Free sugars and non-starchy polysaccharides of finger millet (Eleusine coracana), pearl millet (Pennisetum typhoideum), foxtail millet (Setaria italica) and their malts

First principles modelling of the ion binding capacity of finger millet

Finger millet, a cereal grain widely consumed in India and Africa, has gained more attention in recent years due to its high dietary fibre (arabinoxylan) and trace mineral content, and its climate resilience. The aim of this study was to understand the interactions between potassium (K+), calcium (Ca2+) and zinc (Zn2+) ions and the arabinoxylan structure and determine its ion-binding capacity. Three variations of a proposed model of the arabinoxylan structure were constructed and first principles Density Functional Theory calculations were carried out to determine the cation-binding capacity of the arabinoxylan complexes. Zn2+-arabinoxylan complexes were highly unstable and thermodynamically unfavourable in all three models. Ca2+ and K+ ions, however, form thermodynamically stable complexes, particularly involving two glucuronic acid residues as a binding pocket. Glucuronic acid residues are found to play a key role in stabilising the cation-arabinoxylan complex, and steric effects are more important to the stability than charge density. Our results highlight the most important structural features of the millet fibre regarding ion-storage capacity, and provide valuable preliminary data for confirmatory experimental studies and for the planning of clinical trials where the bioavailability of bound ions following digestion may be tested.

Varietal and processing influence on nutritional and phytochemical properties of finger millet: A review

Food and nutrition insecurity is a problem for the majority of developing nations; incidentally, some underutilized crops have the potential to increase food security. A minor cereal grain called finger millet (Eleusine coracana L.) is widely cultivated in various regions of India and Africa and is consumed for its numerous health advantages. There is a wealth of research on the nutritional and health benefits of this crop, but little is known about how varietal difference and processing affect these qualities. Therefore, this study reviewed the effects of variety and different processing methods on the nutrition, antinutrients, phytochemicals, and antioxidative properties of finger millet and its probable uses in ensuring nutrition and food security. Finger millet is a nutritious cereal with relatively high values of protein, vitamins, minerals, fibre, and energy. The amount of minerals, particularly calcium and potassium, is larger than what is found in the most popular grains, including wheat and rice. The grain of finger millet is non-glutinous and contains only 1.3% fat; in contrast to other types of millet which are noticeably higher in dietary fibre, protein, ash, and fat. The coloured varieties particularly have high levels of minerals, antioxidants, and phytochemicals. The nutritional and phytochemical qualities of finger millet are affected by the cultivars, varieties, and geographical locations. This study elucidates the qualities of finger millet varieties and methods of processing which will help in the selection of appropriate cultivars for food applications.

Chemical characterization and immunostimulatory activity of phenolic acid bound arabinoxylans derived from foxtail and barnyard millets

The chemical characterization and evaluation of immunostimulating effect of phenolic acid bound arabinoxylan (PA-AXs) isolated from barnyard (PA-AX-B) and foxtail (PA-AX-F) millets were performed. The sugar composition analysis and bound phenolic acids' (caffeic acid, p-coumaric acid, and ferulic acid) content of PA-AXs were examined by gas chromatography and mass spectroscopy (GC-MS) and high performance liquid chromatography (HPLC), respectively. The immunostimulatory activity of PA-AXs was evaluated by studying the effect of PA-AXs on the release of nitric oxide (NO), ROS, and cytokine (TNF-α, IL-1β, and IL-6) in RAW 264.7 murine macrophage cells. The GC-MS results revealed the xylose: arabinose ratio of PA-AX-F and PA-AX-B as 1.96:1.0 and 1.64:1.0, respectively. In HPLC analysis, PA-AX-B showed higher phenolic acid content than PA-AX-F. In RAW 264.7 cells, immunostimulatory activity was established by its increased release of NO, ROS, and cytokine (TNF-α, IL-1β, and IL-6) in a dose-dependent manner. Both PA-AX-B and PA-AX-F exhibited significant immunostimulation in in vitro studies. PRACTICAL APPLICATIONS: Millets are known for the higher content of phenolic acid bound arabinoxylans (PA-AX). The composition of PA-AX varies with different types of millets. In general, rice bran and wheat arabinoxylans are well reported to have significant immunostimulatory and antitumor properties. The bound ferulic acid with arabinoxylan isolated from finger millet bran also possesses immunostimulatory property. As the millets grains, foxtail and barnyard are also rich in PA-AXs, the present study was focused to evaluate the immunostimulatory property of PA-AX derived from two different millets. The study results indicated the immune stimulatory action of millet PA-AX's and thus the purified PA-AX can be explored further to identify the mechanism of action with respect to its immune stimulation property.

