Pulses are an excellent source of protein and fiber (14-32 g of fiber per 100 g of pulses) and its widely accepted that they help in reduction of cardiovascular disease related mortality and the reduction of all-cause mortality. In addition their consumption has been shown to improve satiety and metabolism of glucose and lipids, which makes their consumption ideal for preventing and managing obesity.
But many experience bloating after consuming them
Fermentable Oligo-, Di- and Monosaccharides And Polyols (FODMAPs) are a group of short chain carbohydrates which cannot be digested by humans. They cause flatulence in the intestines by being fermented by the gut microbiota to produce short chain fatty acids, as well as hydrogen gas.
There are five main categories of FODMAPs
Polyols: Polyols are sugar alcohols (sorbitol, mannitol, xylitol and maltitol). Widely prevalent in fruits (apples, cherries, peaches and pears). They are used in the food industry mainly as sweeteners
Fructans: are found naturally in onions and wheat and their pre-biotic effects make them a popular ingredient for various supplements
Fructose: Fructose is considered a FODMAP when it is present in quantities that exceed glucose in a food (for instance: apples, honey)
Lactose: Sugar found in dairy products, and it is digested in the gut using the enzyme lactase. lack of sufficient lactase activity in the gut is common, causing lactose intolerance and resulting in abdominal pain
Galactooligosaccarides: in vegetables like Brussels sprouts and cabbage, and pulses such as beans, lentils, and peas. Of these galactooligosaccharides, there exists a subcategory called alpha-galactosides, which usually is the most prevalent category of FODMAPs in boiled or canned pulses. Is suggetsed that, to reduce the production of flatulence from pulse consumption, these alpha-galactosides must be removed.Alpha-galactoside it's not a single ingredient and its content varies in pulses
Removal methods that you can apply: Soaking & Cooking
Soaking:
Soaking is most traditional method of removing alpha-galactosides from pulses. The dried pulses are placed in a pot of water and allowed to rehydrate over a long period of time (generally overnight). The water-soluble alpha-galactosides are drawn out by osmosis into the soaking water. The addition of water also initiates a metabolic process in the pulse, which serves to further degrade the alpha-galactoside.
Note that different pulses show different levels in alpha-galactoside reduction, despite being treated with the same conditions.
Water temperature is one of the factors affecting the reduction of alpha-galactosides in soaked pulses. Room temperature - 40 degrees Celsius is recommended.
Time is also a factor to consider. 12-16 hours is usually preferable for the most pulses
Cooking
Cooking in this context refers to the process of boiling a food in water at 99° C. Αside from the usual mechanism of diffusion, the additional heat enables the heat hydrolysis of alpha-galactosides within the pulse. One concerning side effect of cooking is that when pulses are cooked without a presoaking treatment, the levels of alpha-galactosides may increase.
Other tips
Try adding a bit of baking soda into the soaking water
Eating legumes on a more regular basis, your body naturally adjusts and flatulence should decrease.
Alpha-galactosidase supplementation may reduce gas production, thus may be helpful in patients with gas-related symptoms.
Bibliography:
Thirunathan P, Manickavasagan A. Processing methods for reducing alpha-galactosides in pulses. Crit Rev Food Sci Nutr. 2019;59(20):3334-3348. doi: 10.1080/10408398.2018.1490886. Epub 2018 Sep 10. PMID: 29993256.
Elango D, Rajendran K, Van der Laan L, Sebastiar S, Raigne J, Thaiparambil NA, El Haddad N, Raja B, Wang W, Ferela A, Chiteri KO, Thudi M, Varshney RK, Chopra S, Singh A, Singh AK. Raffinose Family Oligosaccharides: Friend or Foe for Human and Plant Health? Front Plant Sci. 2022 Feb 17;13:829118. doi: 10.3389/fpls.2022.829118. PMID: 35251100; PMCID: PMC8891438.
Di Stefano M, Miceli E, Gotti S, Missanelli A, Mazzocchi S, Corazza GR. The effect of oral alpha-galactosidase on intestinal gas production and gas-related symptoms. Dig Dis Sci. 2007 Jan;52(1):78-83. doi: 10.1007/s10620-006-9296-9. Epub 2006 Dec 7. PMID: 17151807.