Black olive (Olea europaea L.)

The term black olive generally refers to the ripe drupes of Olea europaea L. that have reached an advanced stage of veraison, with a colour ranging from dark purple to black, or to olives subjected to specific technological processes that produce a stable darkening of the skin. In commercial practice, the “black olive” category therefore includes both naturally black olives (harvested at advanced ripeness and preserved with traditional methods) and oxidised or “artificially blackened” olives, obtained starting even from olives harvested at the green or semi-ripe stage and treated with alkaline solutions and controlled aeration to accelerate colour change.

From a botanical point of view, the black olive belongs to the same species, but the final product depends on the cultivar, ripening stage, and processing method. Naturally black olives usually derive from cultivars intended for table olive production, harvested when the fruit has already accumulated a high proportion of lipids and phenolic compounds, with a pulp that is soft but still structurally intact. Olives obtained through oxidation, by contrast, start from raw material that may differ in varietal origin and maturity, but is subjected to debittering (use of alkaline solutions) and subsequent oxidation under controlled conditions, usually followed by brine preservation or packing in a covering liquid.

The composition of naturally black olives reflects that of fully ripe drupes: a relatively high lipid content (triacylglycerols with a predominance of oleic acid), a gradual reduction in free oleuropein compared with green olives, and the presence of oxidised polyphenols and pigments (in particular anthocyanins and oxidised phenolic derivatives) that contribute to the dark colour. The evolution of the phenolic profile, together with brine fermentation (when applied), influences microbiological stability, taste (tendency towards lower bitterness than green olives), and overall sensory properties. In black olives obtained by oxidation, tissue structure and part of the original phenolic compounds are modified by processing, which may lead to differences from naturally black olives in terms of texture, uniform colour, and organoleptic profile.

From a technological and commercial viewpoint, black olives represent a broad category of table products, used in various culinary preparations, in table olive mixes, and as an ingredient in baked goods and ready meals. The distinction between naturally black olives and oxidised black olives is important for quality control, correct labelling, and the assessment of nutritional and sensory characteristics: in the former, the fruit profile is more closely linked to cultivar and origin, while in the latter, process parameters (time, temperature, solution concentration, oxygen management) play a major role. In all cases, the raw material remains the drupe of Olea europaea L., whose agronomic and technological management determines the final properties of the product marketed as a “black olive.”

Botanical classification

• Botanical name: Olea europaea 

• Botanical family: Oleaceae

• Order: Lamiales

• Class: Magnoliopsida

• Kingdom: Plantae

Indicative nutritional values per 100 g
Average values for 100 g of drained black table olives in brine:

• Energy: about 230–270 kcal

• Protein: 1–2 g

• Carbohydrates: 0–2 g (negligible sugars)

• Total fat: 23–27 g

  • saturated fatty acids: 2–4 g

  • monounsaturated fatty acids (predominant): main fraction

  • polyunsaturated fatty acids: minor fraction

• Fibre: 5–8 g

• Salt (NaCl): 3–6 g (depending on brine strength)

Values vary with cultivar, ripeness, brine composition, oil packing and any additional ingredients.

Key constituents

• Lipids (oil)

  • prevalence of oleic acid (monounsaturated fatty acid, typical of olive oil)

  • smaller fractions of saturated and polyunsaturated fatty acids

• Structural components

  • cell-wall polysaccharides (insoluble and partially soluble dietary fibre)

  • small amount of vegetable proteins

• Minor components

  • phenolic compounds (oleuropein, hydroxytyrosol, tyrosol and derivatives, in variable amounts according to processing)

  • pigments (anthocyanins in naturally ripened dark cultivars)

  • phytosterols and tocopherols (vitamin E)

• Minerals and sodium

  • high sodium content in brined olives

  • small amounts of potassium, calcium and magnesium

Production process
Black table olives can be produced through:

• Harvesting

  • olives harvested at advanced or full ripeness (dark purple to black)

  • hand- or machine-harvesting, with attention to minimise fruit damage

• Debittering and fermentation/conditioning

  • brining (water + salt) with possible spontaneous lactic fermentation

  • in some industrial processes, alkaline treatments and subsequent washing steps are used to accelerate debittering (removal of oleuropein)

• Preservation

  • maintenance in stabilised brine (controlled pH, salt level, possible acidifiers)

  • or packing and preservation in oil (alone or with herbs and spices)

• Possible pasteurisation

  • for jars/cans, a mild heat treatment may be applied to extend shelf-life.

