HW #4 due 2/4 Lab #1 due 2/6 For Friday, read pages 95 - 104 Lecture 6 – Moisture Relationships HW #4 due 2/4 Lab #1 due 2/6 For Friday, read pages 95 - 104 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Equations: Conversion Wet to dry Dry to wet Lecture 6 – Moisture Relationships Equations: Conversion Wet to dry Dry to wet 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Another example A bag containing 1.5 kg of popcorn has been stored in the cabinet for a long time. When heated appropriately, only a few kernels popped. Testing showed that the MCw was 9%. Popcorn pops best at 13%. How much water should be added to bring it to this moisture? 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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…100-200g samples 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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) 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Chemical method Karl Fischer method: page 84 Electrical method Moisture meters Grain capacitance/conductance meter 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Moisture Relationships Chpt 3, Pages 81-105 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Moisture Relationships Chpt 3, Pages 81-105 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Two equations for predicting EMC Henderson or modified Henderson Equation Chung-Pfost equation Each has 2 forms: EMC as a function of temperature and MCd MCd as a function of rel. humidity and temperature 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Modified Henderson: Chung-Pfost: K, N, and C are constants specific to materials (Table 3.2, pg 92) 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Modified Henderson: Chung-Pfost: A, B, E, F, K, N, and C are constants specific to materials (Table 3.2, pg 92) 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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: 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Example: Using the Modified Henderson and the Chung-Pfost Equations: Determine the moisture content of rough rice at 20°C and 35% RH 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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% MCw? 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships 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. 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships Homework: See Lecture 5 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships