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Investigations on the Carbohydrate Digestibility of Finger Millet (Eleusine Coracana) with Special Reference to the Influence of its Seed Coat Constituents

Shobana, S. (2009) Investigations on the Carbohydrate Digestibility of Finger Millet (Eleusine Coracana) with Special Reference to the Influence of its Seed Coat Constituents. PhD thesis, University of Mysore.

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Abstract

Finger millet (Eleusine coracana L.) or ragi is one of the important minor cereals in the Indian subcontinent and also in many of the African countries. The millet foods are known for their higher sustaining power, lower glycemic response and higher satiety scores compared to other cereal foods. The incidence of diabetes and duodenal ulcer are known to be lower among the population using the millet as staple. These health beneficial properties of the millet may be attributed to the special features of its carbohydrates and also to some of its phytochemical contents. The millet contains 6 - 9% protein, 65 - 70% starch, 12 - 18% non-starchy polysaccharides, 1.2 - 1.5% lipids, 2.5 - 3% minerals, 340 - 360 mg% calcium and 270 - 290 mg% phosphorus. It is also a rich source of dietary fibre (15 - 20%), polyphenols (0.3 - 2%) and phytate (0.2 - 0.3%). The seed coat which forms about 15% of the seed matter contains about 70% of the kernel polyphenols and the constituents of the polyphenols are mainly phenolic acids, flavonoids, anthocyanins and tannins. Usually, the millet is pulverized and the whole meal including the seed coat is utilized for the preparation of traditional foods. Since, there are no reports of any adverse effect even on prolonged consumption of the millet foods, it is strongly believed that, the millet seed coat is safe for human consumption, and its constituents contribute for the nutritional benefits of the millet. Diabetes mellitus is a common endocrine disorder characterized by hyperglycemia and it predisposes to some of the chronic complications such as retinopathy, cataract, neuropathy, nephropathy and atherosclerosis. One of the therapeutic approaches to decrease the postprandial hyperglycemia is to slow down the digestion of carbohydrates through inhibition of the carbohydrate digesting enzymes, namely the α-amylase and α-glucosidase and thereby delaying the absorption of glucose. Hyperglycemia plays an important role in the pathogenesis of diabetic complications and one of the most important complication is the protein glycation and advanced glycation end-product (AGE) formation. In the case of uncontrolled hyperglycemia, formation of the AGEs augments the free radical generation leading to the biomolecular damage and subsequently increases the severity of diabetes. Hence, it is highly desirable to i Synopsis provide foods containing antioxidants, modulators of postprandial blood glucose and also inhibitors of protein glycation. The polyphenols, phytate and the carbohydrates of the millet may probably, contribute for the slow digestion and other health beneficial qualities of the millet foods. The scientific information about the role of the millet polyphenols on slowing down its carbohydrate digestibility and also their ability to ameliorate the complications of diabetes are scanty. Hence, generation of scientific information on these aspects would be helpful in identifying the pharmaco-nutritional uses for the millet and also for the development of a special dietary regimen for the diabetic subjects. This could also augment the consumption of the millet thereby increasing its agro-economics. Accordingly, investigations on the nature as well as the nutraceutical potentials of the millet in general and its seed coat in particular with special reference to their influence on the carbohydrate digestibility of the millet were undertaken with the following objectives; 1. Localization of the polyphenols in the millet kernel and preparation of the polyphenols rich fraction of the millet (seed coat matter abbreviated as SCM), by developing a milling protocol and also isolation and characterization of polyphenols, 2. Assessment of the influence of the millet SCM as well as the hydrothermal processing on the in vivo carbohydrate digestibility of millet foods 3. Investigations on the inhibitory properties of the millet polyphenols against α-amylase, α-glucosidase, protein glycation and hydroxyl radical (OH.) mediated protein fragmentation in in vitro model systems, 4. Evaluation of the effect of the millet SCM on the hyperglycemia and its associated complications in diabetic animal models. The experiments conducted and the results obtained with these objectives are presented in the form of the thesis. The subject matter on the special features of the millet carbohydrates, phenolics and the nutritional aspects of the millet forms the Introduction to the thesis. Localization of polyphenols in the millet kernel by histochemical techniques and preparation of the polyphenols rich fraction of the millet following a special milling protocol, and also the extraction as well as characterization of polyphenols in the SCM are ii Synopsis dealt in Chapter I. The influence of the SCM from the native millet and also from the hydrothermally processed millet on the carbohydrate digestibility of millet foods by in vitro and in vivo (in normal and type II diabetic subjects) methods are described in Chapter II. The mode of inhibition of the millet polyphenols against α-amylase and α-glucosidase (the key enzymes involved in blood glucose homeostasis) and besides, the inhibitory properties of the millet polyphenols against fructose induced protein (albumin) glycation as well as AGE formation are elaborated in Chapter III. The salient features of the ameliorative properties of the millet SCM on the complications associated with diabetes such as hyperglycemia induced protein glycation and the AGE formation, dyslipidemia, kidney dysfunction and also cataractogenesis are reported in Chapter IV. Finally, the details of the reference cited in all the chapters are compiled under the reference section.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Finger millet, ragi, millet carbohydrates, health benefits
Subjects: 600 Technology > 08 Food technology > 16 Nutritive value > 01 Carbohydrates
600 Technology > 08 Food technology > 21 Cereals > 05 Ragi (Finger Millet)
Divisions: Grain Science and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 01 Mar 2011 10:09
Last Modified: 28 Dec 2011 10:21
URI: http://ir.cftri.com/id/eprint/9955

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