Dept. of Food Engineering & Technology

EVALUATION OF DRYING CHARACTERISTICS AND QUALITY OF MAIZE DRIED BY TWO STAGE DRYING TECHNIQUES

2022-05-14T08:37:00Z

EVALUATION OF DRYING CHARACTERISTICS AND QUALITY OF MAIZE DRIED BY TWO STAGE DRYING TECHNIQUES Akhtaruzzaman, Md. Drying of freshly harvested maize is a great concern in all maize producing countries. This research was conducted to investigate suitable and efficient two-stage drying options for high moisture maize. First option was employed by fluidized bed drying and tempering followed by sun drying method and second option was carried out in fluidized bed dryer using variable temperature i.e fluidized bed drying at high temperature and tempering followed by further fluidized bed drying at low temperature. First stage drying in fluidized bed dryer was carried out using three temperatures (120, 140 and 1600C) at constant bed thickness of 7.0 cm. After first stage drying, all dried samples were immediately tempered for 45 minutes at grain temperature. Further, all the tempered samples were dried in second stage by sun drying method and in the same fluidized bed dryer using 65 ± 20C, respectively in first and second option of two stage drying. Drying performances in terms of drying time, effective moisture diffusivity and specific energy consumption of the drying options and quality of dried maize were evaluated. Drying results indicated that total drying time required 4.25 hours in first option and 1.41 hours in second option of two-stage drying technique. On the other hand, total drying time for single stage drying (complete sun drying method) required 10 hours. Effective moisture diffusivity of maize kernel was found to be ranged from1.05×10-08 m 2 /s to 1.15×10-08 m 2 /s and 4.4×10-08 m 2 /s to 6.3×10-08 m 2 /s in first and second option, respectively. Specific electrical energy consumption in terms of primary energy and specific thermal energy consumption varied from 0.13 MJ/kg to 0.35 MJ/kg and 0.28 MJ/kg to 0.68 MJ/kg water evaporated for the first stage of fluidized bed drying. Physical properties such bulk density and porosity of the dried product varied between two stage drying and sun drying option. Total color difference of the dried maize obtained from both the two stage drying options was higher (6.32±1.11) in contrast to the sun dried sample (3.64±0.49). The values of % crude protein (6.24±0.27) and % starch content (69.20±0.96) increased during two stages drying whereas amylose content (19.05±0.30 mg/100g) and β-carotene content (0.14±0.02) were found to be decreased in compare to control drying. Even though both the options yielded almost same quality dried product yet second option is preferable for quick drying using lower energy. Therefore, the proposed two-stage drying can be introduced as alternating drying techniques for high moisture maize in commercial drying complexes of Bangladesh. However, further study is required for design and development of commercial dryers to be used at farm level. A THESIS BY Md. Akhtaruzzaman Student No: 1605216 Admission Semester: January-June, 2016 Submitted to the Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and Technology University, Dinajpur-5200 In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE (MS) IN FOOD ENGINEERING AND TECHNOLOGY

OPTIMIZATION OF OSMOTIC DEHYDRATION OF CARROT SLICES UNDER PULSED VACUUM CONDITION IN TERNARY SOLUTION BY RESPONSE SURFACE METHODOLOGY

2022-05-14T06:37:10Z

OPTIMIZATION OF OSMOTIC DEHYDRATION OF CARROT SLICES UNDER PULSED VACUUM CONDITION IN TERNARY SOLUTION BY RESPONSE SURFACE METHODOLOGY HOQUE, A.K.M. MONGURUL The osmotic dehydration (OD) is a treatment in which large portion moisture is removed to obtain minimally processed product. The use of reduced pressure at the beginning of the process is called pulsed vacuum osmotic dehydration (PVOD). In this present work, the influence of independent variables (temperature, salt, and sucrose concentration, and restoration time) on water loss (WL), solute gain (SG) and color change (CC) of carrot slices was studied by response surface methodology. Analysis of results showed that restoration time was the most significant variables (p<0.05) for WL and SG while temperature significantly influenced the Change of color parameter. The optimum operating conditions were found to be restoration time of 182.50 min, solution temperature of 40.55°C, and solution concentration of 46.88oBrix sucrose with 12.50% sodium chloride. Under this operating condition WL, SG and CC were 52.3964% (wb), 11.68% (wb) and 5.98, respectively. The predicted values for independent variables were validated by performing several experiments and the simulated data were found similar to the experimental ones. A THESIS BY A.K.M. MONGURUL HOQUE Student No: 1405199 Session: 2014-15 Semester: July – December, 2015 Submitted to the Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and Technology University, Dinajpur-5200 In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE (MS) IN FOOD ENGINEERING AND TECHNOLOGY

