Food Engineering
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Browsing Food Engineering by Author "Admassu, Shimelis(PhD)"
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Item Development of legume based complementary food Products(Addis Ababa University, 2017-06) Matewos, Sintayehu; Admassu, Shimelis(PhD)The study was conducted with the aim of development of legume based complimentary food products between age group of 6 to 18 months using drum dryer. The products can be used as a protein and energy complimented combining legumes and cereals. Accordingly, chickpea, maize and millet were selected based on their nutritional value, availability in the local market and affordability. By Applying simplex-centroid design, formulation containing 66.66% chickpea, 16.666% maize and 16.666% millet of flour was selected as the best source of protein and energy. The physical properties (viscosity and bulk density), functional properties (water absorption capacity, oil absorption capacity and Dispersibility) were done, the blend with drum temperature only (130, and 150 0C), Drum speed (200 and, 300 rpm) and particle size (0.8 and 1 mm). Sensory characteristics of complementary food products (color, appearance, odor, taste and overall acceptability) were also studied to evaluate the suitability of the product. Using the blend ratio obtained from the design, the product containing 16 % protein, 382.3kcal Energy, 3.07 % of fat and 73.6 % of carbohydrate found in the complimentary food products. The viscosity and bulk density were found highly affected by drum temperature and particle size. As the drum temperature increased from 1300C to 1500C and the drum speed remain at 200 rpm and particle size 1mm. the product viscosity decrease to (13.5*10-2Pa.s, 7.36*10-2Pa.s) respectively. And lower bulk density (0.3999g/ml) were found. As the Particle size increases from (0.8mm, 1mm) the viscosity of the product decrease to (14.4*10-2Pa.s, 7.36*10-2Pa.s; 6.18; 4.91) respectively. Drum speed effect was seen on the proximate chemical composition of the product and physical properties of the product. When the drum speed increase 200 to 300 rpm viscosity was decrease (7.36*10-2, 4.91*10-2Pa.s) respectively. But bulk density showed an increment (0.399 to 0.457 g/ml). The functional properties, water absorption capacity, oil absorption capacity and Dispersibility of the Product (346.7%, 1.834 ml/g and 31.3%) were found to be higher than that of formulated flour (119.3%, 0.845ml/g and 74%) due to starch gelatinization. Results on the calcium, zinc and iron studies showed that (144.4, 1.926, 1.587 mg/100g) respectively and Antinutrient reduction of 43.2% in phytate and 25% in tannin. The sensory results indicated that the product produced with a temperature of 1500C, and drum speed of 300 rpm and particle size of 1mm was perceived as the most accepted product, as compared to the other formulated complementary food products. Key words: Chickpea flour, Millet flour, Maize flour, drum dryer, complementary food products.Item Effect of fermentation on Quality Protein Maize-soybean blends for the production of weaning food(Addis Ababa University, 2011-06) Bekele, Meseret; Admassu, Shimelis(PhD)This research paper aimed mainly at studying the effect of fermentation on QPM-soybean blends with respect to the nutritional quality, antinutrient, proximate & micronutrient compositions, functional & physico-chemical properties, microbiological & sensory analysis. Seed varieties of QPM & soybean (BHQPY-545 & Afgat) were collected from Bako & Hawassa Agricultural Research Centres respectively. After sample preparation, the flour was formulated with QPM to soybean blend ratio of 82:18 using material balance method (protein-carbohydrate ratio). QPMsoybean blend flours were fermented for 24 & 48h by natural & controlled fermentations. Both unfermented and fermented samples were subjected to the analysis. The proximate analysis results before & after fermentation in (%) were 14.72, 17.43 for crude protein; 8.42, 10.2 for crude fat; 7.33, 4.49 for crude fiber; 66.63, 66.90 for total carbohydrates and 400.81Kcal./100g, 412.67Kcal./100g for calorific value. Significant differences (P<0.05) were observed between unfermented & fermented blends in proximate compositions, with specific increment of 15.5% for protein & 3% calorific value. Results of antinutrient content (tannin & phytate) in (mg/100g) were 21.95, BDL & 249.20, 155.75 with notable reduction. Micronutrient increment in (mg/100g) for P, Fe & Zn was 32.57 to 61.9; 3.98 to 7.20 & 2.61 to 4.21 respectively. Fermentation significantly (p<0.05) decreased the antinutrients which resulted in a significant (p<0.05) increase in micronutrients. Fermentation had a significant (p<0.05) increasing effect on pH, dispercebility and oil absorption whereas; decreasing effect on titratable acidity, viscosity; bulk density & water absorption. Microbiological result showed significant (p<0.05) reduction or elimination of undesirable