic, glyceric and glycolic acids. The flavors were bold but well paired.

 Sadly, this is the only picture that I took in the process. The remnants of the half gallon that I started with. Still tasty but very different than at its one year pinnacle.

Sadly, this is the only picture that I took in the process. The remnants of the half gallon that I started with. Still tasty but very different than at its one year pinnacle.

I had the door open to thoughts on "half-drying" as a culinary method from reading Fish That We Eat (Iqaluich Niginaqtuat) by Anore Jones (nooo, not the singer!). Jones is an anthropologist who lived in the Kotzebue Sound region in northwestern Alaska. She lived in the region for about 20 years with direct experience in the communities which were still largely living a subsistence lifestyle. The subsistence strategies for the area relied very heavily on the boreal fish species in the rivers and in the Kotzebue Sound, due to lack of access to the ocean and having a low population of land-based mammals in the area. I've gobbled up any research from this region as most of their fish are available in my area. This book covers every fish located there and every preparation for every fish. Half drying as a culinary technique to change texture was common throughout the book.

 My tattered printed copy of Fish That We Eat has been put to a lot of use. It would be helpful to all northern areas around the world including sub-boreal Minnesota. This can be downloaded online.

My tattered printed copy of Fish That We Eat has been put to a lot of use. It would be helpful to all northern areas around the world including sub-boreal Minnesota. This can be downloaded online.

 

Dehydration is nothing new. It's a common technique that has been expanded into drying and powdering everything. We dry age meats which reduces water levels while enzymes are still doing their work. With making salumi and salami, the water activity levels are important to the process and narrowing the range of microorganisms. So why not use this as a control for fermentation of fruits and vegetables. I was searching for fruit fermentation techniques that didn't run towards alcoholic, but weren't salted either.

With fermentation, there are many potentials for control. Whether we are always cognizant of all the ones we are using at any moment, we are still usually using two or three of the following list:

  • fermentable carbohydate content, which can sometimes be increased by using enzymes such as those provided with koji to make the carbs contained more available.
  • salinity, which can control the ranges of possible bacteria in the substrate. This is especially helpful for lacto-fermentation and in inhibiting some molds.
  • ph; in fermentation, we commonly use microorganisms to make things more acidic for inhibiting certain bacteria, encouraging those we want, while developing flavor. There are many chemical changes made to foods with minerals which fit more with fermentation than other techniques such as lutefisk, masa, hominy, etc. The alkaline changes affect texture (frequently giving more chew and water retention) and commonly increasing assimilation of nutrients from grains.
  • temperature, which can have a big outcome on taste. A fermentation student once brought in some kraut that he'd made but was scared to leave on the counter. In the fridge, the enzymes did their work, while the bacteria worked slow. It was limp, salty, cabbage with very mild acidity reminiscent of flat soda. Kraut made in the heat of summer especially in an Indiana summer always tasted kinda off to me. The chemical cascades fell differently with things acting faster leading to a flavor that I didn't like. A Miso year is spring through fall; it being important to have gone through the summer heat. Gochujang is in opaque crocks in the direct sun. Fish sauce can take months in tropical Thailand and in some cases up to ten years in the colder climes of northern Japan due to temperature. You can also maintain 140f or more and make the process chemical with proteolytic enzymes doing all of the work instead of microorganisms. Commonly cellar temp is the sweet spot for flavor with lacto-ferments.
  • range of active microbes. Misos, kombucha, kefir among others are actions by yeasts and bacteria. Alcohol is action by yeast, which bacteria can then feed on for acetic acid to make vinegar. Yeasts for breads. Bacteria for kraut, kimchi, pickles, and other lacto-ferments. Molds are used for tempeh and koji based ferments with the koji usually being the first stage ferment to others that will follow.
  • oxygen levels. Some bacteria and molds can be inhibited by reduced oxygen. Yeasts and some bacteria can live off of displaced oxygen.
  • humidity, which can affect molds ability to grow or not which is especially important for koji and tempeh.
  • water activity levels. When foods are dehydrated, microorganisms are retarded. Think of the stability of dry grains and legumes compared to the fermentation of grains once soaked such as idli and dosa. Water activity levels are integral to HAACP plans for production salumi plants and equally important for those curing at home.

Certain things almost decide the path for themselves. Making lactofermented pickles, for example, use salinity, ph, and to some degree, temperature. In search of fermented fruit that is not yeast driven, I've tried a few things. One, I've fermented fruit in the fridge with added lacto-bacteria to slow down the yeast. I left these in the fridge for 1-2 years, allowing for enzymes and bacteria to slowly work while inhibiting the yeast, and was very pleased with the results. These were sealed in a jar. There was still some slow yeast action, so some gas built up, but it was verrry slow. I would open the jars occasionally to check the progress. I have some that I want to taste soon, that I've left since summer 2013. I've loved them after a year, but wanted to see what would happen over time if forgotten about.

Back to partially dried cherries... They were delicious coming out of the dehydrator. I put them in a jar making sure to use a rubber spatula to scrape all the juice from the silicone baking sheet into the jar. Living dangerously, I didn't use an airlock and just left the lid a touch loose. I wanted to check on it as it evolved, so the airlock would have been an annoyance. The next day, viscous juice started pooling eventually covering cherries, which I was happy about, since it should decrease the chance of mold. The build up of gas even over the course of the summer was slow. It seemed most of the microbial activity was bacterial with slight yeast action. The development of alcohol was slow, while the flavor and texture was noticeably changing. The pinnacle point was one year out. The bold cherry flavor was there, quite a bit of the original sweetness remained, while the texture had changed and the flavor had matured. There was a touch of alcohol that gave an added mouth feel. It had a feel on the teeth like the chew of masa. There was a pleasing resistance. This was accompanied by the tongue-coating syrup. It was well balanced in a way that it didn't need anything to accompany it, though something dry or crisp would give a lot to it.

Over the course of the next year, the sweetness faded some and more alcohol appeared. There was still chew, but the masa-like stick-to-your-teeth feel was slowly fading a bit over time. The alcohol slowly gave way to acetic acid, muting the pleasant diverse acidity, as the vinegar got louder. These changes were interesting to taste and feel. It was a few months after the two year mark, that the flavor changed a lot. What was something to build a dish around, is now more of a third tier addition. It can add to a dish but needs to be a hushed addition, rounding out other flavors.

Since this was an experiment, I didn't want to go too hard applying the technique to a ton of different foods and lose them all. I did try it on the sweet cherries (sour cherries would be like crybaby candies in their sourness), service berries (Amelanchier), blueberries, and peaches. This method seems to work well on the fruits with juicy nectar like the stone fruit section of the rose family, such as peaches, apricots, and nectarines. I think it could work for over ripe pears. Perhaps partially dried apples, though you may have to add some reduced apple cider to cover over (it seems preferable for the fermentation that it be reduced by dehydration). I think making it with grapes would be delicious with a riff on jelly. Pulpy fruits, like service berries, didn't take to it too well. I ended up eating them before that went bad, because it seemed imminent that they were heading there. I would like to try a batch that will be pureed after the drying step for something like preserves, while most will still go towards this whole-fruit-covered-in-its-syrup original

Give it a shot, and give feedback!