Category: Food Science

Did you ever notice that good chemists are very often also good cooks?…

Environmental Chemistry Field Trip – Day 1, part 3

Overview of Narrow Gauge Spring
Our final destination of the day was Narrow Gauge Spring, which is on the backside of the Mammoth Terraces area. Apparently, there’s only one other place in the entire world – somewhere in China – that has exactly the same kind of conditions as this place.

The process of making this kind of formation requires rainwater, healthy microbe-supporting soil, limestone, and heat. It goes something like this: rainwater seeps down through the soil, where lots of healthy microbial activity uses up the oxygen in it and excretes plenty of extra carbon dioxide into it, making it more acidic. The water sinks into the ground and runs into the limestone, which is Calcium Carbonate (CaCO3). Calcium Carbonate doesn’t dissolve well in plain water at all, but there are two things that make it dissolve better: acid and heat. The heat from the magma under the park and the acidity of the water combine to dissolve a whole lot of the limestone. Then, somewhere, the heated water gets forced back up to the surface through a crack.

Where the water comes back in contact with the air, it can let off the extra carbon dioxide and heat. This doesn’t happen very fast in a deep pool, since this can only happen in a thin area near the top. Where the water overflows, though, it’s very shallow, and the carbon dioxide and heat can escape very quickly into the air. This makes the water suddenly become less acidic and less hot, and all that extra calcium carbonate can no longer stay dissolved. It crystallizes, making a hard calcium carbonate “shell” along the edge of the pool. The edge can end up growing some much over time that it forms an overhang with stalactite-like formations underneath it:

Another view of Narrow Gauge Spring

You can just make out an overhanging area in the upper-left of the photograph.

It was fun taking measurements of the water here. Water freshly removed from a pool initially showed up off the scale on our “Total Dissolved Solids” meters, but if you waited a few seconds the reading would drop down to where the meters could read it, and keep falling. Out of the pool, the water was cooling off quickly enough that the extra dissolved Calcium Carbonate was un-dissolving out of the water in tiny bits even as we stood there.

The water appeared to be about 56°C at the top of the pool where it was initially emerging. If you want an idea of not only that I am a nerd but what kind of nerd I am, I will mention that I think of this as “stewpot temperature”, and often wonder if there is any useful or tasty effects to be discovered in the microbial processes done by thermophilic microbes that live in these conditions. I’ll find out one of these days…

Oh, and a couple of bits of trivia about the Apollinaris Spring area from a couple of posts ago. Firstly, it was apparently named after a spring in Germany with the same name. Secondly, we briefly discussed the chemistry of carbon dioxide in water in class this week, and it turns out that the pH of 5.9 that Apollinaris Spring has is probably more basic than plain distilled water would be.

Now, anyone who’s had basic chemistry is probably a little baffled by this – after all, isn’t a pH of 7 that of pure water by definition? The answer is yes, but we’re not talking about pure water, we’re talking about water exposed to the air, where carbon dioxide can dissolve into the water. Working through the mathematics involved showed that distilled water should end up with a pH of about 5.6-5.7, at least at “standard temperature and pressure” (roughly sea-level air pressure and a temperature of around 72°F.). I have a suspicion as to why the Apollinaris Spring water seems less acidic than I might have expected, though.

They actually took our Apollinaris Spring water and ran it through an analytical instrument of some kind (I wasn’t there for it, but the description of the results made it sound like it was a “liquid chromatography” type of device). They found NO nitrates or nitrites in it. Since we’re talking about spring water percolating through healthy soil, I would have expected some nitrogen. I noticed, though, that although they checked for nitrite and nitrate, they didn’t check for reduced nitrogen – that is, ammonia.

I managed to score a tiny vial of the water during lab last Wednesday. When I get a chance to hit the pet store for some ammonia testing supplies, I’ll check that. If it’s there, it might explain the possibly slightly higher than expected pH. Similar to what happens to carbon dioxide and water, when ammonia (NH3) is dissolved into water(H2O), there tends to be some recombination of the atoms to make “ammonium hydroxide” (NH4OH), which is basic.