Physical properties

• Size and shape

  • variable depending on cultivar (small, medium, occasionally large)

  • mainly oval or ellipsoidal, sometimes slightly asymmetrical

• Pulp texture

  • from firm to soft, depending on ripeness and processing (type/duration of brining, alkaline treatment, pasteurisation)

• Colour

  • dark violet to black

  • may result from natural ripening or from technological treatments; if colourants are used, they must be declared on the label.

Sensory and technological properties

• Flavour

  • distinctly savoury due to high salt content

  • bitterness more or less reduced depending on debittering process

  • possible mild acidity from lactic fermentation or added organic acids

• Aroma

  • fruity notes of ripe olives, sometimes with hints of wine/vinegar (fermented products) or of added herbs and spices

• Texture

  • compact pulp, usually non-fibrous, capable of maintaining integrity in light cooking or in cold preparations

• Technological behaviour

  • good stability in brine or oil if correct preservation conditions are maintained

  • suitable for pitting, slicing and chopping (sauces, spreads, tapenade) without excessive liquid loss when properly drained.

Food applications

• Direct consumption

  • appetizers, snacks, side dishes, mixed salads

  • part of mixed pickles and preserved vegetable assortments

• Ingredient in cooking

  • pasta dishes, risottos, grain salads, one-dish meals

  • meat and fish dishes (stews, braises, baked fish)

  • focaccias, pizzas, savoury pies

  • sauces and spreads (e.g. tapenade, olive-based spreads with anchovies, capers, herbs)

• Food industry

  • ready-to-eat meals, deli salads, pizza toppings and pasta sauces

  • mixed olive–vegetable products for the chilled or ambient shelves.

Nutrition & health

• The content of monounsaturated fats, mainly oleic acid, is considered favourable within a balanced diet, especially when replacing part of saturated fats.

• Phenolic compounds and natural antioxidants can contribute to protection against oxidative stress.

• Dietary fibre supports bowel function and contributes to satiety.

• The main critical point is sodium: in individuals on low-salt diets or with hypertension, intake of brined olives should be moderate; short rinsing in water can reduce surface salt, although some flavour is also lost.

Portion note
A reasonable serving of black table olives can be considered 5–10 olives (about 15–30 g) as part of a balanced meal. This allows one to benefit from the lipid profile and antioxidants while limiting calorie and salt intake.

Allergens and intolerances

• Black olives are not listed among the major allergens under EU legislation.

• Potential issues:

  • presence of additives (preservatives, antioxidants, acidifiers) which may trigger reactions in sensitive individuals

  • presence of other allergenic ingredients in mixed products (e.g. nuts, cheese, anchovies)

  • possible cross-contamination in deli counters and mixed preparations.

Storage and shelf-life

• In brine (jars, cans, tubs)

  • store in a cool, dry place away from direct sunlight

  • once opened, keep olives covered by brine, close properly, refrigerate and consume within the period indicated by the producer.

• In oil

  • ensure complete coverage with oil to limit oxidation and microbial growth

  • store in a cool, dark place; after opening, refrigerate if indicated and consume within a reasonable time.

• Loose products (deli counter)

  • require cold-chain conditions and rapid consumption

  • appearance (absence of off-odours, moulds, excessive turbidity) should be checked carefully.

Safety and regulatory

• Production and marketing must comply with EU and national food safety regulations (hygiene, HACCP, contaminant limits, food-contact materials).

• Any additives (preservatives, acidifiers, authorised colourants) must be permitted by law, used within legal limits and clearly declared in the list of ingredients.

• Proper control of pH, salt concentration and, where applicable, heat treatment is essential to prevent growth of pathogenic microorganisms and toxin formation.

Labelling
On a prepacked black olive product, the label must at least include:

• legal name (e.g. “black olives in brine”, “pitted black olives in olive oil”)

• list of ingredients in descending order (olives, water, salt, oils, acidifiers, antioxidants, flavourings, etc.)

