Usha Dharmaraj

Quality characteristics of biscuits prepared from finger millet seed coat based composite flour

Finger millet seed coat is an edible material and contains good proportion of dietary fibre, minerals and phytochemicals. The seed coat matter (SCM) forms a by-product of millet milling, malting and decortication industries and can be utilised as composite flour in biscuit preparation. The SCM from native, malted and hydrothermally treated millet contained 9.5-12% protein, 2.6-3.7% fat and 40-48% dietary fibre, besides 3-5% polyphenols and 700-860mg/100g of calcium. The biscuits prepared using the composite flour were of crisp texture and exhibited breaking strength of 1480-1690g compared to control biscuits (1560g). The biscuits were of mild grey colour (ΔE=40-50) and exhibited higher protein, dietary fibre and calcium contents. The sensory evaluation of the biscuits indicated that 10% of SCM from native and hydrothermally processed millet and 20% from malted millet could be used in composite biscuit flour.

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.

Physicochemical and Textural Characteristics of Expanded Finger Millet

The decorticated finger millet was subjected to high temperature short time treatment to prepare the expanded product. The product with 5.64 expansion ratio showed a cream color and was very light in weight with a bulk density of 0.14 g/ml and contained 4.69 g/100 g protein, 0.74 g/100 g ether extractives, 72 g/100 g carbohydrates, 11 g/100 g dietary fiber, and 190 mg/100 g calcium. The expanded millet was a crisp product with very low compression values (2.14 N) and contained two thin concentric layers with a vacuole inside. The pasting profile of the product revealed substantial initial viscosity and negligible set back viscosity. The functional and textural properties indicated the possible usage of the product in snacks and supplementary foods.

Influence of hydrothermal processing on functional properties and grain morphology of finger millet

Finger millet was hydrothermally processed followed by decortication. Changes in color, diameter, density, sphericity, thermal and textural characteristics and also some of the functional properties of the millet along with the grain morphology of the kernels after hydrothermal processing and decortication were studied. It was observed that, the millet turned dark after hydrothermal processing and color improved over native millet after decortication. A slight decrease in grain diameter was observed but sphericity of the grains increased on decortication. The soft and fragile endosperm turned into a hard texture and grain hardness increased by about 6 fold. Hydrothermal processing increased solubility and swelling power of the millet at ambient temperature. Pasting profile indicated that, peak viscosity decreased significantly on hydrothermal processing and both hydrothermally processed and decorticated millet exhibited zero breakdown viscosity. Enthalpy was negative for hydrothermally processed millet and positive for decorticated grains. Microscopic studies revealed that the orderly structure of endosperm changed to a coherent mass after hydrothermal processing and the different layers of seed coat get fused with the endosperm.

Cooking Characteristics and Sensory Qualities of Decorticated Finger Millet (Eleusine coracana)

This study examines the cooking characteristics and sensory attributes of decorticated finger millet. Decorticated millet is one of the unique products from finger millet, which can be cooked to discrete grains similar to rice. The cooking qualities of decorticated millet, namely cooking time, soluble loss, and pasting profile, were studied. It was observed that decorticated millet cooks to soft textured grains within 6 min. The moisture content of the cooked grains was 71 g/100 g with a total soluble loss of 3.5 g/100 g. Exposing the cooked millet to atmosphere increased its redness value by 39%. The gelatinization temperature of the decorticated millet was 68°C and its paste showed no breakdown in the viscosity. The hardness of the cooked millet was 0.63N indicating its soft texture. The sensory analysis of the product corroborated with the instrumental results with an overall acceptability score of 8.