Glen Paul: G’day, and welcome to CSIROvod, I’m Glen Paul, where today the research is about healthy and tasty food. I’m at CSIRO’s Food and Nutritional Sciences Laboratory in North Ryde in Sydney, where Scientists are working to get their head around the complex science of food flavour. And as we’re about to find out, there’s a lot more to it than what you might imagine.
Leading the research in flavour and sensory science at the facility is Dr Conor Delahunty. Conor and his team basically work to understand what makes people like or dislike certain foods.
Dr Delahunty: If food doesn’t taste good it won’t be purchased, and this is important when it comes to food quality. At the same time, foods that are too high in fat for example, too high in salt, too high in sugar, there’s a risk that they lead to the development of chronic diseases.
We help the food industry to reformulate food so that it still tastes good, and the consumer will still desire to consume it, but at the same time it complies with nutritional guidelines and meets nutritional recommendations in terms of a healthy diet.
Glen Paul: Measuring taste and aroma, and how one might influence the other, is not an easy task. So Conor took me to meet Scientist Andrew Eddy, the man behind a very sophisticated piece of equipment that was purpose built to provide such answers.
Andrew Eddy: This is our Simultaneous Gustometer and Olfactometer. We integrate in our minds the sense of taste and the sense of aroma to come up with a flavour. The flavour depends not just on how much of a taste and how much of the aroma is there, but how it’s delivered – when it’s delivered within a chewing cycle, whether we sniff it, whether we’re primed by a sniff beforehand, all those sorts of things.
So the idea behind a Simultaneous Gustometer and Olfactometer is to be able to deliver tastes and aromas with the timing and the concentrations that are important in a food, but without having to create the food in the first place. The food structure delivers the timing in a food, and we deliver it by using computers.
Glen Paul: With aroma, appearance, and our expectations influencing the way we perceive taste, children who are tasting things, perhaps for the first time, rely on their sensitive taste buds as well as their sense of smell and other visual cues to decide if a food tastes good or not.
Astrid Poelman: So we’re doing consumer testing with children. A lot of our food preferences are formed, so we’re born with a like for sweet tastes, and a dislike for bitter tastes, but most of our food preferences are formed throughout life, and childhood is one of the most important stages in life to develop food preferences that later then influence also sensory dietary behaviour. So we’re looking into children’s testing to see how food preferences are formed, and with a view to try to encourage children to eat more vegetables.
Glen Paul: Traditionally Brussels sprouts and broccoli are two vegetables that children have a dislike for, but in this laboratory Dr Dimitrios Zabaras is breaking down the flavours of broccoli into their separate parts.
Dr Zabaras: So what we’re trying to do here is to understand what are the chemical signals and the chemical principles behind those undesirable principles that you find in broccoli. Each fraction contains only a part of the total taste profile that you find in the broccoli. The nicest part is the transparent part, because that’s where all the sugars are, and it’s very, very sweet.
Glen Paul: Genes and diet interact when it comes to taste sensitivity, and there’s going to be differences between people. Conor took me to meet Jessica Stewart who is collecting cells from the tongue of a volunteer, to measure the relative expression of different receptors on their tongue.
Jessica Stewart: So we’ll just do a collection now. I’ll take it from the side of your tongue. Just stick your tongue out. And you just use a brush gently, and that’s enough to collect the cells. And then once you’re done, place the cells in this solution, which is used for isolating RNA and DNA. And once these samples are collected we’ll take them upstairs.
Glen Paul: So that’s where we went next, to meet Garry Hannan in the Genomics Unit to find out about the instrument used for genetic analysis.
Dr Hannan: What we have here is a really high technology tool that allows us to investigate all the genes in the human geno, all those genes that we share, about 25 000 of those. Our interest is in the genes that govern taste perception, and in particular those genes that govern novel tastes such as the ability to taste fat. Now, those genes haven’t been discovered yet or identified, but amongst those 25 000 on this tool we expect to be able to locate that particular gene.
Glen Paul: Dr Damian Frank works with equipment that measures flavour and aroma release during consumption. You might bite into a food that hits you with a strong burst of flavour straight up, or it could be a slower process – the food releasing the flavour as you chew.
Dr Frank: We can make an extract of an aroma, or the volatile compounds in food which are very important for creating that unique sensory impression of the food, and analyse it by other techniques. But at the end of the day what is really important is the timing and the amount of how that aroma is released from a food during oral processing or eating. And this instrument here is capable of monitoring or measuring changes in volatile compounds in real time.
So we can have a human subject hooked up to this machine, they can be chewing a piece of cheese, or a novel food that we’ve created in the lab, and we can measure very accurately how the volatile compounds are changing over time. And that ultimately is decisive in creating the, well a huge part of the sensory impression of that food.
Glen Paul: Of course there is another instrument available to test food, and that’s people. Sensory Assessors are employed by CSIRO to taste food, so must have good sensory abilities, and be able to participate in group discussions. This morning a group has come in to taste yoghurt, and Raju Krishnamurthy is taking them through the procedure.
R Krishnamurthy: We’re evaluating for three attributes – strawberry, sweetness, and thickness.
Glen Paul: From here the Panellists make their way to sensory booths, where they’re to compare low fat yoghurt with regular yoghurt. The booths have been bathed in a red light to cloak the food’s appearance. The red fruity looking strawberries in the yoghurt may influence how the Assessors respond to flavour.
The Panellists are separated from a kitchen by small sliding doors, which are used to pass the food through.
The Panellists don’t express likes and dislikes – their role is to objectively measure the intensity of sensory properties of foods that are likely to be important in food acceptance.
By using the computer they can measure taste, odour, and texture. At the end of the day it’s about CSIRO helping the consumer make better choices by better understanding their desires.
Well that’s sensory science in a nutshell, and if you’d like to find out more about CSIRO’s Food and Nutritional Sciences, just go to our website at www.csiro.au.