Bitter olive

A traditional system for the preparation of table olives, involves a treatment of the fresh fruit with a solution of NaOH to hydrolised the bitter glycoside oleuropein, followed by a lactic fermentation in brine. The modifications that take place on pectic polysaccharides of olives (Manzanilla variety) during this process was smdied. Processing induced a net loss of polysaccharides soluble in sodium carbonate and a paralel accumulation of water and Imidazole/HCl soluble polysaccharides. A general decrease of the apparent molecular weight of water and carbonate soluble polysaccharides was also detected. 

Oleuropein (the most abundant bitter principle) and its analog ligstroside, both sec-oiridoid biophenols, were extracted from Hojiblanca black olives (Piperno and others 2004). Secoiridoids are present exclusively in plants of the Oleraceae family (Tripoli and others 2005). Oleuropein is present in high amounts (6000 90 mg/100 g DW) in the leaves of the olive tree (Le Tutour and others 1992), but it is also present in all constituent parts of the fruit peel, pulp, and seed (Servili and others 1999). 

The importance of the Mediterranean diet led to increased research activity on olive oils, which mainly focused, among other issnes, on phenolic substances becanse of their biological activities and of the fact that virgin olive oils are the only vegetable oils that contain them, while tocopherols are widely distributed in such foods. Phenolic substances are responsible for the typical taste of olive oils, characterized by fruity, bitter, and pungent flavors. 

OE033 Maestro-Duran, R., R. Leon-Cabello, OE043 V. Ruiz-Gutierrez, P. Fiestas, and A. Vazquez-Roncero. Bitter phenolic glu-cosides from seeds of olive (Olea europaea). Grasas Aceites (Seville)... 

Various methods are used in extracting the oils from the plant tissue. Many are distilled with water or steam, Hie oil being carried over with the distillate. In others, as for example oil of bitter almonds, the oil develops in the tissues only after fermentation. It is then obtained by distillation. Anollter method, and one especially used for more delicate and valuable oils, is called enfleurage. In this method the flowers containing the oil are spread as a thin layer over a layer of lard or olive oil. The latter absorbs the delicate oil in the flowers, after which distillation may separate the volatile oil from the other. 

Olive fruit has long been used as a food and as a source of edible oil for frying and salad dressings. The phenolic content in olive fruits is known to contribute to the natural bitterness and the final color of fruits (66), and to provide natural antioxidant activity in olive oil... 

The olives themselves contain many phenolic compounds with antioxidant properties. Bouaziz et al. (2005) investigated the olive cultivar Chemlali from Tunisia. Oleuropein (7.14), a bitter glycoside esterified with a phenolic acid, was the major compound present. Phenolic monomers and twelve flavonoids were also identified. The antioxidant activity of the extract was evaluated. Acid hydrolysis of the extract enhanced its antioxidant activity. / -Hydroxyphenyl-cthanol (7.12) and quercetin (1.43) showed antioxidant activities similar to that of 2,6-di-fert-butyl-4-methyl phenol (7.15), a reference compound with known antioxidant properties. It was suggested that a hydroxyl group at the ortho-position on the flavonoid B ring could contribute to the antioxidant activity of the flavonoids. 

The olive mesocarp contains a number of phenolic and polyphenolic compounds and their esters, small amounts of which are present in olive oil (35, 43, 44). These include monohydroxy- and dihydroxy-phenylethanol, including tyrosol and other phenols and a series of carboxy-phenols, including caffeic, o-coumaric, p-coumaric, cinnamic, ferulic, gallic, p-hydroxybenzoic, protocatechuic, sinapic, syringic, and vanillic acids. Benzoic and cinnamic acids are produced by hydrolysis of flavonoids. The hydroxyphenyl-ethanols arise from hydrolysis of oleoeuropein. Their esters are responsible for the bitterness and pepperlike sensation occasionally dominant in the taste of olive oils. 

The olive tree has persistent leaves, blooms in the spring, and produces mature fruits in the late autumn or winter. The unripe fruits are green and bitter, while ripe fruits are purple to black in color. The bitterness of the green, unripe fruits can be removed by soaking them in a solution which is alkaline (high pH) or is saturated with salt. Once the bitterness has been removed, green olives are typically pickled in a salt solution for later eating. 

