Food Engineering
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Browsing Food Engineering by Author "Adamu, Zegeye (Assoc. Prof.)"
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Item Development and Characterization of Pineapple Jam and Utilization of its Peel for Vinegar Production(Addis Ababa University, 2018-12) Teklu, Chalchisa; Adamu, Zegeye (Assoc. Prof.)Fruit extract, sugar (S), pectin(P) and citric acid are the four ingredients needed for jam production. The quality of the jam is highly dependent on the choice of concentrations of each ingredient and processing parameters. The physicochemical composition of pineapple (smooth cayenne variety) fruit pulp, and jam were studied and the results were recorded. Processing of pineapple fruit pulp into jam resulted in a significant increase in physico chemical properties like TSS and TA but a significant decrease in pH, Vitamin C and mineral composition were observed. Subsequently sensory and microbial evaluation were conducted to identify highly acceptable pineapple jam. Processing of pineapple fruit pulp into jam show slightly decrease the nutritional composition of the products. This study investigated good quality pineapple jam formulation using general factorial design (Minitab 17 modeling). Out of 12 pineapple jam samples that were formulated with different ratio of sugar, pectin, and processing temperature samples J10(T:90 o c, S:45%, P:3%), formulation proved as best products in terms of its nutritional composition; sensory and microbial analysis. Production of vinegar by fermentation of pineapple peel using three selected strains of acetic acid bacteria’s (propionic bacterium acid propionic, panteo agglomerans, and pantea disperse) was assessed. Fermentation times of 24h., 48h, and 72h at three levels with two factor full factorial was applied for experimental design and statistical analysis using Minitab 17.1. Aeration rate, temperature, and carbon source were set as constant factors. A total of 10 experiments were conducted at conditions as stated previously with three strains of acetic acid bacteria and fermentation time. Total acetic acid concentration was analyzed using acid base titration method. This experiment shows that propionic bacterium acid-propionic, acetic acid bacterial strain, produce 6.15g/l of acetic acid at fermentation time of 72h.which was higher yield when compared with the other strains used for this research wok. In general, bacterial strain and fermentation time were the most important factors affecting vinegar production.Item Development of gluten-free biscuit from a blend of Teff, Sorghum and Cowpea Flour(Addis Ababa University, 2021-12) Rebka, Temam; Adamu, Zegeye (Assoc. Prof.)The study was conducted to develop gluten-free and protein-rich biscuit to achieve nutritionally improved quality product and reduce celiac problem which arises with gluten content. Teff (Boset variety), Sorghum (Melkam variety) and Cowpea (Bole variety) were collected from Debrezeit and Awash Melkasa Agricultural Research Centers. The raw materials were cleaned, soaked(cowpea), dehulled(cowpea), dried(cowpea), milled and sieved before blended flour preparation. Blend proportions of Teff, Sorghum and Cowpea were prepared as S1 (65%: 20%: 15%), S2 (40%: 25%:35%) and S3 (50%:30%:20%) ratios, respectively using D-optimal design software. In this study, proximate composition, functional properties, anti-nutritional properties, mineral content and sensory analysis were conducted. Biscuit samples were prepared with temperature controlled oven at 205ᵒc for 10 minutes. The results showed that the protein and fat contents of biscuit product were directly proportional to the amount of cowpea flour added in the blend proportion, biscuit having 35% cowpea or S2 being the highest ( 15.4g/100g and 8.5g/100g). Mineral content increment for Fe, Zn and Ca was 9.33 to 12.05, 2.62 to2.95 and 95.34 to 116.3mg/100g respectively with increasing teff proportion. Tannin (23.08mg/100g) and phytates (439.23mg/100g) were higher in higher cowpea and teff addition respectively. Functional properties such as water absorption capacity(2.15ml/gm), oil absorption capacity(1.73ml/g) and bulk density (0.94g/ml) registered the highest values.. pH values of samples were 6.39, 6.49 and 6.45 respectively for S1 (65%: 20%: 15%), S2(40%: 25%:35%) and S3(50%:30%:20%) in