Food Engineering

EFFECTS OF MALT TYPE AND FERMENTATION DURATION ON THE PHYSICOCHEMICAL AND MICROBIAL PROPERTIES AND SENSORY ACCEPTABILITY OF TELLA: AN ETHIOPIAN FERMENTED BEVERAGE

2025-02-12T06:05:57Z

EFFECTS OF MALT TYPE AND FERMENTATION DURATION ON THE PHYSICOCHEMICAL AND MICROBIAL PROPERTIES AND SENSORY ACCEPTABILITY OF TELLA: AN ETHIOPIAN FERMENTED BEVERAGE Rabira Lemessa; (D. Eng.) Solomon Abera; (PhD) Abebe Moges Tella is among the fermented alcoholic beverages that are made from cereal grains and prepared traditionally on a small scale, typically for local consumption in Ethiopia. Hence, it is important to modify its preparation method through controlled fermentation and maintain its shelf life. This study aimed to investigate the effects of malt type and fermentation duration on the physicochemical properties, microbial profile, and sensory acceptability of tella. The experiment was conducted in a full factorial design (3x3) of two factors: the types of malt with three levels (barley, wheat and sorghum malt) and fermentation duration (48, 72, and 96 hours) after difdif phases of tella preparation. The physical properties such as geometric mean diameter, sphericity, thousand kernel weight, bulk density, angle of repose, and malt quality parameters of barley, wheat and sorghum such as germination energy, malting weight loss, moisture contents, friability, and malt extract were studied. The physicochemical properties of tella were significantly (P<0.05) affected by malt type and fermentation duration. For the sample made from wheat malt and 72 hours of fermentation, these parameters have been determined: pH, alcohol content, titratable acidity, total soluble solids, specific gravity, and color value were found to be 4.56, 7.14% (v/v), 0.84%, 5.20%, 1.0028% and 60.70 EBC, respectively. Accordingly, the pH, TSS, and specific gravity were decreased while the alcohol content, titratable acidity, and color value were increased throughout the fermentation time. The microbial profile: 7.10 log CFU/mL yeasts, 7.14 log CFU/mL LAB, and 5.35 log CFU/mL TAMB were also assessed, and sensory acceptability scores of 6.73, 6.58, 6.66, and 6.66 on a scale of 7 points for color, aroma, taste, and overall acceptability, respectively, were recorded. These values were compared and found to be tolerable with previous literature, along with high sensorial acceptability. Therefore, the tella prepared from wheat malt and harvested after 72 hours of fermentation was the most acceptable and might be recommended for consumption. Furthermore, tella made from different malts exhibited good and positive sensory acceptability during 30 days of storage in a refrigerator (4°C), as rated by panelists. Generally, this study gives a direction for future research outputs for producing tella toward expanding its production, standardizing and commercializing it on large markets 104p.

EFFECT OF ROASTING TEMPERATURE AND EXTRACTION TIME ON YIELD AND QUALITY OF SOLVENT-EXTRACTED WATERMELON (Citrullus Lanatus) SEED OIL

