Aniseed - Chemical structure, Production, Main uses in food processing

Aniseed

M. O zgu ven, University of Cukurova, Adana

1 Introduction Source: Pimpinella anisum L. (Syn. Anisum vulgare Gaertn.; Anisum officinarum Mo nch; Apium anisum (L.) Crantz; Carum anisum (L.) Baill.; Selinum anisum (L.) E.H.L. Krause; Pimpinella anisum (var.) cultum Alef; Sison anisum Spreng.; Tragium anisum Link).^1,2

Family: Apiaceae (= Umbelliferae) Synonyms: Aniseed, Anis seed, Anis, Anise, Sweet cumin Parts used: Seeds (fruits), oil

Classification:

Division: Spermatophyta Subdivision: Angiospermae Class: Magnoliospida Subclass: Rosidae

Order: Apiales Family: Apiaceae Genus: Pimpinella³

Anise is an annual plant that reaches an average height of 3050 cm. The plant is completely covered with fine hairs. The root is thin and spindle-shaped, the stem up, stalk- round, grooved and branched upward (see Fig. 1). In midsummer the thin stems are topped with umbrella-shaped clusters of tiny white flowers, which are heavy enough to make the stems flop. They turn into seedlike fruits. Anise is a cross-pollinating species and is genetically heterogeneous. The fruit is an ovoid-pearshaped schizokarp somewhat compressed at the side. The two-part fruits separate heavily. The carpophore is almost two-piece up to the base. Commercially available aniseed usually contains the whole fruits and occasionally parts of the fruitstalk (see Fig. 2). The fruits with the style-foot are 3

5 mm long, 1.52.5 mm wide and 24 mm thick. Vittae (oil ducts) are almost always present embedded in the fruit wall on the dorsal surface, sometimes in or directly beneath the ridges. The fruits are downy. Their colour is greyish-green to greyish-brown.^4,5

Fig. 1 Pimpinella anisum L.

2 Chemical structure

Anise contains:

 14% volatile oil;

 coumarins: bergapten, umbelliprenine, umbelliferone, scopoletin;

 ca. 816% lipids, including fatty acids: 5070% petroselinic acid (C18:1), 2228% oleic acid (C18:1), 59% linoleic acid (C18:2) and 510% saturated fatty acids mostly palmitic acid (C16:0);

 -amyrin, and stigmasterol and its salts (palmitate and stearate);

 flavonoid glycosides: quercetin-3-glucuronide, rutin, luteolin-7-glucoside, isoorientin, isovitexin, apigenin-7-glucoside (apigetrin) etc;

 myristicin;

 ca. 18% protein;

 ca. 50% carbohydrate and others.

Fatty acids can be obtained by extraction, as in the case of caraway, in the remainders of oil extraction via steam distillation. Lauric acid, which is most important to

Fig. 2 Dried aniseed.

oleochemistry, is obtained from petroselinic acid which is found in high quantities (50

70%) in anise. Fatty oil shows excellent future potential. Successful production of anise seed for economical oil production would probably occur if the seed yields could be improved significantly, and high content of oil and essential oils and large quantity of petroselinic acids could be reached.^6,7

The major constituent in volatile oil of aniseed is trans (E)-anethole (7590%⁷; 80

90%⁸; 86%⁹; 9698%¹⁰; 8689%¹¹; 8992%¹²). Methylchavicol (estragole) (4.95%⁹;

1.73.7%¹⁰; 3.65%¹¹; 1.02.4%¹²), anise ketone (para-methoxyphenylacetone)

(0.78%⁹; 0.50.9%¹¹) and -caryophyllene are also present, but in lesser relative amounts. Other components in minor concentrations include anisaldehyde, anisic acid

(oxidation products of anethole), linalool, limonene, -pinene, acetaldehyde, p-cresol, creosol, hydroquinine, -farnasene, -himachalene and ar-curcumene.⁷

3 Production

3.1 Cultivation

Anise is cultivated in Turkey, Egypt, Spain, Russia, Italy, India, Greece, Northern Africa, Argentina, Malta, Romania and Syria. Anise is primarily exported from Turkey, and also from Egypt and Spain in particular. From an industrial standpoint, the quality differences between anise seed from different origins are not significant and therefore specifications need not limit the spice to a specific country of origin.^13,14,15

P. anisum requires a warm and long frost-free growing season of 120 days. The plant needs a hot summer to thrive and for seeds to ripen. The reported life zone for anise production is 8 to 23sC with 0.4 to 1.7 metres of precipitation on a soil pH of 6.3 to 7.3. Anise develops best in deep, rich, well-drained, sandy and calcerous soils. Cold, loamy

and moist soils are unsuitable for the cultivation of anise. During germination anise tolerates salinity up to 160 m NaCl. The thousand seeds weight of the part-fruits amounts to 1.5 to 3.0 g and should have a minimum purity of 90% and a minimum germination of 70%.