I don’t know if that’s what’s going on, but I intend to check.

There’s one more post worth of Field Trip stuff, and then I’ll be back onto other topics. Here’s a hint of what might come up, though: can anybody tell me what the effective pore size of pectin and cornstarch gels might be?…

Environmental Chemistry Field Trip – Day 1, part 2

Our next stop was Appolinaris Spring, which seems to be an uncommon thing in Yellowstone National Park: ordinary springwater. No sulfuric acid, no steam, just plain old water that sinks into the ground and then comes back up later. For most of the park’s history, it seems like this used to be a popular place to stop to get a drink of water.

water emerging from small copper pipes
Although the signs around the spring now all suggest that you really shouldn’t drink it, at least not without filtering it first, I’m kind of kicking myself now for not having tasted it. Perhaps I’ll have to go back on my own time and try it.

Our on-site tests showed a pH of 5.9 (slightly acidic: milk is normally around 6.8 or so, Root Beer somewhere around a more acidic 4.0, cola beverages around 3.0, for reference…), relatively low TDS of about 100ppm, coming out of the ground cool (about 7°C, or 43°F), with very little dissolved Oxygen (about 6.0ppm) and faintly carbonated (300ppm CO2). It reportedly didn’t taste too good, but having foolishly missed out on tasting it, I don’t know why.

There were hints that perhaps contamination from surface water – like rain trickling through bison poo – but quite some time ago they sealed the spring up to protect it from that kind of thing. This is the actual spring now:

Appolinaris Spring is a concrete box in the ground with locked metal tops...
Even so, the signs still try to discourage people from drinking the water coming from the pipes that lead out of the spring, which I take to be the park service covering themselves just in case someone claims to get sick from it. (“Hey, we TOLD you not to drink it!”).

Appolinaris: This spring water has been used by visitors since early days of the park. However modern water tests show periodic contamination. Park waters, even though clear and running are subject to pollution by wildlife. As with all untreated water, purify before drinking.
Periodic pollution by wildlife? What the…

The northern end of a south-bound bisonOh, right. Natural bottled-spring-water flavor. Hey, it’s natural, it’s got to be good for you, right?

And to end this post on a complete and totally baffling non-sequitur: the student lounge I’m sitting in right now has a television constantly tuned to some cheesy mass-media channel. Today it’s “E!®”. I overheard something on it just now that made me sit up and take notice: Evidently “Leprechaun” made a profit. Wow.

One never knows what kind of amazing things one might learn at college…

The Unbearable Limeness of Being

I awaken. Am I alive? The temperature is neither extremely hot nor extremely cold, so I’m apparently not in some punishment-afterlife. And there’s no beer volcano or stripper-factory, so this obviously isn’t heaven. On the other hand, I am experiencing the usual persistent discomfort involved with waking up early in the morning. On the assumption that Catholic “purgatory” would be more dull, I will assume I am still alive, and had better get up and get to class.

Since my previous experiment, I have obviously had to revise my original hypothesis. Since the last caused me no ill effects, I had to abandon the notion that expired gelatin products become a deadly poison. Instead, as I consume this batch of official, non-sugarless Jell-O®-brand Gelatin (Lime flavored), I operate on a new hypothesis:

“Expired instant gelatin products from intact packaging will not harm me if I eat it.”