2025-01-09T06:12:03Z

EFFECT OF ROASTING TEMPERATURE AND EXTRACTION TIME ON YIELD AND QUALITY OF SOLVENT-EXTRACTED WATERMELON (Citrullus Lanatus) SEED OIL HABTAMU TESHOME DACHASA; Solomon Abera (D. Eng.); Dr.Abebe Moges (PhD) Watermelon seeds are the most nutritious seeds. It might produce oil but is typically discarded as food waste once the fruit is consumed. This study aimed to determine how extraction time and roasting temperature influenced the yield and quality of hexane-extracted watermelon (Citrullus lanatus) seed oil. The experiment was designed with two factors, namely roasting temperature with three levels (100, 130, and 1600C) and extraction time with three levels (2, 4, and 6 hr). Nine treatment combinations and the control were evaluated using a full factorial design with three replications. Watermelon seeds were roasted in a hot air oven for 20 minutes, while unroasted seeds were the control. The oil extraction was carried out using hexane. The results indicated that the physical properties of raw watermelon seed were recorded as 9.33 mm in length, 5.51 mm in width, 2.24 mm in thickness, 5.69 mm of arithmetic mean diameter,4.87 mm of geometric mean diameter,52.14% of sphericity,28.970 of angle of repose,412.27 kg/m3 of bulk density, 750.33 kg/m3 of true density,45.39% of porosity, and 6.65% of moisture content. The proximate compositions of watermelon seed obtained were, 4.54% of moisture content, 24.90% of crude protein, 26.10% of crude fat, 29.00% of crude fiber, 12.45% of utilizable carbohydrate, and 3.00% of ash content. The extraction conditions in this study which resulted in a maximum oil yield of 38.60%, extraction efficiency of 96.49%, and extraction loss of 3.81% were 4 hr and 1600C. Thus, roasting temperature and extraction time had a significant (P<0.05) impact on the extraction parameters such as oil yield, extraction efficiency, and extraction loss of watermelon seed oil and the various physiochemical characteristics of the extracted oil, including viscosity, specific gravity, refractive index, moisture content, free fatty acids, iodine value, acid value, smoke point, saponification value, peroxide value, and pH. The following values were obtained for oils extracted at the above indicated conditions of 160°C and 4 hours: 51.17 CP of viscosity, 0.898 of specific gravity, 1.438 of refractive index,1920C smoke point, 0.68% moisture content, 5.50 mgKOH/g acid value, 2.75% of free fatty acid, 94.10 gI2/100g iodine value,11.83 meqO2/kg peroxide value,192.33 mgKOH/g saponification value, and pH value of 4.61. The results recorded for the color value were 13.27 for L*, 3.16 for a*, and 8.24 for b*. The majority of the physicochemical values, as determined by the study, were almost consistent with the WHO/FAO threshold levels of (IV (110-143 gI2/100g), RI (1.465-1.480), PV (10-15 meqO2/kg), SV (190-200 mgKOH/g), and SG (0.88-0.94)) for crude oil. Generally, this study provided important information for anyone developing products in food production, and the optimum roasting temperature and extraction time were resulted in increased yield and quality of extracted watermelon seed oils, which helps a promising and sustainable approach to utilize waste product. 127

EFFECT OF ROASTING TEMPERATURE AND EXTRACTION TIME ON THE PHYSICOCHEMICAL PROPERTIES OF PUMPKIN (Cucurbita pepo sp.) SEED OIL

2024-03-27T06:40:08Z

EFFECT OF ROASTING TEMPERATURE AND EXTRACTION TIME ON THE PHYSICOCHEMICAL PROPERTIES OF PUMPKIN (Cucurbita pepo sp.) SEED OIL DESSALEGN LEGESE NEGEWO; Solomon Abera (Dr. Eng.); Getachew Neme (Ph.D.) Pumpkin seeds, often known as pepitas, are edible, dense with nutrients, and could produce edible oil, but perceived as food waste. This study was intended to determine how roasting temperature and extraction time affected the physicochemical properties of solvent-extracted pumpkin (Cucurbita pepo sp.) seed oil. The experiment was planned with two factors, roasting temperature with three levels (120, 140, and 160oC) and extraction time with three levels (2, 4, and 6 hr). Twelve treatments were implemented in a full factorial design with three replications. Pumpkin seeds were roasted in an electric oven for 15 minutes, while unroasted seeds were used as a control, and solvent extraction was performed using hexane. The results showed that the physical properties of pumpkin seeds were recorded as, 1.55 g/mL of true density, 0.61 g/mL of bulk density, 9.36% of moisture content, and 23.97o of angle of repose. The proximate compositions of pumpkin seed were found as 6.23% moisture content, 30.41% crude protein, 32.33% crude fat, 4.11% crude fiber, 5.10% ash, and 23.59% utilizable carbohydrate. At 160oC roasting temperature and 4 hr extraction time, a maximum oil yield of 39.22%, extraction efficiency of 86.40% and a minimum extraction loss of 1.64% was achieved. Thus, extraction parameters, such as oil yield, extraction efficiency, and extraction loss of pumpkin seed oil were significantly (P<0.05) affected by both roasting temperature and extraction time. The physiochemical properties of extracted oil, namely specific gravity, viscosity, moisture content, refractive index, free fatty acids, iodine value, acid value, smoke point, saponification value and peroxide value were investigated. At a roasting temperature of 160°C and an extraction time of 4 hr, these parameters have been determined: 0.88 specific gravity, 59.71 Cp viscosity, 0.51% moisture content, 1.480 refractive index, 2.64% free fatty acid, 113.12 I2g/100g iodine value, 7.79 mg KOH/g acid value, 150.73°C smoke point, 197.97 mgKOH/g saponification value, and 11.26 meq O2/kg peroxide value. The color values recorded were; 7.51 for L*, 3.49 for a*, and 6.99 for b*. The study found that most of the physicochemical values are nearly in line with the threshold levels advised by WHO/FAO (IV (110-143 I2/100g), RI (1.465-1.480), PV (10- 15meqO2/kg), SV (190-200 mgKOH/g), and SG (0.88-0.94)). Generally, this study offers crucial insights for product initiators in essential oils, food oils, and other industries to utilize pumpkin seeds as potential raw materials. 113