Ripe-fruits seeds germinate relatively quickly. The germination time is 14 days. Only seeds from the previous years harvest germinate well. Long storage quickly reduces germination vigour: seeds stored for five years will no longer germinate. Planting begins when the soil in the beds is warmed. Optimum soil temperature for germination is 18

21sC. It is essential to prepare good seedbeds and to create a good contact between the planted seed and the soil because the seeds are small and have low germination percentage (70%). The planting is carried out in spring or autumn depending on the areas it is cultivated. The seeds with a seeding rate of 2025 kg/ha are sown in rows 2030 cm apart, at a depth of 1 cm. The plant develops slowly after germination and for the following few weeks it is necessary to control weeds closely. It is recommended to apply fertilizers at a rate of 80100 kg K₂O and 5075 kg P₂O₅ per hectare. With nitrogen, it is important to be careful, since excessive nitrogen fertilization results in luxuriant vegetative growth with reduced yields, and increased vulnerability to lodging. 50100 kg/ ha N is normally enough. The small white flowers bloom in midsummer, and seed maturity usually occurs one month after pollination, when the oil content in the dried fruits is about 2.5%. Anise seeds are harvested between from the end of July to the beginning of September, depending on the cultivation areas. Yields of seed up to 500

1000 kg/ha have been achieved. P. anisum is recommended in companion planting to repel aphids and cabbage worms. The flowers attract parasitic wasps.^5,6,16,17,18

Constituents in plant volatile oils are known to be useful in pest control. Various authors have reported that vapours of essential oils extracted from anise were found to be toxic to two greenhouse pests, viz. the carmine spider mite, Tetranychus cinnabarinus and cotton aphid, Aphis gossypii Glov.¹⁹ Sarac and Tunc²⁰ indicated that the essential oil of anise had a high residual toxicity to adults of Tribolium confusum, and was the most repellent to Sitophilus oryzae adults in food preference tests.

3.2 The production of anise oil

The world production of anise oil amounts to 4050 tons per annum. The most significant importing countries of anise oil are the USA and France. Russia, Spain and Poland are among the largest producers of anise oil. There is no distillation of anise oil and no production of anethole in many of the countries which cultivate the crop.^21,22,23

Anise oil is steam distilled from the crushed seeds of the plant Pimpinella anisum. The process of steam distillation is the most widely accepted process for the production of essential oils on a large scale. A still is charged with plant material to be processed. Steam is introduced at the base of the still and the crushed anise seeds volatile elements evaporate with the steam. A condensation process turns this vapour-mix into a liquid form of water and essential oil. The essential oil floats on top of the water and is separated off. The essential oil of aniseed is a colourless to faintly yellow oil which solidifies upon cooling to about 1519sC due to the crystallization of anethole.

Oleoresin anise is a yellowish-green to orange-brown fluid oleoresin. Volatile oil content of oleoresin anise is 1518%. The presence of a large quantity of fixed oil in this product limits its shelf-life and the addition of a permitted antioxidant is advised.²⁴ Anise and anise oil are widely used as flavouring ingredients in all major categories of foods, including alcoholic and non-alcoholic beverages, frozen dairy desserts, sweets, baked

goods, gelatines and puddings, and meat and meat products. The highest average maximum use levels for anise oil are about 0.06% (570 ppm) in alcoholic beverages and

0.07% (681 ppm) in sweets.⁷ Suggested use rate of oleoresin anise is 7.5 to 9%.²⁴ In Turkey the different types of aniseed spirits are distinguished by their anise seed content: Yeni raki (80 g/L aniseed), Kulup raki (100 g/L aniseed) and Altinbas raki (120 g/L aniseed).²⁵

3.3 Stability during storage, irradiation and heat processing

Anise has to be stored away from daylight and kept in a dry place in cool conditions

