Light, photosynthesis help bacteria invade fresh produce
Exposure to light and possibly photosynthesis itself could be helping disease-causing bacteria to be internalized by lettuce leaves, making them impervious to washing, according to research published in the October issue of the journal Applied and Environmental Microbiology.
Salmonella enterica is a common cause of foodborne gastroenteritis, with an estimated number of 1 to 3 million human cases per year in the United States. Fresh produce is increasingly being implicated as a source of infection. One of the largest foodborne outbreaks in recent history, the Salmonella St. Paul outbreak in 2008 which sickened over 1,400 people, was associated with tomatoes and jalapeno peppers.
Previous studies of foodborne pathogens on produce have found that the bacteria do not only attach to the surface of fresh produce but find their way below the surface of the skin through pores called stomata where they can hide from and resist washing and food sanitizers.
In the study, researchers from the Agricultural Research Organization at the Volcani Center in Israel and Tel-Aviv University examined the role that light and photosynthesis might play on the ability of salmonella bacteria to infiltrate lettuce leaves via stomata. Sterile iceberg lettuce leaves were exposed to bacteria either in the light, in the dark, or in the dark after 30 minutes of exposure to light. Incubation in the light or preexposure to light resulted in aggregation of bacteria around open stomata and invasion into the inner leaf tissue. In contrast, incubation in the dark resulted in a scattered attachment pattern and very little internalization.
The researchers believe that the increased propensity for internalization in the light may be due to several factors. First, in the absence of light plants enter a period of dormancy, where stomata are closed and no photosynthesis takes place. In the light, the stomata are open. Additional findings also suggest that the bacteria are attracted to the open stomata by the nutrients produced during photosynthesis which are not present in the dark.
"The elucidation of the mechanism by which Salmonella invades intact leaves has important implications for both pre- and postharvest handling of lettuce and probably other leafy vegetables. The capacity to inhibit internalization should limit bacterial colonization to the phylloplane and consequently might enhance the effectiveness of surface sanitizers," say the researchers.
Applied and Environmental Microbiology is a publication of the American Society for Microbiology. The American Society for Microbiology, headquartered in Washington, D.C., is the largest single life science association, with 40,000 members worldwide. Its members work in educational, research, industrial, and government settings on issues such as the environment, the prevention and treatment of infectious diseases, laboratory and diagnostic medicine, and food and water safety.
Monday, September 28, 2009
Another uplifting article from Eurekalert! essentially letting us know that it doesn't matter how much you wash your produce, it's still going to be swimming in bacteria. Better boost your gut flora before eating that mesclun mix....
Posted by Allison Vaughn at 8:48 PM
Sunday, September 27, 2009
Rare are the occasions that I intentionally camp in degraded, unburned woodlands in the Ozark Highlands. At the beginning of my birthday month, however, I found myself camping on gravel bars and streambanks of the upper Gasconade, Niangua, Current and other rivers surrounded on both sides of each river by crummy woods in rather desperate need of fire. Each night of riverbank camping I gathered kindling for my long-lived fires of punky sycamore and was treated to the bright glowing eyes of wolf spiders, more species than I could count, hunkering down in the thick layer of leaves. (Spider populations, by the way, totally out of context, increasing to unnatural levels due to a lack of fire.)
Strap on a headlamp and head into the millions of acres of unburned woodlands in the Ozark Highlands and you'll see them, too, little green and yellow lights staring at you out of the leaf litter, compound eyes on the many species of spiders, all immobilized by the brilliant light of your headlamp. Glow worms are out too, actually, flat little segmented larvae of fireflies pulsing light as they, too, hunker down in the leaf litter.