OPTIMIZATION OF PROCESS PARAMETERS DURING PULSED MICROWAVE OSMOTIC DEHYDRATION (PMOD) OF BANANA SLICES BY RESPONSE SURFACE METHODOLOGY

2022-05-14T06:33:26Z

OPTIMIZATION OF PROCESS PARAMETERS DURING PULSED MICROWAVE OSMOTIC DEHYDRATION (PMOD) OF BANANA SLICES BY RESPONSE SURFACE METHODOLOGY ISLAM, MD. RAKIBUL The pulsed microwave osmotic dehydration (PMOD) of banana slices was carried out by immersing in sucrose solution. The experiments were conducted using a face-centered central composite design (FCCD) with four factors, viz. slice thickness (5-10 mm), sucrose concentration (40-60oBrix), microwave power (100-1000W), and time (10-50 min) at three levels to take into account the individual and interaction effects of the factors. The sample to solution ratio of 1:30 was kept constant throughout all of the experiments to minimize the cost of processing. Optimization of the process parameters for osmotic dehydration of banana slices was also obtained by response surface methodology. Multiple regression analysis showed that all process factors highly affect linearly on the water loss (WL), solid gain (SG), drying efficiency (DE), and color change (ΔE). Microwave power was found as the most significant factor during pulsed microwave osmotic dehydration (PMOD) of banana slices except for water loss (WL) in which osmosis time was found as the most influential factor (p<0.01). The optimum operating conditions were found to be slice thickness of 9.94 mm, sucrose concentration of 60oBrix, microwave power level of 100W, and time of osmosis of 50 min. Under this operating condition WL, SG and color change were 19.49 % (wb), 6.96% (wb) and 15.06, respectively. The predicted optimum values for independent variables were validated by performing several experiments and the simulated data were found in closeness to the experimental ones. A THESIS BY MD. RAKIBUL ISLAM Student No: 1405198 Session: 2014-15 Semester: July – December, 2015 Submitted to the Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and Technology University, Dinajpur-5200 In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE (MS) IN FOOD ENGINEERING AND TECHNOLOGY

DRYING OF AROMATIC RICE IN FLUIDIZED BED DRYER FOLLOWED BY FIXED BED DRYER AND SUN DRYING METHOD

2022-04-27T07:38:53Z

DRYING OF AROMATIC RICE IN FLUIDIZED BED DRYER FOLLOWED BY FIXED BED DRYER AND SUN DRYING METHOD ROY, GOUTAM CHANDRA Drying and management of aromatic rice (Oryza sativa L.) are important issues because of its increased demand in Bangladesh. Feasibility of two-stage drying of aromatic rice (locally known as Chinigura) and the effects of the drying technique on milling quality were investigated. The milling quality of dried aromatic rice was compared with existing industrial milling results where Louisiana State University (LSU) dryer was used. A laboratory fluidized bed dryer was used for the first stage drying to reduce the initial high moisture content of 22-24% (wb) to 18-19% (wb). A fixed bed dryer and sun drying method were used for the second stage drying for further drying of paddy up to the milling level of 14% (wb) or less. The thicknesses in fluidized bed drying were 8 cm, 10 cm and 12 cm. Three drying air temperatures of 65°C, 85°C and 100°C were applied for each bed thickness. The fixed bed dryer was operated at the temperature of 400C and fixed bed thickness of 30 cm. The tempering of paddy was done at product’s temperature in a closed container for 30 minutes of each dried samples after first stage drying in the fluidized bed dryer. Shorter drying time (4.33 to 4.67 hr) required in application of the two stage drying technique contrast to drying time needed by industrial method (10-12 hours). Two stage drying employing fluidized bed drying and sun drying yielded to 0.6% to 17.35% higher head rice yield than existing industrial drying method. On the other hand, two stage drying with fluidized bed dryer followed by fixed bed dryer gave 4.45% to 14.2% higher head rice yield than industrial drying method. The bed thickness and drying temperature had significant effect on the quality of aromatic rice. On the other hand, milling recovery, whiteness in terms of lightness (L*) and aroma of dried aromatic rice samples were insignificantly varried for all tested samples. Therefore, two-stage drying technique equipped with fluidized bed dryer may be recommended for drying of aromatic rice to save drying time as well as energy. A THESIS BY GOUTAM CHANDRA ROY STUDENT ID: 1405196 SEMESTER: JULY – DECEMBER, 2015 Submitted to the Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and TechnologyUniversity, Dinajpur-5200 In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE (MS) IN FOOD ENGINEERING AND TECHNOLOGY