Fermenting Yogurt With The Help Of Hardware

Fermentation is a natural process that has been exploited by humanity for millennia. Behind such favorites as cheese and beer, it takes just the right conditions to get the desired results. To aid in this process, and to explore the crafts of their ancestors, [Victoria] and [Petar] created an electronic fermentation quilt.

Bulgarian yogurt was the tasty end result from this work.

Anyone familiar with breadmaking will be familiar with throwing a cloth over dough when left to rest. This is all about temperature management, providing optimum conditions for the yeast to work their magic. This fermentation quilt takes things to the next level, integrating soft heater pads and temperature sensing hardware into the fabric itself. Rather than acting as a simple insulator, the quilt can actively supply heat where needed, switching off when reaching the set temperature. In this example, the quilt is set to maintain a temperature of 45 degrees for the optimum production of Bulgarian yogurt.

The fermentation quilt serves as an excellent example of what can be achieved when combining textiles with smart electronics. Tools like Adafruit’s Lilypad and conductive thread all come together to make this a functional and useful device, and shows that electronic textiles aren’t just limited to blinky wearables.

Fermentation is a popular topic among hackers, with [Trent Fehl]’s Supercon talk at the 2019 Supercon covering similar ground from a sourdough perspective. It goes to show that hardware skills can pay off in the kitchen, too!

Engineering Your Way To Better Sourdough (and Other Fermented Goods)

Trent Fehl is an engineer who has worked for such illustrious outfits as SpaceX and Waymo. When he got into baking, he brought those engineering skills home to solve a classic problem in the kitchen: keeping a sourdough starter within the ideal, somewhat oppressive range of acceptable temperatures needed for successful fermentation.

A sourdough starter is a wad of wild yeasts that you make yourself using flour, water, and patience. It’s good for a lot more than just sourdough bread — you can scoop some out of the jar and use it to make pancakes, waffles, pretzels, and a host of other bread-y delights. A starter is a living thing, a container full of fermentation that eats flour and has specific temperature needs. Opinions differ a bit, but the acceptable temperature range for active growth is about 60 F to 82 F. Too cold, and the starter will go dormant, though it can be revived with a little love. But if the starter gets too hot, all the yeasts and bacteria will die.

While there are of course commercial products out there that attempt to solve this problem of temperature control, most of them seem to be aimed at people who live in some wonderland that never gets warmer than 80F. Most of these devices can’t cool, they only provide heat. But what if you live in a place with seasons where the climate ranges from hot and humid to cold and dry?

The answer lies within Chamber, a temperature-regulated haven Trent created that lets these wild yeasts grow and thrive. It uses a Peltier unit to heat and cool the box as needed to keep the mixture fermenting at 26°C /78.8°F.

Thanks to the Peltier unit, Trent can change the temperature inside the chamber simply by alternating the direction of current flow through the Peltier. He’s doing this with an H-bridge module driven by a Raspberry Pi Zero. When it starts to get too warm in the chamber, the fan on the outside wall vents the heat away. A second fan inside the chamber pulls warm air in when it gets too cold.

Trent says that Chamber performs really well, and he’s recorded temperatures as low as 60F and as high as 82F. He mostly uses it for sourdough, but it could work for other temperature-sensitive food sciences like pickling, growing mushrooms, or making yogurt. We think it could be ideal for fermenting kombucha, too.

Chamber works well enough that Trent has put further development on the back burner while he makes use of it. He does have several ideas for improvements, so if you want to help, check out his website and Github repo.

Continue reading “Engineering Your Way To Better Sourdough (and Other Fermented Goods)”

Solar-Powered IoT Sensor Saves Wine Batch From Overheating

Making wine isn’t just about following a recipe, it’s a chemical process that needs to be monitored and managed for best results. The larger the batch, the more painful it is to have something go wrong. This means that the stakes are high for small vineyards such as the family one [Mare] works with, which have insufficient resources to afford high-end equipment yet have the same needs as larger winemakers. The most useful thing to monitor is the temperature profile of the fermentation process, and [Mare] created an exceptional IoT system to do that using LoRa wireless and solar power.

It’s not enough just to measure temperature of the fermenting liquid; viewing how the temperature changes over time is critical to understanding the process and spotting any trouble. [Mare] originally used a Raspberry Pi, I2C temperature sensor, and a Wi-Fi connection to a database to do the monitoring. This was a success, but it was also overkill. To improve the system, the Raspberry Pi was replaced with a LoRaDunchy board, an STM-based module of [Mare]’s own design which is pin-compatible with the Arduino Nano. It includes a battery charger, power management, and LoRa wireless communication. Adding a solar cell and lithium-polymer battery was all it took to figuratively cut the power cord.

Sensing the temperature of fermentation is done by sealing the temperature sensor into a thin aluminum tube, and lowering that into the vat. There it remains, with the LoRaDunchy board periodically waking up to read the sensor and report the tempurature over LoRa before going back to sleep, all the while sipping power from the battery which in turn gets recharged with solar power.

It’s an elegant system that has already paid off. A 500 litre vat of wine generated an alarm when the temperature rose above 24 Celsius for 10 minutes. An email alert allowed the owner to begin mixing the solution and add ice water to put the brakes on the runaway reaction. The temperature dropped and slow fermentation resumed, thanks to the twin powers of gathering the right data, then doing something meaningful with it.

Vineyards and LoRa have joined forces before, for example in the Vinduino project which aims to enable water-smart farming. If you’re unfamiliar with LoRa in general, the LoRa on the ESP32 project page contains a good primer, and if the antenna on the module shown here looks familiar to you it’s because we recently featured [Mare]’s guide on making DIY LoRa antennas from salvaged wire.

