There are some people who would be nervous to hear the food they are about to eat has "a high grapple factor".

Fuchsia Dunlop is not one of them.

Dunlop is a celebrated expert in Sichuan cuisine and the author of a number of bestselling cookery books.

An ingredient like duck tongue, she explains, requires a diner to use their tongue and teeth to "grapple" with the food, working hard to separate the bouncy flesh from the slender spikes of cartilage.

Paying attention to texture, even when it might seem unappealing at first, can have a big impact, Dunlop tells ABC RN's Blueprint for Living.

"If you can develop an appreciation of texture for itself as another dimension of gastronomy, then not only will it open the door to fully appreciating this great cuisine of China – but also it's just life enhancing."

But are we predisposed to enjoy some textures over others?

And why do experts argue there's a connection between texture and undernourishment, depression and anxiety, and life during chemotherapy and COVID-19?

In her memoir, Shark's Fin and Sichuan Pepper, Dunlop dedicates a whole chapter to the importance of texture and mouthfeel in Chinese cuisine.

She describes the "cui" or crispness of fresh crunchy vegetables, the "tan xing" or springy elasticity found in food such as squid balls, and the "shuang" or texture that "evokes a refreshing, bright, slippery, cool sensation in the mouth".

These are not things she's always been well-versed in.

"There were a whole lot of ingredients that were initially incomprehensible to me," Dunlop says.

These include some that Westerners tend to find revolting; ingredients that are "slimy, slithery, bouncy and rubbery", like "the wet crispness of gristle, the brisk snappiness of goose intestines [or] the sticky voluptuousness of that reconstituted dried sea cucumber".

"There was a period when I ate them without pleasure but just with some bafflement ... and now I just love them," says Dunlop.

Professor Russell Keast, director of the Deakin University CASS Food Research Centre, says texture is mainly perceived by a sense of touch and sound in the mouth.

He explains there are three different surfaces in the mouth that sense texture: the tongue, the hard palate and the gums.

In contrast, your fingertip, though sensitive, has only one surface that senses texture.

Also, the mouth has fewer types of nerves to detect mechanical sensations or differences in pressure (known as mechanoreceptors) than in the finger.

This means that while the mouth is excellent at sensing texture, we cannot assume it senses them in the same way our fingers do.

"So, there is a complexity to food texture that we do not fully understand," Professor Keast says.

Add to this the role sound plays in how we perceive texture and things only get more complicated. 

Research published in a 2005 Journal of Sensory Studies article showed that by simply manipulating the volume of what diners heard, researchers could trick people into perceiving a chip to be around 15 per cent crunchier and fresher than if quieter sounds were played instead.

Still, determining what kind of texture you like can be pretty simple: Professor Keast makes clear it's not an academic definition, but that we often fall into one of four categories: crunchers, chewers, suckers or squishers.

"Crunchers" like chocolate with nuts, whereas "chewers" prefer a cherry ripe or chewy caramel.

"Suckers" like something that melts and "squishers" prefer a bar of chocolate with marshmallow filling.

More than simple preferences, the textures we lean towards can have a range of impacts.

Families with children who are neurodivergent can face challenges with hypersensitivity to certain foods and food textures.

It's often dismissed as fussy eating and can be a daily battleground for parents, but there can be more than contrariness to a toddler refusing food, including serious pain and genuine anxiety around eating.

According to a 2010 Academy of Nutrition and Dietetics journal article, understanding texture can help families and caregivers identify suitable and nourishing foods.

The article quotes an adult who lives with autism, as saying his aversion to canned asparagus is "due to its slimy texture", and that he "didn't eat tomatoes for a year" after a cherry tomato burst in his mouth.

"The sensory stimulation of having that small piece of fruit explode in my mouth was too much to bear and I was not going to take any chances of that happening again," he explains.

The man found carrots and celery were intolerable when paired with tuna because of the contrast in texture, but would happily eat the foods on their own.

Professor Keast says better understanding texture could also improve weight loss diets – it takes longer to chew textured foods, which gives our brains more time to register satiation and allows us to feel fuller.

We also know that older people struggle to eat food that's too rough, dry or crunchy, but that smooth or slimy food isn't as appealing.

"Understanding how to increase texture variety to maintain appetite and nutritional status is vital for healthy ageing," Professor Keast says.

Texture becomes more important than ever when people lose their sense of smell, says Katie Phillips, head and neck surgery specialist at the University of Cincinnati College of Medicine.

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Dr Phillips and her team have been studying how a loss of smell and loss of flavour can impact quality of life.

"Your ability to smell has a significant impact on your ability to enjoy food [and] cooking, which both can be social activities," she says.

"We also see people worry about their body hygiene when they cannot smell and about their safety in the context of being able to smell smoke, natural gas and expired food."

Dr Phillips says she has patients who lie awake all night worried they won't smell a gas leak in time.

"We know there is a dramatic association with depression and anxiety, but why this affects certain people more than others is not yet known," she says.

Some of her patients who have acute loss of their sense of smell have found playing with texture and temperature can help.

"[They] are drawn to the chemesthetic qualities of food – for example the texture, carbonation, temperature, mintiness or spiciness of foods – as they can still detect these sensations and … enjoy food."

Dr Phillips says some of her patients who've lost their sense of smell after contracting COVID-19 have told her they enjoy eating cold carrots, "as they have a nice crunch and temperature".

For Ryan Riley's mother Krista, it was chemotherapy, not COVID-19, that robbed her of her sense of taste and smell.

Riley, who is now an author and cook, was 18 years old when his mother was diagnosed with cancer.

"There was so much of the last few years of her life with the treatment that was really, really awful for her. She didn't have any sense of taste. Nothing that she wanted to eat felt good or tasted good," he recalls.

"We'd all sit down for dinner and there'd be no one there; she would be eating but she wouldn't be there. She wouldn't be present because she couldn't enjoy it.

"That was more depressing than anything, because they were the last memories that we had the chance to make," Riley says.

By the end, Krista, who loved food, could only manage iced lollies.

After his mother died, Riley found himself thinking about what could have helped towards the end of Krista's life.

He decided to start a cooking school, Life Kitchen, offering people living with cancer in the UK free cooking classes and free custom recipes.

One signature offering is a pineapple taco, where the pineapple itself is sliced very thinly and becomes a crunchy, juicy shell for the filling.

"For me, it's absolutely, hugely about offering texture. Everyone just thinks texture is soft or hard but it's creamy, it's slippery; it's also about sensation," Riley says.

Another example is a miso white chocolate dessert with berries, in which Riley serves hot sauce over frozen berries. The goal is to create a beautiful contrast in the mouth as the berries start to thaw and soften.

"I always think everyone should be playing around more with hot and cold … because if you can introduce that, you're already upping your dish to a whole other level."

Life Kitchen is now focused on modifying these recipes to suit COVID-19 patients who may have not only lost their sense of taste and smell, but also might be suddenly repelled by ingredients they once liked, like garlic or onion.

Riley believes even in the middle of severe, life-threatening illness, finding pleasure in your food is essential – and empowering.

"Food has the power to heal you mentally," he says.

"It has so much importance to making those memories with the people who you are with," he says.

"It's that sense of normalcy that can ground you [and help you recognise], 'This is my one moment to look after myself, while the whole world still spins'."

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