I don't really understand the fear of spiders. Some of Missouri's finest ecologists are quite frightened by these little creatures who really aren't out to kill or maim ecologists. I don't keep house very well at all because I'm never home, so I allow cellar, tunnel and wolf spiders spiders to have their way in my corners and basement; they keep my rogue walking fruit flies (cultured for my dart frogs, not that I live in squalor...) in check. I help tarantulas across the road each October, gently allowing them to crawl up my arm while I walk them across to the next glade. I've had several tarantulas try, in vain, to spin webs around my forearms, an act which I've taken as high praise for my gentle handling.
But as all of you, my three readers [not counting my baby sister], know, I'm not an entomologist--though I tangentially know Ted, the most astute entomologist, rabid cyclist, and all around cool guy in the Midwest. If the pictures I post tonight are not of spiders, I think he'll tell me (very gently and with a giggle).
While gravel bar camping during the initial stages of my birthday month, I ran across a rather large wolf spider of the genus Hogna (pictured, right). Admittedly, I have never seen a wolf spider so large. Using the headlamp, several other wolf spider species availed themselves to me over the course of the week, none of them wanting to attack me or bite me (of course). One made off with a sliver of yellow onion that I had cut up for beans and rice, comparatively a small spider rushing off the table with a huge chunk of onion. Wolf spiders, though they can grow rather large, are pretty harmless. The worst bite by one of these spiders resembles a bee sting: no necrotic tissue (like a brown recluse bite can cause), no huge black widow welts left behind. They're really a quite harmless, highly diverse group of spiders, really charming and furry. See for yourself--pull out your headlamp from your caving gear and check out your local -likely unburned- woods. Look closely for the glistening of compound spider eyes!
Posted by Allison Vaughn at 7:50 PM
Wednesday, September 23, 2009
In fire-starved woodlands of the traditionally fire-mediated Ozark Highlands, struggling populations of native vegetation sometimes remain visible-- a sprig of big bluestem here, an Aster turbinellus there. By using those relict plant populations as a guide, it’s fairly simple to determine whether you’re in a true forest (uncommon in most of the Ozarks except in Current River country) or a degraded closed woodland in need of fire. The presence or absence of certain plants can play a role in determining landscape types. For example, Aster patens and Silene regia are good, solid woodland plants, appearing in nice woodlands and woodland edges. One is unlikely to find, say, wild ginger or hydrangea in a dry woodland, as both plants require more moisture, commonly found in forests or on the more mesic side of a dry-mesic woodland.
But in the Ozark Highlands, if you find yourself in the front seat of the canoe (the position that serves as the all-important lookout for snags and big rocks and can be just as effective at determining steering position as the rear, despite what the guy in the rear says), you may find yourself surrounded by a whole host of plants that you won't find elsewhere, plants restricted to riverbank natural communities in the Ozark Highlands. If it's not enough to find distinctive plant populations, if you can see the chert gravel through the water and gnarly old cedars clinging to the bluffs, you may be on an Ozark river. Having spent my whole birthday week floating and camping (over and over and over) on two distinct Ozark rivers in two very distinct regions of the Highlands, a common theme occurred, a host of lovely riverbank plants that you won't find in a woodland or on a glade or in any other native landscape in the same quantities as you'll find them there.
Standing out in brilliant red among every other growing thing, cardinal flower (Lobelia cardinalis) was in full bloom last week, literally lining the streambanks with tall, red spikes of flowers. Mixed in among the cardinal flowers are mist flowers (Eupatorium coelestinum), a pale purple version of the common bonesets blooming in crummy woods throughout the Ozarks in September. One of the many species of dodder is in bloom now, wrapping their eerie orange stems around streambank water willows and everything else they can cover.
Of the sedges growing along Ozark riverbanks, Carex haydeni stands out, thick clumps growing along the riverbank for mile after sluggish autumn float mile.
The pawpaws are still hard as rocks these days; I never found a ripe one on roughly 40 miles of riverfrontage, though I found several that animals had tried gnawing into but abandoning the fruit in the end. But on the upper Gasconade, I found the treasure trove of Heteranthera populations.
