Food Engineering

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Browsing Food Engineering by Subject "Amaranth"

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    Optimization of Process Variables to Develop Teff-Amaranth Based Extrudates
    (Addis Ababa University, 2014-06) Berhe, Aregay; Admassu, Shimelis(Professor)
    Response Surface Methodology was adopted to study the effect of barrel temperature (A), screw speed (B), feed moisture content (C) and blend ratio (D) to optimize the proximate composition, physical properties(expansion ratio, bulk density and specific length), functional properties(WAI and WSI) and sensory quality attributes during extrusion process to develop teff-amaranth based extrudates using twin screw co-rotating extruder. Kuncho and red teff grains with voucher numbers DZ-C1-387 and DZ-01-99, respectively and three amaranth varieties (white, pale-white and black amaranth) were studied for proximate composition, mineral content, phytochemical content and functional properties. The moisture contents for DZ-C1-387 and DZ-01-99 were11.12 and 12.27%, respectively. The proximate compositions of DZ-C1-387 were 12.46(protein), 2.82(fat), 2.82(ash), 2.45(crude fiber) and 68.64% (total CHO), respectively, and the proximate composition of DZ-01-99 were 10.19, 2.42, 2.42, 2.51and 70.12% for crude protein, crude fat, ash, crude fiber and total CHO respectively. The energy value of DZ-C1- 387(349.78kcal/100g) was significantly (p<0.05) higher than the energy value of DZ-01-99 (343.02kcal/100g). Among the three amaranth varieties, moisture (10.24), protein (17.85), fat (7.00), ash (2.70), crude fiber (6.86) and total CHO (55.35%), respectively were the proximate compositions for white amaranth. The proximate compositions of pale-white amaranth were11.50, 14.15, 6.30, 5.40, 2.20 and 60.45% for moisture, crude protein, crude fat, crude fiber, ash, total CHO, respectively. The moisture, crude protein, crude fat, crude fiber, ash and total CHO content of the black amaranth were 10.89, 15.30, 6.50, 5.75, 2.40 and 59.16%, respectively. The energy value of white amaranth (354.80kcal/100g) was significantly (p<0.05) higher than the energy values of pale white amaranth (351.10kcal/100g) and black amaranth (351.34kcal/100g), respectively. On the basis of extruded product quality, the extrusion process variables were feed moisture (12, 18, and 24%), teff - amaranth blend ratio (90:10, 85:15 and 80:20%), barrel temperature (110, 130 and 150°C) and screw speed (120, 140 and 160 rpm) through a die of opening about 9.00mm. The extruded products were evaluated for their chemical composition, mineral content, physical properties, functional properties and sensory quality attributes. The optimum extrudate which was obtained at 1300c (barrel temperature), 140rpm (screw speed), 15% (feed moisture content) and 15% amaranth in the feed had 13.70% protein, 3.53% fat, 2.98% fiber, 2.66% ash and 70.27% total CHO and 19.52, 170.47, 5.08, 386.54, 176.98mg/100gm for Fe, Ca, Zn, P and Mg and 33.72% phytates and complete reduction of tannins was observed in this study. The maximum expansion ratio (3.0789), maximum WAI (8.728g/g) and minimum bulk density (0.1614g/cm3) values of the extrudates were observed at 130 0C, 140 rpm, 15% feed moisture content and 85:15 blend ratio. The the maximum specific length(3.6193cm/g) was obtained at 150 0C, 160 rpm, 15% feed moisture content and 80:20 blend ratio and the maximum WSI (22.217%) was obtained at 150 0C,120 rpm, 15 feed moisture content and 80:20 blend ratio. In this study, promising results were obtained for teff- amaranth based extrudate development and process optimization studies. Keywords: Teff, Amaranth, Extrusion, Extrudates, Optimization, Response Surface Methodology
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    Production of Value-Added Amaranth (Amaranthus) and Cereal Based Food Products
    (Addis Ababa University, 2010-03) Martha, Arega; Shimelis, Admassu (Assoc.Prof.)
    Amaranth is easy to grow, nutrient rich and underutilized pseudo cereal that has important role in actions against hunger and malnutrition that occur due to low rainfall conditions. The study focused on the development of bread and malt flour from blends of amaranth with cereals (wheat, maize and rice). Proximate composition, physicochemical and farinographic properties were investigated to characterize raw materials and food products. Factorial design was implemented and experimental data were subjected to ANOVA to check for significant differences (p<0.05). Analysis was done using SAS version 6.12 statistical software. Tukey’s studentized test was used for comparisons of means. Results of proximate composition analysis showed that amaranth had higher protein, fat, ash, iron, zinc, and calcium 14.19%, 7.94%, 2.39%, 13.73mg/100gm, 4.23 mg/100gm, and 76.13 mg/100gm respectively than wheat which had 9.41%, 2.33%, 0.57%, 2.28 mg/100gm, 0.94mg/100gm, and 18.99 mg/100gm respectively. Accordingly, wheat flour showed improvement in the aforementioned contents with increase of amaranth substitution 5-30%. Blending only 5% amaranth improved zinc and calcium contents by17% and 144%. Blending amaranth with wheat lowered phytate contents while exhausting tannin contents to below the detectable limits. Amaranth substitution of 5%-30% increased the water absorption quality of the dough from 52.2 to 54.4%. It also increased dough development time from 3.5 to 5 minutes while decreasing the stability time from 5.6 to 2 minutes. Amaranth flour had the least measurable falling number (61s), low gluten content (gluten free) and dense colour (18.39) which affected the end product’s sensory qualities. However, gluten content of blend flours containing 5-10% amaranth were within recommended range for bread production. Blending significantly(p<0.05) improved colour of amaranth (18.39) in which the value for blend flour containing 5-10% amaranth ranged from 4.45-6.22. The overall flour quality and amaranth bread sensory evaluation indicated that up to 10% amaranth substituted wheat flour baked at 220oC for 18minutes can be effectively used in amaranth bread production. The bread contained 0.59% fat, 8.44% protein, 1.41% fiber, 2.54% ash, 24.3% moisture, 1.18mg/100g zinc, 60mg/100g calcium, 4.6mg/100g iron with 3.2cm3/g bread volume index.Study on malting amaranth, maize and rice indicated optimum steeping/germination time conditions for amaranth, rice and maize malting were at 24h/60h, 36h/72h, and 36h/48h respectively. Nutritionally, the calcium content of blend of malted amaranth and rice flour was higher than blend of malted amaranth and maize flour by more than 28%. Minimal differences were observed in protein, fat, fiber, iron, zinc and phosphorous contents between the two blend (amaranth-rice, amaranth- maize) malt flours. In conclusion, up to 10% amaranth can be incorporated to wheat flour for bread production and a combination of malted amaranth and malted rice are good source of calcium. Economic analysis of the suggested industry level amaranth bread manufacturing is feasible with one year payback. Period. Keywords::Amaranth, cereals, blend, bread, malt