decadence by hand

finely crafted foods and woodenware

Food Microbiology Meets Tradionally-Inspired Ferments for Flavor


Arielle Johnson, the PhD food and flavor chemist of NOMA/MAD, wrote a great article about the use of food microbiology for creating flavors and ingredients by restaurants and home food hobbyists. It describes the union of traditional ferments and fermentation techniques with food science to explore more deeply the potential for cuisine. I am excited to be mentioned among so many chefs that I respect. 

Artisanal Food Microbiology by Arielle Johnson - This link is for the original article in Nature Microbiology. It doesn't work on mobile.

SBS World News Australia - There is one of many spin-off articles referencing the above with mentions of the food projects that many, including me, have going.




Home-Scale Muro or Incubation Chamber for Koji and Tempeh

fermentation, kojidecadencebyhand4 Comments

With making koji and tempeh, having a muro or incubation chamber is a huge help. You get more consistent product and the process becomes more predictable. Most microorganisms have preferred environmental conditions. The closer that you stay to these conditions, the less other microbes you will grow that will ruin your batch. Too hot, too cold, too dry, and too saturated with moisture are all potential problems when making koji and tempeh.

Since I mostly write this for those who are making batches for home use, a good place to start is a wooden box. The wood gives some insulation and deals well with the moisture. With the high humidity, you don't end up with the condensation that you would with uninsulated metal walls. In addition, it can be used as home decor, instead of looking like a large alien object. I have built and advised on some for whom square footage or floor space was limited, so I built tall muros that would hold 6 koji trays at a time. My muro is four feet wide, three feet deep, and three feet tall. With this arrangement, I could fit about 20 trays, but haven't used near that many.

The temperature and moisture can be set using a few controls with a heater and a humidifier. For the temperature control, you can order an STC-1000 or a PID controller such as those from Auber Instruments. Both are affordable, especially if you have the minimal tools required and the wiring. You will be able to keep a narrow range of temperature this way. For the humidity control, you can get a WH8040. There are hundreds of wiring diagrams to be found online for how to wire these up so I will leave that to you. An overview of the typical setup: put both humidity and temperature controls in a project box with each wired to separate electrical outlets. The nice thing about this is that you can use this control combination for many purposes, including egg incubation, starting seeds indoors, meat curing chambers and more. You could even switch out the heater with an air conditioner, or the humidifier with a dehumidifier, for achieving other optimal climates. I do sell muros, which include the wiring and the box, typically affordable items in addition to my labor.

 My first control box. It's ugly, but works great! I've moved towards PID controls such as those from Auber Instruments.

My first control box. It's ugly, but works great! I've moved towards PID controls such as those from Auber Instruments.

For a simpler and more expensive option, there is also a "plug and play" from Auber Instuments Model TH210 that I haven't used but looks promising. There is no wiring to do with this product - you just plug in the heater and humidifier that you purchase separately, and then set the temp and humidity level on the control box.

For home use, my preferred heat source is a ceramic space heater, which moves the muro back up to temp within minutes, keeping your koji happy. They maintain the heat well also, while having lower fire risk compared to many other types of space heater. All in all, they make for the best of the heat options, combining ease, safety, and quality. Don't buy the smallest and cheapest heat source that you can get. Some will have faulty heat controls.

For humidity control, the best humidifier to get is an ultrasonic humidifier. You will have the least microbial issues. You don't want a warm mist type, cool mist type, or any with a filter. Also, always remember to dump your humidifier out after use to allow it to dry if you won't be using it for awhile to prevent unwanted mold.

In Japan, both in home scale and industrial scale, koji trays have been a major component of koji incubation. The trays are an added insulator that also wick away any excess moisture that could pool in other more non-porous containers such as glass or metal. The koji substrate needs oxygen and airspace and excess water can cause undesired bacterial growth. During the process of making koji, the chemical process begins to create heat called "self heat." The koji can overheat causing bacterial growth as well. The optimal koji environment must be maintained for it to finish out properly. It must not overheat, nor do you want to gravely drop the temp. The trays help maintain some heat from which is being created by the koji itself, even while the heater is off. By shaping the growing koji in furrows, you prevent hot pockets and allow for some of the heat to escape.