coliform count & increment of LAB with increasing fermentation time. Fermentation process significantly (p<0.05) affected the product performance analysis. Therefore, gruel prepared from the fermented blend flour at 24h of fermentation and <250μm particle size was acceptable with higher scores of 7.80 for appearance, 7.54 for odor, 8.10 for taste, and 8.50 for overall acceptability, which is not significantly (p>0.05) different from the control. According to the result of the study, both types of fermentation comparably reduced or eliminated antinutrients and improved the nutritional quality of the weaning blend with preference for natural fermentation, which is inexpensive processing method that consumers especially low & medium income families can easily afford good quality product. Key words: Antinutrient, effect, fermentation, micronutrient, natural fermentation, proximate composition, QPM, soybean, Weaning food.Item Effect of Low Temperature Preservation on The Physicochemical and Microbiological Qualitieis of Selected Fish Species of Lake Ziway(Addis Ababa University, 2007-06) Melaku, Mekonnen; Admassu, Shimelis(PhD)With the purpose of determining the effect of frozen storage on quality of fish fillet and evaluating the existing low temperature preservation technique in the case of Fish Production and Marketing Enterprise, samples from the same lot of commercially harvested and processed tilapia fish (Oreochromis niloticus) fillets were frozen at -18 ± 2oc. The physicochemical and microbiological analyses were carried out at regular 15 days interval on tilapia fish fillets stored for up to 90 days. The fresh fish fillets were found to contain 18.52±0.08% protein, 0.37 ± 0.01% fat, 79.87 ± 0.01% moisture and 0.98 ± 0.01% ash contents. During the entire period of storage, the protein, moisture and ash contents were significantly (p < 0.05) decreased to 17.25 ± 0.088%, 78.50 ± 0.71%, and 0.88 ± 0.02% respectively. However, the fat content of the fish fillets increased significantly (p < 0.05) to 0.56 ± 0.01 after 90 days of frozen storage. The TVB-N and pH values were also increased significantly (p < 0.05) from 12.04 ± 0.48 mg N/100g and 6.43 ± 0.01 to 21.75 ± 0.35 mg N/100g and 6.61 ± 0.01 respectively. The total bacterial load in fresh fish fillets was reduced from 2.57x106 to 8.2x105 CFU/g after 90 days of frozen storage. The total coliforms and faecal coliforms were also decreased from 460 MPN/g and 23 MPN/g to 23 MPN/g and undetectable level, respectively. From these results it was concluded that freezing, if not properly used, has a negative effect on reduction of nutritional value of fish products. The storage of tilapia fish fillets under frozen condition showed a significantly (p < 0.05) higher deterioration of product quality. The nutritional quality, as estimated by the proximate composition analysis, underwent a gradual loss of nutrients until day 90, in agreement with loss of freshness of the fish fillets observed for the TVB-N. Furthermore, the results revealed that gradual biochemical changes reduce the quality of frozen fish fillets as the duration of storage increases. Under frozen condition, the overall nutritional quality of tilapia fish fillets was found to depend on duration of frozen storage.Item Evaluation of Cheddar and Cottage Cheese Production From Doe and Ewe Milk(Addis Ababa University, 2010-11) Taye, Bezaye; Admassu, Shimelis(PhD)The study was aimed to produce cheddar and cottage cheese from doe and ewe milk. The sources of milk were from Arsi Negele and Kofele areas of Oromiya region. Cheddar cheeses were made from whole doe, whole ewe milk and their mixtures contained ratio of 25, 50 and 75% of doe and ewe milk using standard procedure for cheddar cheese processing technology. The proximate, microbiological, Physico-chemical, sensory analysis and yield calculation of the cheeses were made at chemical Engineering laboratory, Holleta agricultural research center, Ethiopian health and nutrition research institute.The proximate analysis result showed that cheeses made from 100% doe milk had the lowest moisture content (27.77%) and highest fat content (54.80%) but a lower yield (0.66kg/5kg of whole milk) compared to cheeses made from 100% ewe milk (35.29%, 30.1%, 0.88kg/5kg of whole milk respectively). Other mix ratios had intermediate values between the two specious of cheese (p<0.05). No significant differences in the values of protein, total solid and lactose content of sampled cheeses were found. Microbiological results showed that all cheeses made were within the limit range for acceptable conditions for consumers (< 1* 104 cfu/g). Physico – chemical analysis result showed that whole ewe milk had highest viscosity of all cheeses (3.04mPas). Three main stage of cheddar cheese making was considered for pH measurement. These stages were ripening, cooking and cheddaring. The decrease in pH was most rapid in 100% doe milk and slowest in that of 100% ewe milk. Textural analyses result showed that cheese made