My precious stock of expired JellO® is depleted by one more box, the packet ripped from its cardboard sarcophagus, the contents prepared according to the standard instructions, and consumed hastily last night (the animation from the previous post is the actual container of prepared Lime JellO® made from digital photographs taken between helpings.). You can see the old-style date code on the box. According to Carolyn Wyman’s “JELL-O: A Biography”, the code indicates that it was packaged in 2003 (the “3” at the beginning of the code), on the 343rd day of the year, in the San Leandro (California) packaging facility. Although there is no official “expiration date” shown, given the “expected shelf life” of 24 months, this package is approximately 2 years out of date. And I ate it. I appear to have suffered no ill effects. Not even a decent sugar-rush: the entire box contains 320 calories, barely equivalent to a package of Twinkies®. The flavor even appeared to be perfectly normal. Mmmmmm, Lime JellO…

When I took it out to eat it, I did spot a beautiful if alarming sight, though:

The crystalline-appearing sheets of growth from the edge of the bowl into the gelatin was slightly disturbing. Was I crystallizing something odd out of the gelatin/sugar/flavor solution? The growth resembled infiltration of mold into the gelatin medium enough to slightly worry me. But only slightly.

In fact, as I had most suspected, these turned out to be ice crystals. Quite pretty, but they started slowly melting away after the bowl was allowed to sit at room temperature for fifteen minutes or so – plus, they crunched when I ate them just like ice. Thus encouraged, I ate the gelatin and went to bed. And here I am (sitting in the student lounge between “History of Western Art” and “Introduction to Philosophy”) happily blogging away, apparently unharmed.

Does this prove that expired instant gelatin is harmless? Well, no, not exactly. Scientists never really “prove” anything. Instead, we attempt to “falsify” our hypotheses and theories as best we can. This is where the concept of the “null hypothesis” comes in.

The “Null Hypothesis” here is the situation that, if true, falsifies my hypothesis. In this case, it would be “Expired instant gelatin products from intact packaging will harm me if I eat it.”. However, I did eat expired gelatin products from an intact package and was NOT harmed. Therefore I must “reject the Null Hypothesis”…and therefore my experimental evidence does not fail to support my hypothesis! SUCCESS!

If we are unable to find a condition which renders our hypothesis or theory incorrect after many and varied tests, ideally by several different researchers, then we can be confident that our hypothesis or theory is correct, but we don’t necessarily KNOW that there isn’t some odd undiscovered exception that we don’t know about.

Two samples (this one and the previous sugarless-orange one) is hardly a large number of trials. This doesn’t prove that expired JellO® is always safe, but since I know of no plausible way by which an intact package of instant gelatin could become hazardous I feel pretty comfortable that expired gelatin from intact packaging won’t harm me.

If the package is not intact and contains a fuzzy green lump instead of the usual powder, then it’s a whole other situation, obviously…

I do still have three or four more boxes of the sugarless generic expired gelatin – perhaps I can come up with some more tests. Meanwhile, I do hope that my incredibly brave, life-threatening experiments here will relax nervous expired-JellO eaters everywhere…

Expired JellO®! Flee! FLEE FOR YOUR LIVES!!!!

Expired JellO®! Deadly Poison, or Merely Debilitating? Can a human being withstand the toxic load of an *entire box* of it? Would he suffer embarassingly loud and messy gastrointestinal distress, or would immediate organ failure set in before this could take place? STAY TUNED TO FIND OUT!…

Yes, loyal readers, as I type this I have subjected my own body to unthinkable risks to answer these very questions. That, dear readers, is how much I care about your health and welfare. You can thank me later…

…If I survive!

What does it mean to be an “Applied Empirical Naturalist”, anyway? As a naturalist, I look for natural explanations for natural observations. If I survive this ordeal, I will not explain it as being due to protection by supernatural forces, and conversely if I end up confined to an intensive care unit, my body ravaged by Expired-Gelatin-Syndrome, I will not seek to explain it as divine punishment for violating Kosher. As an Empirical naturalist, I investigate things by actual observation and direct testing wherever possible, rather than purely philosophical means. And – particularly important to me – Applied Empirical Naturalism is intended to convey that I am primarily interested in investigations with practical uses. Discovering the “Pineapple-Upside-Down Quark” with an umpty-brazillion-dollar particle accelerator and six months of supercomputer time to crunch the data wouldn’t do me, personally, much good. Knowing whether expired JellO® is safe to eat or not, however, has obvious practical application. Especially considering that I seem to have about 5 more boxes of the stuff in the pantry.

