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Questions and Answers
What is the formula to calculate mass of dry solid in a food sample?
When converting from wet basis to dry basis moisture content, which of the following is true?
In the example where 20 kg of food is dried from 80% to 50% wet basis, how much water was removed?
What does the principle of conservation of mass state?
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In a membrane separation system, if the waste stream contains 0.5% TS, what is the key component in determining the yield?
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When using steam to peel potatoes, what is the relationship between the temperature of the waste stream and the unpeeled potatoes?
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What is the moisture content of a food sample that has 75% wet basis in terms of mass of dry solid?
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In the context of moisture content calculation, which statement best represents a common misconception?
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What is the formula for calculating moisture content in a food sample?
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If a food sample has a moisture content of 85% wet basis, how is it converted to moisture content dry basis?
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What is the mass of dry solid in a 10 kg food sample with a moisture content of 75% wet basis?
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What is the principle of conservation of mass?
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What is the mass of water removed when a 20 kg food sample at 80% moisture content wet basis is dried to 50%?
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What is the total solid (TS) concentration in the final product after a membrane separation system?
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At what rate is steam supplied for peeling potatoes?
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What is the specific heat of peeled potatoes?
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What is the temperature change for cooling 330 kg of pineapple from 24 °C to 9 °C?
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What is the moisture content of soybeans after soaking overnight?
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What temperature is desired to reduce one liter of soymilk from 85 °C?
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Study Notes
Moisture Content
- The moisture content of a food sample is determined by the ratio of water to dry matter.
- Moisture Content (Wet Basis) is calculated as the mass of water divided by the mass of the food sample. This is expressed as a percentage.
- Moisture Content (Dry Basis) is calculated as the mass of water divided by the mass of dry solid. This is also expressed as a percentage.
Material Balance
- Material balance is based on the principle of conservation of mass, which states that mass cannot be created or destroyed, only transformed.
- In material balance calculations, the total mass entering a system must equal the total mass leaving the system.
- OMB refers to Overall Mass Balance, which considers the total mass of all components entering and leaving the system.
- CMB refers to component mass balance, which considers the mass of individual components entering and leaving the system.
Example Calculations
- Example 1: To convert moisture content from wet basis to dry basis, use the formula: Moisture Content (Dry Basis) = (Moisture Content (Wet Basis) / (1 - Moisture Content (Wet Basis)))
- Example 2: To convert moisture content from dry basis to wet basis, use the formula: Moisture Content (Wet Basis) = (Moisture Content (Dry Basis) / (1 + Moisture Content (Dry Basis)))
- Example 3: To determine the mass of dry solid in a food sample, subtract the mass of water from the total mass of the food sample.
Example 4
- This example demonstrates the principle of conservation of mass in a food processing operation.
Example 5
- This example involves a drying process where the moisture content of a food sample is reduced.
- Calculation: The mass of water removed is calculated by subtracting the mass of dry solid in the final product from the initial mass of the food sample.
Example 6
- This example illustrates a membrane separation system used to concentrate a liquid food.
- The system operates in two stages, with a recycle stream and a waste stream.
- The final product is 100 kg/min with a total solid content of 30%.
Example 7
- This example describes a semi-continuous operation for peeling potatoes using steam.
- The steam is supplied at a rate of 4 kg per 100 kg of unpeeled potatoes.
- Heat transfer occurs as the potatoes are peeled, with the temperature of the potatoes increasing from 17°C to 35°C.
- A waste stream leaves the system at 60°C.
- The specific heat capacities of unpeeled potatoes, waste stream, and peeled potatoes are provided.
Moisture Content
- Moisture content is defined as the ratio of the mass of water in a food sample to the total mass of the sample.
- This concept is relevant for food preservation and processing.
- Moisture content can be expressed in both wet and dry basis.
- Wet basis (W.B.) represents the mass of water in relation to the total mass of the food sample.
- For example, a moisture content of 85% W.B. signifies that 85% of the sample's mass is water.
- Dry basis (D.B.) represents the mass of water in relation to the mass of dry solids in the food sample.
Material Balance
- The principle of conservation of mass states that mass cannot be created or destroyed, only transformed.
- This principle is useful in analyzing food processing systems to track mass flow and changes.
- Example 5 demonstrates how to calculate the amount of water removed during a drying process using material balance.
Examples
- Example 1: Demonstrates the conversion of moisture content from wet basis to dry basis.
- Example 2: Shows how to calculate the moisture content in wet basis when given the moisture content in dry basis.
- Example 3: Explains how to calculate the mass of dry solid in a food sample when given the initial mass and the moisture content in wet basis.
- Example 4: Highlights the use of material balance in food processing.
- Example 5: Demonstrates the application of material balance in calculating water removed during drying.
### Membrane Separation System
- Example 6: Shows the application of material balance in a membrane separation system.
Heat Transfer
- Example 7: Demonstrates the use of heat balance to calculate the quantities of waste stream and peeled potatoes.
- The specific heat of different materials is relevant to calculate heat transfer.
Cooling Water Calculation
- The lab exercise requires calculating the amount of cooling water needed to chill pineapple.
- The temperature changes of both the pineapple and the cooling water are considered.
Soymilk Production
- The lab exercise involves calculating the amount of soymilk produced from a given amount of soybeans.
- Key steps in soymilk production, including soaking, comminution, filtration, and temperature reduction, are outlined.
- Water addition, solid content, and specific gravity are used to determine the soymilk production.
- The calculation involves applying material balance and heat transfer concepts.
Temperature Reduction
- The lab exercise involves the temperature reduction of soymilk using ice.
- The change in solid content after adding ice is calculated.
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Description
This quiz covers essential concepts of moisture content in food samples and material balance principles. Learn to differentiate between wet and dry basis moisture calculations and understand the implications of mass balance in food science. Test your knowledge through various example calculations.