The British Pharmacopoeia gives the following description In colorless monoclinic prisms. No odor taste bitter, followed by a sensation of tingling and numbness. Soluble in 10 parts of alcohol (90 per cent.), in 4 parts of ether, in 0.5 part of chloroform, and in 24 parts of olive oil almost insoluble in water. Melting point 98° C. The dry salt obtained by dissolving cocaine in water acidified, with hydrochloric acid, and evaporating the solution, responds to the tests described under Cocainae Hydrochloridum. Br. 

I have tried often to search behind the sophistication of years for the enchantment I so easily found in those gifts. The essence escapes but its aura remains. To be allowed, no, invited, into the private lives of strangers, and to share their joys and fears, was a chance to exchange the Southern bitter wormwood for a cup of mead with Beowulf or a hot cup of tea and milk with Oliver Twist. When I said aloud, It is a far, far better thing that I do, than I have ever done. . . tears of love filled my eyes at my selflessness. 

Properties Transparent, colorless crystals aromatic, penetrating, slightly acrid odor slightly bitter, sharp taste. D 1.901, mp 52C, bp 97.5C. Slowly volatilizes when exposed to air. Soluble in water, alcohol, chloroform, ether, olive oil, and turpentine oil. 

The olive fruit differs from aU other drupes in its chemical composition due to its relatively low sugar content, 3-6% vs. ca. 12%, high oil content, 12-30% vs. 1-2%, and its characteristic strong bitter taste which, among others, is caused by oleur-opein (1) [4],... 

Approximately 90% of the total annual worldwide olive fruit harvested is used for olive oil production whilst table olives represent about one tenth of this production [3]. For table olive productiOTi, most of the olive fruits have to be processed in order to remove or, at least, reduce the bitter oleuropein component. The olives are usually submitted to fermentation or cured with lye or brine. One of the few exceptions to this rule is the Greek Thrubolea variety that is allowed to ripen on the tree [3]. For olive oil production, the olives are harvested as soon as the fruit reaches its maximum size because by that time the oil content also reaches the maximum amount. For most of the cultivars this stage corresponds to the change in the surface color from slightly pink to purple-pink or black [3]. 

Polyphenols are important for the flavour and the stability of olive oil. When their content exceeds 300 mg/kg the oil may have a bitter taste. Formation of... 

Dark brown, viscid liquid pleasant aromatic odor warm, bitter taste and persistent aftertaste, d 1.150-1.170. Insol in water, olive oil sol in alcohol, chloroform and glacial acetic acid, usually with a slight opalescence. Partly sol in ether, petr ether. 

Hydrochloride, C,H ClN02, crystals, mp 172-175°. Slightly bitter taste followed by numbness of the mouth. Stable in air. One gram dissolves in l ml water. Sol in ale, chloroform. Insol in ether, olive oil. A I I0 aq soln is faintly add to litmus. Alkali carbonates and hydroxides predpi-tate piperocaine base as an oil from aq sol ns of the hydrochloride. LDm in rats 1.3 g/kg s.c. 20 mg/kg i.v. therap cat Local anesthetic. therap Cat (vet) Local anesthetic. 

Oleuropein, the secoiridoid responsible for the bitter taste of olives, was studied in vitro for its antimicrobial activity. Recently, it was investigated against Mycoplasma hominis, Mycoplasma fermentas, Mycoplasma pneumoniae, Mycoplasma pirum [87], O. europaea is a plant resistant to microbe and insectan attack. In particular, oleuropein has been shown to inhibit or stop the growth time of a serial of bacteria and microfungi [88]. In general, this compound is used as a food additive. 

Voltammetric sensors based on chemically modified electrodes (conducting polymers, phthalocyanine complexes) with improved cross-selectivity were developed for the discrimination of bitter solutions [50], The performance and capability were tested by using model solutions of bitterness such as magnesium chloride, quinine, and four phenolic compounds responsible for bitterness in olive oils. The sensors gave electrochemical responses when exposed to the solutions. A multichannel taste sensor was constructed using the sensors with the best stabilities and cross-selectivities and PCA of the signals allowed distinct discrimination of the solutions. 

Slightly lighter in taste and scented, slightly sweet and palatable, mild olive flavor, pleasant, no bitter after taste, no harshness, mellow vegetable taste, quite fruity, fresher taste, etc. 

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