Food Engineering

Permanent URI for this collection

http://etd.aau.edu.et/handle/12345678/130

Browse

Browsing Food Engineering by Issue Date

Filter results by year or month
Now showing 1 - 20 of 127
  • No Thumbnail Available
    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.
  • No Thumbnail Available
    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
  • No Thumbnail Available
    Item
    Evaluation of Imported and Local Wax for Cheese Processing
    (Addis Ababa University, 2007-07) Getachew, Solomon; Admassu, Shimelis (PhD)
    Despite large production and exportation of beeswax, the dairy processors import significant amount of wax for hard cheese coating. The drawback of the local beeswax which is being used for hard cheese processing is the cracking nature of the product, which in turn has an influence in the quality of cheese. The rationale of this study is to evaluate the locally available beeswax for hard cheese coating instead of imported wax. This study was conducted at Dairy Development Enterprise. Three samples were used for this study. Two locally available beeswax produced from honeycomb and from ’tej sefef’ and one imported wax as a control. The production method, which are very important for a good quality of beeswax are described in view of obtaining maximum quality. The physico-chemical characteristics of beeswax and imported wax are discussed. The mean value of the different parameters of the wax from ‘tej sefef’ and from honeycomb indeed, within the intervals commonly accepted by different countries specification. Saponification value (102.8500), specific gravity (0.9619), total volatile matter (0.4500) and melting point (64.3333) are slightly higher in wax from ‘tej sefef’ than wax from honeycomb; 99.7333, 0.9497, 0.3400, 64.1333 respectively. Whereas acid value and ash content are some what higher in wax produced from honeycomb. There was no significant difference between wax from honeycomb and wax from ‘tej sefef’ .The mean value of the different parameters of imported wax used for cheese coating was not within the interval of commonly accepted by different countries except total volatile matter and ash content. Moreover, there were significant difference between the two beeswax and imported wax. In the case of wax for cheese coating, beeswax produced from ‘tej sefef’ was cracked. There was significance difference between imported wax and beeswax produced from ‘tej sefef’ .However, there was no significant difference between imported wax and beeswax produced from honeycomb. The result of the data analysis revealed that beeswax produced from honeycomb gives the most promising result in this study, if the iv optimum processing conditions are maintained to obtain pure beeswax which can meet the standard.
  • No Thumbnail Available
    Item
    Evaluation of Hydrogenation Process, Trans Fatty Acid Level and Some Qualities of Selected Hydrogenated Food Products in The Markets of Addis Ababa
    (Addis Ababa University, 2007-08) Gizaw, Eshetu; Asfaw, Nigist(PhD)
    Mass production of foods and extremely large variety of food products make the quantification of their nutrient composition a difficult task. Regulations on mandatory product labeling vary from country to country, but rarely include details of fatty acid composition. Ethiopia imports several tons of food items composed of entirely fatty acids and considerable amount of fat. However, there is no regulatory basis for control of fatty acid composition. Therefore, the present study has been initiated to evaluate the hydrogenation process and determine the TFA level and some physicochemical characteristics of hydrogenated food products in the markets of Addis Ababa. Samples in triplicate from each of the selected commercial margarines (MO1, MO2, MO3), vegetable ghee (GO1, GO2, GO3) and shortenings (SO1, SO2, SO3) were analyzed for their physicochemical characteristics and fatty acid composition. Physicochemical characteristics were determined following standard methods. The total composition of fatty acids of the isolated fat was determined by gas chromatography (GC). Characterization of the fatty acids was done using commercial standard reference material of fatty acid methyl esters (FAME). The process conditions of hydrogenation at Addis Modjo Edible Oil Complex (AMEOC) were evaluated to see their effects on TFA level. The data obtained from the laboratory analysis were subjected to ANOVA using SPSS software. TFA level of 3% was used as a reference mean (control). All the TFA means were then compared and significance was set at 5% level. The results showed that all the samples contained a considerable amount of TFA ranging from 18.9 to 52.6%, and significant mean differences were observed at p< 0.05. The physicochemical characteristics and other fatty acid values were found to be within the recommended range. Investigation of the hydrogenation process at AMEOC revealed that the high TFA is partly related to the hydrogenation method currently employed in the complex. The present study clearly indicated that the hydrogenated food products in Addis Ababa’s markets contain higher TFA levels compared to the same products studied in Europe and America. In this situation, continuous consumption of both local and imported hydrogenated food products may expose to greater risk of cardiovascular diseases. Reducing trans fatty acids through process optimization and introduction of enzymatic interesterification is unquestionably essential.
