Beta-Carotene: Production, Origin and Use in the Food Industry
Beta-carotene (β-carotene, food colorant E160a) is an orange-red natural pigment from the group of carotenoids. Chemically, it is an unsaturated hydrocarbon molecule (molecular formula C₄₀H₅₆) consisting of eight isoprene units, belonging to the class of terpenes. Beta-carotene is lipophilic (fat-soluble) and practically insoluble in water. It occurs in many plants and gives, for example, carrots, sweet potatoes, pumpkin, spinach and other yellow to dark green vegetables and fruits their color. For humans, beta-carotene is important as a provitamin A, because it can be converted into vitamin A (retinol) in the body as needed. In addition to its function as a vitamin A precursor, beta-carotene itself acts as an antioxidant and protects cells against oxidative damage.
Origin and Production of Beta-Carotene (E160a)
Industrial beta-carotene is obtained in different ways. In principle, one distinguishes natural beta-carotene from plant sources from nature-identical synthetic beta-carotene. According to EU food law, all these variants fall under the E-number E160a, with the following subtypes:
E160a(i) – Beta-carotene, synthetic: By chemical synthesis beta-carotene is industrially produced, which is chemically identical to the natural molecule. Synthetic beta-carotene is usually present as a red-orange crystalline powder and consists predominantly of all-trans-β-carotene (the naturally most frequent isomer form).
E160a(ii) – Carotenes, plant-based: Beta-carotene can be isolated from natural plant raw materials. In practice, beta-carotene-rich materials such as carrots or palm oil are used; by means of solvent extraction a carotenoid concentrate is obtained. This typically contains beta-carotene as the main component and smaller amounts of other carotenes (e.g. α-carotene). Such extracts are often referred to as “natural carotene”.
E160a(iii) – Beta-carotene from Blakeslea trispora: This refers to biotechnologically produced beta-carotene. The fungus Blakeslea trispora – in special high-performance strains (mutants) – produces large amounts of beta-carotene during fermentation. This process has established itself as a cost-efficient method and is today one of the preferred ways of industrial beta-carotene production. The resulting beta-carotene is mainly the all-trans form and highly pure, with only small amounts of other carotenoids (e.g. some γ-carotene).
E160a(iv) – Beta-carotene-containing algae extract: Another natural source is the green alga Dunaliella salina, which accumulates extraordinarily high beta-carotene contents in high-salt environments. In large salt gardens (e.g. in Australia) these microalgae are cultivated and afterwards the beta-carotene is extracted (often with oils or solvents). The resulting algae oleoresin contains, besides beta-carotene, other carotenoids (such as α-carotene, lutein, zeaxanthin), but is also classified under E160a.
In addition to these established processes, genetic engineering production methods are also being researched, e.g. with genetically modified microorganisms, to produce beta-carotene even more efficiently. Independent of origin, all these forms of beta-carotene are chemically identical or very similar – they differ mainly in purity and the spectrum of accompanying substances, but not in their mode of action in the body.
Use of Beta-Carotene in the Food Industry
Beta-carotene has for decades been widely used in foods – on the one hand as a colorant (food additive E160a), on the other hand as a source of vitamin A for nutrient enrichment. As a colorant, beta-carotene serves to color foods yellow to orange or even reddish. It is added to butter and margarine, confectionery, dairy products, cheese, bakery products and doughs, beverages (soft drinks, fruit juices) and many others. The addition is intended to achieve the appetizing appearance expected by consumers – for example, margarine would be nearly whitish by nature without coloring, but is colored butter-yellow by a little beta-carotene. Beta-carotene offers, depending on dosage, a wide color spectrum from pale yellow through intense orange up to orange-red; even peach-pink tones can be achieved with special formulations.
In addition to its coloring effect, beta-carotene also contributes in enriched foods to the supply of vitamin A. In some breakfast cereals, infant foods, ACE beverages (with vitamins A, C, E) and dietary supplements, beta-carotene is specifically added as provitamin A. Beta-carotene is considered safe and well tolerated in the amounts used. An acceptable daily intake (ADI) is not defined for natural carotenes, since toxic effects do not occur in normal intake amounts. Excess beta-carotene is not converted indefinitely into vitamin A by the body, so no acute hypervitaminosis A from beta-carotene alone is to be feared. Very high intakes can, however, lead to a reversible yellow discoloration of the skin (carotenemia), which is harmless. Beta-carotene as an additive is suitable for all population groups and also approved for vegetarian or vegan products.
