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

Potato genome decoded

More than 20 years after the first releasse of the human genome, scientists at the Ludwig-Maximilians-Universität München and the Max Planck Institute for Plant Breeding Research in Cologne, have for the first time decoded the highly complex genome of the potato. This technically demanding study lays the biotechnological foundation to accelerate the breeding of more robust varieties -- a goal in plant breeding for many years and an important step for global food security.

When shopping for potatoes on a market today, buyers may well be going home with a variety that was already available more than 100 years ago. Traditional potato varieties are popular. And yet this example also highlights a lack of diversity among the predominant potato varieties. However, that could soon change: researchers in the group of geneticist Korbinian Schneeberger were able to generate the first full assembly of a potato genome. This paves the way for breeding new, robust varieties:

"The potato is becoming more and more integral to diets worldwide including even Asian countries like China where rice is the traditional staple food. Building on this work, we can now implement genome-assisted breeding of new potato varieties that will be more productive and also resistant to climate change -- this could have a huge impact on delivering food security in the decades to come."

Especially the low diversity makes potato plants susceptible to diseases. This can have stark consequences, most dramatically during the Irish famine of the 1840s, where for several years nearly the entire potato crop rotted in the ground, and millions of people in Europe suffered from starvation simply because the single variety that was grown was not resistant to newly emerging tuber blight. During the Green Revolution of the 1950s and 1960s, scientists and plant breeders succeeded in achieving large increases in the yields of many of our major crop staples like rice or wheat. However, the potato has seen no comparable boost, and efforts to breed new varieties with higher yields have remained largely unsuccessful to the current day.

The reason for this is simple but has proven difficult to tackle -- instead of inheriting one copy of every chromosome from both the father and from the mother (as in humans) potatoes inherit two copies of each chromosome from each parent, making them a species with four copies of each chromosome (tetraploid). Four copies of each chromosome also mean four copies of each gene, and this makes it highly challenging and time-consuming to generate new varieties that harbour a desired combination of individual properties; what's more, multiple copies of each chromosome also make the reconstruction of the potato genome a far greater technical challenge than was the case for the human genome.

The researchers have overcome this longstanding hurdle using a simple yet elegant trick. Instead of trying to differentiate the four, often very similar, chromosome copies from each other, Korbinian Schneeberger together with his colleague Hequan Sun and other co-workers circumvented this problem by sequencing the DNA of large numbers of individual pollen cells. In contrast to all other cells, each pollen cell contains only two random copies of each chromosome; this facilitated the reconstruction of the sequence of the entire genome.

Read more at Science Daily