  • No Thumbnail Available
    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.
  • No Thumbnail Available
    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.
  • No Thumbnail Available
    Item
    Effect of extrusion cooking on some quality attributes of full-fat soy flour and soy protein concentrate from locally grown Soybean (Glycine Max L.) varieties
    (Addis Ababa University, 2009-01) Muhsin, Fouzia; Zegeye, Adamu
    Soybean (Glycine max L.) varieties, Clark 63K and SCS1 were obtained from Jimma Agricultural Research Center. Their seed color and shape, seed density; hundred seed mass, hydration and swelling capacities, hydration and swelling indices, hydration and swelling coefficients were studied according to the standard procedures. The seeds were processed and converted into full fat soy flour (FFSF) and soy protein concentrate (FF-SPC) to study the effect of extrusion. The flours and concentrates from each variety were extruded at a barrel temperature of 140 0C, screw speed of 120rpm, and feed moisture of 30%. The effect on extrudates expansion ratio, specific length, proximate composition, flour and extrudate bulk density (BD), water absorption index (WAI), water solubility index (WSI), oil absorption capacity (OAC), emulsion activity (EA) and stability (ES), foaming capacity (FC) and stability (FS) was studied in triplicate samples. The result of the seed analysis of both varieties showed no statistical significant difference except in swelling coefficient. The bulk density of FFSF is significantly higher than that of FF-SPC flour, while FFSF extrudates have lower bulk density than that of the unprocessed flour. WAI of FF-SPC flour and extrudates of both varieties were found to be significantly higher than that of FFSF. WSI of FFSF flour and extrudates of both varieties are significantly higher than that of FF-SPC flour and extrudates. The OAC of FF-SPC flour is significantly higher than that of FFSF in both varieties, while that of the extrudates is significantly lower than that of their corresponding flours. EA and ES of extrudates of clark 63K and SCS1showed significantly higher values than the corresponding unprocessed flours. In general, the EA of SCS1 products are lower than that of Clark 63K, and the ES of Clark 63K and SCS1 is closer. The FC of FFSF is significantly higher than that of all products of both varieties. The FS of FFSF has been significantly higher than that of FF-SPC while the extrudates of SCS1 showed higher values of FS than that of Clark 63K. Generally, the present study showed that both varieties are suitable for extrusion cooking, with SCS1 slightly better performance. Based on the outcome of the study, the technology for developing an extruded product of soybean varieties has been suggested. Key words: Concentrate; extrusion cooking; flour; soybean
  • No Thumbnail Available
    Item
    Production of Spirulina (Arthrospira) Using Trona As A Major Ingredient of Culture Medium
    (Addis Ababa University, 2009-02) Endrie, Muhiye; Kifle, Zebene(PhD)
    The impressive protein content and rapid growth of Spirulina in entirely alkaline medium have attracted the attention of both researchers and business men. Spirulina is one of the best solutions for the simple production of proteinuous food supplement. The protein content of Spirulina varies between 50 % and 70%. The present study was conducted to investigate the possibility of producing Spirulina in outdoor cultivation technology using a local product (Trona) as a substitute for the three major ingredients (NaHCO3, Na2CO3 & NaCl) in the Zarrouk’s standard culture medium. The standard medium (SM) was prepared from analytical grade chemicals and used as a control. Accordingly, a modified culture medium (MM) was formulated by incorporating Trona (Na2CO3.NaHCO3.2H2O). 400 ml brine sample was taken from Lake Chitu. The sample was filtered, and the SM & MM media, were inoculated in triplicate with the Spirulia contained in the brine. The growth of Spirulina continued for ten days with every 48 h monitoring. The data on Spirulina biomass interms of yield and chlorophyll content were collected. Chemical and microbiogical analyses were done. During the growth cycle, the exponential growth phase was mathematically analyzed. In the scaling-up trial, a plastic dish with a diameter of 60 cm was used in the place of a pond for 7 days. Accordingly, biomass determination, phyico- chmical analysis and sensory evaluation were conducted. The doubling time in the analysis of the exponential growth phase gave close values for both media (SM = 53 h, MM = 51 h). The rest of the data were analyzed and means compared by t-Test using SPSS software at 5% significance level. At the end of the experiment (10th day) the mean value of biomass yield was 823.743 mg/l and 832.498 mg/l for the MM and SM respectively. Cell productivity was 83.221 mg l-1day-1 for the SM and 82.374 mg mgl-1day-1 for the MM. The crude protein content of biomass was 50.53% and to 51.93 % in the MM and SM respectively. The odour of Spirulina in SM was rated 6.333 and that of the MM was rated 5.666, while the taste of the SM was 5.888 and the MM was 5.666. Comparison of the two mean values of yield, proximate analysis and sensory analysis showed that there was no statistically significant difference between the products in the SM and MM. This justifies that Trona can be used in the culture medium to cultivate Spirulina for human consumption. Finally, Spirulina production and processing technology has been outlined. Key words: Culture medium, production, Spirulina, Trona.
