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6

Purification of Orange Peel Oil and Oil Phase by Vacuum Distillation

Mércia de Fátima M. Bettini

Flavor Tec – Aromas de Frutas Ltd, Brazil

CONTENTS

6.1 Introduction.................................................................................................1576.1.1 Steam Distillation.............................................................................1586.1.2 Simple Distillation and Fractional Distillation................................1586.1.3 Vacuum Fractional Distillation ........................................................159

6.1.3.1 Significant Reduction of Thermal Hazard .......................1596.1.3.2 Greater Fractionation Efficiency ......................................1606.1.3.3 Enhanced Purity of Distillate ...........................................160

6.2 Industrial Scale Purification of Orange Peel Oil.........................................1606.2.1 Citrus Industry..................................................................................1606.2.2 Sweet Orange Oil.............................................................................161

6.2.2.1 Purification of Orange Peel Oil........................................1616.2.2.2 Method of Deterpenation — Vacuum

Fractional Distillation .......................................................1626.2.2.3 Folded Oils........................................................................1626.2.2.4 Uses and Applications ......................................................1636.2.2.5 Experimental Results ........................................................163

6.3 Conclusions ..................................................................................................170References..............................................................................................................172

6.1 INTRODUCTION

Distillation is a process of heating a substance until the most volatile constituentschange into the vapor phase, and then cooling the vapors to recover the constituentsin liquid form by condensation. The main purpose of distillation is to separate amixture into individual components by taking advantage of their different level ofvolatilities. Distillation is one of the main methods of extracting essential oils fromplants. The percentage of each constituent in the vapor phase usually depends on

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Functional Food Ingredients and Nutraceuticals

its vapor pressure at a certain temperature. The principle of vacuum distillation maybe applied to substances such as oils that would be damaged by overheating by theconventional method [1]. There are different methods of distillation, depending onthe desired product; some of these processes are described below.

6.1.1 S

TEAM

D

ISTILLATION

Steam distillation is one of the common methods of distillation. Although steamdistillation appears to be the best method for extracting essential oils, supercriticalCO

2

extraction is becoming quite popular. Most aromatherapists believe that essentialoils are only effective when extracted by steam distillation and all other essentialoils should be labeled with their extraction methods, that is, cold pressed oils,concretes, absolutes, and so forth. These preparations should not be confused with“true” essential oils.

In the steam distillation process the material to be extracted is carefully gatheredand placed into a copper or stainless steel vat, known as the distillation chamber.Steam is then generated by heating (preferably low heat) to build pressure withinthe distillation chamber causing the glands of the plant to rupture and release itsessence which is then carried by the steam vapor. The steamy vapor is cooled andcondensed in a coil, which is usually submerged in refrigerated cold water. Thewater and essential oil separate and the essential oils usually stay on top of the waterdue to their lower densities. The water and essential oil are sent to a collectionchamber where the oil is easily skimmed off the top of the distillated water. Thedistillated water may contain many low water soluble components of the plant. Theseby-products of the distillation process are known as “hydrosol” and can be used forskin care, usually for children and the elderly.

When subjecting a plant material to heat or steam as in the distillation process,the physicochemical properties of the material may be altered. The thermolabilcomponents are degraded and here the information given by some authors withregard to the essential oils may be flawed. To achieve effective aromatherapeuticbenefits, it is important to recognize that the extracted essential oils are not alwaysin the same form when they were in the plant. Therefore, when subjecting plantmaterials to heat or steam as in the distillation process, the chemical structures withinthe essential oil after distillation are different than those found in the original plantmaterial. For instance, chamomile is converted to the chemical azulene, which isnot found in the plant itself but is produced during distillation [2].

When designing equipment for high vacuum process, parameters such as pres-sures, pipe sizes, and vessel sizes, must be adequate to avoid excessive vapor speedand pressure drops. The entire system must be free of leaks [3], and compensationfor the excess pressure drop (2 or 3 mm Hg) across the entire system must beincorporated into the design process.

6.1.2 S

IMPLE

D

ISTILLATION

AND

F

RACTIONAL

D

ISTILLATION

If one desires to get a pure compound, the distillation process has to be repeatedmany times and this will make it a cumbersome process. In practice, the vapors are

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condensed and revaporized in fractionating columns connected sequentially in series.Equilibrium between liquid and vapor presumably occur on each plate. However, itis not likely that equilibrium is reached on each plate, therefore, it is imperative tocalculate the plate efficiency, an important design factor. The column is packed withan inert material to promote contact between the liquid and the vapor. One of themost important design factors in packed columns is to prevent channeling — acondition where the vapors and liquid flow in opposite directions without cominginto contact.

