The soundtrack for this post is "Juice" by the alternative rock band Slothrust.
Sometimes I want juice and I'm all out of juice, so I try to make juice from scratch. It never turns out super well, but that doesn't stop me from trying. I'm still figuring out the recipe.
My base recipe begins with water, sugar (either glucose, sucrose, or a glucose/fructose mix like honey), organic acids (citric acid being my first acid of choice), and vitamins (in the form up a ground up vitamin tablet). The vitamin tablet so far has just been vitamin C, which is also an organic acid. I have sometimes added a dash of liqueur or artificial flavoring for taste.
I haven't worked up to adding essential oils for flavor, but they're often components of liqueurs and artificial flavorings, so I kind of have? But before using them directly, I would have to do a lot of research. I'd want to 1) use small dilute quantities, guided by quantities found in actual fruit and quantities used industrially used as food additives, and then still reducing from there for my own prudence/paranoia, 2) avoid essential oils that have been associated in medical literature with toxic effects, even if they are components of normally consumed foods, 3) research whether commercially available essential oils have any adulterants, which they might if they're not processed to food-grade standards. Maybe it's easier to get essential oils out with dichloromethane than it is with steam distillation or whatever.
This recipe isn't very juice-like. What is it missing? Complex carbohydrates for one! Juice should have some starch and some pectin at the least. You get those when you crush plants - cell wall fragments and the like. Juice will also have some cellulose, I think. I don't feel like adding that at the moment. There might be some microcrystalline cellulose used as a filler in multivitamin tablets, honestly, but I haven't found one worth using yet. At the moment, I don't think my juice needs cellulose or other insoluble fiber, but I might reconsider it in the future.
Edit from the future: I'm a little more open to the idea of adding cellulose now, but I'm wondering where to source it. Like, paper is pretty pure cellulose, but it can be manufactured with things I don't want to eat/drink/taste/touch like sodium sulfide, anthraquinone, sodium dithionite, and BPA. I looked up cotton balls, and I got internet people scaring me about dioxin. Maybe I could use... corn husks? Yeah, maybe. I've had worse ideas. Oh coffee filter paper would probably be pretty chemical-free. I could pulverize that. Or I could use a powdered dietary fiber supplement, like psyllium husk powder / plantago seeds contain hemicellulose and heteroxylans.
Pectin powder is available in grocery stores by the gelatin, and in fact it improves the verisimilitude of the drink significantly. Apparently it's made by taking mashed pomace (fruit pulp), especially pomes like apples and quinces which can have pectin of like 10% by mashed weight, and then doing some kind of mineral acid treatment and precipitation. Pretty cool. I've got to read more about that.
I haven't yet decided on a good source of starch. Almond meal tasted good, but more like frosting than like juice. Raw wheat flower is right out. Corn starch sounds bad. Potato starch, maybe? The day I tried almond meal, I saw sunflower seeds in my cabinet and thought that might be a decent way to get a range of carbohydrates into a drink - pulverize the seeds and see what dissolves in water. They're pretty neutral in flavor. And I think I'd get some cellulose that way too, which seems... true to juice. Or I'll find something a little more exotic in the baking aisle. Lots of weird powders there. Oh, I bought honeysuckle powder not so long ago! It's marketed as a sweetener, but it's not sweet at all. It's like a mixture of dirt, sawdust, and molasses. A very brown flavor, mostly bitter. I like it, honestly, but no one I shared it with did. It's better with a sweetener. I don't even know what part of the plant is used to make it, but that's the sort of powder I should try to use for fake juice.
One thing I want from fake juice, which isn't found in my base recipe (or soda or kool-aid), is a certain texture which I imagine, the more I read, is mainly due to soluble cell wall material. A colloidal texture, perhaps? The pectin helped. I hope the starch gets me further along.