  • No Thumbnail Available
    Item
    Neural Network predictive process modeling: Application to food processing
    (Addis Ababa University, 2009-03) Agide, Mesfin; Assefa, Berhanu (PhD)
    Currently, food processing industry is driven by several requirements. This requirement includes ensuring safety, meeting quality standard and customer expectation and reducing production cost to be competent in market. To achieve this requirement they have to operate at optimum process conditions all the time. In food processing, due to the nature of the process, it is difficult to find and operate at the best conditions solely by experience. The Ethiopia food industry is no coping up with such requirement due cost of optimization and low level of education of works operating in the production system. Thus, it is necessary modeling of the process or part of the process to capture the relation of between important process parameters and use the model to control and improve the process better. In addition, it is found necessary to make the model accessible for the operators working in Ethiopian industry. Using artificial neural network method is found to be very good modeling to tool to solve food engineering problems. In this thesis, therefore, artificial neural network method is used to model and tested for selected food industry engineering problems, specifically, water activity prediction, predictive food microbiology and control chart pattern recognition. The model is enclosed in interactive software so that it could also be used by people that do not have sophisticated mathematical and technical skills. The result obtained for all problems shows that neural network modeling can be used to model food process and to predict food process parameters with sufficient accuracy.
  • No Thumbnail Available
    Item
    The Effect of Blend Proportion and Baking Condition on the Quality of Cookie Made from Taro and Wheat Flour Blend
    (Addis Ababa University, 2009-06) Tekle, Abinet; Worku, Solomon(Prefessor)
    The influence of blending proportion of taro and wheat flour and baking temperature on the physicochemical characteristics and sensory qualities of cookie made from taro-wheat flour blend was investigated. Taro and wheat flour were blended using 33.33, 66.67 and 100% proportion using mixture simplex lattice design whereas 140, 150 and 160°C baking temperature was used for baking. The physicochemical characteristics of cookies were evaluated in terms of proximate composition, energy value, water absorption capacity (WAC), oil absorption capacity (OAC), cookie diameter and thickness, spread ratio and cookie breaking strength (texture). The cookie sensory qualities were evaluated in terms of color, flavor, crispiness and overall acceptability. Increase in the taro flour proportion increased the crude fiber, carbohydrate and ash content of the cookies and resulted in a decrease in the protein, fat, moisture content and energy value of the cookie. Temperature only had a significant effect on the moisture and carbohydrate content of the cookies and not on protein, fat, crude fiber and ash content of the cookies. Breaking strength of the cookies significantly (p<0.05) increased whereas cookie diameter, thickness and spread ratio significantly decreased with an increase in taro flour proportion. On the other hand, increase in baking temperature, significantly (p<0.05) increased cookie diameter and thickness. The WAC and OAC were observed to increase with an increase in taro flour proportion in the composite. The sensory quality scores of cookie decreased significantly with increase in taro flour proportion. Moreover, cookies baked at 1600C had low sensory scores for color and flavor as compared those baked at 140 and 150°C. The results of overall acceptability confirmed that replacing of wheat flour with taro flour up to 33.33% for cookie baking was fairly acceptable. Significant decrease in the oxalate content of the cookies with an increase in the taro flour proportion was also observed. The 33.33% taro flour cookie was found not to be significantly different from the control cookies with all quality parameters except with protein, ash, carbohydrate, gross energy and crude fiber content. viii In general, the study indicated that blending taro up to 33.33% with wheat flour and 150°C baking temperature could result in cookies of acceptable quality.
  • No Thumbnail Available
    Item
    Effect of Boiling Temperature on Mineral Content and Antinutritional Factors of Yam and Taro Grown in Southern Ethiopia
    (Addis Ababa University, 2009-06) Ayele, Esayas; Chandravanshi, B.S.