Product Forms and Formulations (Emulsions, Oil-Soluble Concentrates, Powders)
Since beta-carotene is water-insoluble and also sensitive to oxygen and light, the industry has developed various formulations to make it optimally usable in foods. Beta-carotene colorant preparations are available in different product forms, among others as water-dispersible emulsions, as oil-based concentrates and as powdery microencapsulated products. These processed forms facilitate application, increase the stability of the pigment and allow, depending on need, clear or cloudy solutions in beverages, dry mixes etc. The most important product forms are explained below:
Water-dispersible beta-carotene emulsions
For beverages and other aqueous foods, beta-carotene formulations are offered as fine emulsions. Here, beta-carotene is first dissolved in a carrier oil and then dispersed with emulsifiers into tiny droplets in water. Through emulsification and homogenization the fat-soluble substance can be transformed into a seemingly “water-soluble” form. The resulting micro- or nanoemulsions are available as stable, liquid concentrates that can easily be mixed into foods. An emulsion prepared in this way shows a homogeneous color in water; depending on particle size the solution can be clear (with very fine nano-droplets) or deliberately cloudy (for a “juicy” look). Emulsion formulations with beta-carotene typically contain about 1–10% beta-carotene and are adjusted with suitable stabilizers to be light- and heat-stable. In this way, even in acidic or low-fat products yellow to orange shades can be achieved without pigment precipitation. Modern nanoemulsions even allow particularly light yellow tones, since the extremely fine distribution of the pigment optically reduces color saturation.
Oil-soluble concentrates and suspensions
In fat-rich products or for use in oily phases (e.g. margarine, oils, butter, fat emulsions) beta-carotene is used in oil-dissolved form. Here, the pigment is present dissolved or suspended in a vegetable oil (such as sunflower oil) – often in concentrations of approx. 20–30% beta-carotene. Such beta-carotene oil concentrates can be directly incorporated into fat-containing foods and give them a uniform yellow to orange color. A classic example is the coloring of margarine or edible oil by adding a beta-carotene oil extract (e.g. carrot oil). For dietary supplements (vitamin A capsules) oily beta-carotene solutions are also used, which can be filled into soft gelatine capsules. Oil-based preparations have the advantage of high active ingredient concentration and are relatively simple to use, but require that the final product has sufficient fat content so that the beta-carotene is well distributed. In purely aqueous products, oil-based beta-carotene solutions would not disperse, which is why emulsions or powders are preferable there.
Microencapsulated powders (beta-carotene beadlets)
Another important product form is dry powder or so-called beadlets, in which beta-carotene is microencapsulated. Here the pigment is incorporated into a matrix of, for example, modified starch, gelatine, cellulose or other food substances and usually converted into small beads by spray granulation or spray drying. Through this encapsulation technique beta-carotene is protected against oxidation and at the same time made water-dispersible. The resulting fine powder (often orange-yellow colored) can be homogeneously distributed, for example in dry powder mixes (dessert powders, instant drinks, baking mixes) or compressed into tablets if required. When such a powder comes into contact with water, the microcarriers disintegrate and release beta-carotene in the form of very fine particles, which enables uniform coloring. Many commercial beta-carotene powders are “cold-water soluble” and produce a uniform dispersion when stirred in. Typical products contain e.g. 1–10% beta-carotene in the powder. Special starch-based beadlets are also available, which dissolve in liquids and are suitable for clear beverages. Alternatively, there are alginate-encapsulated beadlets, which are particularly robust against mechanical stress and heat (e.g. usable in bakery doughs). Overall, microencapsulated forms allow improved storage stability (slowed down degradation of the carotene by oxygen) and flexible use in different food applications.
In summary, beta-carotene is a versatile food colorant and nutrient, which is obtained from different sources and available in tailored formulations. In the food industry beta-carotene is appreciated both for its natural origin and the wide color spectrum from yellow to orange, as well as for its health benefit as provitamin A. Through modern technologies – from fermentation processes to nanoemulsions to microencapsulation – beta-carotene today is available in stable and easy-to-handle form, to color a wide range of foods attractively and at the same time to enrich them functionally.