Lemon Peel
Food · Fruit · Food, Typed Supps
Most of a lemon's fibre and aroma is in the skin, not the juice.
Stage by stage
- Intake (Oil glands ruptured): Zesting bursts the oil cavities in the coloured layer, releasing the volatile aroma compounds.
- Stomach (Little to digest): Peel is essentially cell wall and water, with almost no available carbohydrate.
- Small intestine (Vitamin C absorbed): Ascorbate is taken up by a saturable transporter; the flavonoids largely pass through unabsorbed.
- Large intestine (Pectin fermented): Pectin from the pith is fermented by gut bacteria into short-chain fatty acids.
Time to effect
- Minutes: The aroma is released the moment the peel is grated and fades within minutes.
Allergens
None of the fourteen major allergens. Derived from what this food is, not from a product label.
Eating patterns
Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Keto, Low-FODMAP, Gluten-free.
In season
November to April in the northern hemisphere, May to October in the southern.
Satiety
The satiety index is measured on 240 kcal servings. At 29 kcal per 100 g that is 828 g of this, which is not a serving anyone eats — so the index has nothing to say about it.
Environmental footprint
0.4 kg CO2e and 83 litres of freshwater per kg, matched to "Citrus fruit" in Poore & Nemecek (2018), Science 360.
Cost band
Cheap — roughly £3 per kg, as a band midpoint rather than a price.
Key nutrients
Nutrition per 100g
- Calories: 29
- Protein: 1.5g
- Carbohydrate: 0g
- of which sugars: 0g
- Fat: 0.3g
- of which saturated: 0g
- Fibre: 10.6g
- Sodium: 6mg
Food vs. supplement
The impressive numbers are per 100g, and a realistic serve is about 2g of zest. Peel earns its place for flavour and, in marmalade quantities, for pectin — not as a vitamin C source.
Kitchen tip
Zest only the coloured layer. The white pith below it holds the bitterness, though it is also where the pectin that sets marmalade comes from.
Common myth
“Lemon alkalises the body.” In reality: Blood pH is held in a narrow range by the lungs and kidneys and no food changes it. The idea comes from the mineral ash left after burning food in a laboratory, which says nothing about what happens in the body.
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