    The purpose of this study was to determine the mineral composition and anti nutritional factors, oxalate and phytate of yam and taro grown in Areka found at about 415Kms southern from Addis Ababa. In addition, the effect of boiling at different temperatures to the mineral compositions and anti nutritional factors together with respective molar ratios oxalate:Ca, phytate:Zn, Ca:phytate and [Ca]x[phytate]:Zn were analyzed. The mineral composition were found to be; 21.8-15.7, Ca;, 11.4-12.1, Na; 7.02 – 7.24, Mg; 6.47-14.14, Zn; 2.04-4.3, Fe;, 0.26-0.88, Mn;, 0.50-0.60, Cu; 0.57 – 0.82, Co; and 0.20-2.15, Ni in mg/100 g for the raw yam samples and 41- 53, Ca; 6.21 – 7.21, Na; 7.32-7.58, Mg; 42-50, Zn; 1.93-3.25, Fe; 1.71 – 5.88, Mn; 0.46 – 0.51, Cu; 0.65 – 0.95, Co; and 0.18 – 0.68 Ni in mg/100 g of raw taro samples. They all show decreasing by boiling except Fe and Ca in one variety of taro (accession No 235999) where they show a bit increment. The antinutritional factor to mineral ratio tends to imply that the relative bioavailability of the minerals after boiling was found to be increased except for that of Iron. These tubers may present health-hazard potential, which in turn demands proper processing before consumption to eliminate the toxic effects of antinutritional factors. Key words: mineral composition, antinutritional factors, oxalates, phytates, yam, taro, effect of boiling, molar ratios, bioavailability.
  • No Thumbnail Available
    Item
    The Effect of Natural Fermentation on Some Antinutritional Factors, Minerals, Proximate Composition and Sensory Characteristics in Sorghum Based Weaning Food
    (Addis Ababa University, 2009-06) Kassa, Mihiret; Abate, Dawit (PhD)
    The effect of natural fermentation of two sorghum cultivars on antinutritional factors (tannin and phytate), minerals (Ca, Fe, Zn and P), proximate analysis and sensory characteristics were investigated. Flours from both cultivars were fermented at room temperature (20- 230 C) for 0, 12, 24, 36 and 48h at a concentration of 1:3 dilutions (w/v). TTA and pH were determined immediately at the end of each fermentation period and the samples were dried at 70o C in air oven drier for 36h. Fermentation caused an increase in the protein, TTA, energy content and improved mineral bioavailability and decrease in fat, carbohydrate, ash, crude fiber, viscosity, antinutritional factors, phytate: mineral molar ratios and pH of sorghum flour. The bioavailability of zinc (phytate: zinc molar ratio <15) after 24-48h fermentation of Gobiye cultivar was found to meet the critical limit. The bioavailability of calcium and iron was below the critical limit in all the samples analyzed; phytate: calcium molar ratio >0.24 and phytate: Fe molar ratio > 0.15. However calcium had no effect on the absorption of zinc ([Calcium x Phytate]: [Zinc] <0.5 millimolar).When the samples were subjected to sensory evaluation, there was no significant difference (p<0.05) in the appearance and aroma of the unfermented and gruel samples fermentation for 12h. The panelists however noted that appearance, aroma, texture, taste and overall acceptability of the gruel prepared from sorghum flour that was subjected to 48h fermentation differ from others and least acceptable. Taste and overall acceptability decreased significantly (p<0.05) along with period of fermentation. Ethiopian weaning mothers should be encouraged to prepare 12 to 24h fermented sorghum based weaning gruels that may blend with either legumes or milk powder by adding some amount of sugar. Further research on cereal based fermented weaning foods needs to be conducted in Ethiopia. Researchers should also take into consideration the incorporation of phytase enzymes into cereal plants to enhance the nutritional value in addition to yield improvement by the application of biotechnology.
