What is Parboiled Rice? Steps of Parboiling. Conventional Drying. Conventional Drying. May 23, Parboiling: Energy Considerations.

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1 Parboiling What is Parboiled Rice? 25 th Annual Industry Alliance Meeting 25 th Industry Alliance Meeting Meeting Location Center of Excellence for Poultry Science Poultry Science Auditorium (A-211) 1260 West Maple, Fayetteville, AR Around 50% of the worlds paddy rice production is parboiled. This is a process in which the paddy (raw) rice is steamed in the husk and then dried. May 24 th 2018 Presenter: Deandrae Smith Advisor: Dr. Griffiths Atungulu Produces a grain that cooks separate and fluffy - No sticky grains. Popular choice in food service industry. Steps of Parboiling Conventional Drying Step Moisture Content (% w.b) Harvested Cleaned Soaked Steamed Dried These steps helps rice maintain HRY and boosts the nutritional profile. Heated Air 40 o F Energy : Natural gas or oil Energy Transfer Mass Transfer Convection (Faster) Surface Desorption Surface Heating Conduction (Slow) H 2 O (l) Diffusion Rice Kernel Conventional Drying Parboiling: Energy Considerations Rotary drum dryer Types Column dryer Utilizes both electrical and thermal energy. Parboiling and drying: > 90 % of total energy required in a rice milling system. Parboiling Method Energy Requirement (J/kg-paddy rice) Energy Requirement (BTU/lb-paddy rice) Rice Processing Engineering Center (RPEC) Central Food Technology Research Institute (CFTRI) Pressure Parboiling (FAO, 1969 and Islam et al. 2004). (Sehgal et al. 1982). 1

2 Convective Heating: HRY Microwave Drying Whole Surface Heating Broken Differential stresses develop. Grain fails in tension; causing fissuring. Broken grain = ½ value of head rice. Total Head Rice 100 Total Rough Rice MW Energy Energy : Electricity Air Energy Transfer Mass Transfer Radiation (Fastest) Surface Evaporation Volumetric Heating Energy Absorption >212 o F High Energy H 2 O (g) Diffusion Rice Kernel Microwave vs. Convective MW heating exemplifies a technology with great potential for applications in parboiling; Desirable physical and chemical characteristics Energy Efficiency Shorter processing times Equal/better retention of: Vitamin B1 Vitamin B2 Vitamin B6 Vitamin C Folic acid (Cross & Fung 1982; Hoffman & Zabik 1985). Past Research The volumetric heating associated with MW heating was able to reduce inter-kernel moisture content (MC) and temperature gradients during the drying process. Hypothesis The volumetric heating and the high heat flux accorded by the MWs are able to achieve single pass parboiled rice drying with desirable physicochemical and sensory attributes. Objectives To explore the feasibility of using an industrial microwave for a batch drying operation at 915 MHz frequency for drying parboiled rice. To determine the implications of increasing steam durations and soaking temperatures. Parameters Studied Final Moisture Content MRY and HRY Parboiled rice physicochemical and sensory attributes. Experimental Design Parboiling conditions Soaking Steamin Temp. Duratio Temp Duration Duration ( o F) n. ( o C) (h) (min) (min) g Microwave Treatments Heating Power (BTU/h) Power (kw) Measured Properties MC Head rice Milled rice Color Freshly-harvested, 71 long grain rice 15 SLC Initial MC: 23-25% w.b Protein Cultivars: Chenier Viscosity Control Samples dried to 12.5% (wb) in EMC chamber set at conditions: 778 F / 25C, 65% RH 2