Metabolite changes during natural and lactic acid bacteria fermentations in pastes of soybeans and soybean-maize blends

The effect of natural and lactic acid bacteria (LAB) fermentation processes on metabolite changes in pastes of soybeans and soybean-maize blends was studied. Pastes composed of 100% soybeans, 90% soybeans and 10% maize, and 75% soybeans and 25% maize were naturally fermented (NFP), and were fermented by lactic acid bacteria (LFP). LAB fermentation processes were facilitated through back-slopping using a traditional fermented gruel, thobwa as an inoculum. Naturally fermented pastes were designated 100S, 90S, and 75S, while LFP were designated 100SBS, 90SBS, and 75SBS. All samples, except 75SBS, showed highest increase in soluble protein content at 48 h and this was highest in 100S (49%) followed by 90SBS (15%), while increases in 100SBS, 90S, and 75S were about 12%. Significant (P < 0.05) increases in total amino acids throughout fermentation were attributed to cysteine in 100S and 90S; and methionine in 100S and 90SBS. A 3.2% increase in sum of total amino acids was observed in 75SBS at 72 h, while decreases up to 7.4% in 100SBS at 48 and 72 h, 6.8% in 100S at 48 h and 4.7% in 75S at 72 h were observed. Increases in free amino acids throughout fermentation were observed in glutamate (NFP and 75SBS), GABA and alanine (LFP). Lactic acid was 2.5- to 3.5-fold higher in LFP than in NFP, and other organic acids detected were acetate and succinate. Maltose levels were the highest among the reducing sugars and were two to four times higher in LFP than in NFP at the beginning of the fermentation, but at 72 h, only fructose levels were significantly (P < 0.05) higher in LFP than in NFP. Enzyme activities were higher in LFP at 0 h, but at 72 h, the enzyme activities were higher in NFP. Both fermentation processes improved nutritional quality through increased protein and amino acid solubility and degradation of phytic acid (85% in NFP and 49% in LFP by 72 h).

Finger millet (Ragi, Eleusine coracana L.): a review of its nutritional properties, processing, and plausible health benefits

Finger millet or ragi is one of the ancient millets in India (2300 BC), and this review focuses on its antiquity, consumption, nutrient composition, processing, and health benefits. Of all the cereals and millets, finger millet has the highest amount of calcium (344mg%) and potassium (408mg%). It has higher dietary fiber, minerals, and sulfur containing amino acids compared to white rice, the current major staple in India. Despite finger millet's rich nutrient profile, recent studies indicate lower consumption of millets in general by urban Indians. Finger millet is processed by milling, malting, fermentation, popping, and decortication. Noodles, vermicilli, pasta, Indian sweet (halwa) mixes, papads, soups, and bakery products from finger millet are also emerging. In vitro and in vivo (animal) studies indicated the blood glucose lowering, cholesterol lowering, antiulcerative, wound healing properties, etc., of finger millet. However, appropriate intervention or randomized clinical trials are lacking on these health effects. Glycemic index (GI) studies on finger millet preparations indicate low to high values, but most of the studies were conducted with outdated methodology. Hence, appropriate GI testing of finger millet preparations and short- and long-term human intervention trials may be helpful to establish evidence-based health benefits.