from 100% doe milk was harder (0.65 N/g) and less brittle than those from their combination. The cheese from 100% ewe milk is the softest (0.30 N/g) compared to mix ratios and whole doe milk. Sensory analysis result showed that cheeses made from 50% ewe and 50% doe milk received, in general higher scores for body texture (8.94), flavor (8.81) and overall acceptability (8.98) than cheeses from whole and their combinations (p<0.05). The mean yield of cottage cheese was 0.33kg/ 2kg of whole milk and 0.45kg/ 2kg of whole milk for 100% doe milk and 100% ewe, respectively. From over all analysis the best acceptable and quality cheese was obtained from mix ratio of 50% ewe and 50% doe milk. The thesis generally includes processing technology and evaluation of cheddar cheese made from doe and/or ewe milk. As a result an economically feasible production system has been recommended by scaling up to industry level.Item Evaluation of Ethanol Production from Intermediate Cane Molasses by Yeast (Saccharomyces Cerevisiae )(Addis Ababa University, 2007-12) Abebe, Fekadu; Admassu, Shimelis(PhD)The present study analyzes the influence of modification of sugar crystallization from three to two stages and tried to optimize both sugar and ethanol production from sugar cane source. The efficiency of sugar crystallization process was determined by simulation at Wonji Shoa Sugar Factory (WSSF). Economical advantages in optimizing the sugar and ethanol productions were compared with the factory’s existing working norms. Batch fermentation of molasses samples using saccharomyces cerevisiae was carried out at fermentation temperature of 30 (+1) o C, pH of 5.5 (+ 0.1) and ammonia supplement of 2 g/L in Erlenmeyer flask of 250 mL. The parameters varied were total sugar as invert (TSAI) in the fermentation broth of prepared molasses from both two and three crystallization stages and the amount of dry yeast in the inoculums (1,3,5 g/L). The measured values were concentration of the produced alcohol and the residual sugar. From the obtained data of alcohol concentration and residual sugar; the ethanol yield was calculated. All results obtained were subjected to SPSS and significance was set at 5% level. Alcohol concentration was found to vary from highest of 83 g/L to lowest of 36 g /L for molasses B (mB) and from highest of 53 g/L to lowest of 30 g/L for molasses final (mF), while residual sugar concentration varied from lowest of 26 to highest of 73 g/L for mB and 34 to 78 for mF. The calculated ethanol yield varied from highest of 0.47 g/g to 0.19 g/g and from 0.31 g/g to 0.16 g/g for mB and mF respectively. The variation was statistically significant (p 0.05).unfermentable sugar (%w/w) of 4.64 and 5.55 was obtained fro mB and mF respectively. Microorganisms’ results as total viable count were found as 378 CFU per 10 g of sample for mB and 428 CFU per 10 g of sample for mF. The net sugar produced was 12.61 % and 11.76 % cane from three and two crystallization system, whereas final molasses of 3.73 % and 4.79 % cane in three and two stage respectively were obtained. In the modification (from three to two stages), about 6.7% decreases in sugar product, an increase in molasses production quantity by about 28.4% and an increase in molasses TSAI content by about 28.8% respectively were obtained . The overall economic return by modification of the crystallization system indicates that there was additional income of 19.83 Eth. birr per ton of cane through optimum production of sugar and ethanol. The obtained results reveal that the modification in sugar crystallization system can bring over all improvement in both sugar and distillery plants and found economically feasible in the studied cases. Besides the economic return, the modification system tends to reduce the high recirculation of material, the energy utilization and the crystallization area capacity than the existing three crystallization system, with out affecting the product quality.Item Studies on The Development of Baker’s Yeast Using Cane Molasses(Addis Ababa University, 2008-01) Damtew, Wondimagegen; Admassu, Shimelis(PhD)Three yeast strains were used for biomass production of baker’s yeast using wine, brewer and baker’s yeast strains. The effect of growing yeast saccharomayces cerevisiae on cane molasses with respect to baker’s yeast production was assayed. All yeast strains were cultured in YPD microbiological media and cane molasses media; their growth properties and biomass yield were examined using different substrate concentration of cane molasses and different nitrogen source chemical compounds. The studies on the feasibility of different types of yeast growth on cane molasses has been analyzed here. As a result of the kinetics study of growth of three yeast strains shows that baker’s yeast strain gives the best results to know a generation time reduced high growth rate and a high quantity of biomass. The maximum biomass yield and protein concentration was obtained with the 5 %(w/v) cane molasses of