the blend proportions respectively. The highest overall sensory acceptability score was 7.8(S3) which was liked moderately next to the control biscuit sample. S3 also scored highest in texture (7.65), appearance (7.8) and taste (7.65) parameters whereas the color (7.7) of S1 biscuit sample was better liked by panelists.Item Development of Weaning Food from a Blend of Oat, Rice and Cowpea Flour(Addis Ababa University, 2021-12) Sewbesew, Tefera; Adamu, Zegeye (Assoc. Prof.)Cereals and legumes are highly cultivated plants in Ethiopia.They contain high macro and micronutrients, but they have anti-nutritional factors by nature which limit the bioavailability of food nutrients.This study focused on development of weaning food from Oat, Rice, and Cowpea flour for the age group of 6 to 24 months babies. This age is a critical period of mental, physical, and intellectual development.Raw materials were selected based on nutritional availability. Roasting method was used at 100,120, and 140 oc, Blending ratio refers 60 to 70% cereals and 30 to 40% legumes.Ratio1(50% Oat,10% Rice,40%Cowpea) contained higher protein content than Ratio2 and Ratio3 this is because of the avalibilty of high amount of Cowpea. Optimization using Minitab 17 software was used in order to formulate the nutrient and to compare the product from commercial product which is FAFFA flour.The roasting process and blending ratio had a significant (P<0.05) effect on proximate composition, functional properties, anti-nutritional factor, mineral content, and microbial analysis.According to optimized result P2,P3&P9 labled weaning products have been found good nutrietious especially P3(ratio1with140oc roasting temperature) was selected of having optimum protein and energy containing 18.1%protein, 4.9%fat, 70.8%carbohydrate and 400.2kcal energy.As roasting temperature incresed the same ratio of protein,fat, ash and mineral contents were significantly (P<0.05) increased but moisture and fiber contents were decreased. WaterAbsorption Capacity(WAC) and Oil Absorption Capacity(OAC) of the formulated products ranged between 2.01 to 2.85 and 1.57 to 1.94ml/g,respectively,which were higher than the raw material values.Bulk density of the formulated products were lower than the raw material values due to roasting.After processing both phytate and tannin content of formulated products were decreased due to roasting so increased bioavalablity of products.Item Effect of Process Conditions on Soymilk Storage Stability(Addis Ababa University, 2018-11) Mesay, Abera; Adamu, Zegeye (Assoc. Prof.)Effect of process conditions such as soaking time (ST), germination time (GT) and grinding cum blanching temperature (BT) on physicochemical characteristics, proximate composition, microbial stability and sensory acceptability of soymilk was studied during 21 days of cold storage (4ºC). Soymilk was prepared from soybean (Clark 63k) using a combination of Cornel and Deodorization methods of soymilk processing. Sprouted and un-sprouted soybean seeds were subjected to a combination of process conditions namely: soaking time (8h and 24h) and grinding cum blanching temperature (90°C and 100°C) used for soymilk preparation. Soymilk prepared by traditional method and the reference of USDA nutrient requirement were used as control. Soymilk from sprouted soybean seeds showed an increase in protein content (wb) of 12%, a reduction in fat (wb) of 17% and phytate (db) of 15%. Physicochemical characteristics, microbial load and proximate composition of soymilk showed significant difference (P<0.05) between treatments and during storage time. Good physical stability showed on soymilk prepared from sprouted soybean during 21 days of cold storage. Response optimization result in optimal soymilk process conditions (ST= 24h, GT=72 h and BT= 100°C), (ST= 8h, GT = 0h and BT= 100°C), (ST= 24h, GT= 0h and BT= 90°C) and (ST= 24h, GT= 72h and BT= 90°C) selected based on maximum value of viscosity and colour (whiteness) value of soymilk samples. Soymilk samples were within allowable microbial limit during 7 days of cold storage with comparable pH of fresh cow milk. Validation of the optimal process from sensory panellist perspective indicated that there were no significant (P>0.05) differences between samples on overall liking. Thus, soymilk from sprouted soybean seed (ST=24h, GT=72h and BT=100°C) was