Juice is also colorful. So we could add some color. Most food dyes which bakers use are not natural and not worth adding, even to fake juice. Two natural plant pigments I considered using for color are lycopene and quercetin. You can get those in supplements in health food stores. I think the supplements come with a lot of filler and binder though. Also, apparently quercetin has quite poor water-solubility, so putting it in your drink seems like it wouldn't work very well and can't be very true-to-nature. If you look on the ingredients for cranberry cocktail, you're likely to find beet juice used for color. Using juice as an ingredient to make juice from scratch is cheating though. I need a few more steps of processing between the plant and my kitchen. Like we could dry the juice to powder and then.... do something to remove non-pigments? I don't know. Like ferment the sugars to ethanol and then freeze dry to powder maybe (Though removing water from wine by freezing (freeze-jacking) is technically illegal in the U.S. unless you've got a license to distill). Or use a volatile solvent? Maybe pigments and sugars have widely different solubility in isopropanol or acetone. But then you're risking getting isopropanol in your juice. Not ideal. Maybe membrane filtration would concentrate larger pigments in the retentate and pass simpler sugars in the permeate? Carotene is another plant pigment I considered, but it doesn't have any taste, supposedly. And I don't remember seeing it for sale in brick and mortar stores. I think it's probably easier to get beta carotene as a supplement than alpha, but they'd both probably be fine if you want some color or provitamin A.
Edit form the future: Chlorophyll! I could add some chlorophyll as a pigment. That's a good idea. Also the carotenoids lutein and zeaxanthin. I would stay away from the pigment hesperidin. Hesperidin and quercetin literature are both split between enthusiastic hippies claiming only health benefits and establishment sources claiming only health risks. My guess is that the pigments are fine in the quantities we normally eat them from natural sources, but supplementing with them might be a bad idea if you've got other health conditions like pregnancy or low INR or whatever, but not so bad an idea that it's obviously hazardous based on natural observations and anecdotes. Whatever.
That was the state of my recipe for a while until I found a recipe for apple juice:
Apple juice is a mixture of sugars (primarily fructose, glucose, and sucrose), oligosaccharides, and polysacharides (e.g., starch) together with malic, quinic, and citromalic acids, tannins (i.e., polyphenols), amides and other nitrogenous compounds, soluble pectin, vitamin C, minerals, and a diverse range of esters that give the juice a typical apple-like aroma (e.g., ethyl- and methyl-iso-valerate).
That's from "Handbook of Natural Antimicrobials for Food Safety and Quality", Chapter 16, (Pina-Pérez, Rodrigo, Martinez).
The oligosaccharides are a little interesting. I'm not sure which ones they are, where to get them, and whether they're likely to matter for flavor or texture once I've already got simple sugars, pectin, and starch. Pectin is a structurally messy polysaccharide whose main monomer is a sugar called galacturonic acid, but there can be tons of other sugars too like rhamnose, galactose, arabinose, and xylose. If you have little oligomer chains of just galacturonic acid, then it's called polygalacturonic acid or "pectic acid". That's probably a major oligosaccharide in juice. Other oligosaccharides are going to have multiple sugars and be kind of structurally messy like pectin. Maybe some xyloglucans and arabinogalactans and who knows what else. Weird mixes of weird sugars with weird bonds between them. Just use pectin. It's fine.
The mention of polyphenolic acids and tannins is also quite interesting. I don't know much about the classes of tannins or their extraction. Some tannins are apparently anti-nutrients, so I should maybe avoid those. There are both hydrolyzable and condensed tannins in plants? Whatever that means. And one way to get tannins is by boiling plant matter, and a higher pH, at least above 5.2, helps with the general effort of extraction. Boiling fruits to get tannins feels like cheating. That's just juice. Boiling nuts feels a little less cheat-y somehow, maybe because they're not sweet or juicy. Boiling tea leaves seems fine, but I don't want caffeine in my juice. Boiling hardwood or bark to get tannins doesn't feel like cheating at all to me; it sounds awesome. But I'd want to investigate whether those tannins differ from the ones in apple juice in important ways. One of my favorite pieces of laboratory glassware is the soxhlet extractor - kind of like a cross between a coffee maker and a Pythagorean siphon cup. It's also good for concentrating tannins, if you've got one.
I need to learn more about other phenolic compounds in juices, such as flavan-3-ols/catechins and other bioflavonoids. Anthocyanin pigments are also flavonoids. Lots to review.