• net weight and, where applicable, drained weight

• name and address of producer or packer, lot number, best-before or use-by date

• reference nutritional values per 100 g

• specific storage conditions (e.g. “once opened, keep refrigerated and consume within …”)

• clear highlighting (usually bold) of any allergens present among the ingredients.

Troubleshooting

• Off-odour or off-flavour (excessive fermentation, rancidity, mould)

  • possible causes: poor storage conditions, broken cold chain, non-hermetic containers, oxidation of packing oil

  • action: do not consume the product; check expiry dates and storage conditions; improve stock rotation and temperature control.

• Olives too salty

  • possible causes: overly concentrated brine, reduction of brine volume during storage

  • action: for household use, briefly rinse or soak in water before consumption; at process level, adjust brine concentration and process controls.

• Olives excessively soft or mushy

  • possible causes: over-ripeness, excessive alkaline treatment, too intense pasteurisation, mechanical damage

  • action: retune timing and conditions of technological treatments, improve raw-material selection and handling.

Sustainability and supply chain

• Production of black table olives typically takes place in Mediterranean olive-growing systems, ranging from traditional to intensive orchards.

• Sustainability aspects depend on:

  • soil management (erosion control, rational water use)

  • plant protection strategies (controlled use of plant protection products, adoption of integrated or organic practices)

  • by-product management (pomace, wastewaters) to reduce environmental impact.

• Certified supply chains (e.g. organic, PDO/PGI for specific cultivars and regions) can offer enhanced guarantees of traceability and compliance with environmental and social criteria.

Main INCI functions (cosmetics)
In cosmetics, the reference ingredient is olive oil (not distinguished by table olive type). Common INCI names include:

• Olea Europaea (Olive) Fruit Oil

  • emollient function: softens and moisturises skin

  • conditioning effect in hair products

  • antioxidant contribution due to phenolic compounds and tocopherols

  • possible auxiliary role in emulsifying and solubilising, depending on the formulation.

• Olea Europaea (Olive) Oil Unsaponifiables

  • used in targeted formulations for its emollient and protective properties.

Conclusion
Black olives are a characteristic ingredient of Mediterranean cuisine, with a nutritional profile marked by predominantly monounsaturated fats, phenolic compounds and dietary fibre. They offer intense flavour and high technological versatility (appetisers, condiments, ready meals). The main factor requiring attention is the relatively high salt content of brined products, which calls for mindful consumption, especially in individuals who need to limit sodium intake. When included in a balanced diet and sourced from well-managed supply chains, black olives can contribute positively to overall diet quality and can be compatible with environmental sustainability goals and territorial enhancement.

Studies

In the olive there are bioactive compounds useful for human health such as polyphenols, proteins (1).

The anthocyanin content of the black olive is slightly higher than that of the green olive.

The amount of phenolic compounds is significant and explains the antioxidant activity of olive and olive oil:

• phenols are present in quantities between 317mg/100g and 2657mg/100g.
• gallic acid from 7mg/100g to 35mg/100g
• 3,4-Dihydroxybenzoic acid 33mg/100g to 25mg/100g

These values change substantially depending on the type of oleander, harvest period and other parameters (2).

The good protein and amino acid content of olive and in particular maslinic acid, a tripenoid, have shown that, together with moderate exercise, they can increase muscle mass, grip strength, knee pain and thus prevent disability related to mobility in older people (3).

Olive cultivation is damaged by the so-called "Olive Fly" (Bactrocera oleae).

Black olive studies

Black olive , Olive fruit fly studies

References________________________________________

(1) Montealegre C, Esteve C, García MC, García-Ruiz C, Marina ML. Proteins in olive fruit and oil. Crit Rev Food Sci Nutr. 2014;54(5):611-24. doi: 10.1080/10408398.2011.598639. PMID: 24261535.

Abstract. This paper is a comprehensive review grouping the information on the extraction, characterization, and quantitation of olive and olive oil proteins and providing a practical guide about these proteins. Most characterized olive proteins are located in the fruit, mainly in the seed, where different oleosins and storage proteins have been found. Unlike the seed, the olive pulp contains a lower protein content having been described a polypeptide of 4.6 kDa and a thaumain-like protein. Other important proteins studied in olive fruits have been enzymes which could play important roles in olives characteristics. Part of these proteins is transferred from the fruit to the oil during the manufacturing process of olive oil. In fact, the same polypeptide of 4.6 kDa found in the pulp has been described in the olive oil and, additionally, the presence of other proteins and enzymes have also been described. Protein profiles have recently been proposed as an interesting strategy for the varietal classification of olive fruits and oils. Nevertheless, there is still a lot of knowledge without being explored requiring new studies focused on the determination and characterization of these proteins.

