The Difference Between Black and Green Olives

One of the most frequently asked questions: do black and green olives come from different trees? No. They are the same fruit — the difference lies only in when they are picked.

The single difference: ripeness

Green olives are picked once the fruit has reached full size but before it changes colour. Black olives are left on the tree and picked when fully ripe. In between lies a purplish, turning stage; fruit picked then is sold as "pink" or "turning" olives.

Taste and texture

Green olives are firmer and denser, sharper in taste and distinctly bitter. They resist the bite.

Black olives are softer, oilier and sweeter. Their aroma is rounder and their bitterness milder.

Nutritionally

The two are close, but there are two tendencies:

• Oil content is higher in black olives; oil accumulates as the fruit ripens.
• Polyphenols are higher in green olives and fall with ripeness.
• Black olives are a notable source of iron.

Salt content, however, depends far more on the curing method than on colour — see the nutritional profile of olives for detail.

⚠ Darkened "black" olives

There is one practice worth knowing about. Some of the inexpensive black olives on the market are not black at all: they are green olives darkened with ferrous gluconate (E579). It is a fast, cheap way of turning fruit black chemically rather than ripening it on the tree.

How to tell:

• Read the ingredients. If ferrous gluconate or E579 appears, the olives have been darkened; declaring the additive is mandatory.
• Be suspicious of a colour that is too even. Naturally ripened black olives vary in tone from fruit to fruit; darkened ones are a uniform matte black.
• Look at the stone. In a naturally black olive the stone darkens too; in a darkened one it stays pale.

Darkened olives are not harmful and are a legal product — but they carry neither the aroma of ripe fruit nor the nutritional profile of naturally black olives. It is enough to know what you are paying for.

Which is for what?

• Breakfast: either; black is the common choice for being softer.
• Greek salad: naturally black olives such as Kalamata.
• Cooking (casseroles, pasta sauce): black olives hold together in heat and give up their flavour.
• Meze and marinating: green olives suit better with their firmer texture.
• Martinis and stuffed olives: green, especially Manzanilla.

Which variety suits which use is set out in detail in olive varieties.