Edit from the future: There's a structural thing called a flavone backbone. It's got three rings made of fifteen carbons and an oxygen. Lots of phytochemicals have the flavone backbone. They're called flavonoids. Most red, blue, and purple plant pigments are flavonoids, specifically called anthocyanins. Lots of white, yellow, and brown plant pigments are flavonoids, specifically called anthoxanthins. The yellow flavonoid pigments, anthoxanthins, come in two families, and I don't know what distinguishes them structurally. Presence of a "O=C<" ketone group maybe? Or presence of a hydroxyl group in position 3 of some carbon ring? Or something else. Anyway:
1) Flavan-3-ols: Low molecular weight flavan-3-ols are mostly white or colorless? Flavan-3-ols include catechin, epicatechin, gallocatechin, and epigallocatechin. I don't know enough about them and their occurrence in juice. Sometimes the flavan-3-ols form esters with gallic acid. Sometimes they oligomerize into proanthocyanidins, or polymerize into tannins. The proanthocyanidins in cranberries might help with UTIs and the ones in wine might help with cardiovascular buildup of atherosclerotic plaque.
2) Flavonols: Flavanols are the other kind of yellowish flavonoid pigment. There are lots of them that have only ever been found in one or two plants, and then four of them that have been found in dozens of plants. The four famous ones are: quercetin, fisetin, kaempferol, myricetin.
Here's a list of some plants which contain those four famous flavanols, assembled from random and non-reputable sources:
* Quercetin: apples, cranberries, onions, grapes, citrus fruits, tomatoes,
* Fisetin: strawberries, apples, grapes, persimmons, kiwis, peaches, tomatoes, onions, cucumbers.
* Kaempferol: apples, grapes, tomatoes, peaches, blackberries, raspberries, potatoes, onions, broccoli/kale/Brussels sprouts, squash, cucumbers, lettuce, green beans, spinach, green tea, strawberries, gooseberries, cranberries, peas.
* Myricetin: grapes, walnuts, black currants, cranberries, oranges, tomatoes
So if you have some of those in your artificial juice, that seems fine and true to nature. Flavanols can also link up with sugars to form flavanol glycosides, e.g. rutin is a combination of quercetin, rhamnose, and glucose.
The same as with the yellow flavonoid pigments, the red/blue flavonoid pigments can come in plain versions (anthocyanidins) and glycoside versions bound to sugars (anthocyanins). The most common anthocyanidins without sugar are cyanidin, delphinidin, and pelargonidin - like 70% of what's found in plants. Peonidin, malvidin, and petunidin make up another 20%. Most of the glycoside versions, the anthocyanins, just have glucose as the sugar binding to one of those 6 anthocyanidins, but somehow there are like 500 different ones? I've probably said something wrong.
Oh! You know how apple juice is yellow-y brown? That's for the same reason that a cut apple goes brown. Oxidative enzymatic browning! Here's how it works! Maybe! You start with an enzyme called polyphenol oxidase, PPO. Peroxidase enzymes might also be involved, but less famously. The PPO enzyme can 1) turn monophenols (including pyrogallol and the amino acid tyrosine) into o-diphenols, 2) turn o-diphenols (including chlorogenic acid) into o-quinones, and 3) polymerize o-quinones (including indole-5,6-quinone and chlorogenic acid quinone) into pigments. These are melanin pigments - often called catechol melanins to distinguish them from animal melanins. Iron might be involved in the reaction somewhere? But not in the enzyme. The PPO enzyme has copper. Also, I know I didn't mention oxygen anywhere in the process. That's because I don't know where it is in the process. I also don't know how this PPO-based view of tannin formation aligns with (proanthocyanidins as oligomers of flavan-3-ols and tannins as polymers of flavan-3-ols). I'm still working on it.
So, adding some number of monophenols, o-diphenols, o-quinones, and catechol melanins might make fake juice more juice-like. From reading about this, I've developed an interest in several monophenolic organic acids which occur in small amounts in plants and some fruits: caffeic acid, quinic acid, gallic acid, and p-coumaric acid. Some if not all of these are found as intermediates in lignin biosynthesis in woody plants.
One last kind of phenolic phytochemical we haven't touched on is the stilbenoids. The only stilbenoid I know about is resveratrol: it's particularly found in the skin of grapes, blueberries, raspberries, mulberries, et cetera.