The number of theoretical plates is determined under a specific set of operatingconditions during the construction of the column. The efficiency of design is referredto as the Height Equivalent per Theoretical Plate (HETP).

When all the vapors that go up through the column condense and flow backdown, the returning liquid is called the reflux. The total reflux consists of the totalproduct received from the outlet when no distillate is produced. As soon as theproduct is drawn from the condensed vapors, the amount of liquid returning throughthe column is reduced and produces changes to the operating conditions of thecolumn. If all the condensed vapors are drawn off, then there will be no downflowto wash the upcoming vapors and in effect the column would stop functioningaltogether and become just a long pipe. However, most columns would retain someamount of reflux and, for practical considerations, there would be some heat lossesthrough radiation and convection along the column [3].

6.1.3 V

ACUUM

F

RACTIONAL

D

ISTILLATION

Vacuum distillation is a method of distilling substances at temperatures below theirnormal boiling point (standard atmospheric pressure). By reducing the pressure, amuch lower distillation temperature will be required.

High vacuum distillation may be used for certain classes of chemical compoundsthat decompose, polymerize, react, or are destroyed by conventional distillationmethods. Low cost per pound and high throughput may be obtained on certain groupsof compounds such as vitamins, epoxy resins, highly concentrated pure fatty acids,plasticizers, fatty acid nitrogen compounds, and a host of other heat-sensitive mate-rials which may require only deodorizing and decolorizing. The pharmaceuticalindustry, in their continuing search for new products with high and intermediatemolecular weights, finds that it is still an invaluable commercial practice to separateproducts by molecular weight from excess reactants and catalysts.

6.1.3.1 Significant Reduction of Thermal Hazard

High vacuum distillation is a safe process to separate mixtures of organic or siliconcompounds, most of which cannot withstand prolonged heating above 250ºC withoutexcessive structural change or decomposition. As opposed to conventional atmo-spheric and pressure packed distillation towers, the high vacuum process utilizes theheat of condensation as a source of radiant heat emission to heat the surface filmon the evaporator. With short residence time and lower distilling temperatures,thermal hazard to the organic material is greatly reduced.



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6.1.3.2 Greater Fractionation Efficiency

The best approach to a mechanical method of creating a uniform film thickness witha fast-moving liquid is to feed the liquid to the center of a heated spinning disc. Bycentrifugal action, the material spreads as a film across the heated disc that intimatelyfaces a large condensing surface. The lighter compound evaporates and condensesin a fraction of a second. The heavier residues that are not evaporated slide off theouter edge of the disc into a concentric residue collector and are discharged. Thedegree of separation is a function of the molecular weight differences of the distilledmixture. The greater the difference in the molecular weights, the purer the distillate.The closer the molecular weights of the mixture are, the less efficient is the frac-tionation process, resulting in the need for successive runs of the distillate.

6.1.3.3 Enhanced Purity of Distillate

Purity of the distillate also depends on the film thickness. Controlling positivepressure and supply to the heated evaporator surface will usually provide a uniformfilm throughout the distillation.

The absence of air molecules in the high vacuum distillation column permitsmost of the distilling molecules to reach the condenser with relatively few moleculesreturning to the liquid film surface in the evaporator. Experimental results show arelationship between the molecular weight and distillation temperature for a broadrange of different materials. There is no predictable temperature at which distillationmay occur; condensation begins whenever a sufficient temperature difference occursbetween the evaporator and condenser. There is an infinite number of sets of oper-ating conditions for every material that is fed through the system. Since pressure isconstant, the only variables are flow rate (governing film thickness) and evaporatortemperature [4].

6.2 INDUSTRIAL SCALE PURIFICATION OF ORANGE PEEL OIL

The orange peel oil and essences are produced by the orange juice industry, as willbe explained in Sections 6.2.1, citrus industry and 6.2.2.1, purification of orangepeel oil.

With the objective of preparing products rich in aromatic compounds, com-pounds that are very important for flavor, the deterpenation process on those oilsand essences will be discussed in Sections 6.2.2.2 and 6.2.2.3.

