Future in Food: Educators

Narrator: Everyone is familiar with the idea that substances are either solid, liquid or gas.

In the real world things are not always this simple.

Look at this smoke: it is behaving like a gas but if you look closely you can clearly see it is made up of solid particles suspended in a gas, which in this case is air. So is it a solid or a gas?

We call this sort of two-phase system a colloid, and they come in all sorts. In this case, smoke is a gas-solid colloid. Here are some other examples: you can have liquid-gas colloid or a solid-gas colloid or a solid-liquid colloid or even solid-solid colloid.

Today we're going to look at liquid-liquid colloids, specifically colloids made from two liquids that don't mix.

This sort of colloid is called an emulsion, and these are very important in the food industry.

The problem is that oil and water don't mix. This can be a problem if you want to make an emulsion that is going to last for more than a few seconds. In the food industry we get around this by adding substances called emulsifiers.

Here is a mixture of oil and vinegar. Vinegar is mainly water and behaves in the same way. To investigate emulsions, we're using mixtures of oil and water. To make it easier to see, we have dyed the oil component using a fat soluble dye, Sudan red. This dissolves in the oil, giving it a red color which doesn't spread into the water layer.

Now we're going to try to use a few emulsifying agents. To make it a fair test, we're going to use the same amount of each. The ones we're going to use are egg yolk, as used in many sauces; detergent, in this case washing up
liquid; mustard, as used in salad dressings; and a commercial emulsifier.

Now we put a different emulsifying agent into each sample.

Now we need to mix the layers to create our emulsions. When this is done commercially a blender is used, but in the classroom it is possible to use smaller quantities and simply shake the mixtures vigorously for one minute.

Leave the samples for a few minutes, and wait and see what happens.

You can see that all of the emulsifiers have slowed the separation of the two layers.

Looking at the samples it seems that egg yolk is the most effective at this.

It's perhaps surprising that it is more effective than the commercial emulsifier, but there are many other factors to be considered from preparing food products than simply the stability of the emulsion: taste, texture, cost and many others.

Paul McKnight: My name is Paul McKnight and I'm a senior research and development manager at Macphie of Glenbervie.

Macphie is our leading food ingredients manufacturer, who develop and manufacture products for the food industry.

Emulsions are essential to our products, because a number of different properties are required across your shelf life.

When you think of emulsions you think of oil and water, or water and oil, but when you reflect on everyday products such as muffins you have to create a stable batter in order to have the same finished product consistency.

Our products contain emulsifiers, they contain starches, gums, gels to ensure the product stays in solution. One example would be the dairy cream alternatives that we manufacture, and it's essential that they remain in solution over the shelf life, and that the product remains stable, but not too stable that it takes too long to work.

I've always had an interest in science and food and I worked in kitchens whenever I was younger, and later as a chef to pay my way through university.

Future problems that I see the industry facing are the ones that you read about in the FGD press at the moment. So there's fat, sugar is a huge one at the moment, and knowing that we've already experienced the salt reduction over the last decade, and the impacts that that's had on the food industry, the likely requirement for reduction in calorific delivery is probably going to be one of the biggest ones.

The best part about my job is seeing our finished products up on the shelf, whether that's me that's developed them personally or the team.

For anyone that was interested in getting a job in the food industry, I would encourage them to develop their analytical skills and also their approaching sciences specifically with chemistry.

Narrator: When food goes off or becomes rancid, this is due to a complicated series of reactions which are mainly types of oxidation. The food industry slows down these reactions so that their products last as long as possible. Many of these foods contain oils, and it is the oxidation of these particular products that we'll be looking at today.

There are several ways companies try to keep their oil-containing products in good condition. As an oxidation reaction, if you remove oxygen the process will be slowed down. Crisp packets, for instance, are filled with nitrogen rather than oxygen-containing air.

The two most important environmental factors that determine how quickly oils go off are the temperature they are stored at and the amount of light. That is what the first experiment is going to investigate.

We are using lard in this experiment. Along with many other commercial fats and oils, it contains antioxidants to increase its shelf life. If you want the reaction to proceed faster you can use fat, which can be collected from cooking bacon, sausages or even oily fish.

To visualize the process we mix betacarotene in with a fat. Betacarotene is a terpine, a highly unsaturated compound that behaves similarly to fats. Betacarotene is orange - it gives carrots their colour - and when it's oxidized it goes colorless.

Now to the experiment. Take a small disc of filter paper and dip it into the fat. Take it out then place it in a petri dish. Repeat this until you have four discs in four petri dishes.

First we look at temperature and light. Dish A and Dish B are kept at room temperature, A in the dark and B in bright light, ideally on a window sill. Dish C is placed in the fridge and Dish D in an incubator set at around 40° Centigrade. Both of these will also be in the dark once the doors are closed. Leave these where they are for four to five days.

The second experiment will look at the effect of chemicals on this process. As before, prepare some discs of betacarotene-coloured fat and place them in petri dishes. This time treat the dishes as follows: one just with water, which is our control; two with a sea salt solution; three with a commercial antioxidant, in this case BHA. Now place all of them in an incubator at around 40°; leave them for 4 to 5 days.

Now let's look at the first experiment. You can clearly see that the dish left in the light has no colour left at all. Of the others, the colder the temperature the more of the original color that is left. So the message here seems to be: keep your fats and oils cool and in the dark.