selected as acceptable with better storage stability, nutritional / anti-nutritional profile and physicochemical characteristics as confirmed by sensory acceptance. The result clearly showed 70% acceptance and 65% purchase intent of the soymilk. The improvement in proximate composition was seen in soymilk from sprouted soybeans, showing that sprouting could be beneficial for preparing soymilk with higher nutritional and lower anti-nutritional profile.Item Production and Characterization of Quality Biscuits from the Blend of Banana and Wheat Flours(Addis Ababa University, 2021-11) Koak, Mot Kuechuor; Adamu, Zegeye (Assoc. Prof.)Banana (Musasp.) is cheap and has been grown in most parts of Ethiopia. In its green stage, banana contains mainly carbohydrate especially starch; therefore, it is suited to use as the source of starch and flour. Then banana flour was used for starch isolation using 0.05N NaOH. The gelatinization temperature ranges obtained from differential scanning calorimetry (DSC) were 66.50°C, 75.16°C and 86.54oC for starches. The study was also carried out to determine the biscuit making potentials of cooking banana and wheat flour blends. Accordingly, all the banana flour and starch samples were characterized, and biscuit samples were subjected to laboratory analysis for proximate and minerals using standard methods. Supplementation of wheat flour with cooking banana flour significantly p<0.05) increased the ash (1.34-2.10%), crude fibre (1.06-2.81%) and moisture contents (2.77-8.91%) of the cookies while a decrease in the fat (31.37-29.28%), protein (8.31-7.53%) and carbohydrate (55.15-49.37%) was observed. The sensory results also showed that cookies with 10% substitution of cooking banana flour were preferable for colour, texture, aroma and taste, and this compared favourably with 100% wheat flour cookies. The minerals were 5.89-6.12mg Ca, 0.48-0.82mg Fe, and 22.10-23.93mg P. The present result showed that cooking banana flour has high potential as value added ingredient in cookies production for household utilization.Item Production and Characterization of starch Based Antimicrobial Packaging Film through Incorporation of Plumbago Zeylanica (Amira) Root Crude Extract(AAU, 2018-06) Melak, Muche; Adamu, Zegeye (Assoc. Prof.)Antimicrobial packaging is one of the most promising active packaging systems. Starch based film is considered an economical and environmentally-friendly material for antimicrobial packaging. This study aimed at the development of food packaging from corn starch incorporated with methanol extract of plumbago zeylanica root as antimicrobial agents. The antimicrobial activity of the extract was tested on three bacterial strains namely Staphylococcus aureus, Salmonella typhi, E. coli and one fungal strain known as aspergilla niger. Inhibition of bacterial growth was examined using zone of inhibition test on solid media. For this 200 µl of various concentrations, 200mg/ml 100mg/ml, 50mg/ml and 25mg/ml plant extract were added into 8 mm hole diameter using micropipette. Hence 200µl of 200mg/ml extract could inhibit 13.5, 8.75, 10.5 and 27 mm diameter for Salmonella typhi, E. coli, staphylococcus aureus and Aspergilla niger respectively. Minimum inhibitory concentration was determined involving broth dilution method. From minimum inhibitory concentration findings, 1.25mg/ml, 2.5mg/ml ,1.25mg/ml and 0.625 mg/ml crude extract in liquid medium completely inhibited the growth of S. aureus, E. coli, Salmonella typhi and aspergilla niger respectively. This result showed that plumbago zeylanica exhibited a potential antimicrobial activity on selected pathogenic microorganisms. Consequently, the control and antimicrobial agent films were produced by casting method. From the observations, antimicrobial packaging films exhibited inhibitory zones. Interestingly, a wide clear zone on solid media was observed for Salmonella typhi and aspergilla niger growth inhibition whereas inhibition for E. coli and Staphylococcus aureus were not as effective as Salmonella typhi and aspergilla niger. These results showed that the incorporation of plumbago zeylanica extract had a significant influence on the growth of each selected microorganism (P<0.05). Overall, the current study manifested that plasticized corn starch can be regarded as a promising biodegradable antimicrobial packaging film.