 These are inspired by the traditional koji trays of Japan, and I make them from a Eastern White Cedar. They are completely food grade and ready to use.

These are inspired by the traditional koji trays of Japan, and I make them from a Eastern White Cedar. They are completely food grade and ready to use.

If you want to build your own muro, I hope you find this helpful. Feel free to contact me with questions. Hit me up either way if you make one with this format; it would be fun to know people are finding it useful. For those wishing to have one made, contact me and we can come up with something to work for your needs and home.

The Making of a Sizeable and Quality Dehydrator

decadencebyhand1 Comment

At he risk of sounding like an infomercial (I have nothing to sell related to this, so I'll continue), I've always disliked off-the-shelf dehydrators. They are good for drying fruits in small quantities, but herbs are always an issue because is hard to fit very much inside. Alternatively, drying herb bundles slowly by hanging around the house is not ideal either, as there is oxidization during the slow drying process leading to flavor loss. Across the board with off-the-shelf dehydrators, I am unhappy by the flavor loss created by the heated drying process. One major part of dehydrating is airflow to pick up and whisk away the moisture. Low humidity airflow can speed that process up a lot.

I wanted something that would allow for drying whatever quantity, big or small, of food I need to dry. I didn't want to waste harvested food by having a bottleneck at the humidifier.

I mitigate these issues by making a large dehumidifier through a process that I have been using since 2009. What are we trying to do when dehydrating? Remove moisture. There is a higher absolute humidity with higher temps, so the air can pick up more moisture which is one reason most of the shelf dehydrators use heat. Also, size-wise they can more compactly add a heater than give sufficient air flow.  Due to those using heat, people assume that the heat is necessary. Using a dehumidifier, you go straight for the goal, with less added heat. The process by which a dehumidifier removes moisture creates a small amount of heat, but its still lower than a purchased dehydrator. My current dehydrator is in my basement so the temps during harvest time remain low with the coolness of the basement.

I built a large wooden box (3 feet tall x 4 ft wide x 2 ft deep) and put the dehumidifier inside with the humidity set to zero. In previous homes, I have used a closet, which was great for drying very large amounts of things. I added a box fan to the equation for extra airflow, since the closet was so sizeable. I also had a speed rack inside with baking sheets and woven mats for drying shelves in addition to herbs hanging overhead. With the current box and dehumidifier, if I put the fan setting on high, there is sufficient airflow. You could add small fans that produce little heat by salvaging computer fans wired to an old cell phone charger for power.  Inside the box, I have two lips that run the length of the box on opposing sides. I cut dowels to length to span this gap. From there, I can hang whole basil bushes or bundles of parsley before the frost. This last year, we clear cut all the parsley before the frost and then hung and dried all of the bundles.

What is required to make one yourself... a contained space that can be a closet or a dedicated box, a dehumidifier, an outlet nearby, a way to tie up the herbs and other things that need to hang, and perhaps a fan if the airflow isn't sufficient. It is also nice to have sheet trays as well as silicone baking sheets on top (silicone is especially nice for drying fruit because as the fruit dries, it gets sticky and you can easily obtain both the stickiness and the fruit from the sheet this way).

 This is the baking sheet and silicone baking mat that I use when drying fruits for those such as in the Partial Dried Ferments post. These are very helpful for drying fruits and veggies that will get sticky. I can remove nearly all of the tacky bits that had been juice.

This is the baking sheet and silicone baking mat that I use when drying fruits for those such as in the Partial Dried Ferments post. These are very helpful for drying fruits and veggies that will get sticky. I can remove nearly all of the tacky bits that had been juice.

I'll update with pics at a later date, when the dehydrator is more active. Its not seeing much action currently with a northern winter. I wanted to post a how-to now, so that if you find it interesting, you will be able to get going on it before harvest times begin.

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


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!

Maclura pomifera (Osage orange) might be edible and may be delicious..

foraging, wild foodsdecadencebyhand2 Comments

In 2005, I watched a documentary on Pacific Islanders. In the documentary, a fruit called breadfruit was discussed as being a significant food source for the people of those islands. In Jared Diamond’s Collapse, he writes about pits of fermenting breadfruit after storms destroyed everything on the island. The people in the book would live off of the fermented paste until they could get things growing again, because the buried fermented paste was edible for well over a decade.