Tall, rangy populations of the fall yellow flowering Verbesina draped over the riparian corridor, mobbed by yellow butterflies that resembled (in form) the cabbage whites.
The fall blooming Phlox appeared after a few miles deep into the float trips, unseen in the early or late miles.
Vernonia crinita and its' bright purple blooms are out in force now, and the common Hibiscus lasiocarpus can be seen in full flower on riverbanks now.
Of course, you know you're on an Ozark river when you see the steeply eroded streambanks resulting from years of grazing, timber harvest, and mismanagement of the adacent uplands. Or, worse still, when you're 10 miles into your float and you come across mile after mile of foul cyanobacteria blooming in the water from all the cows on the banks and standing in your once-pristine Ozark river. Jump off rocks and rope swings are no longer very much fun, but it makes you grateful for all the great plants that are still there, despite the abuse.
Posted by Allison Vaughn at 9:48 PM
Saturday, September 19, 2009
(For the one or two people I don't know who may stumble across this page in search of, say, "Aster patens" or "U Road," a quick note about the role of the following post--unintended for my four or five loyal readers who already know me well: I'm really picky about wine. I'm really picky about everything I eat and drink, actually, and it's no fault of the wineries I visit that they produce sweet junk that I won't taste. I think merlot is gross and sticky sweet and I won't get near it. My grail wine is a solid Oregon pinot noir--big, complex, buttery, oaky, a wine as interesting as the Willamette Valley landscape itself. Nevertheless, my opinion of wine is just that, my opinion. But to each his or her own, drink what you want, that's cool, but I'm setting out this fall into the Ozarks to find truly great wine made with Norton grapes and aged in our fine, stately Quercus alba. I really dig hearty red wine and have been known to go into places in and around Eminence after a three day float and ask rather seriously if I could "perhaps see a wine list." Oh, I recognize it's a little silly, looking for great wine in tiny town restaurants in the Ozark Highlands, but we have some great wineries here--some well known, one great one hardly even signed off County Road 1000 (there really is one, a CR 1000). I've learned that Ozark wineries are responsible for some of the state's best wine, so my quest for a great Norton isn't so silly after all, and maybe one day soon I can go into River Rat's off the Current River and find a Westphalia Cabernet Franc on the menu to accompany my pizza.)
Not too long ago, I was slightly excoriated for ginning up a list of crayfish present in the ditches and sloughs at my former job site. A few years ago, I went out every day for a few days a week in the spring with turkey necks and Louisiana-made crayfish nets to sample crayfish. It was really as simple as that. I wasn't planning on publishing my crayfish survey, or even writing a full scale report. My boss just wanted a list of crayfish, so I surveyed the waterways, keyed out some crayfish, and sent my boss a list of what I found. He probably said, "huh, cool" upon receipt and shelved the list. Two years later, I was called out, asked over and over about my methodology, about the process, are there GPS points where I found each animal? What was I hoping to gain with my survey? Did I submit a full report to the state? Did I have vouchers? I explained -much to the dismay of my caller- that I went out, I don't know, in May? I had some turkey necks, some spare time, some crayfish nets...just to see what was out there. I interpreted the steely silence on the other end of my phone for what it was.
So, I'll try to outline a really simple "methodology" for my survey of super dry red wines produced in the Ozark Highlands American Viticulture Area: For starters, I don't like driving on weekends because I commute a long distance during the work week. While it's possible to set out on a Friday and visit each winery in the Ozarks that produces a capable Norton and Chambourcin in the course of three days, I really don't like driving and the stillness associated with it. Hence, I don't know much about the well-regarded and plentiful wineries around Ste. Genevieve (3 hours or more from Columbia) or even the new ones that slope westwards off the Ozark dome towards the Osage Plains that I'm curious about because I know the soils of that region pretty well (no direct route from Columbia; approx. 3.5 hours drive).