Going on to the second experiment, you can see that compared with the water control the others have faded less due to their antioxidant activity.

Kevin Block: I'm Kevin Block. I'm the new product development project manager for Baxters Food Group. Oxidative rancidity, from a Baxters point of view, is probably most applicable to when we do the pastry, because of the fat content that we put into the pastry, and we're layering it, we'll leave it to rest for a short period of time, just a number of hours, but then we have to use it within 24 hours in our guidelines, the maximum time, even though it's chilled storage. The oxidative acidity will basically make everything taste off and it'll turn the
pastry so you're getting that kind of sourness, I think is maybe the easiest way to describe it.

Controlling the process: if you understand the process you can control the process and that's the critical part is that understanding.

We've got quite an extensive laboratory on site. We've got a large quality control and quality assurance department so we need to understand how the reaction occurs if you like, what drives it and what makes it happen, so you can actually avoid it. So keeping things at a lower temperature, that helps; keeping it in a room with very little light, that helps. So if you understand what causes it, you can then ensure that you do as much as possible, as simply and as cheaply as possible, to avoid it.

We need good food technologists, scientists, everybody that can come together and create good quality food products. We need them and without the skill base behind it we will suffer. We are suffering at the moment; we already are short of food technologists, food scientists.

If you want a career in the food industry, just go for it. Just go and do it. It is so satisfying. You get to meet fascinating people; you get to eat some phenomenal products; and you get to go to some really interesting places as well.

When you see somebody going into a supermarket and picking up your product that you've made, and you've helped be, through that whole thing of taking it from somebody's idea and somebody's concept through to a safe, nutritional, good product on the shelf.

Working with food's great. It's absolutely magic and, yes, I couldn't recommend it more and that's coming from an engineer.

Narrator: Have you ever eaten Asian food? If you have, then you've certainly eaten soy sauce.

There are many different varieties of soy sauce from many different countries in East Asia. We're probably most familiar with the sauces from China. These come in two main types: dark, which is mainly used for dipping or sprinkling on food, and light which is more often used as a cooking ingredient.

Have you ever wondered what it's made of? It starts with these soya beans. They are
boiled to soften them and then mixed with grains such as wheat, barley or rice,
and they're also mixed with brine. They're then fermented using a particular variety of aspergillus mould.

One of the reasons soy sauce is so popular is that it gives food a big hit of umami.
Umami is the fifth basic taste after sweet, sour, sugar and salt, and it's a sort of
savoury flavour.

This umami flavouring is due to the presence of amino acids, particularly glutamic acid. In fact the salt monosodium glutamate is often used in Chinese cookery to enhance flavour in the same way we might use salt.

In the case of soy sauce we will use thin layer chromatography or TLC to analyse which particular amino acids are present.

You will all be familiar with paper chromatography. TLC works in the same way to separate substances according to their solubilities and how they react with the material the plate is made of. TLC uses a thin layer of silica or alumina on a plastic backing.

Here we are going to use TLC to investigate the amino acids present in three different types of soy sauce. We have a dark soy sauce, a light soy sauce and a sample from some supermarket sushi.

Take the TLC plate and lightly draw a pencil line about one centimetre from the bottom.
Apply a very small spot of your soy sauce, only a couple of millimeters or so. If your plate is wide enough you can put further spots along the plate.

Once you've applied the spots, place the TLC plate in the beaker so the bottom just dips into the solvent. Now cover and wait.

Once the solvent has reached a good height remove it and let it dry. The amino acids are not visible to the naked eye so we need to use a reagent which will enable us to see them. The reagent we use is ninhydrin: it is available either as a spray or as a solution you dip the plate into.

The solvent is harmful so this should be done in a fume cupboard. We let it dry again but still there is nothing to be seen. This is because the reaction needs heat to work. We place the TLC plates on a hot plate at 60 to 70 degrees.

You can now see that spots have appeared at different points on the TLC plate. Each spot represents a different amino acid.

You can see that the three samples we used have slightly different patterns as spots, meaning that they contain some different amino acids.

Dr Jonathan Wilkin: My name is Dr Jonathan Wilkin and I'm from Aberdeen University and I'm a senior food technologist.

As a food technologist you have to be able to do as much as possible because you have to apply your trade to most things, so it's anywhere from product development, consumer studies and technical analysis within labs.

Thin layer chromatography is a really important part of the food industry. It shows you the basis, the foundation of how chromatography works and how it works is the size of the molecule and how fast they move and that's really important in the food industry because we can look at things like aflatoxins and other toxins using HPLCs or we can look at lipids and fatty acids with using gas chromatography, so they use the same principles as your TLC plates, but they're in a much more advanced way, which is how we use them in the food industry.

My career path for where I am? It started off as doing home economics and chemistry at A level and then I went off and did a food science and technology degree, and then I went into industry and worked for three years and then I came back into academia and did my PhD in food chemistry and then I got a job as a senior food technologist at Abertay University in Scotland.

The biggest problem we've got in the foreseeable future is sugar and how to reduce sugar down and keep a product that tastes good and has the same structure.

In the food industry as a whole worldwide we're going to have to have more protein because it's the one thing that will keep the whole world fed so protein is a really important thing, and proteins and sugars are all chemicals, so chemistry is really important.

So get your chemistry, get your sciences in. We need people with the chemistry brain to help us in the food industry. And they are the people that will solve the big, big issues that we have.