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Khapli wheat: Low gluten grain good for diabetes, CVD
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Saturday, 31 August, 2019, 14 : 00 PM [IST]
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Dr Neha Joshi
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Introduction
Emmer wheat (Triticum turgidum, subsp.Dicoccum), commonly known as ‘khapli’ wheat is a low gluten grain that is used in the treatment of diabetes and cardiovascular diseases. Emmer wheat is traditionally cultivated in Karnataka, southern Maharashtra, Saurashtra region of coastal Gujarat, parts of Tamil Nadu and Andhra Pradesh. It is known by different names in India popathiya (Gujarat), khapli (Maharashtra), ravva (Andhra Pradesh), godhumalu (Tamil Nadu), and samba (Karnataka)
The name khapli was given to this variety of T. dicoccum because the glume or the husk remains tightly adhered to the grain even after harvest and is only separated by pounding. It is one of the earliest domesticated plants and has been a staple crop over millennia. It is now a minor crop, cultivated mainly in isolated, marginal areas. Its main value lies in its ability to give good yields on poor soils and resistance. It is sown traditionally on black cotton soil in November and harvested in March. This species besides possessing high yield potential of 42 to 45 q/ ha is also found to confer resistance to biotic and abiotic stresses. Increasing interest in natural and organic products has led to the 'rediscovery' of dicoccum wheats, not only for their nutritional and health properties but also because it is amenable to low input and organic farming systems.
Nutritional Composition of Khapli Wheat Carbohydrates
Starch is the main storage carbohydrate in wheat kernels, accounting for 61 – 68% of the grain, whereas sugars account for 2 - 3%. It is a primary functional component in cereal grains, its content and characteristics are known to substantially affect the quality of wheat and its end products. From a nutritional point of view, starch is rich source of energy and influence the level of glycaemia. The total dietary fibre content of emmer wheat is about 10 - 12% consisting majorly of insoluble fractions (80-85% of the total fibre). The aleurone cells which form the outer layer of the endosperm consist of 35-40% of total fibre out of which 29% is ß-glucan, 65% is arabinoxylan and about 2% each of cellulose and glucomannan.
Proteins
Emmer wheat is reported to have higher protein content and a higher participation of the aleurone layer in the kernel. The main amino acids in this variety of wheat are glutamic acid (˜30gm/1000gm protein) and proline (˜10 gm/1000gm protein), and the quantitatively minor amino acids are tryptophan (˜1.30 gm/ 1000gm protein) and methionine (˜1.5 gm/1000gm protein). Certain studies have shown that emmer wheat has high lysine content (3.1-3.65%). The content of the albumin and globulin fractions in emmer wheat is considerable, representing about 30 – 39% of total proteins. The average percentages of gliadin and glutenin in whole-meal emmer are about 37% (range 33 – 39%) and 29% (range 27 – 33%) of total protein, respectively.
Lipids
The lipid content of emmer has been reported in very few investigations. Lipids are minor grain constituents, accounting for about 3% of the wheat kernel. They are more concentrated in germ (which contains 28.5% of lipids) and in the aleurone layer (8.0%) than in endosperm (1.5%). Even though being a minor constituent, cereal lipids are quite a complex family of components, present both as free and bound to various other constituents in the cereal, including proteins and starch. The primary fatty acid is lonoleic (C18:2) (60% of total fatty acids), followed by oleic (C18:1) (19% of total fatty acids), palmitic (C16:0) (16% of total fatty acids), linolenic (C18:3) (4% of total fatty acids), and stearic acid (C18:0) (1% of total fatty acids). Emmer wheat belongs to the tetraploid species which contain significantly larger amounts of sterols and stanols. The main phytosterol in emmer wheat is ß-sitosterol, followed by campesterol and stigmasterol.
