LIQUID COMPOSITION INCLUDING CITRUS PERICARP ESSENTIAL OIL

Abstract

A liquid composition including 0.2-3.5 vol % of a pericarp essential oil, including 10-300 mg/kg/Acid of limonin, including 10-50 mg/kg/Acid of rutin, having an acidity of 2.0% or less, and being suitable for blending in a beverage. Preferably, the pericarp essential oil, the limonin, and the rutin are derived from citrus fruit, and the liquid composition is preferably obtained using the pericarp of a citrus fruit from which the outermost layer is removed to a degree that oil glands are not broken.

Claims

1. A liquid composition comprising an essential oil from peel, limonin, and rutin, wherein a content of the essential oil from peel is in a range of 0.2-3.5% by volume based on the total amount of the composition; wherein a concentration of the limonin with respect to acidity is in the range of 10-300 mg/kg/Acid; wherein a concentration of the rutin with respect to acidity is in the range of 10-50 mg/kg/Acid; wherein a rutin to limonin weight ratio (rutin/limonin) is 1 or less; and wherein the acidity is 2.0% or less.

2. The liquid composition according to claim 1, wherein the limonin is derived from one or more fruits.

3. The liquid composition according to claim 1, wherein the rutin is derived from one or more fruits.

4. The liquid composition according to claim 1 obtained by use of a solvent and a citrus fruit peel from which a super surface layer has been removed in a thickness such that oil sacs are not ruptured.

5. A drink comprising the liquid composition according to claim 1 at a concentration in a range of 0.1-15% by weight based on the total weight of the drink.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a cross section of a citrus fruit.

[0024] FIG. 2 shows an enlarged view of a part of FIG. 1. Super surface layer 1 is to be removed in the invention.

[0025] FIG. 3 shows photographs of the appearance of citrus fruits before and after removal of the super surface layer. In each photograph, the one on the left is before the removal and the one on the right is after the removal. The photograph on the top shows lemon, the second is lime, the third is white grapefruit, and the bottom is orange.

DESCRIPTION OF EMBODIMENTS

[0026] <Essential Oils From Peel>

[0027] The composition of the present invention contains essential oils from peel in amounts ranging from 0.2 to 3.5% by volume based on the total amount of the composition. The essential oils from peel are a class of fragrant compounds that are mainly collected from the peels of citrus fruits. The fruit's essential oils are based on terpene compounds such as monoterpenes and sesquiterpenes and differ from oils and fats that are based on glycerides. Essential oils can be collected from plants by various methods including steam distillation, expression, solvent extraction, unfleurage, maceration, and supercritical extraction. Although the essential oils from peel to be used in the present invention may be obtained by any of these methods, it is preferable to use the essential oil components that are obtained by expression.

[0028] The term expression as used herein refers to a method in which a physical force is applied to the peel of a fruit so that an essential oil is obtained from oil cells present in the colored portion of the peel. In a known example of the expression process, the peel is mechanically bruised to rupture oil sacs, from which an essential oil is extracted (Florida Citrus Oils, Kesterson, et al., Technical Bulletin 749, December 1971, pp 15-20.) As will be described later, the peel containing an essential oil may be emulsified under crushing in water and this method is also included in the expression process. The citrus peel includes a dark colored flavedo portion and a white fibrous albedo portion, with the flavedo containing a lot of oil sacs containing a large amount of essential oil (see FIG. 1 quoted from Kajitsu no Jiten (Dictionary of Fruits), published by Asakura Shoten, 2008, p. 198.) In the present invention, the peel, or the flavedo in particular, is collected and by emulsifying the oil sac-containing peel as it is crushed in water, a liquid composition can be obtained that contains the essential oil from peel. In the process, the peel or flavedo is preferably collected in such a way that the oil sacs are kept intact as much as possible until they are ruptured within water. By maintaining the oil sacs intact until they are emulsified in water, the essential oil in the oil sacs can be prevented from making direct contact with oxygen to reduce the possibility that the aroma components in the essential oil may deteriorate upon oxidation. The thus obtained essential oil from peel is advantageous in that it is less susceptible to heat and oxygen and that, therefore, the aroma components will experience less deterioration. When the cold press method or other conventional technique for obtaining an essential oil from peel is employed, it is necessary to take an essential oil out of oil sacs before the process completes, so its aroma components may deteriorate under direct action of oxygen.