Rather than following highways or bedrock type, I've designated regions that will be explored every couple of weeks this fall based on my desire to drive and availability of Nortons. Like other wine-producing states, Missouri has designated "wine trails" that course through the state, small collections of wineries that can be explored in an afternoon, conveniently located near one another. I learned today that these wine trails are not determined by landform, growing conditions, or even the Missouri Grape and Wine Board.
We actually have four designated Missouri Wine Trails: The Missouri River region (a sort of okay region of not great-too sweet wine and few wineries); Hermann (exceptional); Route du Vin (around the lovely Ste. Genevieve area); and Ozark Mountain Region Trail (located over on the western edge in an area I wouldn't call mountainous, though great wineries). But these wine trails exist because the wineries in these regions worked together to come up with a name for their area (not based on land types like in Oregon), and because they plan similar events such as food pairing tastings or newly released wine tasting weekends. Ironically, one of Missouri's oldest wine-producing regions, an area with several nice wineries and the motherlode of grape vines, doesn't have it's own wine trail. Again, no fault of the state, but of the wineries who haven't really collaborated.
Having floated Ozark rivers for the past week and spent the night camping on the Gasconade last night, I decided that our first venture would be into the nearby St. James region, the land of grape stands (4M Vineyards), solid Nortons, and historic post oak savanna country. While most of this former open woodland-savanna landscape has been converted to the trashy but ubiquitous Eupatorium altissimum-fescue-cattle natural community type, that charming little city park with the sandstone glade that I want to burn exists here, too. Thousands of acres of restorable woodlands just waiting for a fire program can be found in this area. But winding through the acres and acres of grape vines and overstocked dense woodlands, one would be hard pressed to find an intact landscape or even one worth photographing for a sense of place, but for the beautiful low, undulating acres of grape vines.
Two of the region's most popular vineyards are located in St. James on I-44: St. James Winery boasts healthy sales of their sweet stuff statewide, but their Norton is outstanding (especially the 2005 vintage, which you can find discounted for some reason). I've stopped into their winery before, maybe five years ago, and fell for their Norton, though couldn't afford a bottle thanks to my 8$/hr. job. So I skipped St. James today, but drove a little further down the service road to Meramec Vineyards.
A charming little bistro, outdoor seating, a bocce court and a well-lit, tastefully appointed tasting room are housed in an older building surrounded by zinnias and trellised grape vines. It's all very bright and cheery inside Meramec Vineyards. Unlike St. James Winery who distributes their product all over the state, Meramec Vineyard wines can only be found at one grocery store in St. Louis, online, and at the I-44 winery.
My tasting consisted of the only three wines characterized as "dry reds"--two Nortons and a blend that the barrister called "like a merlot." And like a merlot, this one was way too sweet and boring for my taste (but people who like merlot would probably like it). The Nortons, on the other hand, aged in French oak barrels instead of Missouri white oak for some reason, were rather distinctive and unlike any other Norton I've met. Meramec Vineyards' Nortons were so vastly distinctive from other Nortons that I began drowning the poor, dear barrister in no fewer than 20 questions, with only one or two he could answer. Their 2004 Norton was reminiscent of a 2002 Taurino Salice Salentino--elegant, tasting like a Stargazer lily smells, not as brambly as the 2005. I don't know why they use French oak barrels, but their Nortons are really quite nice. I bought a bottle of the 2004, commented on the charming labels for all the sweet junk, and set out for winery #2.
Continue north on Hwy. B out of St. James, make a right on Co. Rd. 1000. Follow 1000 for several miles until U Road, where you'll make a left. Keep your eyes peeled for a very small vertical white board on a mailbox with tiny black letters written on it that say "Heinrichshaus." Make a right on the adjacent gravel road, pass through restorable woodlands with Aster patens, Aster turbinellus, and sprigs of big bluestem breaking through the leaf litter, and you'll end up at a tiny brown house with chairs scattered outside. Heinrichshaus Winery
has operated in the area for 30 years, specializing in very serious dry wines. Press the button on the walkie talkie provided on the door and wait a few minutes for a darling German man with brilliant eyes wearing an old straw hat, a stately German shepherd by his side, to invite you in.