EFFECTS OF BLENDING RATIOS OF BARLEY, POTATO AND FERMENTATION DURATION ON QUALITY OF SORGHUM BASED INJERA

2024-03-27T06:12:51Z

EFFECTS OF BLENDING RATIOS OF BARLEY, POTATO AND FERMENTATION DURATION ON QUALITY OF SORGHUM BASED INJERA Faris Mohammed Adem; Solomon Abera (Dr.Eng.) Injera is Ethiopian staple food, which is widely consumed in all parts of the country. Injera 100% made from sorghum flour is characterized by sticky, firm and friable, when stored. The practice of combining sorghum and potato flour for injera making and little scientific research is done on sorghum-barley-potato flour blended injera. Thus, this study was conducted to investigate the effect of blending ratio of barley and potato flour and fermentation duration on quality of sorghum based injera. The experiment was done by full factorial design with two factors; blending ratios and fermentation duration. Twelve combinations of treatments were done in triplicate. Proportions of sorghum were 80, 70, and 50%, of barley were 15, 20, and 25%, and of potato were 5, 10, and 25%. The fermentation durations were 24, 48 and 72 hour. Functional property of flours were 1.98-2.44 g/g water absorption capacity, 0.80-1.25 g/g oil absorption capacity, 56.50-69.33% disperse-ability, 8.24-11.17 g/g swelling power. The percentage of retained particle size were increased from (0.66-0.80%) to (49.82, 49.88 and 54.32%) while mesh size decreased from 500 μm to 125 μm. Bulk density and angle of repose were 0.60-0.85 g/ml and 28.63-44.30, respectively. The proximate composition of flours such as, moisture content, fat, protein, fiber, ash content, carbohydrate and total energy were 11.99-12.75%, 2.72-3.06%, 15.33-16.27%, 5.47-5.98%, 1.77-2.14%, 60.90-61.59% and 332.16-336.34 Kcal/100g, respectively. Mineral contents of flours such as zinc, calcium and iron contents were 4.91-6.34, 7.34-38.90, and 7.43-16.87 mg/100g, respectively. The mineral contents of injera were 7.98 mg/100g zinc, 15.93-19.62 mg/100g calcium, and 15.92-19.88 mg/100g iron content. Proximate composition of injera were 57.20-63.33% moisture content, 1.52-1.94% fat, 9.85-12.78% protein, 1.29-1.78% fiber, 1.80-2.34% ash content, 20.68-27.46% carbohydrate, and 139.12-165.97 Kcal/100g total energy. The pH, tannin and phytic acid of composite injera were 3.41-4.03, 14.50-16.87 mg/100g and 220.46-282.16 mg/100g, respectively. From the blended product, B1T3 was the best selected injera product. 141