[0029] The fruits to be used for obtaining essential oils from peel may be either of the genus Citrus or the genus Fortunella, both of which are generally consumed as food; for attaining maximum effects of the present invention, the genus Citrus is particularly preferred. Specific examples of the genus Citrus include; flavorful acid citruses (Citrus limon, Citrus aurantifolla, Citrus junos, Citrus spaerocarpa, Citrus aurantium, Citrus sudachi, Citrus depressa, Citrus medica, Citrus medica var. sarcodactylus (Buddha's hand), etc.); oranges (Citrus sinensis) (Valencia orange, Navel orange, Blood orange, etc.); grapefruits (Citrus paradisi) (marsh, ruby, etc.); other citruses (Citrus natsudaidai, Citrus hassaku, Citrus tamurana, Citrus grandisparadisi (Oroblanco), Citrus reticulata cv. Dekopon, etc.); tangors (Citrus iyo, Citrus tankan, Citrus unshiusinensis, Citrus sinensis (Harumi), etc.); tangelos (Citrustangelo cv. Seminole, Citrus sinensis (Minneola), etc.); buntans (Citrus maxima, Citrus grandis (Banpeiyu), etc.); Satsuma mandarins (mandarin orange, Citrus kinokuni, Citrus unshiu, Citrus reticulata cv. Ponkan, Citrus tachibana, etc.) The genus Fortunella includes Fortunella crassifolia, Fortunella japonica, Fortunella margarita, etc. In particular, those citrus fruits whose juice itself is so strong in acidity or bitterness that it cannot be incorporated in large quantities in drinks are preferred for use in the present invention. Examples of such citrus fruits include those having juice with an acidity of at least 1.5%, preferably at least 2.0%, more preferably at least 3.0%, and even more preferably at least 4.0%. Citrus fruits having very low sugar contents compared to acidity are also preferred in the present invention since they present a relatively strong perceivable sour taste. Examples of such citrus fruits having very low sugar contents compared to acidity include those having a Brix-acid ratio of 10 or less, preferably 8 or less, more preferably 5 or less, and particularly preferably 3 or less. The acidity as used herein is determined by first measuring the content of organic acids such as citric acid and malic acid by neutralization titration with sodium hydroxide, calculating the same in terms of citric acid, and expressing the converted value in percentage. The Brix-acid ratio refers to degrees Brix (a value indicated in percentage upon measurement with a sugar refractometer) as divided by acidity. Table 1 lists the degrees Brix, acidity and Brix-acid ratio for typical citrus fruits. Fruits that are advantageous for the present invention are exemplified by flavorful acid citruses such as Citrus limon, Citrus aurantifolia, Citrus sudachi, Citrus sphaerocarpa, Citrus depressa, and Citrus junos.

TABLE-US-00001 TABLE 1 <Acidity and degrees Brix of citrus fruits> Citrus Types Brix (%) Acidity (%) Brix-acid ratio Citrus limon 7.00 4.50 1.56 Citrus aurantifolia 9.10 6.00 1.52 Citrus junos 8.90 4.28 2.08 Citrus sphaerocarpa 9.10 4.40 2.07 Citrus sudachi 8.20 6.63 1.24 Citrus depressa 9.20 4.18 2.20 Citrus sinensis 11.0 0.80 13.75 Citrus paradisi 9.90 1.36 7.28 Citrus natsudaidai 11.1 1.51 7.35 Citrus tamurana 10.2 1.88 5.43 Citrus reticulata cv. Dekopon 14.4 1.39 10.36 Citrus iyo 12.1 1.05 11.52 Citrus unshiu sinensis 12.0 0.97 12.37 Citrus maxima 10.3 1.13 9.11 Citrus unshiu 10.2 0.72 14.17 Citrus reticulata cv. Ponkan 10.0 0.73 13.70

[0030] The concentration of the essential oil in the liquid composition ranges from 0.2 to 3.5% by volume based on the total amount of the composition. Preferably, it ranges from 0.3 to 3.0% by volume, more preferably from 0.4 to 2.5% by volume, even more preferably from 0.4 to 2.0% by volume, and particularly preferably from 0.4 to 1.5% by volume. The concentration of the essential oil from peel in the composition can be measured with an essential oil testing apparatus, or a distillation system using an essential oil quantifying device, as will be described below in the Examples.

[0031] <Limonin>

[0032] The composition of the present invention comprises limonin. Limonin is known to be present in fruits in the form of glycoside (limonin glucoside; Formula 1) or a form obtained by removing sugar from glycoside (limonoate A-ring lactone; Formula 2). Neither of Limonin glucoside and limonoate A-ring lactone presents bitterness. It is known that, after juice has been squeezed from fruits, limonoate A-ring lactone is closed under the acidic condition of the juice and converted into limonin (7,16-dioxo-7,16-dideoxylimondiol, C.sub.26H.sub.30O.sub.8; Formula 3), which produces intense bitterness.