I felt like I was back in Tivoli, maybe on the outskirts of Bologna, as I ducked into his dark and dank tasting room.
The walls of Heinrichshaus Winery are lined with dusty wine bottles housing elegant medals, early Missouri wine campaign posters, botanical drawings of grapes from the early 1900s--one frame housing two plates, one of the Norton grape, the other of the Cynthiana grape, thus negating all of the claims that "Norton and Cynthiana are the same grape." A proclamation created by one of Heinrichshaus Winery's long time customers rests on his shelves; years ago, Heinrich was crowned "King of Chambourcin," a fine, fine designation that encouraged me to stop looking around his little building and start tasting his wines. Walking back to the table, I noticed his lovely old, dark, scratched, worn hardwood floors bore signs of repeated foot traffic that stand testament to his 30 successful years in the wine making business.
As Heinrich situated himself behind the tasting table, he explained to me that he only makes dry wines because "that's how wine is supposed to be made." I walked behind the table and hugged his sturdy, yet trim, frame. So I didn't have to tell him "I'll only try your dry wines" because that's all he makes. He added that he only uses Missouri white oak barrels, and he'll use them over and over again. "Oaking is overrated," he told me. I countered with a line my colleague once told me over a hearty Norton, "green white oak never tasted so good."
Before stopping in the St. James Tourism Information Center for my map of the area's wineries, I had never heard of Heinrichshaus Winery. I've never seen his wines in stores, never seen a sign for the winery, never even heard it mentioned by fellow dry red wine lovers. As he poured the first taste of a 2006 Chambourcin, his charming labels tastefully drawn by his late wife, he explained that he subsists strictly on return visitors to his winery and online sales. I couldn't believe it. For 30 years, folks in and around St. James have patronized him so frequently that he's never had a problem selling his wine and staying in business (and I always thought folks in Missouri preferred all that sweet junk that everyone makes). Unlike other wineries, Heinrichshaus Winery doesn't charge as much for his dry wines--his 2005 Cynthiana and 2006 Chambourcin? Under 10$. His blend, named Prairie Rouge (possibly after the area's now defunct savanna landscape) costs a mere $12. He doesn't operate a fancy winery restaurant, he doesn't spend money on marketing, and his wines are among the nicest I've had in Missouri. Friends and family members will regularly receive Heinrichshaus wines for Christmas, and you, too, can buy his wine online here or at his little brown house.
The cloudy afternoon was young, despite the lengthy conversation at Heinrichshaus, and it dawned on me that I hadn't eaten anything all day but two s'mores over a stick fire for breakfast. Surely one of the other wineries around St. James sold food, so we set out south on Highway 8 towards Steelville in search of more dry reds and cheese.
For a couple of years now, I've seen Peaceful Bend Vineyard's wines on sale at the Osage Beach HyVee. Their blends are named after Ozark creeks and streams: Yadkin Creek, Huzzah Valley, Meramec, and so forth. The cheerful winery barn with brightly painted walls and pale hardwood flooring hosts a handful of tables, a cooler with cheese, sausage and crackers for sale, a little merchandise, and a long wooden tasting bar. Regulars traipsed through all day, camping outside with snacks and wine, spending the afternoon under the white oaks. There's a great vibe down there, situated as they are in hilly woodlands near the floating locus of the Ozarks.
I tasted their three dry reds, the Meramec, Norton, and Forche Renault. Still a little sweet for my taste, we settled on a bottle of the fun, lighter red, the Forche Renault. A blast of cherries and a smooth oaky finish traveled well with the round of Gouda and wheat crackers they sell inside. It's a charming place, but if you don't like cats, don't sit near the railing outside; the two winery cats really lived up to my overarching negative opinion of cats in general (an animal I rather despise for their impacts to wildlife): these two paw at you with their claws extended and mew for food. And if you ignore them to pet the wonderful three Labrador retrievers who sit quietly and kindly at your feet? The cats will hiss and scratch the dogs. I'd like to imagine I met the cats on a bad day, but these two really solidified my long held anti-cat bias.
