Equilibrium moisture content of rice and rice products

Transcription

1 Equilibrium moisture content of rice and rice products Rusty Bautista Terry Siebenmorgen 2008 Annual Industry Alliance Meeting Center for Excellence in Poultry Science Auditorium University of Arkansas May 21, 2008

2 Objectives Determine rice component mass fractions Equilibrium moisture content Desorption and adsorption isotherms

3 EMC concept

4 Equilibrium Moisture Content The MC grain will come to when there is no moisture transfer between the grain and surrounding air

5 H 2 O H 2 O Drying Rewetting (moisture adsorption) Equilibrium Equilibrium moisture content no moisture transfer from the air to the kernel or vice versa.

6 Factors Affecting EMC Air conditions Temperature Relative humidity

7 EMC Relations: If RH remains constant; T EMC If T remains constant; RH EMC

8 Factors Affecting EMC 25 Equilibrium Moisture Content (% w.b.) F 50 F 68 F 122 F Relative Humidity (%)

9 Equilibrium Relative Humidity Table Equilibrium moisture content (EMC) of rough rice as a function of temperature and MC a Temperature Relative Humidity % ( F) a based on the Modified Henderson Equation (ASAE, 1997)

10 Factors Affecting EMC Air conditions Chemical constituency

11 Factors Affecting EMC Different grains and forms have different EMCs. At 70 o F and 80% RH: Grain Type Corn Hard Wheat Soybean Rice EMC(%w.b.) (Calculated based on Chung Equation)

12 Factors Affecting EMC Different components of grains have different EMCs. At 77 o F and 75% RH: Rice Rough rice Brown rice White rice EMC (%w.b.) (Measured based on laboratory observations)

13 Factors Affecting Rice EMC Varieties Types (long-, medium-, short-grain) Harvest MC

14 Importance of EMC Drying: MC (w.b.) 20% T, RH EMC EMC Drying Duration

15 Air Temperature EMC Kernel MC Air RH If EMC were 14%, Kernel MC = 12%, kernel would gain MC If EMC were 10%, Kernel MC = 12%, kernel would dry and decrease MC

16 Fissuring in rice kernels H 2 O H 2 O

17 Materials Rice Jupiter (medium-grain) Wells (long-grain) CL730 (long-grain, hybrid) Parboiled Kellogg s cereals process end-product

18 Materials Rice components/products: Rough Brown Head Brokens Hulls Bran

19 Platinous Temperature & Humidity Chamber

20 Chamber Test Area

21 Schematic of the EMC apparatus Linear actuator Load cell Load connector Sample baskets (19) Thermocouple (9) PC Cover Data logger Actuator control

22 Procedures

23 Temperature profiles inside the 60 o C/20%RH Air Air Air Air RH 1=16.1% Thermocouple LC 16 LC 15 LC 14 LC 13 LC load cell T 5=62.9 o C T 7=62.5 o C T 6=61.4 o C RH Sensor LC 12 LC 11 LC 10 LC 9 T 11=62.7 o C T 3=62.4 o C T 1=61.3 o C LC 8 LC 7 LC 6 LC 5 T 2=62.9 o C T 4=62.5 o C T 8=61.2 o C LC 4 LC 3 LC 2 LC 1 T 9=61.3 o C T 10=63.2 o C T 12=62.4 o C

24 Temperature profiles in the o C/20%RH T1 T2 T3 Temperature, o C Final MC std=0.22 pp Duration, min. T4 T5 T6 T7 T8 T9 T10 T11 T12

25 19 Products/samples locations inside the oven Air Air Air Air #15 Wellshead #13 Wellsrough #19 Wellshulls #16 Wellsbrokens #14 Wellsbrown Thermocouple LC load cell RH Sensor #12 Jupiterbran #11 Jupiterhead #10 Jupiterbrown #9 Jupiterrough #18 Wells bran #8 Jupiter brokens #7 CL730 head #6 CL730 brown #5 CL730 rough #4 EP1 #3 Parboiledmilled #17 EP2 #2 Parboiledbrown #1 Parboiledrough

26 Clean Rough rice %MC Boerner divider 150 g 150 g Oven MC Dehull/THU Oven MC Dehull/THU Brown rice Mill, McGill#2 Rough Hulls Brown rice Head Brokens Bran Head Brokens Bran Mass & Oven MC Oven MC 15 g 5 g 15 g 15 g 15 g 5 g

27

28 Drying curves

29 Example of EMCs

30 Example of rice components Hull, 17.0% Hull, 16.1% Brown rice, 83.0% Brown rice, 83.9% Jupiter (medium-grain) Wells (long-grain)

31 Example of rice components Hull, 16.5% Brown rice, 83.5% CL730 (long-grain)

32 Example of rice components Hull, 16.5% Brown rice, 83.5% Parboiled (long-grain)

33 Wells, 5% Bran, 9.8% Wells, 9% Head rice, 68.6% Brokens, 4.6% Wells (long-grain)

34 Acknowledgement We are grateful to Kellogg s for providing the specialized oven and the Rice Processing Program Industry Alliance Sponsors for the financial support of this project.

35 Thank you!

36 Jupiter and Wells rough rice %MC Boerner divider 150 g 150 g Oven MC Dehull/Kett Oven MC Dehull/THU Mill, McGill#2 Rough Hulls Brown rice Head Brokens Bran Oven MC Oven MC 15 g 5 g 15 g 15 g 15 g 5 g

37 CL730 and Parboiled rough Rice %MC Boerner sample divider 150 g 150 g Oven MC Dehull w/ Kett Oven MC Dehull w/ THU Mill w/ McGill#2 Hulls Brown rice Head rice Oven MC Oven MC 5 g 5 g 15 g