##STR00001##

[0033] The concentration of limonin in the composition of the present invention is preferably in the range of 10-300 mg/kg/Acid, more preferably in the range of 15-200 mg/kg/Acid, and even more preferably in the range of 20-150 mg/kg/Acid. The unit mg/kg/Acid derives from the concentration of limonin in the composition (mg/kg) as a result of dividing it by the acidity of the composition. The acidity as used herein is determined by first measuring the content of organic acids in the composition by neutralization titration with sodium hydroxide, calculating the same in terms of citric acid, and expressing the converted value in percentage. In the present invention, the concentration of limonin in the composition refers to the concentration of the substance of Formula 3.

[0034] The concentration of limonin in the liquid composition can be adjusted by adding a commercially available limonin into the composition. Alternatively, as will be understood from the method to be described later, the same result can be obtained by emulsifying the essential oil-containing peel or flavedo as they are crushed within water so that the fruit-derived limonin is extracted into the liquid composition. The limonin concentration in the liquid composition can be measured by use of LC-MS, as will be described later in the Examples.

[0035] The limonin in the liquid composition of the present invention is preferably derived from citrus fruits although this is not the sole example of limonin that can be used in the present invention. By using the peel-derived limonin and combining it with the essential oil from peel, there would be obtained a composition whose aroma and flavor is even closer to that of natural citrus fruits.

[0036] <Rutin>

[0037] The composition of the present invention comprises rutin. The concentration of rutin in the composition of the present invention is in the range 10-50 mg/kg/Acid, preferably in the range of 15-45 mg/kg/Acid. By incorporating rutin in the liquid composition at a certain range of concentration, the limonin bitterness can be reduced. However, in a case where limonin is present together with rutin having a certain proportion or more, the intense bitterness of limonin may be even increased by rutin. The rutin to limonin weight ratio (rutin/limonin) is preferably 1 or less, more preferably 0.8 or less, yet more preferably 0.6 or less. The term intense bitterness as used herein refers to a physical stimulus caused by shrinkage of the mucosa of tongue and represents excessive or unpleasant bitterness which differs from moderate bitterness acceptable as a chemical stimulus. In general, it is known that bitter substances in small amounts, not greater than their thresholds, provide foods and dishes with complex, rich flavors and tastes. It is also known that bitterness has a contrast effect with sweetness. However, the bitterness of limonin in the peel and others of citrus fruit is an irritating, excessive bitterness, which is often perceived as unpleasant. This invention may selectively reduce this intense bitterness by suppressing the rutin to limonin ratio to be 1 or less.

[0038] Rutin (quercetin-3-glucoside, molecular formula C.sub.27H.sub.30O.sub.16) is a type of flavone glycosides and is known to be contained in soba (Fagopyrum exculentum), asparagus, etc., and it is also known to be contained in the peel and others of citrus fruits. The rutin in the liquid composition of the present invention is preferably derived from citrus fruits although this is not the sole example of rutin that can be used in the present invention. The concentration of rutin can be adjusted by adding a certain amount of commercially available rutin into the composition containing essential oil from peel and limonin or removing an appropriate amount of rutin from the composition. As will be understood from the method to be described later, the liquid composition may be obtained by emulsifying the essential oil-containing peel or flavedo as they are crushed within water so that the peel-derived essential oil and limonin are extracted into the liquid composition. In this case, usually, a large amount of rutin is also extracted into the liquid composition, so an appropriate amount of rutin needs to be removed to limit the rutin/limonin ratio to lie within the above-mentioned ranges. In this regard, the present inventors have found a convenient method for limiting the rutin/limonin ratio in the composition to lie within the above-mentioned ranges, namely, they have found that the concentration of rutin can be reduced by removing the super surface layer of peel very thinly (at such a thickness that oil sacs are kept intact) before crushing the peel or flavedo within water. Although it was already known that rutin is contained in the peel of citrus fruits, the present inventors first found out that the content of rutin is high, in particular, near the outer surface of the peel. The rutin concentration in the liquid composition can be measured by use of LC-MS, as will be described later in the Examples.

