Lecture 6 – Moisture Relationships Announcements 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 HW#5 Assignment Problem 1: A grain storage facility in Oklahoma must store soybeans at 11% mcw or less to prevent molding and rancidity due to the summer temperatures. The facility has 16380 kg at 9% mcw in storage. A producer would like to sell 13600 kg of his soybeans at 14.5% mcw to the facility. A) Should the manager of the facility buy this canola to mix with the seed already in storage? B) How many kg of soybeans can the manager buy under these conditions? Problem 2: A drying system must remove excess moisture content from corn so that the corn will not mold or become toxic. The corn is placed in the bin at 32% mcw. Safe storage takes place at 12% mcw If the bin holds 175,000 bushels, how much water should the drying system remove to achieve the necessary moisture content? (note the conversion necessary for bushels and kg or lbs.) 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships

Lecture 6 – Moisture Relationships HW#5 Assignment Problem 3: An aeration equipment manufacturer is designing a system for an elevator facility to dry canola using ambient air aeration. The facility manager wishes to be able to accept 15% mc canola. Generally canola would be harvested in June. If the Mesonet says that the rh average for June is 60% and the average temperature is 85°F., what is the driest the manager can expect to dry the canola under these conditions? Problem 4: Convert each of the moisture contents in problems 1 - 3 to dry basis. You should have 6 moisture contents. 1/28/08 BAE2023 Physical Properties of Biological Materials Lecture 6 Moisture Relationships