José Francisco dos Santos Silveira, Jr., and Alicia de Francisco, PhD, from the Department of Food Science and Technology of the Federal University of Santa Catarina, Florianópolis, Brazil, outlined how different tropical starchy plants could be the future of starch production in their paper “Unconventional Food Plants as an Alternative in Starch Production,” first published in the March/April issue of Cereal Foods World.

As consumers are more interested in clean label ingredients, chemically modified starches can be a barrier to winning over these consumers to bakery and snack products. In their paper, Mr. Francisco dos Santos Silveira and Dr. de Francisco illustrate the potential in five tropical plants to meet the functionality of chemically modified starches.

Baking & Snack: Why do you think tropical starchy food plants hold so much promise as alternatives for modified starches? How is climate change impacting that conversation?

Mr. Francisco dos Santos Silveira: The exploration of starchy non-conventional food plants may revolutionize what we currently know about starches for specific uses.

(From left) José Francisco dos Santos Silveira Jr., and Alicia de Francisco, PhD
The different physicochemical characteristics of their native starch granules may result in different levels of enzyme hydrolysis, which in turn may yield different rheological properties from the native commercial starches we know but similar to those of chemically modified starches such as high paste clarity and stability to freeze-thaw cycles. These properties may even be potentialized with physical modification processes that do not utilize chemicals. This is an important factor that influences climate change.

Industrial agriculture is one of the leading promoters of greenhouse gases (GHGs). The expansion of monocultures has even invaded some preservation areas in underdeveloped regions. In contrast, implementation of family agroecological systems, not only produce less GHGs but also contributes to reversing climate change by soil carbon sequestration. Besides opening new markets, the starch extraction from tubers and roots from these unconventional plants will also contribute to economical sustainability and income stability to the producer regions.

You listed five tropical food plants that have a lot of potential. Why are the sizes and shapes of these plants’ starch granules so promising?

Mr. Francisco dos Santos Silveira: Starch shape just helps to identify the origin of the starch. On the other hand, starch size affects its functional attributes such as gelatinization temperature, swelling power, pasting properties and viscosity. The sizes of the five tropical plants are different from those of cereals.

H. coronarium and X. sagittifolium present smaller starch granule sizes (2-12 µm), which could be an option for fat substitution since their small size compares to that of fat droplets giving similar sensory perception. Smaller granules are also more susceptible to enzymatic hydrolysis.

The other three plants C. edulis, D. bulbifera, and H. coronarium have a mean size of starch (38 – 45 µm) larger than that of cereal starches. Starch with large granules is easier to extract, less susceptible to enzymatic hydrolysis, gelatinize at lower temperatures with higher swelling power.

The starch from each of these alternative food sources has an array of attributes that could be widely explored. 

Which of these five tropical food plants might have functionality for bakery applications? Is there any speculation as to how they could be used in baked goods?

Mr. Francisco dos Santos Silveira: The growing market for gluten-free products opens a possibility for the use of non-conventional starchy food plants. In fact, their starch is traditionally being used to make bread, cakes, cookies and desserts by the local farmers. For example, the starch from C. Edulis is widely used in Colombia in the production of a snack known as “achira.” The same starch is used in several Asiatic countries in the production of pasta products with mechanical resistance, low soluble losses during cooking and appealing transparency.

Starch with small starch size, as previously mentioned, can be used as fat substitutes. Could also be part of baking powder.

The non-conventional food plants may also contain antioxidants and could result in flours and starches with added nutraceutical potential. This possibility could yield products with protective health properties.

What can C. esculentus’ use in horchata de chufa tells us about its potential for uses in other foods?

Dr. de Fransicso: Cyperus esculentus might be the most promising prime material among the other tubers presented here from the point of view of its underutilization in contrast to its great productivity. The spontaneous production of about 5-12 t/ha of tubers in a wide geographic extension suggests that its yield in a planted field might be greater than crops like soybean, for example.

The main use for this plant is the Horchata de Chufa, a beverage quite popular in Spain. The solid residues from the production of this beverage have been studied as sources of fiber, antioxidants, and phenolic compounds. Some of the food products that are being explored are gluten-free products, cookies, oil, ice cream and even in flavored spreads such as oil-garlic. Some of these are locally produced in the Valencia region. C. Esculentus has great potential to be used food and beverages, as a source of fiber, antioxidants and oil.

What do the characteristics of H. coronarium’s starch – high amylose content, low crystallinity and pastes with high viscosity – mean for its potential in food, especially bakery?

Dr. de Fransicso: The high amylose content of H. coronarium’s starch, which is even higher than commercial starches such as corn, rice and cassava, suggests that it needs more energy to gelatinize.  Low crystallinity indicates granules with amorphous structure that makes the starch easier to swell, so it should give a uniform paste with a softer texture where the clarity of the gel is not required,  such as in sauces and creams. Since this starch is very prone to retrogradation, it should not be used in products that will have freeze-thaw cycles. Fermentation could yield a starch with decreased retrogradation. The expansion capacity of the starch granules could be a good attribute for expanded products such as extruded breakfast cereals and snacks.

The high final viscosity of H. coronarium starch after the cooling period is also a result of the high amylose content, and it yields firm gels. This property could make it usable in food products that require firmness such as some desserts and cakes. It is also possible to obtain pastes with low maximum viscosity using mechanical agitation during heating. This is caused by the presence of highly branched and short amylopectin chains that increase stability and rigidity.

The H. coronarium starch is also resistant to enzymatic digestion, which makes it desirable for low glycemic index products.

What makes X. sagittifolium so promising? What functionality could it bring to food?

The agricultural productivity the tubers from X. sagittifolium is about 30 ton/ha with an average starch yield of 20% (in relation to the tubers initial weight). This represents a starch productivity potential of almost 10 ton/ha. It should be noted that this is not an industrialized process.

The starch from X. sagittifolium has small size granules and as mentioned before could have potential as a fat substitute. The creamy aspect of its paste makes it desirable for sauces, which is one of the current ways to incorporate it in foods; however, it does not have good stability in freeze-thaw cycles.