Tuesday, May 27, 2014

Lupin tempe and fried lupin hulls

Lupin tempe is highly touted, and apparently one of the most promising possibilities for expanding the presence of lupins in the human food supply. Tempe (or "tempeh", if you prefer the crude anglicization) is made by growing fungus, usually Rhizopus oligosporus (sometimes also with Rhizopus orzae and other minor components) on beans (usually soy beans, but a wide range of substrates are possible). Tempe is a traditional food in Indonesia and is recently becoming popular in Europe and North America. I've made soybean tempe several times and it's turned out well, so I was excited to try to make lupin tempe. Differences between soy and lupin that may make the process different are that lupins are tougher (more fiber, less oil) than soy beans and have a much thicker hull.

"The Book of Tempeh" gives a simple recipe for lupin tempe: "The seeds are simply dehulled, soaked for 12 hours in excess water, boiled for 30 minutes in the same water, then drained cooled, inoculated and incubated at 86 F (30 C) for 20 to 24 hours"

One challenge I face is that my lupins still have the hulls, commercial producers of lupin tempe use giant industrial dehullers to remove the hulls from dried lupins. I think it is possible to create a device that will de-hull soaked lupins (basically you'd just need 2 rollers separated by about 0.6 cm), but I don't have one, so I de-hulled the lupins by hand. I thought sprouting them first might make them a little easier to de-hull, and also make them less fibrous easier for the fungus to grow on them, so I started by sprouting the beans for 24 hours.

An essential ingredient in making tempe is the starter culture, the fungus spores that you inoculate the beans with. Here are all of the sources I know of for Tempe started: Tempeh Starter Shop, Cultures for Health, organic-cultures, tempeh.info, Top Cultures, tempehstarter.com, sometimes it's also possible to find it on e-bay. GEM cultures list it on their website, but seem to be perpetually out of stock (which is a real shame because they seem to be the only source on the US West Coast). The only place I've ever bought starter from, was tempehstarter.com, theirs is a mix of R. oligosporus and R. oryzae, and ships from Indonesia. I ordered from them because gram for gram (and including shipping), they are cheaper than any of the other places (however, it may be that some of the other sources sell a more concentrated mix, I don't know).

Another essential aspect is incubation temperature. Which should be around 30-35 C. Some people build special incubators for this. I've found that if I just leave my oven light on, the oven warms to approximately the right temperature. Eventually the tempe will start releasing heat, from the active metabolism of the fungus digesting the beans. So if the oven gets too hot, I move the tempe to the corner of the oven furthest away from the light.

The Rhizopus grows best at low pH, apparently this is traditionally achieved by an initial bacterial fermentation (by bacteria that are found naturally in the water in Indonesia). Low pH can also be achieved by adding vinegar (which is what I do, and you probably should too).

The Rhizopus are aerobes. That means they need oxygen to thrive. However, they also need humidity. The need for oxygen means you shouldn't pile the beans too deep I think about 2-3 cm deep is ideal, but for sure don't go any deeper than 5 cm. If you have a nice tempe incubator, you shouldn't have to worry too much about humidity. People like me, with more makeshift arrangements, can cover the tempe with plastic wrap and cut some slits in the plastic wrap (which is what I do), or grow the tempe in plastic sandwich bags and punch holes in the sandwich bag (which is what I've seen on quite a few other blogs).

Lupin Tempe:
  1. Soak seeds 3 days
  2. Drain and keep covered at room temperature for 24 hours to sprout
  3. Boil for 30 minutes
  4. Drain the hot water, add some cold water and manually de-hull the beans
  5. Drain, put on the stove briefly, just to boil off any excess water (without drying out the beans)
  6. Put beans into a 9 x 5 bread pan
  7. Mix in 1 tsp white vinegar
  8. Mix in 1 tsp starter
  9. Cover with plastic wrap, but cut vents in the wrap.
  10. Incubate for 24 to 36 hours at about 32 C (I achieve this by keeping the light on in my oven)
    • After 24 hours it looked (and tasted) pretty good (see pictures below), but I decided to give it another 8-12 hours. I generally take it out of the incubator right about when the first gray/black tufts start appearing, and when a faint ammonia smell is present. After 24 hours, neither of these signs were present, so I let it go a bit longer. After 35 hours, those signs still weren't present but I stopped the incubation anyways.
  11. Remove from incubator and either freeze, or cook

