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Green Banana Flour: A novel gluten-free starch
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Saturday, 02 September, 2017, 08 : 00 AM [IST]
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Neha Pandit Tembe
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Green Banana (Kaccha Kela), a vegetable once restricted to just chips, Indian vegetable (sabzi) preparation and for purpose of religious fasting is now finding a renewed life in the form of Green Banana Flour. It has gained a lot of popularity these days as great gluten-free and healthy flour option. Green/ Raw Banana Flour (henceforth referred to as flour or GBF) is the main byproduct of green banana and has become a common way to preserve the fruit.
Since old times, especially in African countries, Raw Banana Flour was looked upon as a cheaper alternative to wheat and other cereal flours. It was commonly given to infants as an energy-dense food. But now in fact it’s being promoted as better than maida and wheat flour due to its several health benefits, especially, to celiacs and gluten-sensitive people.
The process of making the flour traditionally involved peeling, cutting, and sun drying of the raw bananas before the mechanical grinding process. Today in commercial setups, the basic process remains the same except even peels are used, and grinding-drying are not manual but automated. The GBF process requires 8–10 kg of raw green bananas to produce 1 kg of Banana Flour, thus explaining the reason for slightly higher costing.
Various studies report the carbohydrate content of flour ranged from 75.00% to 89.00% depending on stage of maturity, variety and processing steps. Carbohydrate composition breakup indicated the flour to contain 2.8% soluble sugars, 70.0% starch (making it high starch food) and 12.0% non-starch polysaccharides as per one of the study. The Green Banana Flours, mainly unpeeled, are good sources of fibre and resistant starch (RS) with an average of 21.91g/100g and 68.02g/100g respectively. Maturity level of a green banana influences the starch content thus one needs to consider the same when processing.
So what is this RS?
Resistant starch is any starch or starch digestion products that are not digested and absorbed in the upper digestive tract and, so, pass to the large bowel. Here, RS is a good substrate for fermentation which increases short chain fatty acid concentrations and lowers bowel pH. There are four major categories of RS: RS 1,2,3,4 depending on source.
This presence of RS categorises green banana a functional food (prebiotic). Since the RS stimulates the proliferation of beneficial acidophilus bacteria in humans, its intake is recommended in cases of constipation, diarrhoea, colitis, ulcerative colitis, gastric ulcer, uremia, nephritis, gout, cardiovascular disease, and celiac disease. Moreover, great part of the RS found in GBF is the type 2 (RS2) which is not easily hydrolysed in the human body, therefore offers positive effect on the human colon and implications for health in view of the reduction of postprandial glycemic and insulinemic levels when ingested. RS has also been shown to reduce adiposity (also depends on other dietary parameters) in rodent and few human studies thus may be helpful for reduction in obesity. One can imagine the widespread applications it may have.
Rather a study claimed that Green Banana Resistant Starch is the richest form of resistant starch as about 1Tbsp can fulfil a day’s requirement of fibre. It contains natural inulin soluble fibre, dietary fibre, and fermentable fibre. Certainly one of the most nutrient dense flours.
The protein content was found in an average of 4.76g/100g, being classified as a low biological value protein with lysine as the first limiting amino acid. Potassium is the predominant mineral in banana flour. Fresh green banana is a good source of vitamin C, but almost 65% is lost during the preparation of flour. Oxalate content (1.1–1.6%) of Banana Flour is nutritionally insignificant.
The flour is entirely sugar-free, scientifically tested to contain 5HTP (Serotonin – a magnitude of benefits in itself which is best known for making you happy), rich in magnesium, potassium, zinc, and Vitamin B3 and B6. Tests indicated the flour to be slow cooking and to have a moderate thickening power.
Just as resistant starches, fibres in the peel especially insoluble such as cellulose and hemicellulose are not digested by the human organism due to the absence of enzymes capable of digesting this structure. Thus, undigested fibre is fermented by the colonic flora, which generates Short Chain Fatty Acids and other byproducts beneficial for human health. Thus green banana is of great value in several pathological conditions. The peel has a high mineral content too. As mentioned previously, due to the bland taste and adaptable nature, the flour is today used for making several products but cakes, cookies, bread being major. It is also used as thickener instead of grain starch.
This flour is high starch definitely but one must remember that while promoting it as rich in RS, the maturity of bananas and processing of the flour would have great effect on the content which needs to be studied.
But despite the high production across the world, around one-fifth of all banana harvested is wasted and rejected fruits are normally disposed improperly. Many times raw bananas go waste if they are unsuitable for retail sales/ exports, but they may be used for making flour, thus a good option to control food waste. Also since the flour has a very adaptable flavour and texture, the applications are wide for food processing right from sauces, mayonnaise, pates to breads, noodles, pasta, bakery goods and so on.
When one hears about any flour as an alternative to wheat, one wonders how it compares to wheat in formulations. Surprisingly, GBF in high-standard form, bakes incredibly well and is a very rare gluten-free flour which rises and holds well even when baked. Like other gluten-free flours, it will require a binding agent like gums/chia/ egg in certain recipes but beyond that not much changes required.
Banana Flour is currently slightly more expensive than many other gluten-free flours on the market, but that could change as companies find more efficient ways to produce the flour without sacrificing nutritional value. Already products like cookies, noodles, cakes, and energy bars are successfully tried using the flour without affecting the taste and acceptability. The industry is at an infancy stage but soon the nutritional benefits of green/raw banana starch would be appreciated and find wide acceptability as well as demand as the industry develops interest for creating new products with Raw Banana Flour and consumers become more aware of its benefits and applications.
(The author is a nutritionist and founder of Snack Right. She can be reached at neha.pandits@gmail.com)
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