Science news in brief: From lab-grown steak to the world's loudest birdsong

And other news from around the world

Sheets of gelatine fibres, as pictured here, create a base for muscle cells to grow on
Sheets of gelatine fibres, as pictured here, create a base for muscle cells to grow on

Lab-grown steak gets a little muscle

The alt-meat industry has created quite a sizzle, promising delicious burgers, steaks and even sushi that is grown from animal cells in the lab.

But most cellular agriculture still looks like mush. The manufacturing process – which starts with animal muscle and fat grown from stem cells in petri dishes – is fine for making burgers, but it fails to provide the kind of texture needed for more substantial cuts of meat, like steaks.

But scientists at Harvard University are reporting in a new study that they have found how to more closely mimic the form and flavour of real meat, by growing the muscle cells of cows and rabbits on a gelatine scaffold. Their research was published in the journal Science of Food.

To mimic this cellular environment, Kevin Kit Parker, a bioengineer at Harvard, and his colleagues decided to make scaffolds out of different concentrations of gelatine, a protein product derived from collagen. When collagen-rich meat cuts, such as beef chuck, are cooked, the heat naturally melts collagen fibres into softer gelatine, giving meat its succulent texture, Parker says.

To make gelatine microfibres, the researchers dissolved commercially available gelatine powder in water and spun it like cotton candy. Rotating the gelatinous slurry at high speeds allowed fibres to form at the bottom of the spinner. Using enzymes, the researchers then cross-linked the fibres to form a strong, woven structure for cells to grow on.

Rabbit and cow cells latched onto the gelatine scaffold, growing until they formed about a square inch of muscle.

To test whether the final product resembled the texture and behaviour of meat that chefs and home cooks use every day, the researchers performed a variety of food industry analyses: simulating cooking by heating the lab-grown meat on a hot plate, compressing it as if with a meat mallet and measuring the force needed to cut each piece of meat. They found that their lab-grown meat fell in between the springiness of a hamburger and a beef tenderloin.

Katsura leaves have a brown sugar scent

Ah autumn, time to sniff that pumpkin spice and… katsura?

Sugar, red and Japanese maples: you can drive up and down the East Coast of the US to enjoy their fiery pyrotechnic shows each fall. Along the way, you may want to stop, take a deep breath and try to catch a whiff of the katsura tree’s sweet scent.

Autumn seems to belong to pumpkin spice, and odours are often overlooked when it comes to fall foliage. We rave about how leaves die colourful deaths and rarely discuss how their scent changes with old age. But right about now, the leaves of the katsura, found all over New York City and in many other parts of the United States, are just beginning to turn.

Autumn’s earthy scent is the work of fungi and bacteria that decompose plant matter in the soil. But a chemical reaction in katsura leaves conjures fall spice, caramel and burnt sugar. As the leaves ignite, changing from plum purple or green to yellow, they abandon the hay-like smell of leftover chlorophyll and adopt a scent more appropriate for a bakery.

A team led by Ralf Berger, a flavour researcher in Germany, collected and analysed leaves from katsura trees throughout the year, and found maltol, a chemical compound used in flavour enhancers, perfume and incense.

Scientists have discovered crabs have a better memory than previously thought

It’s right turns only for some crabs in laboratory maze

Shore crabs can learn to navigate a lab-rat-style maze and remember it weeks later, according to a new study. While crabs that have never seen the maze before bump around aimlessly, experienced crabs race to the finish line with no wrong turns. The study, one of the few to look at whether crustaceans can perform such feats, suggests that crabs are quite capable of remembering routes.

Maze running could also be a way to measure the effects of changes in the sea, such as ocean acidification and warming, on crabs’ cognitive abilities.

The draw of nectar helped butterflies evolve

How the butterfly discovered daylight

Once upon a time, perhaps some 300 million years ago, a tiny stream-dwelling insect akin to a caddis fly crawled from the water and began to live on mosses and other land plants. The creature would become the ancestor of the 160,000 species of moths and butterflies that populate Earth today.

A new study explains why nocturnal moths evolved into daytime butterflies. It wasn’t to avoid darkness-loving bats, as biologists once thought, but to enjoy an abundant new drink: the nectar of flowering plants.

The researchers reconstructed the ancient timeline using DNA sequences of contemporary moths and butterflies. They calculated that the ancestral moth emerged some 300 million years ago, at the end of the Carboniferous era, well before the oldest known moth fossil, which is only 200 million years old.

The bellbird’s song rivals the loudness of a pile driver (AFP/Getty)

He sings very loudly, just not very well

The pressures of sexual selection have made peacocks gorgeous, wood thrushes sonorous and birds of paradise great dancers. The white bellbird has a different quality.

This goofball boasts the loudest birdsong ever recorded, according to a new paper. And he sings the most piercing note right into potential mates’ faces.

The white bellbird is a favourite among birders in Brazil. When several sing at once, they are “deafening”, and sound like “several blacksmiths trying to compete”, says Arthur Gomes, a student who contributed to the research. Until a few years ago, assessing the amplitude, or loudness, of birdsong required an unusual amount of devotion and tech-savvy. But new tools are making the pursuit much easier.

© New York Times

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