[0039] <Acidity>

[0040] If the essential oils from peel of citrus fruits are placed under high acidity conditions, they will readily deteriorate to smell like chemicals. The composition of the present invention, being reduced in acidity, can be used as an aroma composition that is natural and fresh with less deterioration. The composition of the present invention has an acidity of 2.0% or less, preferably 0.1-1.5%, more preferably 0.2-1.2%, and even more preferably 0.2-1.0%. The present inventors found that the intense bitterness of the composition could be reduced further effectively by adjusting the acidity of the composition to lie within the above-stated ranges, in addition to lowering the rutin/limonin ratio to 1 or less. As stated above, the acidity as used herein is determined by first measuring the content of organic acids such as citric acid and malic acid by neutralization titration with sodium hydroxide, calculating the same in terms of citric acid, and expressing the converted value in percentage by weight. The comminuted juice from high acidity fruits has a problem that it cannot be included in large quantities in drinks since the drinks become so sour that they are not easy to drink. In this regard, the liquid composition with low acidity of the present invention is advantageous not only in that the perceivable intense bitterness of limonin is lowered, as described above, but also in that large amounts of aroma components of fruit's essential oils can be incorpoated in drinks because the composition can be incorporated in large amounts in the drinks.

[0041] The liquid composition of the present invention having a specified amount of fruit's essential oil, a rutin/limonin ratio of 1 or less, and an acidity of 2.0% or less can be produced, for example, by use of citrus fruit peel from which the super surface layer is removed in a thickness such that oil sacs are not ruptured (i.e., the rutin-reduced citrus fruit peel) and a solvent such as water.

[0042] <Liquid Composition>

[0043] The composition of the present invention is in a liquid state at room temperature under atmospheric pressure. Preferably, the composition comprises water as the main solvent. The composition preferably has a pH of less than 5. The low pH condition is advantageous for suppressing the growth of spoilage microorganisms.

[0044] As will be described later in a more specific way, one possible method for producing the liquid composition of the present invention comprises the following procedure: the peel or flavedo having oil sacs containing an essential oil is emulsified as it is crushed in water, whereupon the fruit's essential oil is taken out of the oil sacs into the water and, at the same time, the limonin is extracted from the peel into the water. As a result, the liquid composition can be produced without including any components other than the fruit and water and it serves as a liquid flavoring characterized by no food additives used. By the term no additives used is meant that none of the additives on the List of Products on the Registry of Existing Additives specified in the Japan Food Sanitation Act have been externally added.

[0045] The liquid composition of the present invention may be incorporated into foods and drinks for the purpose of flavoring them. In the case of drinks, for example, the composition may be incorporated at concentrations varying from 0.1 to 15% by weight, preferably from 0.2 to 10% by weight, depending on the flavor to be imparted. Being an aqueous composition that is low in either acidity alone or both acidity and degrees Brix and which is relatively high in the content of essential oil from peel, the liquid composition of the present invention has an advantage in that it can be incorporated into drinks in large enough amounts to ensure that the aroma components of the essential oil from peel are amply contained in the drinks. Particularly in the case of producing drinks with the taste of high acidity citrus fruit, the aroma of the fruit can be fully reproduced within the drinks. The liquid composition of the present invention can also be used to impart the flavor of fruit to black tea and other tea beverages. The drinks in which the liquid composition of the present invention may be used are not particularly limited and may include various types such as alcoholic beverages, alcohol-free beverages, carbonated drinks, juice-containing drinks, and tea-based drinks. It is worth particular mention that if the liquid composition does not contain alcohol (ethanol), it can advantageously be used to flavor alcohol-free drinks. In particular, it can advantageously be used to flavor drinks (non-alcohol drinks) of low juice content which is in the range of about 1-30% by weight, preferably 1-20% by weight, and more preferably 1-10% by weight, and this enables the manufacture of drinks that reproduce the fragrance of natural fruits. By using the liquid composition of the present invention, it is also possible to manufacture drinks that contain no synthetic additives such as synthetic flavors and surfactants.

[0046] <Production Method>

[0047] In the course of producing fruit juices from fruits having different rutin concentrations in peel, the present inventors found that, by adjusting amounts of essential oil from peel, limonin, and rutin, as well as acidity, a liquid composition which does not have perceivable irritating bitterness and has a fresh aroma and flavor close to that of natural fruits can be obtained.

[0048] The liquid composition of the present invention can be produced by adjusting the amounts of the essential oil from peel, limonin and rutin, as well as acidity. If desired, the composition can be produced using only a fruit or fruits and water in accordance with the method described below, which is given here for illustrative purposes only and is not the sole example that can be employed. The liquid composition that solely consists of fruit-derived components and water presents an aroma more like a natural fruit and, hence, is preferred.