6.2.1 C

ITRUS

I

NDUSTRY

Citrus juice processing generates a large amount of wastes with almost 50% of thefruit weight ending up as waste in the form of peel, segment, membranes, rags, andseeds. Besides that, during juice concentration, volatile constituents contained in thevapor phase are condensed by the aroma recovery systems. The depletion of theseflavoring components results in decreased juice quality. Unless these compounds




161

are reincorporated back into the juice, the nutritional value will be diminished. Thearoma recovery system consists of two separate phases: essence oil (oil phase) andaqueous essences (water phase). The average yield of these products is very low.All these products are rich in aldehydes, esters, and other special volatile compounds.As the storage and transportation of these products are expensive, the evaluation ofthe concentration processes is of great interest [5]. It is very important that thespecial light fractions and the concentration of flavoring volatile compounds fromthe oil phase and peel oil be obtained by vacuum fractional distillation.

6.2.2 S

WEET

O

RANGE

O

IL

Expressed sweet orange oil is primarily used for flavoring beverages, soft drinks,ice cream, sweets, pharmaceutical preparations, and also perfumes. It containslimonene, minor amounts of other monoterpene hydrocarbons, linalol

terpineol,aliphatic alcohols, and aldehydes such as octanal, nonanal, decanal, traces of thesesquiterpenic aldehydes and alpha and beta sinensal, methyl anthranilate, cou-marins, and waxes. For flavoring foods and beverages, the so-called concentratedterpeneless oils or folded oils are preferred and are commercially available.

6.2.2.1 Purification of Orange Peel Oil

Sweet orange oil is expressed from the fresh peels of ripe citrus fruitsaurantiumL.var.dulcis (Citrus sinensis Os beck) (fam. Rutaceae). The tree probably originatedfrom the Far East between the Himalayas and Southwest China. It is now cultivatedin the United States (California, Texas, and Florida), throughout the Mediterraneanregion (southern Italy, Sicily, Spain, Algeria, Tunisia, Morocco, Israel, and Cyprus),South Africa, Brazil, and the West Indies.

The main producers of the equipment that expresses oil are the United Statesand Cyprus, whereas the hand-pressed equipment is produced in Guinea [6]. Manyinvestigators have pointed out that the quality of citrus oils is dependent upon manyfactors such as soil type, weather, method of extraction, and maturity of the fruit.

Citrus oils are located in the oval, balloon-shaped oil sacs or vesicles located inthe outer ring or flavedo of the fruit. Winton and Winton [1] described the exactlocation of these oil sacs in their discussion of the microscopic structure of theflavedo of the orange.

To extract the oil from the peel of citrus fruits, the oil sacs must be ruptured byeither pressure or rasping. The methods used in Florida were investigated by vonLoesecke and Pulley [6] and they revealed that extraction method had an effect onthe quality of the oil [7].

Cold-pressed citrus oils may be further processed to remove all or part of theterpenes and sesquiterpenes. The resulting products are known as

terpenefree, ter-peneless

, or

sesquiterpeneless

oils. For products with low sesquiterpene concentra-tions, the term terpeneless is generaly used. Citrus oils from which terpenes havebeen removed are also called

folded oils

as the remaining flavorful oxygenatedcompounds are more concentrated. The degree of concentration is often calculated



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from the ratio of the principal constituent in the concentrated oil to that in the primeoil from which it was made.

6.2.2.2 Method of Deterpenation — Vacuum Fractional Distillation

The bulk of terpeneless oils are produced by fractional distillation under high vacuum(1 to 2 mm Hg) so that the oil boils at a relatively low temperature to ensure minimumdamage to the heat sensitive constituents during the long distillation period. At thesepressures the boiling points of the constituents may be too low for efficient separa-tion, but as the terpenes are rarely separated individually, this is usually a designproblem, and reflux balance can be readily solved if necessary.

The aromatic vapors rise through a fractionating column that enables fractionsat defined boiling ranges to be separated and collected.

Depending on the nature of the starting material and the desired character ofthe end product, the various fractions may be reblended as necessary and anyunwanted fractions rejected [8].

6.2.2.3 Folded Oils

Folded orange oil is the concentrated product obtained from the winterized oil offresh oranges. The process used will remove unneeded materials while retaining thehighly aromatic components. Folded oils are several times more potent than theoriginal oil and maintain the best fragrance. The two primary commercial varietiesof folded orange oil are 5-fold and 10-fold. The higher the fold (distillation) themore concentrated is the finished product. Stable emulsions are more easily formedwith folded oils since they required less oil to produce the desired flavor andfragrance levels [9]. The oil is primarily used as a flavoring agent for both foods,beverages, and pharmaceutical products, and is 10 times stronger than the usualorange oil.

