Food is one of the biggest expenses for most people. The usual advice is to avoid eating at restaurants and buying pre-prepared food, instead making your own meals from base ingredients. While it's true that these steps can save thousands of dollars, I am also interested in optimizing the recipes and base ingredients themselves. In addition to cost, I also would rather not sacrifice taste or spend many hours preparing and cleaning up meals, and my health will always be the most important variable.
Any quick analysis of base ingredients will reveal that meat is the usually the most expensive food that people eat. This makes sense because animals have to eat many times their weight in plants before they can be harvested for meat. However, meat has a high amount of complete protein (all essential amino acids), which is quite difficult and sometimes expensive to find from other sources of food.
With that in mind, I've been researching other types of protein sources. Nutritional yeast, ie yeast which has been grown and cooked/dried, can have an extremely high amount of complete protein. I've seen estimates from 50-60g per 100g. Chicken breast, the highest % protein meat that I know of, has about 31g per 100g by comparison. Yeast can also be acquired at low cost from the store in the form of bakers or brewers yeast, or even from the natural environment for free, as with sour dough bread or traditional apple cider recipes. Because yeast is a living organism, you can essentially convert extremely cheap ingredients like flour or sugar into a very dense protein source, and you can make as much as you want as long you keep adding more food for the yeast and mixing it from time to time.
So essentially, just from some simple back of a napkin math, it looks like I could get maybe 200g of complete protein from around $0.10 of flour or sugar. A small amount of labor would be involved, since I would have to prepare and store the culture. A similar amount of complete protein from chicken breast would cost around $5.00. Seems worth looking into?
Has anyone tried cooking with inactivated homemade yeast? I'm guessing it would be a great addition to a bread recipe. Maybe it could be added to soup? Are there any other similar protein sources around this price point? Are there any downsides to eating, say, 100g of yeast per day?
Nutritional yeast for dietary protein and fiber?
Re: Nutritional yeast for dietary protein and fiber?
Eating 100 grams of nutritional yeast/day would be about $5 per serving.
From my understanding, sourdough/wild yeast/homemade yeast does not have as much protein density, if any. Protein comes from the things that are used to feed it and bake with, like flour. One slice of sourdough bread is around 8 g of protein, using a high protein bread flour. You'd have to eat a whole loaf to get anywhere near 100g. It'd be cheap, though not as much as you're figuring. I make my own sourdough bread weekly and each one costs about $1.50.
It's also worth considering that wheat is not a complete protein. But I think the biggest limiter is bioavailability. Wheat is low on the scale (53-65% bioavailability) and while you may be consuming 200g of protein, your body will only be able to make use of about half of it.
I'd guess a loaf of my bread has just over 100g total. Assuming somehow I can eat 4 loaves a day, that's ~400g of protein. Figuring in bioavailability I should hit your 200g goal. I'm still lacking certain proteins and I've spent $6 (and a lot of effort). I'd much rather eat meat/eggs/lentils/beans etc.
From my understanding, sourdough/wild yeast/homemade yeast does not have as much protein density, if any. Protein comes from the things that are used to feed it and bake with, like flour. One slice of sourdough bread is around 8 g of protein, using a high protein bread flour. You'd have to eat a whole loaf to get anywhere near 100g. It'd be cheap, though not as much as you're figuring. I make my own sourdough bread weekly and each one costs about $1.50.
It's also worth considering that wheat is not a complete protein. But I think the biggest limiter is bioavailability. Wheat is low on the scale (53-65% bioavailability) and while you may be consuming 200g of protein, your body will only be able to make use of about half of it.
I'd guess a loaf of my bread has just over 100g total. Assuming somehow I can eat 4 loaves a day, that's ~400g of protein. Figuring in bioavailability I should hit your 200g goal. I'm still lacking certain proteins and I've spent $6 (and a lot of effort). I'd much rather eat meat/eggs/lentils/beans etc.
Re: Nutritional yeast for dietary protein and fiber?
In a Danish podcast with Michellin chef and world champ Rasmus Kofod, there is a lot of talk about yeast because he is vegan. It gives a great umami taste. Though I dont think it can be eaten in large quantities, at least in the podcast they only mention it as a small addon.
Re: Nutritional yeast for dietary protein and fiber?
@theanimal My understanding is that humans and most plants lack the ability to convert things like flour and sugar into essential amino acids, but yeast can make these conversions. That's why nutritional yeast can be produced by feeding a slightly different strain of bread/brewing yeast a diet of mainly glucose, a type of sugar. In other words, no need to feed it with a complete protein source - the same reason that you don't have to feed a cow a complete protein in order to make milk or beef. I'm considering using bulk sugar (~17.5 cents per 100g) or white flour (~8.2 cents per 100g). I understand this would likely mean less vitamins and minerals than whole wheat but I'm OK with that as long as the protein is still there. I'm not 100% sure about the details of this though, I would love to find a more detailed source showing what strain of yeast, what they were fed, and what the final amino acid profile was, etc, but I haven't seen anything like that yet. I imagine different strains of yeast produce different amounts of protein and have a different flavor. Instead of making sour dough bread, I am thinking of making bulk yeast, boiling it, then dehydrating it for use as an additive in multiple recipes similarly to commercial nutritional yeast production. This would have the benefit of giving it a shelf life of over a year. I think making something like this would be great (notice there is no flour/sugar included in the ingredients): https://fdc.nal.usda.gov/fdc-app.html#/ ... /nutrients
@Bonde Thanks for the info, I'll take a look.