[0049] In the case of a fruit that contains a large amount of limonin in the peel, it is necessary to reduce rutin in the peel. To address this problem, first, the super surface layer of the peel of a citrus fruit is removed by slicing the peel thinly enough not to rupture oil sacs in flavedo. The present inventors found that the content of rutin is high, in particular, in the super surface layer of the peel; that rutin increases the intense bitterness of limonin in the peel; and that, by removing the super surface layer of the peel, the concentration of rutin may be selectively reduced thereby to reduce the intense bitterness of the peel. The super surface layer is portion 1 shown in FIG. 2. In general, the super surface layer has a thickness of within 1 mm from the outer surface of the peel, preferably within 0.9 mm, more preferably within 0.8 mm, yet more preferably within 0.7 mm, depending on types and sizes of fruits, and is thin to a degree that most oil sacs remain without being ruptured. By removing the super surface layer in such a way that the oil sacs are kept intact as much as possible, aroma components in the oil sacs can be maintained while reducing the bitterness of peel. Further, although it is known that the aroma components contained in the essential oil in the oil sacs (peel oil) can be easily oxidized and deteriorated, such deterioration of the essential oil can be reduced by keeping the oil sacs intact as much as possible to prevent the essential oil from directly contacting the atmosphere (oxygen). When removing the super surface layer, it is preferable that more than 50% of the number of oil sacs remain without being ruptured, more preferably 70% or more, and yet more preferably 90% or more. The oil sacs can be observed either with an optical microscope or with the naked eye. The super surface layer of peel is preferably removed in an area which accounts for 50% or more of the total outer surface area of the peel, more preferably, 80% or more, yet more preferably 90% or more. It can also be observed with the naked eye whether the super surface layer was removed. If the super surface layer of peel has been removed, the color of the outer surface of the peel slightly changes. For example, in lemons and oranges, redness is reduced and whiteness and yellowness are slightly increased, or the color becomes greenish (see FIG. 3).

[0050] In the process of removing the super surface layer of peel, use of tools such as knives or home peelers is not preferable because oil sacs might be ruptured. As a method for solely slicing the super surface layer without rupturing oil sacs of the peel, it is preferable to use rotating drum peeling machines for root vegetables like potato. These peeling machines are disclosed in JP Patent No. 4497427 specification, JP Patent No. 4247923 specification, JP Utility Model Registration No. 3084921 specification, and others. A rotating drum peeling machine has a pair of cylindrical rotating drums rotating outwards from each other at the top. In the present invention, it is preferable to use a peeling machine without having projections such as blades or nibs on its rotating drums. If a peeling machine having such projections on its rotating drums is used for peeling citrus fruits, oil sacs in the peel might be destroyed. As a rotating drum without such projections, for example, a drum having a perforated surface with many holes may preferably be used.

[0051] The foregoing operations are necessary for fruits that contain a large amount of rutin in the super surface layer of the peel, but the operations may be omitted for some types of fruits that contain less rutin in the peel.

[0052] Second, the peel is collected from the fruit by a commonly employed technique. The collected peel consists of a dark colored flavedo portion having oil sacs and a white fibrous albedo portion. Containing no oil sacs, the albedo portion of the peel has less aroma components than the flavedo portion does; in addition, depending on the fruit from which it is derived, the albedo portion may present a bitter taste. Thus, when collecting the peel, the flavedo portion may be collected after most of the albedo portion has been removed from the peel. In this process, a small amount of the albedo portion may become included in the flavedo portion. In the process of collecting the peel or flavedo, care is preferably taken to ensure that the oil sacs in the flavedo are least destroyed. By not destroying the oil sacs, the essential oil contained in the oil sacs can be protected from oxidative deterioration.

[0053] The collected peel or flavedo is then mixed with water. The mixing ratio of water to peel (by weight) is preferably in the range of from about 0.5:1 to about 2.5:1, more preferably from about 0.6:1 to about 1.8:1, even more preferably from about 0.7:1 to about 1.5:1, and particularly preferably from about 0.7:1 to about 1:1. In this case, a pectin-containing fruit part (e.g. albedo or segment membrane) may be mixed in small amounts. After mixing the peel with water, an apparatus such as a mixer or homogenizer that is capable of dispersing the peel in water while shredding it into pieces may be used to form an emulsion in water of the essential oil contained in the oil sacs in the peel and to extract components such as glycerophospholipids and pectin from the peel into water, whereby the emulsion stability of oil drops (essential oil components) is improved. If the peel or flavedo collected with care being taken to keep the oil sacs intact as much as possible is mixed with water and the essential oil is emulsified while rupturing the oil sacs within water, direct contact of the essential oil with the atmosphere can be avoided to reduce its deterioration. From the resulting mixture of water and the disrupted peel, the solids content is centrifugally or otherwise removed to give a liquid composition. The thus obtained liquid composition solely consists of water and the fruit components and, in the absence of any off-flavors due to components other than the fruit, it presents an aroma and flavor resembling those of natural fruit. As a further advantage, during the production of the liquid composition, the aroma components will undergo less oxidative deterioration and the produced composition presents a fresh aroma and flavor.

