What does the current trend for pickling have to do with being born? Recent scientific thinking suggests that passing through the mother's birth canal is a crucial stage in laying down a person's gut flora – what's termed a "probiotic gulp" – and that babies born by cesarean section are more likely to encounter problems such as allergies and asthma later in life. Within this burgeoning area of research, there are questions over whether we can compensate for this by swabbing babies with vaginal fluid as they are born by C-section, with conflicting reports about the benefits this brings.
Along with forays into faecal transplants as a means of treating illnesses by repopulating the guts of unhealthy people with microbes from the healthy, we are in the middle of a bacteria boom, with research happening across the board into connections between the microbiome and a huge range of health problems including depression, obesity and even strokes.
Which brings us to gherkins and fads like kefir and kombucha: we pickle foods not just because they taste good but because they're said to introduce microbes that keep the gut in balance. In truth, the gut's microbiome – the word for microorganisms in any given environment, not just the stomach – changes throughout our lives, and we have a limited understanding of how probiotic foods and supplements help to keep us healthy. But what's the science behind pickling, and should you believe the hype?
Pickling foods preserves them because vinegar is a high acidity environment in which few bacteria can survive. “Pathogens do not relish acids,” says Glenn Gibson, food microbiologist at Reading University. Vinegar prevents the growth of cells and can kill some cells. Pickling foods in salty brine initiates a process of anaerobic fermentation which transforms sugars into lactic acids (that creates tanginess) similar to how yeast kicks off the fermentation that converts sugars into ethanol to make alcohol. With fermentation, reductions in sugar and increases in acidity again create a hostile environment for bacteria. Meanwhile, saltiness preserves crunch.
How good are pickled foods for you, really? According to Bruno Xavier, a food scientist at Cornell University, pickling creates an environment similar in acidity to the stomach, a first barrier to pathogens. Not only does this mean the destruction of potentially harmful bacteria, it also means that the ‘good bacteria’ used and generated in fermentation are more likely to survive the stomach’s acidic environment to the end of the small intestine or the large intestine where they do their work. “The stomach is acidic, small intestine slightly alkaline and large intestine slightly acidic to neutral,” Gibson explains. “Oral microbes like probiotics need to resist the very low pH in the stomach, with some doing better than others.” Pathogens – shigella for instance – will be less competitive because they are not exposed to the pre-acidity.
Probiotics have come in for some flak in recent years. In 2009 it was revealed that they were also being marketed as food for pigs, said to improve weight gain by ten per cent through "maintaining the integrity of the gastrointestinal flora". This was surely not what the 60 per cent of households now purchasing probiotic products were hoping to achieve. There's certainly a lot of dodgy science out there – and Xavier says it is "extremely complicated to infer anything definitive about the ability of these microbes to provide beneficial effects".
At the heart of this good-for-the-gut tale lies kombucha, a fermented, slightly effervescent sweetened tea drink thought to have originated in northeastern China, which is popular among yoga bunnies on the West Coast and commonly available in hibiscus flavour and in a quinoa suspension. In the UK, its rise has been more muted but still notable: Equinox Kombucha has gone from selling in the thousands to the hundreds of thousands in only six years. The Yorkshire-based business sells kombucha in four flavours for £1.80 a bottle using green tea. “Please don’t shake me, I am raw, organic, unpasteurised and ALIVE!” reads a label on the bottle.
You make Kombucha by mixing a sugary tea with a kombucha starter, “much as you would with sourdough bread or yoghurt or anything like that that has a culture,” says Daniel Spayne, Equinox’s CEO. The starter is made from a bit of kombucha left to ferment over time, making it very strong and bitter. “Where kombucha’s a litte bit different is we add what’s called a SCOBY – which is a Symbiotic Colony of Bacteria and Yeast.” This is a gelatinous disc that floats on top of the water, grows and forms a seal meaning the mixture ferments in a healthy way. This SCOBY, a mixture of bacteria and yeast, eats the sugar, caffeine, tannins, what have you, and performs a complex chemical reaction. After about a month, it’s ready to drink.
Many of the foods that have become popular in the fermentation trend hail from East Asia where rice is often a staple – Amy Bentley, professor of food at New York University, says many pickles developed to be “used as relishes and accents to make large quantities of grains more palatable”, such as kimchi with rice. Korean pickled cabbage, kimchi, is another staple pickle; only a couple of years ago WooJae Chung of New York brand Kimchi Kooks set up the company with his mother using inherited family recipes, and the firm has gone from strength to strength. Its recipe depends particularly “on salting and brining the cabbage to an ideal level so that proper fermentation to reach necessary level of acidity is achieved and that the cabbage (or whichever main medium) retains healthy and bouncy texture,” Chung says.
In Japan, many important parts of the cuisine are made using koji, a cooked rice or soybean inoculated with the fermentation culture Aspergillus oryzae, in turn used to make mirin, soy sauce and sake. Items such as Nattō – a powerful-smelling dish made from soybeans fermented with Bacillus subtilis, served with soy sauce, karashi mustard and Japanese bunching onion – have been making their way into western markets too. Japanese "good bacteria" company Yakult pioneered the fermentation fad when it entered European markets in the nineties with its fermented milk drink.
Chef and pickling enthusiast Rosie McBurney has been known to try her hand at making umeboshi: Japanese pickled plums which become extremely sour and salty after being brined for months in barrels with weights put on top. These are a delicacy usually eaten with rice and shiso leaves. Maybe next on the horizon of western importations will be the Chinese salted duck egg delicacy, or (unpickled, but better yet) the thousand-year-aged-egg which – fake news – is made over a few weeks or months by preserving duck, chicken or quail eggs in a mix of clay, ash, salt, quicklime and rice hulls, turning the eggwhite beautifully black and translucent, the yolk dark green.
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This article was originally published by WIRED UK