Concentrated fractions with high contents of fragrant compounds such as ethyl-butyrate, valencene, aldehyde C 10, and others, can be obtained. Their smell andtaste, that come from the original esters and aldehydes of the raw materials, are verygood.

Cold-pressed orange and grapefruit oils contain about 90% d-limonene.D-limonene is a hydrocarbon and has the following structure

CH3

CH3

H2C




163

D-limonene boils at 178ºC, and it is generally thought that d-limonene contrib-utes very little to citrus flavor. However the oil flavor and taste can be varied byadjusting the d-limonene concentration. In general, the term five-fold oil is usedwhen starting with 5 lb of cold-pressed orange oil and distilling 4 lb; the remaining1 lb is referred to as five-fold oil.

The folding of oils is surrounded by secrecy and mysticism and various flavorhouses have developed their own methods. Some use solvent extraction, usuallyabout 70% ethanol followed by chilling to separate the extracted oil.

Since d-limonene boils at about 27ºC and 2 mm Hg, and reliable mechanicalvacuum pumps are available, it is possible to fractionate d-limonene at 5 to 10 mmHg absolute pressure. This is probably the most common method used today. Thereare some low boiling point esters and aldehydes that are distilled with d-limonene,and their separation and recovery is presently the subject of research.

6.2.2.4 Uses and Applications

Folded orange oils are used as a food ingredient and also as a flavor enhancer inbeverages. They can be incorporated into new and existing formulations to enhancefragance and color. A wide array of industrial applications from general purposecleaning to air fresheners have been enhanced by the addition of folded orange oils[10].

Original citrus oils are characterized by the presence of large percentages ofterpenes (C

10

/H

16

) and smaller amounts of sesquiterpenes (C

15

/H

24

).Both of them, original and folded oils, carry oxygenated compounds comprising

alcohols, aldehydes, ketones, acids, and esters, which are responsible for the char-acteristic odor and flavor profiles. The terpenoid composition of various originalcitrus oils is similar, and their principal component is d-limonene. The terpenespossess little intrinsic odor or flavor value but it would be incorrect to say that theyhave no flavoring effect. An original citrus oil from which the terpenes have beenremoved is significantly flatter and lacks the characteristic freshness associated witha complete peel oil [8]. When part of its terpenes is removed, folded oils will beobtained.

6.2.2.5 Experimental Results

Figure 6.1 illustrates the industrial production of essences, as oil and water phases.In one of the stages of the evaporator, there is a column where the volatile com-pounds, the oil and water phase, are evaporated and recovered in a tank.

The Essence Recovery System is connected to TASTE evaporators (ThermallyShort Time Evaporator) which have the first juice stage in the first evaporator effect(that is, the first stage is the hottest effect or boiler steam effect). The essence-bearingvapors are “boiled-off” with the water vapors in the first stage. The vapors arecondensed in the shell side of the second stage (second effect). The essence-bearingvapors rise to the top of the shell side of the second stage and through a series ofbaffles in the tube nest to remove as much condensable water vapor as possible. Thenoncondensable portion of these vapors is removed through the vent line at the top



FIGURE 6.1

Recovery system of water phase plus oil phase in the orange juice industry.

Barometric isolation valve

Off

Essence valve

On

Column vacuum gauge

Water out valve

Essence vacuum gauge

No 2 T/N vacuum

2 T/N

Water out

Overheadcondenser

Reflux chamber

Stripping cal & reboiler

Essence recovery column assy

Water to baro cond

Hot well

Botton seal tank

Flow meter

Steam header

Atm

ste

am

Bo

tto

m d

um

p

Ho

t w

ater

to

ho

t w

ell

Noncondensable

Product &noncondensable cooler

Back pres regulator & strainer

Ammonia surge drum

Dual pressure

Relief valve

Matering valve

Sporian UMC-DA-5 Liquid level control

Scr

ub

ber

Co

nd

ense

r

NH

3 li

qu

id i

n

NH

3 li

qu

id o

ut

Barometric condenser

Ammonia surge drum

Essence storage tank

500 Gal cold wat

tank

To hot well

Water

To essence vacuum gauge

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of the tube, which is connected to the barometric condenser with a bypass for theessence system. This is also repeated in the next tube.