  • No Thumbnail Available
    Item
    Chemical Composition and The Effects of Traditional Processing on Nutritional Composition of Gibto (Lupinus Albus. L) Grown in, Gojam Area
    (Addis Ababa University, 2009-06) Getachew, Paulos; Umeta, Melaku(PhD)
    Lupin seeds (Lupinus albus), grown in Ethiopia (Gojam area) were nutritionally investigated. This study was conducted in order to evaluate the effects of some commonly applied traditional processing methods on the nutritional and chemical composition of Lupinus albus. Traditional processing methods are observed to be effective in reducing anti-nutritional factors, meanwhile their effects on the nutritional composition is not wel investigated. Accordingly, the current study focused on the effects of traditional processing methods on the nutritional and chemical composition of Lupinus albus. Three traditional processing methods (i.e. soaking after roasting for 5 days, soaking after boiling for 5days, and germination for 48 hrs) were taken under investigation. The parameters analysed were proximate composition, anti-nutritional factors, mineral composition and fatty acid profile. The official methods used were AOAC (2000), Osborne and Voogot (1978), Haborne (1973) and Latta and Eskin (1980) for Proximate composition and fatty acid profile analyses, mineral analysis, total alkaloid determination, and phytate content analysis respectively. The hull size of the two cultivars from Dangla and Tilili were 16.22% and 19.30% respectively. Moisture, protein, fat, crude fiber, ash, utilizable carbohydrates and gross energy for the Dangla sample were 6.94, 37.87, 9.34, 11.08, 2.80, 38.92% and 391.19 (KCal/100 gm) respectively. Similarly, for the Tilili sample the values were 8.04, 39.71, 8.79, 11.07, 2.90, 37.56% and 388.12 (KCal/100 gm). The anti-nutritional factors studied were total alkaloids and phytate. The results for the Dangla sample were 2.46% and 144.33 mg/100 gm for total alkaloids and phytate respectively. Similarly, for the Tilili sample the values were 2.26% and 143.96 mg/100 gm. The mineral composition of the two cultivars was also investigated. Accordingly, the Dangla sample has 6.00, 2.11, 58.43, 8.93 mg/100 gm contents of Fe, Zn, Mn and Mg respectively. The values of the same types of minerals for the Tilili sample were 6.72, 1.81, 63.54, 59.14 and 9.46 mg/100 gm respectively. In the two cultivars an average value of 24.5% saturated and 74.5% unsaturated fatty acid levels were recorded. The un-saturated fatty acids found in the oil are predominantly, Oleic and Linoleic acid, while the saturated ones include Palmitic, Stearic and Eikosanic acids. Traditional processing methods have shown both an increasing and decreasing effects on the various chemical and nutritional compositions of the raw seed. Among the treatments the commonly used soaking after roasting method was found to reduce the alkaloid content effectively, at same time showing improvement in the nutritional composition. Nutritional compositions like protein and oil have shown an improvement on soaking after roasting treatment. The mineral composition of the raw seed was also affected by the various treatments applied. Except for Zn content all the minerals analyzed have shown a reduction in the treatments. Mn content was found to exceed the safety limit for daily intake. The effects of soaking after roasting and boiling on the fatty acid profile of the oil were insignificant. But germination has reduced the contents of some of the fatty acids significantly. In all the cases the predominant un-saturated fatty acid found on both sample types was oleic acid. It can be concluded that Lupinus albus was an excellent food source with high nutritional value. The total alkaloid content can be reduced effectively after the various traditional processing methods such as soaking after roasting and boiling. These processes including germination also have a potential to enhance the nutritional composition of the raw seed. After some of the treatments (i.e. except germination) the oil content has increased. And having high amounts of un-saturated fatty acids and oil content, it could be a potential oil crop. Key words: Lupinus albus, soaking, roasting, boiling, and germination
  • No Thumbnail Available
    Item
    Improvement of Shelf Life of ‘Injera’ Using Chemical Preservatives
    (Addis Ababa University, 2009-06) Zewdu, Ashagrie; Abate, Dawit (PhD)
    Injera is staple Ethiopian fermented bread which can be made from different types of cereals, particularly from tef (Eragrostis tef). About two-third of Ethiopian diet consists of injera and it accounts for about two-third of the daily protein intake of Ethiopian population. It has a very high nutritional value, as it is rich in calcium and iron. Unfortunately, injera has a short shelf life of 3-4 days essentially due to mould spoilage. The use of weak organic acid as preservatives is allowed in acidic foods, primarily as mould inhibitor. In this study, the influence of some commonly used chemical preservatives, benzoic acid, sodium benzoate, potassium sorbate and calcium propionate was investigated by isolation of moulds before and during its ambient storage for 12 days. The preservatives were added immediately before baking at the concentration of 0.1% of benzoic acid/ sodium benzoate, 0.2 % of potassium sorbate, 0.3 % of calcium propionate and 0. 2 % blend of the four (wt/wt) as recommended by Food and Drug Administration. Three fungal species: Aspergillus niger, Penicillium sp and Rhizopus sp found to be responsible in injera spoilage. Penicillium and Rhizopus are more dominant at the temperature of between 16-200c, while Aspergillus niger is more dominant at higher temperature of between 25-320c. Injera samples had a pH and moisture content of 3.38- 3.45 and 62-65%, respectively. Antimicrobial activities of the preservatives investigated prolong the shelf life of injera up to12 days. The effectiveness of preservation was ranked as sodium benzoate>benzoic acid>potassium sorbate>blend >calcium propionate showing that benzoates and benzoic acid are the most effective. The incorporation of benzoic acid and its salt while preparing injera at home or in larger scale processing should be practiced so as to save a significant amount of injera that is lost due to mould spoilage.