So, here I sit, perhaps writing my very last words ever before Expired-Gelatin-Shock causes my brains to swell up and explode messily and fatally from my ears like the popping of two superintelligent zits, in the service of Science. Here, then, is my story.

I begin by building my dire experiment around the following excessively-formal Valid Argument:

Upon expiration, JellO® becomes a deadly poison which causes great harm to those who dare ingest it
I prepare and consume an entire box of expired JellO®
Therefore, I suffer great harm due to its ingestion.

Last night, I plucked from the depths of my pantry an expired-2½-years-ago box of sugarless orange-flavored gelatin with which to begin this investigation. I blew the layer of dust off of the box, and carefully opened it, half-expecting to find some strange mutant gelatin-beast had developed in it over the years since expiration. One hand poised to protect myself should the creature leap from the box to eat my face in anger of being disturbed, I was both relieved and slightly disappointed to find nothing more than a foil packet containing what sounded like perfectly ordinary gelatin-powder. The packet proved to be intact, and the happy orange powder poured into a freshly-cleaned dish in a manner perfectly imitating that of wholesome non-expired gelatin. I dismissed the faint demonic snickering sound I seemed to hear as a figment of my fevered imagination and prepared the gelatin powder in the usual manner.

I took up my electric kettle, containing distilled water, and threw the switch. Seconds passed into minutes. Minutes passed into more minutes. Then, the water began boiling vigorously, and I applied one cup (8 fluid ounces) of this to the dish of powder, stirring it with a tablespoon. It seemed to take at least two minutes of continuous stirring, but the deceptively innocent-looking powder finally dissolved without the slightest scent of brimstone. As prescribed by the instructions on the box, I added a further 8 fluid ounces of cold water (from the tap of my kitchen sink), stirred briefly to mix, and placed the dish in the refrigerator to gel overnight.

I lay awake in bed for hours, wondering if I was doing the right thing. Was I insane? Did I not remember the tales of Jeckyll and Hyde? Of Doctor Frankenstein? Of Pons and Fleischman? What horrible fate was I setting myself up for? Finally, I dropped into a fitful slumber, disturbed only by dreams of amorphous orange demons stalking me to feast upon my soul…

Day broke, and this very afternoon I took the now solidified mass from the refrigerator. This was it. My last chance to avoid whatever hellish abuses this disturbingly orange substance had planned for me. But no…it was far too late to turn back now. I took up my spoon, and devoured every last bit of happy orange jiggliness.

This was approximately seven hours ago. In the intervening time, I have experienced the following symptoms: Occasional thirst, mild generalized anxiety about the near future, hunger, and an urge to write this blog post in a hyperbolic language more suited to an H.P. Lovecraft story than a scientific report. In other words…I appear to have been entirely unaffected, despite consuming an entire box of expired gelatin.

I’ve been taught that when hypothesis-testing, one considers the “null hypothesis”. That is, the hypothesis that would falsify the one that I’m starting with. In this case, it would be something to the effect of “I will suffer no harm whatsoever from eating expired JellO®”. Given the results in this experiment I must – in the tortured language of philosophical science – “fail to reject the null hypothesis”, because my results show no evidence whatsoever that I have suffered harm from eating expired gelatin. In other words, I cannot rationally cling to my original hypothesis as written, and must confess that perhaps expired instant gelatin still in intact packaging may, in fact, be harmless.

Ah, but I know what happens now. “Cad!”, you cry! “Fraud! Sham! This experiment is, like, totally bogus! This is not normal JellO® but a sugar-free impostor! And furthermore, this isn’t even JellO®-brand gelatin, but a cheap knock-off brand! How dare you, sir, feed us this crap, which proves nothing!”