Raspberry Pi Tracks Starter Fermentation For Optimized Sourdough

Those of you who’ve never had a real sourdough have never had real bread. Good food fights back a little when you eat it, and a proper sourdough, with its crispy crust and tangy center, certainly fits the bill. Sourdough aficionados, your humble writer included, all have recipes that we pretend are ancient family secrets while in reality we’re all just guessing. Sourdough is partly science, partly art, but mostly delicious black magic.

In an effort to demystify his sourdough process, [Justin Lam] has gone digital with this image processing sourdough starter monitor. Sourdough breads are leavened not by the addition of brewers yeast (Saccharomyces cerevisiae), but by the inclusion of a starter,  a vibrant ecosystem of wild yeasts that is carefully nurtured, sometimes for years. Like any other living thing, it needs to be fed, a task that should happen at the point of maximum fermentation. Rather than guess when this might be, [Justin] used a Raspberry Pi Zero and PiCam to capture a time-lapse video of the starter as the beasties within give off their CO₂, thus expanding it up inside its container. A little Python does the work of thresholding and finding the top of the starter as it rises, allowing [Justin] to plot height of the starter over time. He found that peak height, and therefore peak fermentation, occurs about six hours after feeding. He has used his data to better inform his feeding schedule and to learn how best to revive neglected starters.

Surprisingly, this isn’t the first time we’ve discussed sourdough here. It seems that someone uses Git for iterative sourdough recipe development, and we once featured a foundry made from a pyrolyzed loaf of sourdough.

Continue reading “Raspberry Pi Tracks Starter Fermentation For Optimized Sourdough”

Listen To Your Fermentation To Monitor Its Progress

If you are a wine, beer, or cider maker, you’ll know the ritual of checking for fermentation. As the yeast does its work of turning sugar into alcohol, carbon dioxide bubbles froth on the surface of your developing brew, and if your fermentation container has an airlock, large bubbles pass through the water within it on a regular basis. Your ears become attuned to the regular “Plop… plop… plop” sound they make, and from their interval you can tell what stage you have reached.

[Chris] automated this listening for fermentation bubbles, placing a microphone next to his airlock and detecting amplitude spikes through two techniques: one using an FFT algorithm and the other a bandpass filter. Both techniques yielded similar graphs for fermentation activity over time.

He has a few ideas for improvement, but notes that his system is vulnerable to external noises. There is also an admission that using light to detect bubbles might be a more practical solution as we have shown you more than once with other projects, but as with so many projects on these pages, it is the joy of the tech as much as the practicality that matters.

IoT Device Pulls Its Weight In Home Brewing

The iSpindel floating in a test solution.

Brewing beer or making wine at home isn’t complicated but it does require an attention to detail and a willingness to measure and sanitize things multiple times, particularly when tracking the progress of fermentation. This job has gotten easier thanks to the iSpindel project; an ESP8266 based IoT device intended as a DIY alternative to a costly commercial solution.

Hydrometer [Source: grapestompers.com]

Tracking fermentation normally involves a simple yet critical piece of equipment called a hydrometer (shown left), which measures the specific gravity or relative density of a liquid. A hydrometer is used by winemakers and brewers to determine how much sugar remains in a solution, therefore indicating the progress of the fermentation process. Using a hydrometer involves first sanitizing all equipment. Then a sample is taken from the fermenting liquid, put into a tall receptacle, the hydrometer inserted and the result recorded. Then the sample is returned and everything is cleaned. [Editor (and brewer)’s note: The sample is not returned. It’s got all manner of bacteria on/in it. Throw those 20 ml away!] This process is repeated multiple times, sometimes daily. Every time the batch is opened also increases the risk of contamination. Continue reading “IoT Device Pulls Its Weight In Home Brewing”

Fail Of The Week: Exploding Fermentation

It’s no secret that hackers like fermentation, both the process and the end results. I myself have a crock of sauerkraut happily bubbling away in the kitchen right now. Fermentation can lead to tasty endpoints, and the process itself, which basically amounts to controlled rotting, is a fascinating set of biochemical reactions. But done wrong, fermentation can result in injury, as it did at CCC this year when a fermentation vessel exploded.

"It was the one on the left, officer. He did it."
“It was the one on the left, officer. He did it.”

Exactly what happened isn’t really clear, except that Food Hacking Base ran a number of workshops at CCC 2015, several of which involved fermented foods or drinks. A Grolsch-style bottle with a ceramic flip-top was apparently used as a fermentation vessel, but unfortunately the seal was not broken. The bottle found its way to another tent at CCC, this one running an SMD soldering workshop. Carbon dioxide gas built up enough pressure in the bottle to shatter it and send shrapnel flying through the workshop tent. According to a discussion thread on the incident, “people got hurt and need to go to the hospital because glas [sic] particles were stuck in their faces, a throat was cut and an eyelid bleeding.” The explosion was quite energetic, because, “we also found a 20cm long piece of glass that went trough [sic] the ceiling of the tent and propelled for another 4-5 meters afterwards.”

We’ve seen lots of Hackaday projects involving instrumentation and automation of fermentation, including some with really large vessels. The potential for destruction if such a vessel isn’t properly vented is pretty high. At the very least, you’ll be left with a really big mess to clean up. Be careful out there – microbes are not to be trifled with. We don’t want to give you the wrong idea about CCC; this year was incredible as [Elliot Williams] reported during his time there.

Now it’s off to the kitchen to check on my kraut.

[Thanks to Morgan for the tip.]