(DAB 10 Eur, O AB 90, Helv VII). The average loss of the content of the volatile oil has been calculated at 1% of the original content per month. The content of trans-anethole decreases from 89% to 73% during a storage of six weeks with the influence of sunlight, while the content of cis-anethole increases from 0.8 to 4.5% and the content of anisaldehyde from 0.8 to 7.0%. At the same time additional decomposition products are formed. Investigations on airsealed, grinded aniseed clearly show changes of odour within the first 12 months if the temperature of storage exceeds 5sC. Because of the sensitivity to light and oxidation it is recommended that the volatile oil of anise is stored in well filled and well closed containers (glass or tin, but not plastic) protected against daylight (DAB 10, BP 88, PFX, O AB 90, HELV VII). Moreover, PFX demands a storage temperature below 10sC and BP 88 a storage temperature below 25sC. With the influence of daylight, trans-anethole is transformed into its more toxic isomer cis- anethole.²⁶

It is reported that there is an increase in anise ketone, anisaldehyde and anisic acid⁹ and decrease in trans-anethole²⁷ of anise oil during long-term storage. Moisture content of the seeds or humidity of the storage atmosphere is the most important parameter to be considered in preserving the desired properties of anise. At high moisture levels deteriorative reactions and off-flavours are inevitable in addition to the increased rate of loss of volatile oil by diffusion. Oxidation reactions are responsible for the loss of oil during storage by converting the components mostly to acids and aldehydes. Also, daylight catalyzes oxidative reactions and increases the rate of deterioration. Extreme variations in the moisture content of the storage atmosphere favour oil evaporation and particularly oxidation.²⁸ The dimers of anethole (dianethole) and anisaldehyde

(dianisoin) are mentioned repeatedly in the literature^14,29,30 and are supposedly responsible for the oestrogenic activity in old drugs and in stored oils under exposure to sunlight, and air could not be found after thorough investigation.³¹

One interesting item to note in this spice is that when the ground product is irradiated, a slightly putrid off odour and flavour results. This contradicts most research that irradiation does not change the chemical properties of a spice when treated. It is possible that it does, in limited cases, change the flavour balance of essential oils.¹⁵ Similarly numerous authors report that volatile oil of anise, extracted after irradiation with 1.5 and

10 kGy -rays, contained the most oxygenated compounds, and irradiation caused a general increase in oxygenated compounds at 1 kGy.³² Farag-Zaied et al.³³ indicated that

-irradiation was effective in decontamination, especially at 10 kGy, but caused losses in the major components of flavour such as anethole, methylchavicol and anisealdehyde in anise.

Thermal treatment at 70sC for 15 minutes reduced the microbial count and pathogenic microbes, improving the anethole in anise, and washing the spice removed some of the microbes but improved markedly the anise flavour. Thermal and washing treatments may

be of value as simple natural techniques to produce spices with a good flavour and with an acceptable level of contamination.

Bendini et al.³⁴ detected linear, unsaturated hydrocarbons in aniseed samples treated with -rays or microwaves. The microwave treatment of aniseeds did not modify the hydrocarbon profile with respect to the untreated samples. In contrast, -irradiation gave rise to a series of unsaturated hydrocarbons of which C16:2, C16:1, C17:2 and C17:1 were determined. In most cases, when these products were quantified, their amounts increased with the dose of radiation. C17:1 could be considered as the marker of the - irradiation treatment. The essential oil of anise extracted from -irradiated and microwaved fruits exhibit antioxidant properties. -irradiation and microwave treatments have no effect on the antioxidant properties of essential oil. Essential oil extracted from the -irradiated fruits are more effective as antioxidants than those produced from microwaved fruits.^35,36

4 Main uses in food processing

Aniseeds long popularity throughout so many lands stems from its many uses: flavourant, culinary, household, cosmetic and medicinal. While the entire plant is fragrant, it is the fruit of anise, commercially called aniseed, that has been highly valued since antiquity. Aniseed is one of the oldest spices used widely for flavouring curries, breads, soups, baked goods such as German springerle, and Italian biscotti, sweets (e.g. licorice candies, especially aniseed-balls), dried figs, desserts, cream cheese, pickles, coleslaw, egg dishes, non-alcoholic beverage. It is a favourite flavouring for alcoholic drinks in the Mediterranean region, such as French Pastis, Pernod, Anisette, and Ricard, Greek Ouzo, Turkish Raki and Arabian Arak, and also South American Aguardiente, Russian Allasch, Puerto Rican Tres Castillos. Aniseed oil is a component in German Boonekamp, Benediktener, Goldwasser and Spanish Pacharan and Ojen. Anisette combines anise, coriander and fennel seeds in sweet vodka. Anise and anise oils are used in Italian sausage, pepperoni, pizza topping and other processed meat items. Anise is an essential component of Italian anise cake and cookies. All parts of the plant can be used in the kitchen. The flowers and the leaves can be added to fruit salads. Freshly-chopped leaves also enhance dips, cheese spreads, vegetables, or green salads. Mixed into stews and soups, the stem and roots of anise give just a hint of licorice.^{6,15,16,18,26}