And so, heading north into Rolla with six bottles of exquisite wine for my rack, we stopped into Panera for decaf coffee. There, I ran into a well-traveled engineer who works for the same outfit I work for. When he overheard me mention to the barista that I had visited the wineries in the area, he asked if I made it out to Sibyl's (St. James' fancy restaurant) and Heinrichshaus Winery. I explained that yes, I went to Sibyl's earlier this year and found the winery today. He threw up his hands, knocked back his head and said I was welcome to go back to Columbia now, because "you've seen everything there is to see here."
Posted by Allison Vaughn at 8:50 PM
Saturday, September 12, 2009
How can you tell the difference between a grape and an elephant?
"Grapes are purple."
What did Tarzan say when he saw the elephants coming over the hill?
"Look, here come the elephants!"
What did Charles de Gaulle say when he saw the elephants coming over the hill?
"Voila les elephants!"
What did Tarzan's Jane say when she saw the elephants coming over the hill?
"Look, here come the grapes!" (Jane was color blind.)
Drive I-44 around St. James these days and you'll see them, too, the grape stands stocked with fresh Concords and homemade grape jelly, maybe grape pies on a good day. We're amidst grape harvest in the Ozark Highlands, and thanks to the wet summer we've had, the Concords have never been juicier. Rumor holds (I heard the whisper myself!) that next week, the same vendors around 4-M Vineyards will be selling the classy Norton grapes for personal wine making enterprises. Oh, this is all very interesting and exciting, though I have yet to call the coopers in Lebanon to find out if I can buy a Barbie-sized white oak barrel for aging my own Norton. I think I know what they'll say...after they laugh.
Visit dry chert woodlands throughout the Ozarks, especially those that have seen fire in recent years, and try the little but super sweet native summer grape, Vitis aestivalis, a staple in burned woodlands. Folks in the Ozarks traditionally harvest these wild grapes for jelly-making, as it's darned near impossible to find decent grapes in grocery stores. Wildlife appreciate summer grapes, too. In mid-June, roughly two months before the grapes were ripe, I watched two yellow-breasted chats completely denude a few unripe clusters from vines all tangled up in oak sprouts and sassafras.
Missouri hosts over 6 wild grape species, from the riverbank variety (V. rupestris) which grows profusely on gravel bars in the St. Francois Mountains, to winter grape (V. cinerea), whose fruits aren't ripe until late fall, months after anyone cares about making jelly.
When I lived in southeast Missouri, I helped out with the grape harvest at the region's best winery (River Ridge). I stayed close by the men in charge of the vineyard those days, asking multiple questions about tending grapes in Missouri. I learned so much about viticulture in Missouri that I was a little flummoxed when they gave me money for my efforts that afternoon.
I no longer live near good wineries, but in the next few weeks, in celebration of my birthday, I will be visiting little known wineries in the Ozark Highlands on an official Norton Tasting Tour. If anyone's making pinot noir or cabernet franc, I'll try those, too. This is scientific research, you know, so I'll publish my findings.
Posted by Allison Vaughn at 8:19 PM
Wednesday, September 09, 2009
What a fun route! Cyclists will pass a few vineyards where quiet folks sell amazing freshly harvested Concords out of little clapboard huts with Grapes! painted on the side. They'll go through some pretty hilly terrain tomorrow, through the Gasconade River Hills, ending up in the beautiful (but sort of vacant) downtown Jefferson City. Maybe, at that point, someone will explain to our new governor that this is an event that really should be funded by the state....
Posted by Allison Vaughn at 7:17 PM