Make Sauerkraut! | Science (2024)

Let’smakesauerkrautathome!

Fermentationisanoldmethodtraditionallyusedtopreservefoodbeyondtheirshelf-life.Inadditiontopreservingthefood,thefermentationprocessalsoaltersthefoodintosomethingincrediblytastyandgivesitadditionalhealthbenefits.Todaywewillbemakingsauerkraut.Sauerkrautisfermentedcabbage—it’sbotheasytomakeandverynutritional.

Howiscabbage(sauerkraut)fermented?

Sauerkrautismadepossiblebytheactionof(hard-working)microbesthroughaprocesscalledlactic-acidfermentation.Letmeexplain:Therearegoodbacteriathatcanbefoundonthesurfaceofthecabbage,onerelevantbacteriumhereiscalledLactobacillus.YoumightbefamiliarwithLactobacillusifyou’veeverhadyogurt(Lactobacillusisusedinmakingyogurtandcheese).Whenthecabbageismixedwithbrine(highsaltsolution)andallowedtositinanoxygen-freeenvironment,Lactobacillusbeginstoconvertthesugarinthecabbageintolacticacid.Lacticacidgivessauerkrautit*distinctivesourtasteandpreventsthegrowthofharmfulbacteria.

Lactobacillusbacteriaaretheactiveworkerswhomakesauerkraut(andotherfermentedproducts)possible.Thesebeneficialbacteriaoccurnaturallyinmanyplacesincludingfruits,vegetables,andevenonourskin!Lactobacillushastwomainpropertiesthatmakethemusefulforfermentation:

1. They survive in an oxygen-free environment (anoxic), as in when submerged under brine in mason jars
2. They tolerate high salt well, unlike many other bacteria (including the bad ones)

ThesepropertiesallowustofermentthecabbagewithoutkillingtheLactobacillus.Lacticacidfermentationallowsthegoodbacteriatostayanddotheirthingwhileatthesametimediscouragingthebadbacteria.

Howlongdoesittakeforlactic-acidfermentationtokickin?

Forasmall-sizedbatch(quartercabbagehead)liketheonewe’remakingtoday,theminimumtimeneededforfermentationisapproximatelythreedays.Ifyouleavethesauerkrautafterthosethreedays,itwillcontinuetofermentandbecomeyummier!Theruleofthumbwhenitcomestosauerkrautistojustkeeptastingthesauerkrautuntilthetasteistoyourliking.Thesauerkrautit*elfshouldbesafetoeatateverystageoftheprocess,sothereisnoreal‘fermentationtime’.

Canfermentationgowrong?

Simpleanswer—notreally!Youmayseebubblesorwhite‘froth’onthesurfaceofyoursauerkraut,buttheseareallsignsoffermentationtakingplace.

Itisalsopossibletoseemoldgrowingonthesurfaceofyoursauerkraut.Ifyouseemold,don’tpanic!Yoursauerkrautisstilllikelygood(it’spreservedbythelacticacidproducedbyLactobacillus).Moldformswhenthecabbageisn’tfullysubmergedunderbrineorifit’stoowarminyourkitchen.Whatyoucandohereisscoopoffthemoldandproceedwithfermentation.Thatsaid,it’simportanttouseyourbestjudgmentwhenfermentingfood.Ifsomethingtastesorsmells‘moldy’orgross,trustyoursensesandtossthesauerkraut.

Readytomakesauerkraut?Let’sdoit.

Whatyou’llneed(ingredients):

• Mason jar
• Glass weights
• Lid (see note below)
• Medium-sized green cabbage (~ 3 lbs)
• 1 ½ tablespoons salt
• 1-2 tablespoon caraway seeds (optional)

HowtomakeSauerkraut(instructions):

1. Make sure everything is clean- Wash your mason jars, work surface, utensils, and your hands with soap and water.
2. Slice the cabbage- Remove the outer leaves and cores from the cabbage. Slice the cabbage into thin, ribbon-like, slices (you might want to ask an adult to help you with this step).
3. Add some salt- Place the sliced cabbage in a large, clean, bowl. Sprinkle about 1 ½ tablespoons of salt over the cabbage. Knead and squeeze the cabbage/salt with your hands for approximately five to ten minutes. At first, it won't seem like nothing is happening but be patient. After a few minutes, you should notice that the cabbage is releasing liquid. Continue kneading and squishing the cabbage until there is enough liquid brine to cover the cabbage in the jar. Now you can add the caraway seeds if you want to use them for added flavor.
4. Move the cabbage to your jar - Stuff the cabbage tightly into a clean jar. Pour liquid brine from the bowl into the jar. If required, add a little water to make sure the brine liquid covers the cabbage entirely.
5. Add glass weight and cover the top- Add the glass weights and cover the top of the jar (preferably using a clean piece of cloth). If you are just using a mason jar, you can do this by adding a smaller jar that fits inside the lid of the mason jar and covering both jars with a cloth and a rubber band.The glass weight keeps the cabbage under the brine, which keeps the fermentation environment oxygen-free.
6. Wait for Lactobacillus to start the fermentation process- Fermentation will begin within a day or so and will take between two and five weeks depending on the conditions in the fermentation container. For the first few days, take a look at your mason jar, you’ll want to look for signs of Lactobacillus ‘activity’. Bubbling and foaming usually begin within about three days, depending on the temperature of your kitchen. And once you see bubbles forming (carbon dioxide being released), you’ll know that fermentation is underway. When a week passes, check for taste. Taste is the best measure here, so check it often and stop the fermentation process when you get the desired taste. Also always make sure to keep the jar covered with a clean cloth. This will allow airflow but prevent dust from getting into your sauerkraut.

Note:Itisnormaltoseebubbles,white‘froth’,orfoamontopduringthefermentation.Ifyouseewhite‘froth’,youcanjustscoopitout.Youshouldn'tseeanyactualmold,though.Ifyoudo,scrapeitoffthetop,andmakesuretherestofthecabbageisfullysubmergedunderwater(brine).

Oncefermented,sauerkrautcanbeeatenrightaway,oryoucanstoreitinthefridge.

Howdoyouknowwhenfermentationisdone,andthesauerkrautisreadytoeat?

Fermentationiscompletewhenyoursauerkrauttastespleasantlysour.So,ifyou’venoticedsignsofactivefermentation,likebubbles,anditsmellspleasantlysour,thenyoursauerkrautisreadyforeating.Youcanalsocontinuetoletthecabbageferment,soitdevelopsa‘rich’flavor.Andjustmoveittothefridgewhenittastesrighttoyou.

Wewouldlovetosharethisexperiencewithyou!Takeapicofyourresultsandtag@WaterlooScionInstagramorTwitter.