A more healthful, gluten-free flour made from sweet potatoes

Orange, starchy sweet potatoes are great mashed, cut into fries or just roasted whole. But you likely haven't considered grinding them into a flour and baking them into your next batch of cookies -- or at least, not yet! Recent research published in ACS Food Science & Technology has reported the best method to turn sweet potatoes into gluten-free flours that are packed with antioxidants and perfect for thickening or baking.

Wheat flour has been used for tens of thousands of years, and likely isn't going away anytime soon. But for those who face gluten intolerance or have celiac disease, the gluten proteins in wheat flour can lead to stomach pain, nausea and even intestinal damage. Several gluten-free options are either already available or in development, including those made from banana peels, almonds and various grains. But an up-and-coming contender is derived from sweet potatoes, as the hearty tuber is packed with antioxidants and nutrients, along with a slightly sweet flavor and hint of color.

Before it can become a common ingredient in store-bought baked goods, the best practices for processing the flour need to be established. Though previous studies have investigated a variety of parameters, including the way the potatoes are dried and milled, none have yet determined how these different steps could interact with one another to produce flours best suited for certain products. So, Ofelia Rouzaud-Sández and colleagues wanted to investigate how two drying temperatures and grinding processes affected the properties of orange sweet potato flour.

To create their flours, the team prepared samples of orange sweet potatoes (Ipomoea batatas) dried at either 122 or 176 F then ground them once or twice. They investigated many parameters for each sample, comparing them to store-bought sweet potato flour and a traditional wheat one. Regardless of drying temperature, grinding once damaged just enough of the starch to make it ideal for fermented products, such as gluten-free breads. Grinding twice further disrupted the starch's crystallinity, producing thickening agents ideal for porridges or sauces. When baked into a loaf of bread, the high-temperature-dried, single-ground sample featured higher antioxidant capacity than both the store-bought version and the wheat flour. The researchers say that these findings could help expand the applications for orange sweet potato flour, both for home cooks and the packaged food industry.

From Science Daily

Blowing bubbles in dough to bake perfect yeast-free pizza

In typical breads, yeast produces bubbles via a biochemical process, causing dough to rise and develop into light, airy, and tasty treats. Without that yeast, it is difficult to make morsels with the same characteristic taste and texture. The perfect, yeast-free pizza, as such a food, presents an important challenge for bakers and yeast-intolerant crust enthusiasts across the globe.

In Physics of Fluids, by AIP Publishing, researchers from the University of Naples Federico II developed a method to leaven pizza dough without yeast.

The team, which included its very own professional pizza-maker/graduate student, prepared the dough by mixing water, flour, and salt and placing it in a hot autoclave, an industrial device designed to raise temperature and pressure.

From there, the process is like the one used to produce carbonation in soda. Gas is dissolved into the dough at high pressure, and bubbles form in the dough as pressure is released during baking. In comparison to other scientific experiments, the pressures involved were mild. They can be obtained by a typical at-home coffee maker.

However, the scientists-turned-bakers had to be cautious with the pressure release. Compared to soda, pizza dough does not respond as nicely to an abrupt change in pressure.

"The key to the process is to design the pressure release rate not to stress the dough, which likes to expand gently," said author Ernesto Di Maio.

The authors evaluated their dough with rheology, which measures the flow and deformation of a material. Fine-tuning the pressure release through rheological analysis made it possible to gently inflate bubbles to the desired extent.

"We mainly studied how dough behaves with and without yeast. How the softness changes with leavening, and how the dough responds to a temperature program during baking," said author Rossana Pasquino. "This was fundamental to designing the pressure protocol for the dough without yeast."

After many unofficial taste tests, the researchers are purchasing a larger, food-grade autoclave that will make full-sized pizzas in future experiments. They hope to see their idea used in pizza shops.

"We had a lot of fun applying things we know well to delicious polymers, instead of our typical and sometimes boring smelly plastics," said Pasquino. "The idea of approaching food samples with the same technologies and knowledge used for thermoplastic polymers was surprisingly successful!"

As a person with a yeast allergy, Di Maio is also excited about applications for other leavened products like bread, cakes, and snacks.

Read more at Science Daily