Evaluation of Biochemical and Nutritional Profile During Processing of Pearl Millet (Pennisetum glaucum L.) To Different Products

Abstract

In this study a popular variety (ICTP) of pearl millet procured from Regional Station, Bijapur, University of Agricultural Science, Dharward, India was used. The variety was found to have 9% moisture, 1.54% ash, 10.8% protein, 73% starch and 20.3 amylose The variety was found to contain 0.3 and 0.13 mg/100g thiamin and riboflavin, respectively, 314 and 7.5 mg/100 g P and Fe, respectively. It contained 930, 315 and 87 mg/100g phytic acid, polyphenols and C-glycosylflavones, respectively and 2.35 TIU/mg trypsin inhibitor. The material was subjected to traditional processing, viz. ,fermentation (ageen), domestic cooking (aseda), dehulling and damirga preparation in addition to popping and extrusion cooking. The effect of these processes on the functional properties and nutritive value of pearl millet were investigated. Results showed that extrusion and cooking elevated the WAC from 1.25 to 4.1 and to 3.8g/g, respectively. Popping was found to enhance FAC from 0.7 to 1.97 g/g. Dehulling and cooking improved EC from 116 to 131 and to 154 ml/g, respectively. All products showed significantly (p X04; 0.05) reduced FC. Extrusion, dehulling and damirga preparation resulted in significant reduction in ash (11-16%), protein (12-14%), thiamin (17-43%), riboflavin (15-50%), Fe (22-23%), and P (31-33%). Amylose content was not affected by dehulling, but significantly reduced due to extrusion and damirga preparation. Fermentation, popping and cooking did not affect ash, Fe, and protein, but significantly (p X04; 0.05) reduced starch (3-11%) and P (1-8%). Amylose was not affected by popping, but was significantly (p X04; 0.05) reduced as a result of cooking and fermentation. Cooking increased thiamin content significantly (10%), but riboflavin was insignificantly increased, whereas fermentation increased riboflavin significantly (p X04; 0.05) (54%), but reduced thiamin by 33%. Popping significantly reduced both of them. Phytic acid was unaffected by cooking, but in the rest of the products it was significantly (p X04; 0.05) lowered in the range from 9% (dehulled) to 80% (extruded damirga). For all products polyphenols showed a significant reduction from 5% (aseeda) to 79% (extruded damirga). C-glycosylflavones was significantly (p X04; 0.05) elevated due to popping and fermentation up to 49% and 15%, respectively, but it was significantly (p X04; 0.05) reduced for the remaining products in the range of 2% (aseda) to 36% (extruded damirga). Trypsin inhibitor activity was significantly reduced (49-88%) in most of the products, but it was increased significantly (p X04; 0.05) by 2% and 25% in dehulled and damirga, respectively. The amino acid profile of the native and processed products (ageen, damirga, dehulled and extruded dehulled) showed a common observation indicating an increase in aspartic, threonine and phenylalanine. Histidine, arginine, tyrosine and leucine increased after dehulling but decreased in the others. Drastic reduction was observed in lysine notably in ageen, however it increased in the dehulled product. Fermentation was found to cause a gradual decline in pH (from 5.1 to 3.7), starch (from 72 to 65%), thiamin (from 0.3 to 0.2 mg/100g). Riboflavine level remained unchanged during the first 6 h (0.13 mg/100g) thereafter it increased gradually towards the end of fermentation (0.2 mg/100g). fermentation for 6 h reduced protein significantly (p X04; 0.05) (from 10.8 to 8.8%) thereafter it gradually increased till the end (10.4%). Gel permeation chromatography of native and processed pearl millet resulted in two fractions: Fraction- I (a high molecular weight branched fraction) and fraction- II (a low molecular linear fraction). Fraction- II in the processed products (except popped) increased by 4-73% compared to fraction- II of the native, with corresponding decrease in fraction- I