Let's talk about the "amides and other nitrogenous compounds". I've looked through a few papers on the nitrogen content of fruit juices. The better ones are from like the 1920s to 1940s for some reason. The "amides" are amino acids with amide functional groups in the side chains, namely glutamine and asparagine. Those two make up a significant fraction of the nitrogen in fruit juices and behave chemically differently enough from other amino acids that we could identify and measure them 100 years ago. Modern papers also talk about arginine a fair bit, which is another amino acid with a lot of nitrogen. I'm not sure which other amino acids are present in juice in which quantities. Total guess: aspartic acid, glutamic acid, serine, threonine, isoleucine, and tyrosine are generally represented more than the other guys. In quantifying nitrogen content of fruit juices, old-timey papers often measure ammonia. There's much less of it than of the amides, and it probably comes from decomposition of the amides. I imagine some of that decomposition happens in juice without our intervention and some of it happens in the chemical analysis with lead acetate and hydrogen sulfide and whatever else they had to use back then.
Fruit juices also have some peptides, proteins, enzymes. I don't know much about them and I can't find anyone who does. One group distinguished peptides by their molecular weight and could identify juices by the presence of peptides with those weights. That's all I've got so far. Ooh, I think you can get vegan pea protein in grocery stores or health food stores near the whey and casein protein. If you want to add traces of plant proteins to your juice, that's an option.
I should look more at grape juice literature. I'm sure the wine people have figured out in detail what kinds and amounts nitrogen grape juice has to offer to their yeasts.
Edit: In "Pathogenesis-Related Proteins in Grape" (Enoki and Suzuki, 2016), catalogs six kinds of pathogen--related defense proteins found in grapes:
* thaumatin-like proteins/osmotins
* β-1,3-glucanases
* chitinases
* ribonucleases
* lipid-transfer proteins
* oxalate oxidases/germins
.
Fantastic. The osmotins are expressed more in plants when the plants are dried out / under osmotic stress. I think the glucanases have an antifungal function. The chitinases function as both fungicides and insecticides. The others also exist. Based on "Grape and wine proteins" (Marangon et al, 2009), the osmotins and chitinases are actually the main proteins in grape juice (90%), not just the main ones associated with pathogen resistance. Marangon et alia also identified some lipid-transfer proteins, some PR-4 type proteins (a specific kind of chitinase), and an invertase enzyme which breaks sucrose into glucose and fructose monomers. Those are also in grapes in some appreciable quantity of the total protein.
When I search for structural proteins in cell walls, I mostly find references to "extensin" proteins. After those, the most important seem to be glycine-rich proteins, proline-rich proteins, and arabinogalactan proteins. Lectins might also go here? I don't much about lectins. ...
Lots of cereal grains have poorly water-soluble proteins with high amounts of proline and glutamine, called prolamine proteins. Examples lifted from Wikipedia: wheat (gliadin), barley (hordein), rye (secalin), corn (zein), sorghum (kafirin), and oats (avenin). These are concentrated in the endosperms of the grains. So if you want to make barley juice from scratch, it seems right to add some prolamine proteins.
Nuts and legumes famously have different and complementary proteins to cereal grains, right? What do those look like? Maybe between grain proteins and nut + legume proteins, we can get a pretty good idea of what proteins occur in seeds generally. ...
Let's also look briefly at proteins in seeds used as food which aren't neatly categorized as grains, angiosperm nuts, or legumes. In particular: cocoa beans, coffee beans, poppy seeds, sunflower seeds, pumpkin seeds, and pine nuts. ...
There are, like, thousands of named enzymes in plants that are proteins with catalytic functions. I can't talk about them all and I don't know which ones are important to a juice recipe. I scraped a table of contents from a book on plant enzymes and these were the most frequent words ending in "-ase": (catalase, catecholase, cellobiase, cellulase, cresolase, elastase, esterase, glucosidase, isomerase, laccase, lipase, lyase, oxidase, peptidase, peroxidase, phosphatase, polymerase, protease, proteinase, reductase, tyrosinase). I hope you find that list useful?
Did you know that many plants have lactase and galactosidase enzymes? Just like the mammalian small intestine. Pretty cool. Not sure anyone knows why.
From the fact that plant tissues are made of starch, fiber, oils, and proteins, we can be sure that plants have machinery for building and destroying those polymers, including amylase, cellulase, lipase, and protease enzymes. Maybe some of those are juice-like. Bromelain from pineapples and papain from papayas are two famous protease enzymes sometimes used in marinades and tenderizing seasoning for meat.