Determination of the volatile composition in brown millet, milled millet and millet bran by gas chromatography/mass spectrometry

The volatile compounds from brown millet (BM), milled millet (MM) and millet bran (MB) were extracted using simultaneous distillation/extraction with a Likens-Nickerson apparatus. The extracts were analysed using gas chromatography coupled with mass spectrometry (GC-MS). A total of 65 volatile compounds were identified in all of the samples. Among these compounds, 51, 51 and 49 belonged to BM, MM and MB, respectively. Aldehydes and benzene derivatives were the most numerous among all of the compounds. Three compounds (hexanal, hexadecanoic acid and 2-methylnaphthalene) were dominant in the BM and MM materials. Eight compounds (hexanal, nonanal, (E)-2-nonenal, naphthalene, 2-methylnaphthalene, 1-methylnaphthalene, hexadecanoic acid and 2-pentylfuran) were dominant in the MB materials. Apart from the aromatic molecules, which were present in all fractions, compounds present only in BM, MM or MB were also identified.

Effect of processing on the microstructure of finger millet by X-ray diffraction and scanning electron microscopy

Finger millet is one of the important minor cereals, and carbohydrates form its major chemical constituent. Recently, the millet is processed to prepare hydrothermally treated (HM), decorticated (DM), expanded (EM) and popped (PM) products. The present research aims to study the changes in the microstructure of carbohydrates using X-ray diffraction and scanning electron microscopy. Processing the millet brought in significant changes in the carbohydrates. The native millet exhibited A-type pattern of X-ray diffraction with major peaks at 2θ values of 15.3, 17.86 and 23.15°, whereas, all other products showed V-type pattern with single major peak at 2θ values ranging from 19.39 to 19.81°. The corresponding lattice spacing and the number of unit cells in a particular direction of reflection also reduced revealing that crystallinity of starch has been decreased depending upon the processing conditions. Scanning electron microscopic studies also revealed that the orderly pattern of starch granules changed into a coherent mass due to hydrothermal treatment, while high temperature short time treatment rendered a honey-comb like structure to the product. However, the total carbohydrates and non-starch polysaccharide contents almost remained the same in all the products except for DM and EM, but the individual carbohydrate components changed significantly depending on the type of processing.

Finger millet: Eleusine coracana

Finger millet (Eleusine coracana) is a grass crop grown in Africa, India Nepal, and many countries of Asia. The plant and grain is resistant to drought, pests, and pathogens. It is rich in polyphenols and particularly in calcium. The double headed trypsin, α-amylase inhibitor from this grain has been isolated and characterized extensively. One major use for the grain is the making of fermented beverages after malting. α-Amylase and β-amylase are produced during germination. Food made from malted ragi is traditionally used for weaning and has been the source of low viscosity weaning foods that can deliver more energy per feed than those based on gelatinized starch. There is some evidence that foods from finger millet have a low gylcaemic index and are good for diabetic patients. Decortication, puffing, extrusion, and expansion are some of the new uses that the grain has been put to.

Structural analysis of arabinoxylans isolated from native and malted finger millet (Eleusine coracana, ragi)

Structural elucidation of purified arabinoxylans isolated from finger millet and its malt by methylation, GLC-MS, periodate oxidation, Smith degradation, NMR, IR, optical rotation, and oligosaccharide analysis indicated that the backbone was a 1,4-beta-D-xylan, with the majority of the residues substituted at C-3. The major oligosaccharide generated by endo xylanase treatment was homogeneous with a molecular weight of 1865 Da corresponding to 14 pentose residues as determined by MALDI-TOF-MS and gel filtration on Biogel P-2. The structural analysis of this oligosaccharide showed that it contained 8 xylose and 6 arabinose residues, substituted at C-3 (monosubstituted) and at both C-2 and C-3 (disubstituted).