@Bonde Thanks for the info, I'll take a look.
Re: Nutritional yeast for dietary protein and fiber?
I think you'll find this paper of interest: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8780597/
My apologies, I stand corrected!
My apologies, I stand corrected!
Re: Nutritional yeast for dietary protein and fiber?
@theanimal Looks like exactly the paper I was trying to find, thanks!
Re: Nutritional yeast for dietary protein and fiber?
OK so, according to the paper, nutritional yeast is arguably even better than meat in terms of protein content. This is especially true considering the low cost and the fact that it can be grown from things which are otherwise not edible for humans and animals. This is further enhanced by heating and dehydrating the yeast for storage. However, a major problem for an DIYers wanting to make their own is the high RNA content.
From the paper:
"The consumption of yeast protein with high contents of nucleic acids could cause serious problem such as gout and kidney stone for individuals who have disfunction in purine metabolism [89,90]. Then, before consumption, yeast SCP biomass needs a reduced number of nucleic acids to 1% so it can considered as having the acceptable level of nucleic acids for using as feed or food [89]. SCP with high nucleic acid concentration is only allowed to feed animals with short life spans [91]. The reduction or removal of nucleic acid content in SCP is achieved by using various methods, such as: chemical treatment with NaOH, thermal shock, activation of endogenous nucleases (ribonucleases) in the final stage of the stationary phase by extending the yeast cultivation time or heat treatment (60–90 °C), addition of ribonucleases to the cultivation process, or it can be used as immobilized enzymes [7,12,92,93]. Moreover, for reduction of nucleic acid, Yadav et al. [94] treated the yeast biomass with two-step method with a novel combination of chemicals (N-lauroylsarcosine and NH4OH), which reduced the nucleic acid content to below 2%."
So some people may have issues with gout and kidney stones (ouch!) if they consume large amounts of the raw product. There are a few ways to counteract this, such as the method in this patent: https://patents.google.com/patent/US3968009
The authors above heated the yeast culture to 68C briefly before incubating at 52C for two hours. They also adjusted the pH to 8.0, likely with NaOH (lye). A cheap pH meter and some lye are around $10 each on amazon, but lye is corrosive so there is a bit of a safety concern. I think this could be done fairly easy with a thermometer and a water bath in a lab, or using a digital temperature controller plug ($35 on amazon) and a crockpot or other electric heating device like a hotplate or countertop oven. I'm also not sure if there is a way to determine the concentration of remaining nucleic acids outside of a lab? In any case, it is possible to make it yourself at home but more difficult that I initially thought.
On the other hand, purchased nutritional yeast is around 81 cents per ounce in bulk or $12.80 per pound minimum. Even with double the protein content, this is still a lot more expensive per gram of protein than chicken, milk, and eggs. I'd say it's only worth it if you wanna make it yourself in bulk or for people following a vegan diet. Maintaining a small yeast culture in the fridge for use in bread making also saves money on buying yeast from the store.
From the paper:
"The consumption of yeast protein with high contents of nucleic acids could cause serious problem such as gout and kidney stone for individuals who have disfunction in purine metabolism [89,90]. Then, before consumption, yeast SCP biomass needs a reduced number of nucleic acids to 1% so it can considered as having the acceptable level of nucleic acids for using as feed or food [89]. SCP with high nucleic acid concentration is only allowed to feed animals with short life spans [91]. The reduction or removal of nucleic acid content in SCP is achieved by using various methods, such as: chemical treatment with NaOH, thermal shock, activation of endogenous nucleases (ribonucleases) in the final stage of the stationary phase by extending the yeast cultivation time or heat treatment (60–90 °C), addition of ribonucleases to the cultivation process, or it can be used as immobilized enzymes [7,12,92,93]. Moreover, for reduction of nucleic acid, Yadav et al. [94] treated the yeast biomass with two-step method with a novel combination of chemicals (N-lauroylsarcosine and NH4OH), which reduced the nucleic acid content to below 2%."
So some people may have issues with gout and kidney stones (ouch!) if they consume large amounts of the raw product. There are a few ways to counteract this, such as the method in this patent: https://patents.google.com/patent/US3968009
The authors above heated the yeast culture to 68C briefly before incubating at 52C for two hours. They also adjusted the pH to 8.0, likely with NaOH (lye). A cheap pH meter and some lye are around $10 each on amazon, but lye is corrosive so there is a bit of a safety concern. I think this could be done fairly easy with a thermometer and a water bath in a lab, or using a digital temperature controller plug ($35 on amazon) and a crockpot or other electric heating device like a hotplate or countertop oven. I'm also not sure if there is a way to determine the concentration of remaining nucleic acids outside of a lab? In any case, it is possible to make it yourself at home but more difficult that I initially thought.
On the other hand, purchased nutritional yeast is around 81 cents per ounce in bulk or $12.80 per pound minimum. Even with double the protein content, this is still a lot more expensive per gram of protein than chicken, milk, and eggs. I'd say it's only worth it if you wanna make it yourself in bulk or for people following a vegan diet. Maintaining a small yeast culture in the fridge for use in bread making also saves money on buying yeast from the store.