Next the recipe mentions soluble pectin and vitamin C, which we've also covered. Then comes "Minerals". "Minerals" are what food scientists call chemical elements, probably because they don't know chemistry or mineralogy. I suppose we could add some chemical elements to the fake juice. After the inescapable (C, H, O, N), and the (Na, Cl) which most people get more than enough of in their diets, the main elements for nutrition are a few non-metals (P, S), light metals (Ca, K, Mg), and heavy metals (Fe, Zn). We could probably hit all of these at once by pulverizing a decent multivitamin. No, I don't know a single decent multivitamin. But in principle, this should be doable.
Next in the apple juice recipe, "a diverse range of esters" is a good way to get flavors into fake juice. Esters also appear as components in essential oils (alongside the more obvious terpenoid compounds) and some artificial flavorings. I'm not planning to buy individual esters directly. If I did, I would probably start with methyl butyrate and ethyl butyrate; I have a standing interest in those two. But there are dozen if not hundreds of organic esters suitable for flavoring, and lots of them are fruity, and lots of them are nontoxic / generally recognized as safe in the amounts that you'd use for flavoring. If you're making fake juice and have access to interesting esters, then more flavor to you.
So, to make juice: start with the base recipe of water, sugar, organic acids, and vitamins. Then ...
1) Definitely add pectin.
2) Figure out a starch source at least as good as potato starch or pulverized sunflower seeds or honeysuckle powder. Other pant matter like corn husks or psyllium might have some use if you want insoluble fiber polysaccharides.
3) Consider adding tannins if you can get them, maybe from boiling leaves or nuts, provided that what you get out isn't terribly anti-nutritive.
4) Try to figure out a source of anthocyanin pigments, possibly extracting them from beet juice just to put them back in to the fake-juice. Other phenolic compounds like monophenolic organic acids (e.g. caffeic, quinic, gallic, and p-coumaric acid) and things derived from them by the action of the polyphenol oxidase enzyme, PPO, are cool and juice-like, but I don't have any idea of how to get them. Catechol melanin pigments produced by oxidative browning are among these.
5) Other pigments like lycopene, beta carotene, chlorophyll, lutein, and zeaxanthin are a little interesting. They're plant-like, to be sure. They'll give your juice some color. Some of them are tasteless and some taste bad. I'm willing to try all of them in small to moderate amounts eventually.
6) If you want your fake-juice to have a juice-like amino acid profile, start by adding the free amino acids of glutamine, asparagine, and arginine. If you want more chemical structure and nutritive balance/variety than that, try pea protein.
7) Trace chemical element nutrients are fine. I doubt they'll impact the flavor or texture much. If you're already adding vitamins to your juice, you might well already be getting these for free.
8) Pure esters are delicious and juice-like if you have them, but they're also a component of artificial flavorings and food-grade essential oils, which are probably easier to get locally.
Happy imbibing.
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Suppose you specifically want to recreate soursop juice for some reason. You'll want a mix of malic, citric, and ascorbic acids and a recipe with a bunch of esters. The Good Scents company has a tidy web page cataloguing the ingredients and ratios from three such recipes, as found in a patent by Manuel Rodriguez-Flores and Sonia Rivera-Gonzalez. The recipes even come in order of increasing complexity, if you want to choose your level of commitment to Soursop verisimilitude.
All the recipes have these four esters, (methyl 2-hexenoate, methyl hexanoate, methyl 2-butenoate, methyl butyrate), in similar ratios and in that order of decreasing prevalence. Rounding to integer percentages, the first recipe has 47%, 30%, 13%, and 10% of those esters respectively and nothing else. The second recipe keeps all of that, but adds in two carboxylic acids (butyric acid and hexanoic / caproic acid) and a terpene alcohol (linalool). The patent does not specify whether the linalool is the S-enantiomer, the R-enantiomer or a mixture. The final recipe also adds in tiny amounts of methyl nicotinate and methyl cinnamate (aka methyl 3-phenyl-2-propenoate), less than a tenth of a percent each.
These seem like very good recipes. In other literature, I've also seen ethyl acetate, methyl butanoate, ethyl butanoate, and methyl leucate mentioned as significant volatile components contributing to soursop flavor and aroma, alongside dozens of others that pop up whenever someone gets their hands on a gas chromatograph mass spectrometer.
I'd like to propose a 0th recipe, simpler than the others: 60% methyl 2-hexenoate and 40% methyl hexanoate. Will it be startlingly close? No. Will it be delicious? Yes.