  • No Thumbnail Available
    Item
    Effect of Processing on Some Physicochemical Composition and Antinutritional Factors of Locally Grown Cassava (Manihot Esculenta Crantz) Varieties
    (Addis Ababa University, 2009-07) Abera, Tilahun; Admasu, Shimelis(PhD)
    The effect of boiling and natural fermentation on Qulle and Kello cassava varieties collected from southern Ethiopia were studied for their physicochemical composition and antinutritional factors. The moisture content of the samples was 9.47±0.47% for Qulle variety and 8.48±0.02% for Kello variety for raw samples. Based on dry weight basis, the ash, fat, protein, crude fibre and total carbohydrate were 3.45±0.20, 0.88±0.10, 1.32±0.06, 3.44±0.00, and 90.55±0.19 % respectively for the raw sample of Qulle variety and 2.43±0.13, 1.02±0.10, 1.47±0.02, 2.82±0.14, 91.76±0.84 % for the raw sample of Kello variety. The energy values are 376.86±1.28 and 386.55±1.93 Kcal/100g for the samples of Qulle and Kello variety respectively. Among the antinutritional factors analyzed, the level of cyanide, phytate, tannin and oxalate were determined to be 4.62±0.01, 543.97±0.74, 1.70±0.33 and 24.93±0.08 mg/100g in raw Qulle sample respectively and 5.04±0.02, 168.24±5.53, 1.82±0.03 and 86.18±0.10 mg/100g in raw Kello sample respectively. Significant difference (p<0.05) was observed in level of all the antinutrients of the two varieties. A reduction of 59.52%, 68.10%, 91.94% and 15.40% in the level of cyanide, phytate, tannin and oxalate was achieved by cooking process respectively and fermentation brought about 77.60%,%, 88.4%, 92.4% and 67.30%, in the level of cyanide, phytate, tannin and oxalates in Qulle samples. Cyanide, phytate, tannin and oxalate were reduced by 25.20%, 14.1%, 64.80% and 32.50% by cooking and a 43.70%, 37.90%, 90.70% and 87.50% reduction was achieved by fermentation for Kello samples. Natural fermentation has resulted in significant reduction in all types of antinutrients, particularly, phytates. Qulle variety is preferable where the antinutrients are significantly reduced more by processing as compared to Kello variety except for the oxalate content.
  • No Thumbnail Available
    Item
    Nutritional Composition, Physicochemical and Functional Properties of Some Capsicum Varieties Grown in Ethiopia
    (Addis Ababa University, 2009-07) Kinfe, Esayas; Admassu, Shimelies(PhD)
    This study was conducted to generate base line information on nutritional composition, physicochemical and functional properties of three capsicum varieties which are grown in Ethiopia. In relation to proximate composition, Marako fana (Capsicum annum), Bako local (Capsicum annum) and Oda haro (Capsicum annum) contained 9.156%, 9.043% and 8.744% moisture, 11.809%, 8.728% and 9.210% crude protein, 27.264%, 25.966% and 28.566% crude fiber, 11.1625%, 9.518% and 9.147% oleoresin, 89.011 mg/100g, 84.011 mg/100g and 84.818 mg/100g vitamin C, 1.685 mg/100g, 1.670 mg/100g and 1.754 mg/100g potassium, 27.156 mg/100g, 38.205 mg/100g and 54.565 mg/100g calcium and 7.236 mg/100g, 6.876 mg/100g and 9.554 mg/100g iron on wet weight basis. In case of physicochemical properties, functional properties and antinutritional factors, Marako fana, Bako local and Oda haro contained 648331 ICU, 520687 ICU and 478085 ICU color value, 0.217 %, 0.174% and 0.161% capsacinoide, 0.034%, 0.022% and 0.021% paprika, 13.96 N/pod, 4.66 N/pod and 4.21 N/pod firmness and 8.667%, 9.667% and 10.333% gel formation capacity 0.142 mg/100g, 0.164 mg/100g and 0.148 mg/100g tannin and phytate was below detection. The analysis of variance and LSD test done on the above results at P< 0.05 revealed that protein, oleoresin, color value, paprika content, firmness and gel forming capacity of Marako fana were significantly higher than the other two varieties while its tannin content was less. Potassium, calcium and iron content of Oda haro were significantly higher than the rest two varieties. But all the three varieties had comparable moisture, fiber, vitamin C and capsacinoide. Hence, Marako fana is preferable for large scale production of oleoresin and paprika. It is good coloring agent and can be used in food formulation like sauces in a better maner. Oda haro is nutritionally preferable for its potassium, calcium and iron. All have comparable pungency.
