Green banana flour: A powerful new tool in the digestive health toolbox?
The NuBana brand (owned by IAG), which debuted at the IFT show last year, produces several grades of green banana flour from Ecuador. Its first two products - N100, which delivers the processing benefits of a native, cook-up starch with unusual viscosifying properties; and P500, a pre-gelatinized flour that thickens in cold water and can replace gums and hydrocolloids – are clean label functional ingredients being tested in everything from beverages, sauces, pasta and puddings to cereal bars, fruit fillings, crackers and baby food.
However, its latest innovation, NuBana RS65 (labeled as ‘green banana flour’ or ‘dried green bananas’) - which has around 65% resistant starch - is a functional health ingredient with myriad health benefits, said Rhonda Witwer, VP marketing and business development at IAG.
“The sooner we can get away from the concept that all fibers are the same and understand the value of consuming many different types for specific health benefits, the better."
Not all starches are the same…
There are different kinds of starch, which are metabolized differently, she explained, with rapidly digesting starches breaking down quickly in the small intestine before entering the bloodstream as a nutrient; slowly digesting low-glycemic starches providing energy without spiking blood sugar, but still metabolized in the small intestine; and resistant starch, an insoluble dietary fiber which resists digestion in the small intestine and reaches the large intestine, where it its fermented.
The fermentation produces beneficial short-chain fatty acids such as butyrate, explained Witwer, an expert in resistant starch, which she spent years studying during her time at National Starch (now part of Ingredion), which markets high amylose corn starch brand Hi-Maize.
There are more than 160 human studies on unmodified resistant starch. Many are on corn but a growing number (30+) have looked at green banana flour, said Witwer, addressing digestibility, insulin and glycemic response, colonic health and fermentation, satiety and weight, and other metabolic effects.
Green banana flour also has prebiotic effects in that it promotes the growth of beneficial bacteria such as Ruminococcus bromii, Akkermansia, and Bifidobacteria, and reduces the prevalence and growth of potentially harmful bacteria in the large intestine, while a growing body of research also suggests it helps maintain integrity of the intestinal mucosal barrier, triggers beneficial changes in gene expression and tackles diarrhea, she said.
“Butyrate is the preferred fuel for healthy colonocytes [the cells lining the colon], but is also a powerful bioactive contributing to digestive health. A recent review article (Bedford and Gong, Animal Nutrition 2017) states: 'Butyrate is not only a primary nutrient that provides energy to colonocytes, but also a cellular mediator regulating multiple functions of gut cells and beyond, including gene expression, cell differentiation, gut tissue development, immune modulation, oxidative stress reduction, and diarrhea control.'
“Numerous clinicals have shown that resistant starch from bananas, green bananas, and high amylose corn help stop diarrhea from multiple causes. It is believed that the butyrate causes the re-absorption of sodium in the large intestine. The movement of sodium triggers the re-absorption of water due to osmotic pressure. Other fermentable fibers have not shown similar effects.”
So how can manufacturers use NuBana RS65?
“RS65 is ideal as a standalone superfruit powder that consumers can add to their own foods and beverages, smoothies and shake mixes, powdered supplements or snack/energy bars that are not baked,” said Witwer. The crucial point for firms looking to use it for its health benefits, she said, is that RS65 is not heated, as this degrades the resistant starch.
“If you disrupt the granule by heat or shear you can lose the resistant starch, so I’m a little concerned when I see companies out there promoting the benefits of resistant starch on products where the starch will be cooked out [for example baking mixes where the ingredients will be exposed to high heat].”
The resistant starch in green banana flour is classified as a dietary fiber by the FDA
NuBana RS65 is dried via a patent-protected process to preserve its high levels of resistant starch and slowly released digestible starch. The resistant starch is not isolated or extracted and is automatically classified as (insoluble) dietary fiber on the Nutrition Facts label, she explained.
It is not therefore required to go through a petition process, unlike high amylose cornstarch (Resistant Starch 2), retrograded cornstarch (Resistant Starch 3), resistant wheat and maize starch (Resistant Starch 4), she added.
“Green banana is more consumer-friendly ingredient than corn, so we see a tremendous opportunity, particularly in the natural products industry. The problem with inulin and FOS – which are easy to use - is that they can cause gas and discomfort for some people, even at low levels. With green banana flour there are clear strong benefits and you don’t get the bloating and gas.”
International Agriculture Group (IAG) is led by fruit industry veterans including Maurice Moragne, CEO, who has held senior roles at Chiquita, Patagonia Foods and Naturipe Foods; Jackie Fera, VP of sales & customer development, who previously worked for Chiquita, Heinz, Mars and Unilever; and Ken Billings, strategic advisor, who has worked at Chiquita and Naturipe. Rhonda Witwer, VP marketing and business development, is an expert in resistant starch who worked at Ingredion for more than a decade before setting up the consultancy Witwer Works.