A balanced diet contains proteins and fats as well as carbohydrates - VCE - SSCE Chemistry - Question 4 - 2002 - Paper 1

To calculate energy content, use the formula:

$\Delta T = T_{final} - T_{initial} = 56.8°C - 21.0°C = 35.8 K$

Calculate the heat energy absorbed by the water:

$Q = m \times c \times \Delta T$

Where:

• $m$ = mass of water in kg (1 L of water = 1 kg)
• $c$ = specific heat capacity of water (4.18 kJ/kg·K)
• $\\Delta T$ = temperature change in K

So, substituting values:

$Q = 1 \times 4.18 \times 35.8 = 149.6 kJ$

Now, to find the energy per gram of the oil:

$\text{Energy content} = \frac{Q}{\text{mass of oil}} = \frac{149.6}{4.75} = 31.5 kJ/g$

An emulsifier's function in salad dressing is to keep the oil and water mixed, acting as a surface active agent. This allows the two immiscible liquids to combine and remain stable by reducing the surface tension between them.

The function of an antioxidant in salad dressing is to prevent spoilage of the oil by reducing oxidative damage. Antioxidants work by neutralizing free radicals and preventing lipid oxidation, which helps maintain the flavor and nutritional quality of the dressing.