3 Methods MHz Industrial Microwave Soaked for 3 hours 71, 73 and 76 o C Hot Water Bath 3 3 Autoclave 915 MHz Industrial MW 64 kpa 5, 10 and 15 min Placed in MW Safe Trays kj/kg 4 Transmitter (1), Wave Guide (2), Heating Zone (3), Conveyor Belt (4), and Control Panel (5) Tempered Cooled Milling yields Rice mill Calculate: MRY HRY Incubator 4 60 o C EMC Chamber 24 o C, 65% RH Rice Dehuller Shaker Table Analysis Statistical Analysis JMP version , SAS Institute was used to perform: Analysis of variance (ANOVA) Level of significance (α) set at: 5% for comparing means Near Infrared Spectroscopy Rapid Visco Analysis 3

4 Final MC (%) MRY(%) HRY(%) Final MC (%) Final MC (%) MRY(%) HRY(%) Results: Effect Summary Response Final MC (%) Specific Energy Steam Duration Soaking Temperature FMC (%); o F (76 o C) IMC: 31.33% IMC: 32.53% IMC: 30.81% 13.75% Response MRY (%) Response HRY (%) Steam Duration Soaking Temperature Soaking Temperature Specific Energy Specific Energy Steam Duration Will show data for o F (71 o C) to o F (76 o C) soaking Temperature! Highest FMC (%); o F (73 o C) IMC: 30.70% IMC: 31.90% IMC: 32.13% FMC (%); o F (71 o C) IMC: 29.87% IMC: 31.09% IMC: 30.21% 14.75% 14.06% Lowest MRY & HRY (%); o F (76 o C) 73.35% MRY & HRY (%); o F (73 o C) 71.25% Control: 72.50% Control: 72.49% Control: 72.44% Control: 75.11% Control: 74.98% Control: 74.96% 65.15% 70.15% Control: 66.53% Control: 74.07% Highest 4

5 MRY(%) HRY(%) Protein (%) TCD SLC (%) Peak Viscosity (cp) Final Viscosity (cp) MRY & HRY (%); o F (71 o C) 71.25% Response TCD Results: Effect Summary Response Protein (%) Control: 73.87% Control: 73.53% Control: 73.49% 62.55% Soaking Temperature Steam Duration Specific Energy Soaking Temperature Specific Energy Steam Duration Control: 73.13% Lowest Response SLC (%) Soaking Temperature Steam Duration Specific Energy Response Peak and Final Viscosity (cp) PValue Specific Energy Soaking Temperature Steam Duration Will show data for o F (73 o C) soaking Temperature! NIR; o F (73 o C) 0.38% RVA; o F (73 o C) Peak Viscosity = Max viscosity prior to sample cooling. Control: 0.66% 4.75% Control: 133 Cp 125 cp Control: 6.31% Final Viscosity = Viscosity after sample cooling. Soft and glutinous texture Control: Brown Rice Lab Standard 2.05 Control: 187 cp 250 cp Delta E <13 units; human visual perception to color change negligible Increasing Specific Energy had statistically significant effects on Viscosity! Summary Summary Increasing Soak Temp: 160 o F -169 o F / 71 o C 76 o C Initial MC: Increased MRY: Decreased (Peak: 163 o F / 73 o C) HRY: Decreased (Peak: 163 o F / 73 o C) Protein: Decreased Fat: Increased Delta E: NS Increasing Steam Duration: 5 15 min Final MC: Decreased MRY: Decreased HRY: Increased Protein: NS SLC: NS Delta E: NS Peak Viscosity: NS Setback Viscosity: NS Increasing MW Specific Energy: BTU/lb / kj/kg Final MC: Decreased MRY: NS HRY: NS Protein: Decreased Fat: Decreased (Trough: 215 BTU/lb / 500 kj/kg) Delta E: NS Peak Viscosity: Decreased Setback Viscosity: Decreased Recommendation: Soaking/Steaming: 163 o F / 73 o C, 10 min Recommendation: MW Energy: 344 BTU/lb / 800 kj/kg 5

6 Questions? Advisor Dr. Griffiths Atungulu Research Group Dr. Gbenga Olatunde Shantae Wilson Zeinab Shad Soraya Shafiekhani Rebecca Bruce Thank You!! 6