  • No Thumbnail Available
    Item
    Improvement of Energy and Nutrients Density of Sorghum Based Weaning Food Using Germination
    (Addis Ababa University, 2009-07) Tizazu, Shimelis; Urga, Kelbesa
    Weaning foods prepared commercially are not available and if available, unaffordable for the poor in developing countries. Weaning foods prepared traditionally from locally available raw materials such as cereal and/or legume flours have a high viscosity when reconstituted, which limits the total food intake by the infants. Weaning foods from plant sources are also high in antinutrients content which decreases nutrients bioavailability. The main objective of this study was to investigate the possibilities of improving the energy and nutrients density of sorghumbased weaning foods using germination. Two varieties of sorghum (Sorghum bicolor) (L.) Moench) seeds (varieties 76T1#23 and Meko) were collected for this study. Sorghum seeds were cleaned, soaked for 22 hours at room temperature (22±20C) and germinated for 36 and 48 hours at the soaking temperature. The germinated seeds were dried at 550C for 24 hours and milled into flour. The ungerminated sorghum seeds were also dried at 550C for 2 hours and milled. Using ungerminated and geminated sorghum flour and blend of the two in ratios of 85:15, 75:25, 50:50 and 75:25, eleven weaning foods were formulated for each of the two sorghum varieties. Germination of sorghum seeds increased significantly (P<0.05) the contents (%) of crude protein from 12.25 to 12.65 and from 10.44 to 10.87; of total phosphorus (mg/100g)from 208.42 to 223.26 and from 183.04 to 193.56; non-phytate phosphorous from 95.95 to 169.69 and from 52.02 to 136.14; iron from 8.21 to 11.99 and 7.19 to 10.98; zinc from 1.86 to 2.01 and from 1.78 to 1.89; calcium from 17.09 to 25.93 and from 20.99 to 29.62 for varieties 76T1#23 and Meko, respectively. In contrast, germination of sorghum grain decreased phytic acid levels (mg/100g) from 399.12 to 190.11 and from 464.94 to 203.76 and (molar ratios) of phytate to iron from 4.12 VIII to 1.35 and from 5.49 to 1.58; phytate to zinc from 21.18 to 9.31 and from 25.72 to 10.64; and viscosity values (cP) at 13% dry matter concentration from 8689.74 to 2386.78 and from 8794.78 to 2415.19; at 5% dry matter concentration from 2893.78 to 1142.11 and from 2987.43 to 1149.2, respectively. The sensory panelists preferred the gruel that contained 15% of germinated sorghum flour for all the sensory attributes investigated; while gruels prepared from 100% germinated sorghum flour was least preferred. Hence, germination appeared to be a promising food processing method to improve the nutrients and energy density and to decrease phytate levels and viscosity values of weaning food gruels significantly and to increased food intake in infants.
  • No Thumbnail Available
    Item
    Production and characterization of Protein isolates from locally produced mustard meal for the development of biscuit
    (Addis Ababa University, 2009-12) Mekonnen, Missael; Shiferaw, Gizachew
    A process for the preparation of Holetta 1 mustard protein isolate, comprising steps such as ground the seed, removal of oil with hexane, followed by extraction at alkaline pH 10, 11 and 12. The protein was subjected to separation by centrifugation, neutralization, washing and freeze-drying. The parameters evaluated were protein yield, purity and presence of some antinutritional factors. The protein yield was 56-80%.The purity of the protein isolate was 73.29%, 75.40% and 68.225 at pH value of 10, 11 and 12 respectively. The antinutritional factors levels of defatted meal was as follows, glucosinolates represents 5.1%, phytate was 3.19% and tannins was 0.35% but after processing its value was 0.013%, 0.035 and 0.65% at pH10, 0.012%, 0.03% and 0.75% at pH11 and 0.02%, 0.215% and 1.45% at pH12 respectively. The lowest protein solubility was achieved at pH 5.some functional properties such as water adsorption(WA), fat adsorption (FA), emulsifying activiy (EA) and foaming capacity (FC) were evaluated.Holetta1 mustard defatted meal were compared with soybean meal in terms of functional properties. The tested result showed a high water absorbtion and was superior to soybean meal in FA, EA and foaming properties The chemical composition results of mustard variety of Holleta 1 defatted meal was 38.42% of protein, 5.03% of ash, 7.10% of moisture, 31.15% of fiber, 7.79% of crude fat and 10.53% of carbohydrate but after processing, the mustard precipitated protein isolate contained 75.40% of protein, 2.64% of ash, 7.97% of moisture, 0.08% of fiber, 12.61% of