Vitamins
Tocopherols and tocotrienols, grouped as tocols and recognised as vitamin E, are a class of lipid-soluble antioxidants synthesised only by photosynthetic plants. The amount of total tocols of emmer wheat range between 19.7 and 69.85 mg/100 g d.b. with weighted mean 46.37 mg/100 g d.b. The emmer wheat consists around 0.5 mg/100 g d.b., 0.2 mg/100 g d.b., and 6.8 mg/100 g d.b. of thiamin, riboflavin, and niacin, respectively. These niacin and thiamine levels would provide a substantial proportion of the human requirements in balanced diets, but the riboflavin level would not supplement deficiencies in other components of the diet. The ‘Healthgrain’ project compared the folate levels in ancient versus modern wheat species. The study showed that the folate content was slightly higher in durum wheat (0.74 mg/100 g d.b.) and emmer (0.69 mg/100 g d.b.).
Minerals
The ash content varies between 0.85% and 2.46% (DW), respectively and the total mineral content is found to be 1.14 to 2.46% of the total weight. Emmer Wheat is rich in selenium (powerful antioxidant) (ranging from 150.6 to 325.8 µg*kg-1), zinc (mean 22.8 mg*kg-1) and iron (mean 34.1 mg*kg-1).
Bioactive Components
Polyphenol and carotenoid contents in emmer wheat grown in different parts of the world ranged from 508 to 2355 µg/g and 1.63 to 4.90 µg/g flour, respectively. Some researchers reported ß-carotene values ranging from 3.3 to 7.4 µg/g. Among the carotenoids, lutein (0.451 to 5.21 mg/100 g d.b.) is the major carotenoid identified followed by zeaxanthin. Ferulic acid is the major phenolic acid reported in wheat. Its content in emmer wheat is reported to vary as low as 323 µg/g to as high as 759 µg/g.
Health Benefits
A study was conducted to on the impact of incorporation of emmer wheat in diet on lipid profile and blood glucose levels of diabetic subjects. It showed that incorporation of emmer whole wheat flour in the diet of diabetic patients resulted in 11% reduction each in total lipids, triglycerides and LDL-cholesterol concentration, over a six-week study period. Data also indicated that there was a marginal decrease in fasting blood glucose levels in the subjects supplemented with emmer wheat. The research concluded that nutritious emmer wheat, with special therapeutic quality, can be substituted for commercial bread wheat as health food.
Gluten is an important functional protein, which is responsible for the viscoelastic property of the wheat dough. However, consumption of wheat causes celiac disease in susceptible individuals. Some varieties of emmer wheat are devoid of noxious gluten proteins; however, more immunological and clinical research is required to establish their suitability for celiac patients.
Polyphenols, carotenoids, and tocols exhibit antioxidant properties and reported to have health benefits in amelioration of cancer, cardiovascular disease, and diabetes. Emmer wheat contains high tocopherol-to-tocotrienol (T3/T) ratio. A high T3/T ratio in the diet was reported to be important due to the hypocholesterolemic action of T3. Polyphenols are also reported to inhibit a-amylase and a-glucosidase activities, which result in decreased postprandial glucose level. Lutein has various health benefits including in improving eye health and vision. High Phytosterol content may have a role in preventing colon cancer and reducing total serum cholesterol.
Conclusion
Increasing demand for traditional, natural, and fibre-rich food has stimulated a renewed interest in this ancient cereal. Emmer wheat, a minor cereal today, should know a new development due to its high nutritive value, lower starch digestibility, high dietary fibre content, low glycemic index, high satiety value and higher content of antioxidant compounds which have resulted in various health benefits. It is rich in bioactive compounds, and exhibits certain nutraceuticals properties as well.
However, the studies carried out on nutritional and clinical studies are very limited to substantiate their health beneficial effects. Hence, it will be important to carry out in-depth studies using animal or human models with varieties grown in different regions so that the therapeutic potential of this hidden cereal can be explored and put to practice.
(The author is a consulting nutritionist and lecturer at College of Home Science, Nirmal Niketan, Mumbai.)
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