I answer in two parts: Firstly, ladies and gentlemen who are my readers, I assure you that the contents of the less-famous brand and the official Kraft® Foods brand are essentially identical, and indeed, might conceivably have come from the same source. It’s common practice for one factory’s product to be shipped to multiple sellers who each offer it under their own label, as the wide variety of affected brands during the recent “salmonella peanut butter” scare demonstrated. And secondly: as it happens, I also have in my possession a box of JellO®-brand lime-flavored gelatin, WITH sugar, which although it lists no obvious “expiration date”, has a code stamped on the box indicating that it was originally packaged in late 2003, and therefore should have exceeded the expected 24-month shelf-life about the same time as today’s test subject did. I swear to you, dear readers, that I will repeat my experiment with this sample next.

Stay tuned: “Expired JellO II: Lime’s Revenge”, coming soon to a blog near you!

UPDATE: The Expired JellO® Saga continues here!

The Oldest Microbiology Book (that I own)

There’s this thing that some people do sometimes when they’ve been getting stressed out in one place for a while. I hadn’t done it in so long I can’t remember what it’s called. You know, where you Leave the area and then avoid it for a while. Oh, yes, that was it, a vacate-shun. Anyway, leaving the barren desert wastelands of the West, we headed east, and spent a few days admiring the area around the midpoint of the Appalachian Trail: Harpers Ferry, West Virginia. (Incidentally, I can recommend the “Angler’s Inn” Bed and Breakfast there, and the whole time there was incredibly delightful to me. I think I’d love to move to the area.).

I was delighted to note that there was an Old Book store in downtown Harpers Ferry. One thing about the Eastern US is that it’s been settled by book-using folks for somewhat longer than the West, so it would seem it’s easier to find really good Old Books. I found a publication of a 110-year-old microbiology book. In decent condition, for just over $20, no less! Not counting the (relatively modern) reprint of Micrographia that I picked up from a library sale, this makes it by far the oldest microbiology book I own now.

Oh, yes, did I mention I collect (casually) old books, especially old scientific and technical books?

The book in question, published in 1897, is “Story of Germ Life”, by Herbert William Conn. Not to be confused with Harold Joel Conn of “Conn’s Biological Stains” fame…who happens to be Herbert William Conn’s son. To be fair, the book *I* got was actually a republication from 1904, so only 103 years old…back when copyright was more rational (7 years, plus an OPTIONAL 7 more years. Thus explaining why my republication came out 7 years after the original.) It appears to have been part of a series called “Library of Valuable Knowledge”. The bookstore actually had another one of them, but I don’t remember what its topic was.

“Story of Germ Life” isn’t really a textbook so much as an overview of the subject of “Bacteriology” (as understood in 1897) for otherwise well-educated people – the kind of book I don’t think there are enough of these days. The Gutenbook project actually has a plain-text-only version of the book online here. Of course, then you miss out on the incredibly useful illustrations:

I always find it interesting to go back and see the earlier stages of scientific endeavors – especially as relates to my own interests. There always seem to be things that have since been forgotten, abandoned, or glossed over in them.

H.W. Conn seems to have been most interested in dairy microbiology, so there is a substantial amount of space devoted to it. I’ve heard of “blue milk” before (Yummy!….Pseudomonas?), but not Red or Yellow milk. He also devotes space to discussing the affect of “good” (and “bad”) bacterial cultures on butter, cream, and cheeses. I’m not even sure if butter is cultured these days, or if they just churn it up fresh and cold with minimal growth. Dangit, one of these days we’re just going to have to move somewhere we can keep a miniature dairy cow so I can do some experimentation with real unpasteurized fresh milk.

Bacterial phylogeny was so quaint back then. “Bacillus acidi lacti.” Ha! I love it. Interestingly, the term “Schizomycete” doesn’t appear anywhere in the text, though that may or may not be because it was considered unnecessarily technical for the intended audience. There’s actually very little about microbiological methods, too, which is the one major disappointment for me. Oh well, still interesting stuff. Conn actually mentions various “industrial” uses of bacteria including retting (soaking fibrous plants like flax or hemp so that bacteria eat the softer plant material to free the fibers), the roles of different bacterial cultures in curing tobacco, and even a fermentation in the production of opium (which Conn says is fungal rather than bacterial).