While driving past a park in the fall in Indianapolis later that same year, I spotted hundreds of fruits laying on the ground by a creek. “These look sooooo much like breadfruit,” I thought.  I quickly pulled over, and ran to the tree. I knew that they were Osage orange but there was remarkable similarity to my limited knowledge of breadfruit, that I simply hadn’t associated before this point. This was/is the largest Osage orange tree I’ve ever seen, adding to the surreal-ness of it all. In my excitement, I talked to some people in town who had done some foraging. In a somewhat belittling attitude (maybe shaming me with their own previous excitement and then failures), they told me it was a waste of time because the fruit was too waxy, too full of latex that gums up everything that it touches. Usually, I perservere in trying things that could maybe fail, but the reprimand sunk my Osage ship.

A couple years later at a Christmas gathering in 2011, my uncle told me a story from his work as a field biologist for the DNR. According to him, there where some students from Nepal attending Eastern Illinois University working on a project with him. While driving down a two-track, they got excited when seeing a tree fruit. “Cutter fruit, cutter fruit!” they yelled. My uncle asked them if they were referring to the green fruits that they had just passed, and they assented, so he pulled over for the students. When the group got out to survey the fruits, the students agreed it looked like cutter fruit. My uncle told them about the latex inside, and they agreed that cutterfruit has a latex inside. They said that when it is processed they cover their hands, knives, and cutting board with oil to keep every thing from getting gummy.

I am unsure if the fruit they were referring to was breadfruit, since breadfruit is a tropical fruit. I think maybe it was another similar fruit of the same family, but its another reason to look into osage orange. Polynesians gave up rice production when expanding out of southeast Asia in order to grow breadfruit which was better suited to the islands they would inhabit. Osage orange, breadfruit, and some fruits from Nepal are all in the Moraceae family. This is the family of figs and mulberries. In fact, I usually spot Osage as having a very similar growth habit as mulberry but with more golden colored bark. There are some thousand species of trees and shrubs in that family.There are a lot of edible species for both humans and other animals. The leaves and shoots of many members of this family are used for tree hay for livestock. There are few poisonous species, a notable one that is used for poison darts in the South American rainforest.

Many members of the same genus as breadfruit are described as milky and chestnut flavored. A lot of the genus has oil rich seeds. Squirrels go through the hassle of ripping open osage for the seeds, which suggests a high caloric value of the seed.

Cooking methods for breadfruit and relatives commonly involve fat in some way. There are many recipes for quick cooking in high temperature fat, as well as many with the fruit being slow cooked in fat such as in a pit roast. There might be some people reading this thinking that if Osage orange had edible uses, then Native Americans would have used it. Looking at foods utilized by different cultures can be very interesting. There are mushrooms revered in France that are rarely consumed in China and vice versa, due to the preferable cooking method for the mushroom and the commonality of the method in that area. So I would suggest that Native Americans may not have valued or utilized Osage, like other cultures have.

Breadfruit like many fruits seems to be available fresh for a short time of the year, and at least in Polynesia when used as a staple, the fruits were fermented. Some things I’ve read suggest that they are harvested somewhat under ripe. If trying out Osage, I’d suggest trying to harvest them under ripe, preferably before they begin to fall.

I have interest in the edibility of Osage, yet I don’t eat many carbohydrates which leads to me missing the optimal time for harvest. Not eating many carbs reduces my investment in osage, but intrigue and curiosity still drives pursuit. I was only able to harvest mature fruits this year. hunting season and simultaneously settling into a new home caused me to miss them at their under-ripe stage.

This year, my experience with Osage consisted of the following: with the fruit cut open, you can see the milky latex. It smelled of citrus and was faintly sweet. The inside has two parts. One part is the core and is starchy, akin to a baking potato. The other was a starch/citrus hybrid (citrus isn’t actually in the same family). I cooked a little of both, but cooked more of the starchy core. I fried them in some pasture raised pork lard. The flavor was like a mix of slightly undercooked potato with eggplant. Most of the citrus-y notes were gone. I would like to try making the fermented paste next year.