The research, published in the journal Food Chemistry, taps into the trend for development of ingredients with health and wellness functionality.
Addition of flour made from unripe bananas increased the resistant starch content by more than 12 per cent, without adversely affecting quality of the final pasta product, report the researchers from the Centro de Desarrollo de Productos Bioticos del IPN in Morelos, Mexico and the Universidad Complutense de Madrid.
"Pasta products containing banana flour exhibit a low rate of carbohydrate enzymatic hydrolysis and they could help broaden the range of low-glycaemic index foods available to the consumer," wrote lead author Maribel Ovando-Martinez.
"Moreover, this food contains increased levels of indigestible compounds (resistant starch and non-starch polysaccharides) that may be beneficial for intestinal health."
Pasta formulation
The banana flour was used with traditional semolina wheat durum to prepare spaghetti, with durum:banana flour ratios of 100:0, 85:15, 70:30, and 55:45.
"Whole durum wheat is employed in traditional pasta manufacture because of the unique rheological properties of its proteins," explained the researchers. "Partial or complete substitution of durum wheat semolina with fibre material can result in negative changes to pasta quality, including increased cooking loss."
In order to ensure a good quality pasta, a cooking loss of no more than eight per cent is considered acceptable, said the researchers.
"Hence, the spaghetti containing different level of banana flour was within the expected values of cooking loss and could be considered as spaghetti of good cooking quality," they stated.
In terms of indigestible starch, addition of the banana flour increased this, relative to the 100 per cent durum wheat pasta, which had a resistant starch value of only 1.11 per cent. The pasta containing the highest concentration of banana flour contained the most resistant starch, at 12.42 per cent, said the researchers.
Additionally, the nutritional content was further enhanced by the presence of antioxidant polyphenols and tannins in the banana fibre. Again, the pasta with the highest banana flour content (45 per cent) contained the highest quantity of extractable polyphenols (1.68 mg per g) and condensed tannins (17.67 mg per g).
"The banana flour used to develop the spaghetti was obtained from green or immature
bananas, which at this point possesses an astringent flavour, which is due to the content or condensed tannins or proanthocyanidins. The higher antioxidant capacity of pasta with added banana flour was due to the condensed tannins present in the banana flour," wrote the researchers.
Despite the promising results from the study in terms of nutritional content and pasta "quality", more research is needed to establish if the banana flour adversely affects the sensory profile, include taste and mouthfeel of the resulting pasta.
Other fruit flours
Only recently, researchers from Nova Scotia Agricultural College in Canada reported that apple skin, an under-utilised food-processing by-product, could offer the food industry a novel and healthy-boosting source of fibre for bakery.
Incorporation of apple skin powder into muffins were found to be higher in fibre and have a higher antioxidant content than standard muffins, they reported in Food Chemistry (Vol. 107, Pages 1217-1224).
Insoluble fibre contains cellulose, hemicellulose and lignin and cannot be dissolved in water, unlike soluble fibre. It is found in wheat or cereal bran and in most vegetables and fruits.
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2008.07.035
"Unripe banana flour as an ingredient to increase the indigestible carbohydrates of pasta"
Authors: M. Ovando-Martinez, S. Sayago-Ayerdi, E. Agama-Acevedo, I. Goni,
L.A. Bello-Perez