The essential oil is valuable in perfumery, in dentrifices as an antiseptic, toothpaste, mouthwashes, soaps, detergents, lotions and skin creams, in tobacco manufacture, with maximum use levels of 0.25% oil in perfumes. It is also used to mask undesirable odours in drug and cosmetic products. The oil is used for production of anethole and sometimes as sensitizer for bleaching colours in photography.^7,16,23

5 Functional properties

The pharmaceutical data mentioned in the literature mainly refer to anise oil and anethole. Anethole is structurally related to the catecholamines adrenaline, noradrenaline and dopamine.³⁷ Anise oil and anethole have a number of functional properties:

 antibacterial

 antifungal

 antioxidant

 stimulant, carminative and expectorant.

The antibacterial activities of the essential oil distilled from Pimpinella anisum against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Corynebacterium ovis were evaluated. Against S. pyogenes, aniseed oil was equally effective in the pure state and at dilution up to 1:1000. Against C. ovis, aniseed oil was equally effective at dilutions up to 1:100 and at higher dilutions.³⁸ The inhibitory properties of anise essential oil, alone or in combination with either benzoic acid or methyl-paraben, against Listeria monocytogenes and Salmonella enteriditis were investigated. S. enteriditis was particularly sensitive to inhibition by combinations of anise essential oil with methyl- paraben. L. monocytogenes was less sensitive but exhibited significant reductions in growth in response to combinations of essential oil with methyl-paraben.³⁹

Kubo⁴⁰ reported that anethole, a naturally occurring phenylpropanoid extracted from aniseed, exhibited a broad antimicrobial spectrum and the antifungal activity (against Candida albicans) of two sesquiterpene dialdehydes, polygodial and warburganal

(extracted from Polygonum hydropiper), was increased 32 fold when combined with low concentrations of anethole. In a study of the volatile oil from aniseed, significant antifungal activity against members of the genera Alternaria, Aspergillus, Cladosporium, Fusarium and Penicillium was recorded at concentrations of 500 ppm, the active constituent having been identified as anethole.⁴¹ Anethole also inhibits growth of mycotoxin producing Aspergillus species in culture. Anethole has been reported to be mutagenic in Ames Salmonella reversion assay. Anethole, anisaldehyde and myristicin

(in aniseed), along with d-carvone (present in P. anisum plant), have been found to have mild insecticidal properties.⁷ Pharmacological studies were carried out in rats and mice, and anise oil showed significant antipyretic activities in rats.⁴² Curtis⁴³ reports that synthetic versions of compounds in herbs and spices such as trans-anethole have inhibitory and lethal activity against food spoilage yeast Debaromyces hansenii.

There is some evidence of anise oils effectiveness as an antioxidant. Gurdip et al.⁴⁴ investigated the antioxidant activity of essential oil from spice materials on stored sunflower oil and found that anise oil possessed excellent antioxidant effects, better than those of synthetic antioxidant, butylated hydroxytoluene.

Anise oil is reported to be carminative and expectorant. The reputed lactogogic action of anise has been attributed to anethole, which exerts a competitive antagonism at dopamine receptor sites (dopamine inhibits prolactin secretion), and to the action of polymerized anethole, which is structurally related to the oestrogenic compounds stilbene and stilboestrol. Anethole is also structurally related to the hallucinogenic compound myristicin. Bergapten, in combination with ultraviolet light, has been used in the treatment of psoriasis.³⁷ Anise oil is used as carminative, stimulant, mild spasmolytic, weak antibacterial, and expectorant in cough mixtures and lozenges, among other preparations. It can be used internally for dyspeptic complaints and externally as an inhalant for congestion of the respiratory tract. The whole, crushed, or ground crude drug can be used for infusion, and other galenical preparations; e.g. several instant teas as powders containing aqueous extracts of aniseed, or as tea paste, some preparations with micro-encapsulated anise oil. Anise seed and anise oil are subjects of German official monographs; 3.0 g of seed or 0.3 g of essential oil (mean daily dose) allowed as a bronchial expectorant for upper respiratory tract congestion and as gastrointestinal spasmolytic.^7,31

Anise may have other potential health benefits. The effect of the beverage extracts anise on absorption of iron was tested in tied-off intestinal segments of rats. Results

showed that the beverage of anise promoted Fe absorption.⁴⁵ Preparations containing 5