After 35 hours in the incubator, I removed the tempecut it into strips, and pan fried it at medium heat in grape seed oil. The taste is pretty similar to soy tempe I think. Lupin tempe has a bit coarser texture, and there are definitely distinct lupin undertones to the taste, but they aren't overpowering at all. I like it. I will definitely make it again. And the point is proved: you can make lupin tempe at home using pretty much the same process as for soy tempe!

Edit: I gave some to a real genuine Indonesian and she said, "It's ok. Kind of bitter. I like soy tempe better. Did you de-hull it by hand, because I think you missed some, it's a little crunchy." If that's not a ringing endorsement, I don't know what is.

Fried Lupin Hulls:
De-hulling lupins is a total pain. Also, once you're done you've got a big pile of hulls just begging to be eaten or cooked or anything except thrown away. Honestly, I like them just fine plain, just in the state they come off the beans. But I was curious to see if they were any good fried. So I tossed them in the frying pan with some oil. The result: fried lupin hulls taste fantastic, just like a bread crust. Unfortunately they don't have a very appealing texture: at first they are crunchy like popcorn skin, then once they've been in your mouth awhile, they reabsorb water and get chewy and tough. I think they'd work best as a garnish, for instance on a salad or sprinkled into a sandwich (I tried this and it gives the sandwich a nice crunch, but it's tough to taste in there), or maybe as a minor ingredient in a trail mix or something.

Next time:
I'll just use diced, hull-on lupins. It's too much work to remove the hulls manually. The folks at makethebesttempeh found that just slicing soybeans with a food processor without de-hulling them was enough to make the beans suitable for growing Rhizopus and making tempe. I bet this will work just fine for lupins as well. Nevertheless, I hope someone starts selling de-hulled lupins in the US someday, but I don't think this is likely to happen. As it is, it's almost impossible to even find de-hulled soy beans. Michael from Lupina LLC told me their White Sweet Lupins are better for tempe than their Australian Sweet Lupins (which I used for the present experiment), so when I make another order, I'll be sure to order some of those and try them out too. I'm not sure if I'll bother sprouting the beans next time or not.

After 24 hours of sprouting. These guys grow quick!
Lupins after sprouting, boiling, and hulling. On the right is a coffee mug full of hulls. If I hadn't packed it down, it would be overflowing.
Innoculated, vinegared, covered in plastic wrap with slits cut, and ready to incubate!
After incubating 24 hours.

Side view of lupin tempe after 24 hours.

Pan fried piece of 24 hour tempe.

Tempe after incubating for 35 hours.
Cross section of 35 hour lupin tempe.
35 hour tempe pan fried until golden brown on both sides.

Pan fried lupin hulls.

additional tempe references:


  1. Hi - Great article. I bought 10 pounds of lupini beans from https://foodtolive.com/. I soaked overnight, pressure cooked, split hemp seeds and make tempeh. The tempeh came out great. However, it was bitter and I had the symptoms of Alkaloid poisoning, like blurred vision and dry mouth. So, I threw out that batch.

    I now have a batch of lupini soaking and will follow your directions. Have you noticed the bitter taste in the tempeh you made?

    1. I've never had any negative symptoms from eating lupin tempeh. The tempeh I made was a little bitter, but I think that was from the hulls, which I did not completely remove. When I later used de-hulled lupins, the tempeh was more mild.

      I do know that the alkaloid levels can be very different depending on the cultivar of lupin. Lupins with the word "sweet" in the name usually have lower levels of alkaloids. The ones you got are not called "sweet" so they may have higher alkaloid levels than the ones I got.

      To remove alkaloids, you need to soak and drain every day for up to 9 days. I would recommend following the directions on the site you bought them from, where they recommend boiling, and then 3 to 5 days of soaking. I would boil one more time at the end before starting the tempeh to sterilize them.