crude fat and 1.31% of carbohydrate. In addition to the above, this study evaluated the effectiveness of substituting different concentrations of mustard protein isolated (MPI) on the physicochemical and sensory properties of biscuits. Proximate chemical analysis results of biscuits showed that fortification increased protein contents from 9.67% to 12.77% as well as increased moisture and fat content from 4.18% and 8.26% to 9.46% and 8.49% respectively but carbohydrate content was decrease from 76.79% to 68.16%. Fortification processes were conducted by substituting specified concentrations (3%, 6%, and 9%) MPI from the total percent of wheat flour (100%). Results indicated that fortification decreased spread factor compared with the control (100% wheat flour). Sensory results showed that as the fortified MPI ratios increased xiii most of liking attributes decreased. Sensory analysis also showed that 3% of fortified MPI provided the best quality ratios within each type of fortification. Fortification of MPI could be used in production of high-protein biscuits. The result obtained for fortification of biscuit with mustard protein isolate, the incorporation of MPI ratio increase with the decrease of hardness (strength) from 20.2N, 20N, 17.2N and 15.7N for control (100% wheat flour), 3% MPI, 6%MPI and 9% MPI fortified biscuit respectively. Regarding to profitability, gross earning will be 46,200,000birr, ROI = 26.84%, pay back period = 3.2 year and break even point = 17.54%
  • No Thumbnail Available
    Item
    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
  • No Thumbnail Available
    Item
    Effect of Extrusion Operating Conditions on Aflatoxin Reduction and Product Characteristics of Corn-Peanut Flakes
    (Addis Ababa University, 2010-04) Molla, Aynadis; Zegey, Adamu
    The study was conducted with the objective of reducing aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) as a function of extruder operating conditions such as initial moisture content of samples (17% and 21%) barrel temperature (140, 160, and 180 0C), and screw speed (150,200 and 250 rpm) when naturally contaminated composite of corn and fully defatted peanut meal (70/30 ratio) was extrusion-cooked to produce corn flakes. Factorial design was used to conduct the experiment. The amounts of aflatoxin in extruded and unextruded composite samples were measured by using high-performance liquid chromatography (HPLC). Accordingly, the effect of the operating conditions on the physicochemical properties (bulk density, expansion ratio, specific length, fresh product moisture content, water absorption index (WAI), water solubility index (WSI), water holding capacity (WHC), and sensory characteristics (hardness and crispness) on composite of corn and fully defatted peanut meal (70/30 ratio) was investigated. The collected data were subjected to analysis of variance using SPSS statistical soft ware. Extrusion-cooking was observed to reduce aflatoxin (AF) content, which ranged from 60% to 93% depending on the type of AF significantly (P<0.05). Temperature and screw speed had a significant effect on the reduction of AFB1, but moisture content was not found to be a significant factor affecting the levels of AFB1. Major reduction was found at highest temperature (160 0C), as AFB1 and AFB2 were more reduced at it. The water solubility index of extrudates increased with temperature, but decreased with feed moisture content. WAI increased with increased barrel temperature and moisture levels. As barrel temperature increased from 140 0C to 1800C, WAI increased from 4.810 to 5.799 respectively and it was increased from5.317 to 5.417 when moisture grew from 17% to 21 %. WSI increased from 10.641 to 11.798 when the barrel temperature grew from 140 0C to 180 0C. Feed moisture and WSI showed inverse relationship. Screw speed showed direct correlation with WSI, which is as screw speed increased from 150 rpm to 250 rpm, WSI increased by 10.404 to 12.394, respectively. WHC increased from 5.612 to 6.841 when the barrel temperature increase from 1400C to 1800C. As feed moisture content increased from 17% to 21% WHC increased from 6.244 to 6.483. The results indicated that this new product had good flavor and color than pure corn flakes, but it is less crispy. It had also over all acceptances greater than 5. In conclusion 1600C barrel x temperature, 17% moisture content and 150rpm screw speed has been found to be ideal operating variables for reducing aflatoxin and improving the quality of the corn-peanut flakes. Key words: Aflatoxin, Extrusion cooking, High Performance liquid Chromatography (HPLC)