EXAMPLES

[0054] On the following pages, several examples of the present invention are given but it should be understood that the present invention is by no means limited to these Examples.

[0055] (1) Measurement of Degrees Brix

[0056] Measurement of degrees Brix (%) was performed with a digital refractometer (manufactured by ATAGO CO., LTD.; Model No. RX-5000) at 20 C.

[0057] (2) Measurement of Acidity

[0058] Ten grams of a liquid composition was diluted to a prescribed volume, thereby making a test solution. A given amount of the test solution was titrated with a 0.1 mol/L sodium hydroxide standard solution using phenolphthalein as a pH indicator and the titratable acidity was calculated by the following formula:

Acidity (%)=K(TB)F(100/A)(1/W)100

[0059] K: calculated for citric acid=0.0064

[0060] T: the amount of 0.1 mol/L sodium hydroxide solution used for titration (ml)

[0061] B: the amount of 0.1 mol/L sodium hydroxide solution used for titration in the same amount of water (ml)

[0062] F: the factor of 0.1 mol/L sodium hydroxide solution

[0063] A: the volume of sample taken for titration (ml)

[0064] W: the weight of sample taken for preparation (g).sub.o

[0065] (3) Measurement of the Essential Oil's Content

[0066] To measure the essential oil's content in the composition, an essential oil quantifying apparatus was used. A round-bottom flask equipped with a condenser capable of trapping the essential oil was charged with 100 mL of the liquid composition, 2 L of distilled water, and boiling stones; atmospheric distillation was performed under heating at about 100 C. for an hour and the amount of the essential oil (mL) collecting in the trap tube was measured to calculate the content of the essential oil.

[0067] (4) Measurement of Limonin and Rutin

[0068] Limonin and rutin were analyzed by use of LC-MS.

(Preparation of Samples)

[0069] Samples for analysis were prepared by the following methods. First, 10 g of the liquid composition was weighed in a centrifugal glass tube (A). Note that when the liquid composition had a degrees Brix of 10% or more, 5 g was weighed; in the case of 20% or more, 2.5 g was weighed; and in the case of 30% or more, 1 g was weighed; in either case, the weighed liquid composition was diluted to 10 mL with distilled water for liquid chromatography. Subsequently, 20 mL of ethanol for liquid chromatography was added and the mixture was vigorously agitated with a vortex mixer for one minute or longer. When high viscosity prevented effective mixing, vigorous manual shaking was optionally performed. The intimate mixture was subjected to a centrifuge (1620 G30 min at 20 C.) and the supernatant was transferred into another centrifugal glass tube (B). To the precipitate, 20 mL of ethanol for liquid chromatography was added and after breaking the solids loose enough with a suitable device such as a dispensing spoon, the mixture was vigorously agitated with a vortex mixer for one minute or longer. After centrifugation with a centrifuge (1620 G30 min at 20 C.), the supernatant was charged into the centrifugal tube (B). The collected supernatants in the centrifugal tube (B) were further centrifuged (1620 G30 min at 20 C.) and the resulting supernatant was transferred into a 50-mL measuring flask and diluted with ethanol to the marked line. The well mixed supernatant was further diluted 10-fold with ethanol for liquid chromatography and passed through a preliminarily ethanol-washed PTFE filter (product of Toyo Roshi Kaisha, LTD; ADVANTEC DISMIC-25HP 25HP020AN, with a pore size of 0.20 m and a diameter of 25 mm) to prepare samples for analysis.

(Conditions for LC Analysis)

[0070] HPLC apparatus: Nexera XR Series (product of Shimadzu Corporation; equipped with system controller, CBM-20A; feed pump, LC-20ADXR; on-line degasser, DGU-20A3; auto-sampler, SIL-20ACXR; column oven, CTO-20A; and UV/VIS detector, SPD-20A) [0071] Column: CAPCELL CORE AQ (particle size, 2.7 m; inside diameter, 2.1 mm150 mm; product of Shiseido Company, Limited) [0072] Mobile phase A: 0.1% aqueous solution of formic acid [0073] Mobile phase B: acetonitrile [0074] Flow rate: 0.6 mL/min [0075] Density gradient conditions: 0.0-0.5 min (15% B).fwdarw.6.0 min (25% B), with 10.0 min (75% B).fwdarw.10.1-11.0 min (100% B), with 3.0 min equilibration by the initial mobile phase [0076] Column temperature: 40 C. [0077] Sample injection: injected in a volume of 2.0 L [0078] Sample charge into mass spectrometer: 1.8-11.0 min