(2) Özcan MM, Fındık S, AlJuhaimi F, Ghafoor K, Babiker EE, Adiamo OQ. The effect of harvest time and varieties on total phenolics, antioxidant activity and phenolic compounds of olive fruit and leaves. J Food Sci Technol. 2019 May;56(5):2373-2385. doi: 10.1007/s13197-019-03650-8. Epub 2019 Apr 10. PMID: 31168120;

Abstract. The effect of harvest periods on total phenol, antioxidant activity, individual phenolic compounds of fruit and leaves of Tavşan Yüreği, Memecik, Edremit, Ayvalık and Gemlik olive varieties grown in Turkey were investigated. The highest total phenol (317.70 mg/100 g and 2657.81 mg/100 g) were observed in Tavşan Yüreği olive fruit and Ayvalık leaves harvested in December, respectively. The highest antioxidant activities (83.84%) were determined in Edremit fruit harvested in August and 83.33% in either Edremit olive leaves harvested in November and Tavşan Yüreği leaves harvested in December. The olive fruit contained gallic acid ranging from 7.18 mg/100 g (August) to 35.85 mg/100 g (December) in case of Ayvalık and 2.09 mg/100 g (November) to 21.62 mg/100 g (December) in Edremit. Gemlik olives showed higher gallic acid contents compared to the other varieties, however it depended significantly on harvest time in all cases. 3,4-Dihydroxybenzoic acid contents ranged from 33.11 mg/100 g (October) to 25.17 mg/100 g (September) in Memecik olives; 12.17 mg/100 g (August) to 33.11 mg/100 g (December) in case of Tavşan Yüreği olives depending on harvest time. The 3,4-dihydroxybenzoic acid contents of Memecik leaves ranged between 122.25 mg/100 g (September) to 196.58 mg/100 g (August) and that of Tavşan Yüreği leaves changed between 99.38 mg/100 g (November) and 179.90 mg/100 g (August). The leaves of these two varieties contained significantly (p < 0.01) higher 3,4-dihydroxybenzoic acid contents than other varieties. The highest gallic acid (144.83 mg/100 g) was detected in Memecik leaves (September) whereas lowest were found in Gemlik leaves collected in October.

(3) Nagai N, Yagyu S, Hata A, Nirengi S, Kotani K, Moritani T, Sakane N. Maslinic acid derived from olive fruit in combination with resistance training improves muscle mass and mobility functions in the elderly. J Clin Biochem Nutr. 2019 May;64(3):224-230. doi: 10.3164/jcbn.18-104.

Abstract. Maslinic acid, derived from olive fruit, reduces pro-inflammation cytokines, which are involved in muscle fiber atrophy. Therefore, the maslinic acid ingestion may enhance the muscular response to resistance training through anti-inflammatory action. We therefore conducted a parallel, double-blind, randomized, placebo-controlled trial that examined whether a combination of maslinic acid supplementation and resistance training improve mobility functions in community-dwelling elderly persons. Over a 12-week period, 36 participants underwent moderate resistance training and are assigned to the maslinic acid supplementation (n = 17, 60 mg/day) or the placebo (n = 19) group. At baseline and at 12-weeks, we assessed body composition, grip strength, walking speed, leg strength, mobility functions, and knee pain scores. Following the 12-weeks, skeletal muscle mass, segmental muscle mass (right arm, left arm, and trunk) and knee pain score of the right leg were significantly improved in the maslinic acid group, while there was no change or parameters had worsened in the placebo group. Grip strength of the better side significantly increased only in the maslinic acid group. These results suggest that maslinic acid supplementation combined with moderate resistance training may increase upper muscle mass and grip strength, and reduce knee pain, could be effective for preventing mobility-related disability in elderly persons. Clinical trial registration number: UMIN000017207.