Also, much to my approval, the first 2/3 of the book is not about diseases. Only the last third of the book discusses “parasitic bacteria” and related topics. I leave you with this quote from the book’s 1897 Preface, which I think is still relevant today:

“Few people who read could be found to-day who have not some little idea of these organisms and their relation to disease. It is, however, unfortunately a fact that it is only their relation to disease which has been impressed upon the public. The very word bacteria, or microbe, conveys to most people an idea of evil. The last few years have above all things emphasized the importance of these organisms in many relations entirely independent of disease, but this side of the subject has not yet attracted very general attention, nor does it yet appeal to the reader with any special force. It is the purpose of the following pages to give a brief outline of our knowledge of bacteria and their importance in the world, including not only their well-known agency in causing disease, but their even greater importance as agents in other natural phenomena. It is hoped that the result may be to show that these organisms are to be regarded not primarily in the light of enemies, but as friends, and thus to correct some of the very general but erroneous idea concerning their relation to our life.” — April 1, 1897

What I Learned In School: “Valid” arguments

The new semester has begun on this, my last schedules semester as a mere old Undergraduate. This semester’s primary purpose is to fill in the two vitally important “general education” goals for my current Institute of higher learning: Art Appreciation and Philosophy.

I added a “What I Learned in School Today” category to the blog just because of this semester. My loyal readers (all 2-4 of you…) can look forward to occasional posts on other aspects of my Higher Education as the semester goes along, besides microbiology. On the metaphorical menu over the next 16 weeks: “Introduction to Philosophy” (today’s topic), “History of Western Art“, Applied Calculus, and finally I have a chance to take Environmental Chemistry.

Prior to reading some Plato for next week, we started out “Philosophy 101” with a discussion of “Valid” arguments. In Philosophy, this has a very specific meaning. If you make an argument in the general form of “This, and that, therefore something”, the argument is “valid” when if “This” and “that” are both true, then “something” must also be true.

The thing that most of the class seemed to have trouble with is that being “valid” has nothing to do with whether or not the argument is “sound“, or whether the statements in the argument are true.

An example from the class:

All mammals have lungs.
Whales have lungs.
(Therefore) all whales are mammals.

This is an invalid argument, despite the fact that every statement is actually true. The reason is simply that the fact that whales are mammals does not automatically follow from the fact that they have lungs. (Chickens have lungs, too. Does this mean chickens are mammals?…)

It took two class sessions before most of the class seemed to “get” this. I felt as though I was in Junior High again…though I think this had more to do with watching the freshman girls in front of me passing notes during the class. Come on, kids, grow up! We adults are using IM for that now! Sheesh. Kids today…

On the other hand:

You’ve got to be some kind of genius to attend college and blog at the same time.
I attend college and I blog at the same time.
I am, therefore, a genius.

is a valid argument. As written, if both of the first two statements are true, then the third statement must be true. This is where the value of valid arguments come in – if it turns out that the conclusion is false, then one of the premises must also be false. If anyone were to discover that I am, in fact, not a genius, then either it’s unnecessary to be a genius to blog and go to college at the same time, or perhaps I’m paying someone else to write this stuff for me.

Who cares, I’m a science major, not a philosophy major, right? Except: a properly designed scientific hypothesis should be a premise in a “valid argument”, and an experiment is merely a test to see if the argument is unsound. For example:

All lactic acid bacteria, grown in otherwise sterile milk, will make yogurt.(the underlying hypothesis being tested)
I inoculate sterile milk with a culture of Pediococcus damnosus(the test performed by the experiment)
(Therefore) I obtain yogurt. (Expected results and conclusion of the experiment)

This is (as far as I can tell) a completely valid argument. Now, I haven’t actually done this experiment, but let’s pretend I did, and the end result was a smelly mass that kind of looked like yogurt except it turned out to be slimy rather than firm. I cannot in fairness call it “yogurt”, so my conclusion in the argument is false. Thanks to the magic of Valid Arguments™, I know that either my assumption is wrong (maybe not all lactic acid bacteria turn sterile milk into yogurt after all), or there was a problem with the experiment (perhaps the milk was contaminated with something and wasn’t really sterile, or I grabbed a culture of something other than P.damnosus by mistake.)