(Conditions for Mass Spectroscopy)

[0079] Mass spectrometer: 4000 Q TRAP (product of AB Sciex) [0080] Ionization method: ESI (Turbo Spray), positive mode [0081] Conditions of ionization chamber: CUR, 10; IS, 5500; TEM, 650; GS1, 80; GS2, 60; ihe, ON; CAD, Medium [0082] Detection method: MRM mode [0083] Detection conditions: (Q1.fwdarw.Q3, DP, CE, CXP, EP): [0084] Rutin (611.2.fwdarw.303.1, 76, 25, 12, 10) [0085] Limonin (471.2.fwdarw.425.1, 101, 29, 12, 10) [0086] Peak detection time: Being subject to confirmation with standard samples, the following data may be given as a guide. [0087] Rutin (3.01 min), Limonin (8.80 min)

[0088] (Quantification Method)

[0089] Standard samples were purchased from Wako Pure Chemical Industries, Ltd. At least three standard sample solutions of different concentrations were used and quantification was performed by the absolute calibration method based on the peak areas obtained. In the case of measurements that turned out to give values that were outside the ranges of calibration curves, the factor of dilution with ethanol at the final stage of analysis sample preparation was appropriately adjusted to perform another measurement.

Example 1

[0090] (1) Production of Lemon Aroma Composition

[0091] By use of a rotating drum peeler for root vegetables, the super surface layer of a whole lemon was removed in such a way that 90% or more of oil sacs remained intact. The obtained lemon processed product was cut in halves and most of the pulp, seeds, segment membranes, and albedo was removed from the peel to obtain flavedo from which the super surface layer was removed. The obtained flavedo was mixed with water at a weight ratio of 1:1 and the mixture was milled with a commercial juice mixer, with care being taken to ensure that the mixture would not have a paste-like consistency; after stirring at room temperature for 30 minutes, the mixture was passed through a 40-mesh strainer to effect solid-liquid separation. The liquid phase was thereafter homogenized at 0.2 MPa and the insoluble solids were removed from the resulting suspension by centrifugation (6000 G5 min) and then pasteurized by heating at 90 C. for one minute to thereby prepare a liquid composition (Invention Product 1). A liquid composition (Comparative Example 1) was produced by the same method as used to produce Invention Product 1, except that the super surface layer of a whole lemon was not removed. Invention Product 1 and Comparative Example 1 were compared with each other and the results are shown in Table 3 below. The various components were measured by the methods described above. In Invention Product 1 without the super surface layer, the rutin content with respect to acid was greatly reduced.

[0092] (2) Sensory Evaluation

[0093] Invention Product 1 and Comparative Example 1 were tasted by licking them directly and evaluated for their flavor. The flavor attributes evaluated were the intensity of irritating bitterness and the intensity of a natural fresh aroma, and the grading system was on a 5-point scale using the criteria shown in Table 2 below. The results are shown in Table 3. Although the Invention Product had a high concentration of limonin, the irritating bitterness in it was dramatically reduced compared to that in the Comparative Example. This suggested that, by controlling the concentration of rutin with respect to acidity, the concentration of limonin with respect to acidity, and the ratio thereof, a flavoring liquid could be obtained that had a fresh and strong fragrance and yet was free from irritating bitterness.

[0094] In addition, lemon taste drinks were produced by use of invention Product 1 and Comparative Example 1 prepared in (1) above and were evaluated for their flavor. The samples were formulated according to the recipes shown in Table 4 so that the degrees Brix ( Brix) or the contribution of essential oil content could also be compared, and they were filled into bottles and pasteurized by heating at 85 C. for 5 minutes to produce lemon taste drinks. The results are shown in Table 4. The lemon taste drink produced by use of the Invention Product did not become so sour that it was not hard to drink, even though the Invention Product was incorporated in a large amount in the drink. Further, this drink had a natural fresh fragrance derived from a natural citrus fruit and yet was free from any perceivable irritating bitterness.