bakers` yeast; the effect of different concentration of cane molasses (5%, 10% and 15% sugar concentration) on biomass yield and protein concentration of bakers, wine and brewery yeast strains were studied. Biomass and protein formation was affected by the type of nitrogen present in the medium; high yield of protein being achieved in fermentation medium containing 2 % (w/v) (NH4)2SO4. Conversely medium, containing potassium nitrate had suppressive effect of protein production. Baker’s yeast production was industrialized using baker’s yeast strain in 5%(w/v) cane molasses with addition of ammonium sulphate.The results obtained on industrial scale feasibility study shows that the unit costs for the baker’s yeast production are $2.4 per kilogram, while the local market price for the baker’s yeast is $7.00/kg. It has good market demand and profitability analysis also provides positive results. Keywords: Baker’s yeast (saccharomayces cerevisiae), Biomass, molasses and Single protein.Item Technical Assessment on Viability of Integrated Fruits Processing in Ethiopia(Addis Ababa University, 2007-07) Abebe, Elias; Admassu, Shimelis(PhD)The feasibility study of small scale processing of pineapple jam, mango jam and dried pineapple was studied. The methodology used for the feasibility study incorporates the three environments proposed by Lecup and Nicholson (2000) namely, market, technical (scientific and technological environment) and financial and economic environments. Pineapple cultivars (Ananas Comosus L,) Smooth cayenne and Red spanish at full ripening stage were collected from Teso in Sidama Zone. Mango samples were collected from Shebedino Woreda in Sidama Zone. Physico-chemical characteristics (pH, titerable acidity and soluble solid content) of the pulp, product yield (pulp and jam yield) and organoleptic attributes (color, aroma, flavor, degree of spreadability and acceptability) of the jam formulated from the crops were evaluated to assess the suitability of the local mango and pineapple varieties for jam production and consumer acceptability. It was observed that the pulp extracted from Smooth cayenne cultivar contain higher total soluble solids (16.23° Brix) and lower titrable acidity (0.7%) compared to the Red spanish cultivar. The total soluble solid and titerable acidity of the pulp from the local mango was 15.5° Brix and 0.36% respectively. The pH values of the pulp from both crops were found to be higher than 3.6 which is the maximum limit for formation of optimum gel for High Methoxy Pectin. The pulp yield (60%) and jam yield (95.5%) were higher for Smooth cayenne cultivar as compared to the Red spanish. Jam formulated from Smooth cayenne cultivar has scored the highest mean sensory scores in all quality attributes except in taste. However, panelists have found no significant difference (p<0.05) between the jam formulated form Smooth cayenne cultivar and imported pineapple jam except for flavor. Panelists showed less preference in taste of the jam formulated from Red spanish cultivar. Drying air temperature had an important effect on thin layer drying rate of pineapple slices. Drying at higher temperature, 70°C reduces the drying time by 46.2%, 33.3% and 33.3% for 4 mm, 6 mm and 8 mm slice thickness respectively. vii Slice thickness affected the drying time at all drying temperatures. Drying time was considerably elongated (> 11 hr) for 8 mm slice thickness at all drying air temperatures. The local demand for fruit jam jellies and marmalade is growing rapidly. Between 2003 and 2005, fruit jam, jelly and marmalade import to Ethiopia increase by 257% and 276% in terms of volume and value respectively. The import volume and value for these products reached 268,897 kg and 2,361,745 Birr respectively in 2005. Based on the projected feasible market share of the project the production scale of the processing plant was set at 33 tones per annum with production mix of 26 tones of pineapple and mango jam and 7 tones of dried pineapple. The production system was integrated to process pineapple and mango products to make all year round processing and diversification of products by utilizing availability of pineapple and mango at different times of the year. Most equipments and machineries required for this processing plant are available in local market at reasonable price, special equipments like pulper, peeler/corer, slicer and dryer could be manufactured by local workshop with support from research institutes and universities. The total investment cost of the processing plant including working capital is estimated as Birr 379,750. The project is feasible with IRR (30.1%), NPV (Birr 601,360) and the payback period of (3.3 years) at 15 % profit margin. The project can create employment opportunity for 16 people Moreover the project could contribute to: development of fruit agri-business through improved farm gate price, availability of consumer goods, reduce post harvest loss and lay background for innovations and technology adaptation