PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 1601/14/19 BAE2023 Physical Properties of Biological Materials Lecture 51Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 52–Amount of moisture affects the following:•Density: particle density decreases with increasing moisture content•Force-deformation characteristics•Thermal conductivity•Heat capacity•Electrical resistance: lower resistance with higher moisture contentLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 53–Amount of moisture affects:•Fruits and veggies: 70-95% mc•Grains, seeds, dry food products: < 14%•Meats: 60-80%•MC influences market valueLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 54–Three concepts:•Equilibrium mc•Water activity•Water potentialLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 55–Equilibrium mc•Moisture transfers from product to air during drying. •EMC describes the final moisture reached during drying of lower moisture food products, grains, seeds•Affects rate of drying•Explains mold growth in grainLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 56–Water Activity•Describes rate of deterioration–Water Potential•Describes the effect of moisture loss or gain on volume change and force deformation behavior of fruits and veggiesLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 57–Determining Moisture Content (VERY IMPORTANT)•Wet Basis–% of total weight with water•Dry Basis –Ratio of water weight to dry matter weight•One can be calculated using the otherLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 58–Equations:•Wet basis•Dry basis100 100water waterWtotal water dryW WMW W W� �� �= =� �� �� �+� �� �100waterdrydryWMW� �=� �� �� �total dry wetW W W= +Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 59–Equations:•Conversion–Wet to dry–Dry to wet100100100100wdwdwdMMMMMM� �=� �-� �� �=� �+� �Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 510–Wet basis example700 kg of wheat contains 84 kg of water. What is the MCw ?Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 511–Dry basis example950 kg of oats contains 105 kg of water. What is the MCd ?Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 512–Conversion exampleConvert the wheat and oat examples aboveLecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 513–“How much water did we lose” example750 kg of canola is dried from 17% MCw to 12% MCw How much water is removed during the drying process?Lecture 5 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 514–Another exampleA bin holds 2000 kg of wet grain containing 500 kg of water. This grain is to be dried to a final MC of 14% (wb). What are the initial and final moisture contents of the grain (wb and db)?How much water is removed during drying?Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 515–Another exampleAn elevator has 14,000 kg of wheat at 12% MCw and 25,000 kg of wheat at 17% MCw. The manager has a rule that all stored wheat must be below 15% MCw. If the wheat is mixed together, will it meet the storage criteria?Lecture 6 – Moisture Relationships01/14/19 BAE2023 Physical Properties of Biological Materials Lecture 516–Another exampleA 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?Lecture 6 – Moisture
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