Assuming I carefully recheck the materials and repeat the experiment to confirm that I really am inoculating actually-sterile milk with a definitely clean culture of P.damnosus and continue to get the same results, then my hypothesis – the first premise in the argument – must be false. I have to then go back and revise my hypothesis and test again, until I have a hypothesis that seems to consistently generate true conclusions. Thus, the “valid argument” is the basic tool which allows hypotheses to grow up and become theories.

Incidentally, some Pediococcus damnosus strains are a cause of “ropy” wine, which is why I chose that example. I don’t actually know what, if anything, it would do to pure, sterilized milk, though.

Coming up next: I picked up a 100-year-old microbiology book while on vacation!

Is GFP GRAS?

Woohoo!

One of my longstanding questions has been, is Green Fluorescent Protein safe to put in food?

I always figured that it SHOULD be – it comes from jellyfish, which I know people eat in some cultures (though I’m not sure if any of the ones eaten actually express GFP).

Well, it seems someone in 2003 did a proper test…Check it out!

Sure, this is still some way before the FDA declares it “Generally Regarded As Safe” but it’s one step closer.

Soon, my dream of genetically-engineered “Glogurt®” will become reality! AH, HA HA HA HA HA!

Tasty Acids

The story so far – I’ve got 8 live bacterial cultures (and two yeasts) obtained from a bottle of Peach Lambic, imported from Belgium. I strongly suspect that 6 of the 8 are Pediococcus species, and the other two are in the Lactobacillus genus. It is also possible that some of them might turn out to Leuconostoc or some other genus, but I suspect them all to be in the Order Lactobacillales somewhere, anyway.

Hopefully I’ll be able to get good, definitive sequence data from the bacterial isolates later this week.

Lactic acid seems to be the predominant acid in Lambic ales, produced by the various bacteria which break down the sugars in the beer and spew out lactic acid as a waste product.

Pediococcus also shows up in wines, where it’s associated with “malolactic fermentation” – where it converts the harsher malic acid into the more mellow-tasting lactic acid.

Thinking about this led me to think about the other distinctive acids found in foods. Here’s a listing (in no particular order) of some, with foods associated with their distinct flavors:

  • Lactic acid = “Yogurt” acid (and Sour Cream.  And many types of pickles.)
  • Malic acid = “Apple” acid (“Green Apple” flavor)
  • Tartaric acid = “Grape” acid (Verjuice and “Grape flavor”)
  • Acetic acid = “Vinegar” acid
  • Citric acid = “Lemon/Lime” acid (or “Pixy Stix®” flavor)
  • Propionic acid = Swiss cheese acid

In other news, I need a real microscope of my own.

More Lambic pictures

Ah, that’s better – a more traditional heat-fix/simple stain (using Methylene blue) shows my yeast isolates better:

Sally the maybe-Brettanomyces-type yeast
(“Sally”, a yeast that I suspect is a Brettanomyces-type yeast.)

Sam the...Saccharomyces-type yeast?
(“Sam” now looks awfully small…but more experienced observers than I am said that it could actually be a Saccharomyces-type yeast.)

Lucy the possibly-PediococcusI also got two more Coccoid-Cluster-type Gram-positive bacterial isolates. The look pretty much the same under the microscope, though one had gooey wet, slightly larger colonies than the other’s smaller, hard-lump colonies. I see another one of those tetrads in the hard-lump-colony microscope image.

All told, I now have 10 isolates to check out. I’ve been given the go-ahead to try sequencing on the 8 bacterial isolates so hopefully I’ll be able to get a clear identity for Fred, Sid, Lisa, Lucy, BillyBob, JimBob, BettySue, and MarySue. Sally and Sam will have to wait for now, though I’m looking into ways to characterize them, too.