9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 1 Announcements Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 2 –Measuring moisture content Oven drying…most common Distillation, chemical reactions, electrical resistance or capacitance, near infrared spectroscopy, nuclear magnetic resonance Variation due to how water is bound…chemically or physically Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 3 –Sampling Grain probe or trier (trucks or barges) Diverter sampler (streams of material) Ellis cup (material on a belt) Samples divided by a Boerner divider… g samples Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 4 –Convection Oven Method ASAE Standard S352.1, grain and seeds –Numbered dishes are heated for 1 hour –Grain is placed in dishes and in oven –Removed and placed in desiccator to be brought to room temperature and weighed –Heating times and temp vary by material –Wheat, oats, rye…130°C, 19 hr, 22hr, or 16 hr respectively (just an example) Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 5 –Chemical method Karl Fischer method: page 84 –Electrical method Moisture meters Grain capacitance/conductance meter Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 6 –Equilibrium Moisture Content (EMC) Material moisture content when equilibrium occurs during the exchange of moisture between material and air –Equilibrium Relative Humidity RH of air when equilibrium occurs –Relationship varies with temperature Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 7 Moisture Relationships Chpt 3, Pages

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 8 Moisture Relationships Chpt 3, Pages

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 9 Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 10 Two equations for predicting EMC –Henderson or modified Henderson Equation –Chung-Pfost equation Each has 2 forms: –EMC as a function of temperature and MC d –MC d as a function of rel. humidity and temperature Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 11 –Modified Henderson: –Chung-Pfost: K, N, and C are constants specific to materials (Table 3.2, pg 92) Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 12 –Modified Henderson: –Chung-Pfost: A, B, E, F, K, N, and C are constants specific to materials (Table 3.2, pg 92) Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 13 –When all you know is the % dry matter as fat and % dry matter as nitrogen free extract (% carb which does not include fiber), use this equation from Vemuganti and Pfost: Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 14 –Example: Using the Modified Henderson and the Chung- Pfost Equations: –Determine the moisture content of rough rice at 20°C and 35% RH Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 15 –Example: Using the Modified Henderson and the Chung- Pfost Equations: –If the air temperature is 22°C, what does the rh need to be to dry corn to 15% MC w ? Lecture 7 – Moisture Relationships

9/23/2015BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships 16 –Example: Compute the final moisture content after thoroughly mixing 60 kg of 18% MC corn with 40 kg of 12% MC corn. Compute the final moisture content after mixing 30 kg of 18% MC corn with 40 kg of 12% MC Corn. Lecture 7 – Moisture Relationships