TABLE-US-00002 TABLE 2 Score Degree 4 Perceived intensely 3 Perceived considerably 2 Perceived moderately 1 Perceived slightly 0 Not perceived

TABLE-US-00003 TABLE 3 Invention Comparative product 1 Example 1 Degrees Brix ( Brix: %) 4.2 5.7 Acidity (%) 0.38 0.67 Essential oil content (%) 0.45 1.10 Limonin content per acidity (mg/kg/Acid) 111.8 67.1 Rutin content per acidity (mg/kg/Acid) 47.1 92.7 Rutin/limonin ratio 0.4 1.4 Flavor evaluation 1 4 (Intensity of irritating bitterness) Flavor evaluation 3 4 (Intensity of fresh fragrance)

TABLE-US-00004 TABLE 4 (Unit: g/L) 1 2 3 Comparative Invention Example 1 Product 1 Aroma composition 7.4 4.1 10.0 Granulated sugar 90.0 90.0 90.0 Citric acid anhydride 1.5 1.5 1.5 Purified water q. s. q. s. q. s. Flavor evaluation 4 3 0 (Intensity of irritating bitterness) Flavor evaluation 4 3 3 (Intensity of fresh fragrance)

Example 2

[0095] (1) Production of Lemon Aroma Composition

[0096] By use of a variety of kinds of lemons, lemon aroma compositions were prepared in the same method as used to produce Invention Product 1 of Example 1, and analyses were conducted for various components. The results are shown in Table 5.

[0097] (2) Sensory Evaluation

[0098] To solutions adjusted with sucrose and citric acid anhydride to Brix of 9.0 and an acidity of 0.15%, Invention Products 2 to 11 prepared in (1) above were respectively added in 10 g/L; the samples were then filled into bottles and pasteurized by heating at 85 C. for 5 minutes to produce bottled drinks with lemon taste. The obtained drinks were evaluated for their flavor in the same manner as in Example 1. Invention Products 2 to 11 having acidities, rutin concentrations per acidity, limonin concentrations per acidity, and rutin/limonin concentration ratios that were adjusted to lie within specified ranges were suppressed in irritating bitterness and yet had a fresh and pleasant aroma characteristic of citrus fruit.

TABLE-US-00005 TABLE 5 Invention Invention Invention Invention Invention product 2 product 3 product 4 product 5 product 6 Degrees Brix ( Brix: %) 4.8 4.6 4.1 4.5 4.5 Acidity (%) 0.63 0.63 0.57 0.67 0.57 Essential oil content (%) 0.70 0.65 0.45 0.55 0.80 Limonin content per acidity 96.2 68.7 43.1 42.8 52.0 (mg/kg/Acid) Rutin content per acidity 20.7 19.8 18.6 11.4 18.4 (mg/kg/Acid) Rutin/limonin ratio 0.2 0.3 0.4 0.3 0.4 Invention Invention Invention Invention Invention product 7 product 8 product 9 product 10 product 11 Degrees Brix ( Brix: %) 4.1 3.9 4.1 3.9 4.2 Acidity (%) 0.52 0.36 0.60 0.58 0.60 Essential oil content (%) 0.45 0.45 0.40 0.38 0.50 Limonin content per acidity 92.8 138.5 111.8 29.7 81.7 (mg/kg/Acid) Rutin content per acidity 17.3 39.0 47.1 17.2 13.9 (mg/kg/Acid) Rutin/limonin ratio 0.2 0.3 0.4 0.6 0.2

Example 3

[0099] By use of lime, a lime aroma composition was prepared in the same method as used to produce Invention Product 1 of Example 1, and analyses were conducted for various components. The results are shown in Table 6. In the same manner as in Examples 1 and 2, the sensory evaluation was performed for the composition and a bottled drink containing the composition, and the evaluation showed that the composition and the drink had suppressed irritating bitterness and had a fresh and pleasant aroma characteristic of citrus fruit, and thus were suitable for a flavoring liquid and a bottled drink, respectively.

TABLE-US-00006 TABLE 6 Invention Product 12 Acidity (%) 0.79 Essential oil content (%) 0.35 Limonin concentration per acidity (mg/kg/Acid) 285.1 Rutin concentration per acidity (mg/kg/Acid) 15 Rutin/limonin ratio 0.05

Example 4

[0100] A flavedo fraction obtained from a whole lemon without removing the super surface layer of the lemon was mixed with water and emulsified to prepare a composition, and the components of the obtained composition were analyzed. Table 7 shows the results. In the same manner as in Examples 1 and 2, the sensory evaluation was performed for the composition and a bottled drink containing the composition, and the evaluation showed that the composition and the drink had irritating bitterness, but were suitable for a flavoring liquid and a bottled drink, respectively.

TABLE-US-00007 TABLE 7 Invention Product 13 Acidity (%) 0.54 Essential oil content (%) 0.85 Limonin concentration per acidity (mg/kg/Acid) 128.6 Rutin concentration per acidity (mg/kg/Acid) 15.1 Rutin/limonin ratio 0.12