Food Science: Water Activity and Colligative Properties

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What is the main cause of osmo2c pressure?

The pressure applied to the water

The temperature of water

The presence of large molecules in water

The presence of small molecules that dissolve in water (correct)

Which process describes water movement from a hypotonic solution to a hypertonic solution?

Filtration

Reverse osmosis (correct)

Diffusion

Forward osmosis

In the context of colligative properties, what happens to the boiling point of a concentrated fruit juice when water evaporates?

It decreases significantly

It increases (correct)

It fluctuates randomly

It remains unchanged

Which of the following solutes is not typically associated with colligative properties?

Oxygen Signup and view all the answers

During forward osmosis, which statement is true about the movement of water?

Water moves without energy input Signup and view all the answers

What primarily influences the perishability of foods with the same water content?

The 'state' or thermodynamic 'activity' of water Signup and view all the answers

How does water activity (aw) affect food preservation?

It controls biochemical and microbiological reactions. Signup and view all the answers

What method can be used to prepare moisture sorption isotherms for food products?

Maintaining a weighed sample in a controlled humidity at constant temperature. Signup and view all the answers

What does water activity control during food processing?

Rate of moisture transfer and biochemical reactions Signup and view all the answers

Which of the following is NOT a method for achieving desired relative humidity environments for sorption isotherms?

Introducing artificial flavors Signup and view all the answers

What does the water activity (aw) measure?

The vapor pressure of water relative to pure water Signup and view all the answers

Which carbohydrate is primarily referred to as a sugar consisting of glucose and fructose?

Sucrose Signup and view all the answers

What percentage of the calories in the human diet worldwide is supplied by carbohydrates?

70-80% Signup and view all the answers

What is the primary biological purpose of starch in plants?

To supply energy for germination and growth Signup and view all the answers

Which enzyme is responsible for breaking down complex carbohydrates into glucose?

Amylase Signup and view all the answers

Which element is NOT a component of carbohydrates?

Nitrogen Signup and view all the answers

What can be said about the composition of carbohydrates in terms of their elemental makeup?

They are composed of carbon, hydrogen, and oxygen. Signup and view all the answers

Why is storing pure glucose in seeds considered detrimental?

It leads to immediate death of the seed. Signup and view all the answers

What is the primary composition of a water molecule?

Two hydrogen and one oxygen atom Signup and view all the answers

What unique thermodynamic property does supercooled liquid water possess?

It shows anomalies not present in ice Signup and view all the answers

Why does ice float on water?

Ice has a hexagonal pattern resulting in lower density than liquid water Signup and view all the answers

Which of the following correctly describes the role of water in biological systems?

It composes about 90% of our blood and brain Signup and view all the answers

In what form is water primarily found in plants?

As an intracellular and extracellular component Signup and view all the answers

What does water's role as a 'universal solvent' imply?

It dissolves almost everything, facilitating biochemical reactions Signup and view all the answers

What happens to water molecules when they freeze below 0°C at atmospheric pressure?

They arrange themselves into a hexagonal pattern Signup and view all the answers

Which branch of biological science is primarily involved in the study of water and its properties?

Food Chemistry Signup and view all the answers

What primarily causes foods to freeze faster than they thaw?

Differences in thermal properties of water and ice Signup and view all the answers

How does the thermal conductivity of ice compare to that of water at 0°C?

It is four times greater than that of water Signup and view all the answers

What is the heat capacity of ice compared to liquid water?

It is about one-half that of liquid water Signup and view all the answers

What is the H–O–H bond angle in a water molecule?

104.5° Signup and view all the answers

Which statement correctly describes water's structure?

It has two hydrogen atoms covalently bonded to one oxygen atom Signup and view all the answers

What property does the polar nature of water molecules cause?

Hydrogen atoms acquire a partial positive charge Signup and view all the answers

How does the thermal diffusivity of ice compare to that of water?

Ice has ninefold greater thermal diffusivity Signup and view all the answers

What is the van der Waals radius of the oxygen atom in a water molecule?

1.4 Å Signup and view all the answers