Government targets to reduce salt in our diet could have implications for millers and wheat breeders. Mike Abram reports
Efforts are being made to breed breadmaking wheat varieties that will produce protein quality characteristics to allow millers to continue to reduce the amount of salt in bread.
A new drive to reduce salt in our diets began in 2004, when the Food Standards Agency published voluntary targets to reduce salt in around 85 food categories.
The aim is to reduce daily salt intake to just 6g. Since the start of the campaign daily intake has reduced by around 0.9g, but it was still much higher than the target, at 8.6g, when last surveyed in 2008.
Bread is one of the key targets for the FSA. Around 35% of the salt we consume comes from grain-based products, such as bread and breakfast cereals. The high percentage is as much to do with the amount eaten than the products containing high amounts of salt per se.
But reducing levels isn’t straightforward, explains Charles Speirs, baking science and technology manager for Campden BRI. “Salt isn’t just used to flavour bread, but also for technical purposes.”
In particular, it is important for the large-volume bakers who use the Chorleywood Bread Process. The process can use lower-protein wheats, with chemical improvers, such as ascorbic acid, to produce a loaf of bread in just 3.5 hours.
Dough is rapidly developed using high-energy mixing, which incorporates air that the yeast can then act on before being baked.
But if some salt is removed then the yeast ferments in an uncontrolled way, Dr Speirs says. “It changes the way the bread rises. You can change the level of yeast to compensate, but it can lead to an uneven crumb structure – you end up with an open structure.”
In sandwich bread, in particular, with its fine network of bubbles, the uneven structure is not desirable. “You don’t want big holes that butter drops through. And even where you have bubbles, you want them to be of a similar size.”
Another issue is loaf volume. Generally bread is sold by weight, with premium loaves having an improved structure and greater volume. That also makes them softer, as they are less dense, and helps increase shelf life. But the fear is that less salt will reduce volume.
A FSA-funded project to assess what the impact of reducing salt would be on both crumb structure and volume was set up, with Campden BRI quantifying the likely problems and Nottingham University researching what the causes might be.
But early on another issue became apparent. Reducing salt while using the Chorleywood Bread Process brought more fundamental problems with the dough – it made it less cohesive and more adhesive. “It tended to fall apart, but also stick to the equipment.
“So that became the focus for the project – how do you stop it becoming sticky and falling apart.”
Production methods can play a part, the researchers found. “If you produce the material consistently, slowly and in a cool environment then typically you don’t see problems,” explains Dr Speirs. “But when the process limits are stretched – for example, if the dough is left to prove for 20 to 30 minutes rather than 15, which can happen when producing large batches – then you see problems. A warm bakery can also be an issue.
“And then there are times when you get sticky dough and you can’t explain it. What exacerbates the problem is there is currently no test that will allow you to predict whether you will have sticky dough or not.”
Coming up with a method of predicting how dough will handle is one aim of a Campden BRI-led research club of industry partners, which is funding a four-year PhD student at Birmingham University.
The research, which involves wheat breeder RAGT, will look at whether ingredient changes can solve the problem, as well as looking at whether there is a production fix.
Indeed, ingredient change might be preferable. It would certainly be cheaper, in the longer term, for millers to be able to use raw materials that will tolerate lower salt levels in bread without needing to change their processing procedures or equipment.
There is hope that this could be possible, says Julie Seekings, RAGT’s cereals analytical manager. “Not all varieties react in the same way when you reduce salt.”
The firm has been investigating how different varieties perform in predictive breadmaking tests in its laboratories. But it has had to adapt some of its methodology to mimic the reduction of salt in breadmaking by the millers and bakers.
“Our tests are done without yeast so they don’t fully replicate the breadmaking process,” Mrs Seekings says.
Instead, the firm, in common with other breeders, tests the elasticity and extensibility of dough using Alveograph and Extensograph measurements. Those tests use a standard amount of salt in the flour, which corresponds to a higher level of salt in bread than the 1% millers are now aiming for.
“So we’re testing varieties with lower amounts of added salt to see what happens.”
The initial results suggest that the elasticity and extensibility of the dough produced does not reduce by the same amount for each variety. “It suggests there are lines that are possibly more suited to producing bread with lower salt levels.”
And it doesn’t necessarily follow that the current, good breadmaking varieties will necessarily have the right characteristics for baking with a lower salt content.
The firm’s senior wheat breeder Ed Flatman, says: “The initial testing gives some indication of how reduced salt could change some of the parameters. Some varieties that were only average before, look better under low-salt regimes, for example.”
The likely solution is to breed varieties with stronger rheological properties – increased elasticity or extensibility. “Varieties with those properties wouldn’t necessarily make it onto the current Recommended List,” he points out.
Finding varieties more adapted to a lower-salt baking process has begun by looking for variation in existing varieties, but has been extended to pre-commercial material, he says. “They have a broader range of genetics that we could exploit.”
Beyond that, another option is to look at varieties from the firm’s European breeding programme, or even further afield, for a greater range of genetic variation.
“We know something about the genetics – which combinations of genes make dough with more elasticity or that are more extensible.”
In particular, two types of protein are under scrutiny.
“The largest grain proteins, the glutenins, have the biggest effect on overall quality, and we can select for those. But we may want to also look at the gliadins, where there is more variation,” says Mr Flatman.
That variation will allow breeders to put together more combinations to test for suitability in low salt regimes, he adds.