When the essence system is “on” the noncondensable vapors are routed to theessence system through remote-controlled air-operated valves, and the vent line tothe barometric condenser is shut off.

The essence vapors enter the essence system at the vent condensers. The ventcondenser condenses approximately 90% to 95% of the essence product. Cold wateris used as a condensing medium.

The essence product (condensed) flows downward through a single line to a dirttrap.There are two lines running up from the trap: one line is the essence productline running to the product chillers, the second line is the reflux line, which is usedto control the strength of the essence. The amount of reflux flow is dependent onthe desired strength of the water phase essence. The reflux rate is controlled onlyby the amount of product taken from the system. There is a constant amount ofessence product generated by the overhead condenser, the essence product that doesnot continue through the system flows back to the tube nest as reflux.

The essence product flows from the dirt trap to the double-circuit chiller con-denser. This unit uses flooded NH

3

refrigeration on the shell side. One circuit of thechiller-condenser is used to chill the essence product, and the other circuit is usedto further condense the noncondensable vapors that rise from the vent condenser.

The second circuit (noncondensable) of the chiller condenser is connected tothe bottom of the refrigerated condenser. This condenser is a vertical shell and tubeheat exchanger using flooded NH

3

on the shell side. The noncondensable vaporsflow through the tubes in a final condensing stage. The chilled product flows to thedecanter assembly. The remaining noncondensable vapors flow upward and into theevaporator barometric condenser.

The product lines from the bottom of the scrubber and the final condenser runto the decanter assembly located in the cold wall storage tank. The product line fromthe bottom of the scrubber to the decanter assembly has a flow meter located in theline. This flow meter measures product flow into the decanter assembly.

The essence system product flow is created by vacuum generated by the evap-orator barometric condenser. There is a continuous vacuum path from the evaporatortube to the evaporator barometric condenser, through each unit. The vacuum in theessence system is controlled by remote controlled valves [3].

The purification process of orange peel oil and orange essence oil at Flavor Tecis described by Figure 6.2. Peel oil, oil phase, and water phase, are by-products ofthe citrus processing plants. These products can be concentrated to obtain foldedoils and folded essences (in the case of the oil phase and water phase), besides thespecial light fractions and terpenes. Figure 6.2 shows the flow diagram for theprocessing of raw materials at Flavor Tec. As shown, the light fractions and foldedoils or essences, are processed by vacuum fractional distillation.

As shown in the first step of Figure 6.2, the volatile compounds that will be theraw materials for the FTNF (From The Named Fruit) aromas, are obtained from thenatural fruit in the citrus processing plant, as follow: the peel oil comes from thepeel in a special process of washing, cleaning, centrifugation, and dewaxing. The



166


oil phase and water phase are also recovered by the citrus juice process, as shownin Figure 6.1.

In the Flavor Tec process these raw materials feed the distillation equipment toproduce the folded oils or folded essences, plus terpenes and light fractions by highvacuum fractional distillation (second and third steps in Figure 6.2).

By blending the different percentages of the folded oils, folded essences, andlight fractions, the FTNF aromas are produced at Flavor Tec. The percentage of eachof the compounds, will change according to the needs of the final flavor, for example,freshness, sweetness, ripeness, and so forth. All the distilled products are evaluatedby physicochemical and sensory analytical methods.

After the analytical evaluations of all the obtained products are completed, theirshelf life at room temperature and cold store will be studied. The shelf life of theFTNF aromas used in citrus juices will also be evaluated.

Based on these evaluations it will be possible to guarantee the quality of thearomas, as well as their addition to the final feed. A typical industrial fractionalvacuum distillation plant is shown in Figure 6.3. In order to increase the yield andquality of the final products at Flavor Tec, the distillator is continuously fed withraw materials 24 hours a day.

Figure 6.4 shows the chromatographic profile of a 10-fold orange oil. Figure6.5 shows the profile of the orange terpene obtained during the distillation process.The average yield of the terpenes on the process of a 10-fold oil is about 90% andabout 80% on the process of a 5-fold oil. The purity grade of d-Limonene is aminimum of 96% by high-resolution gas chromatography (HRGC). The different

FIGURE 6.2

Citrus oils concentration at Flavor Tec by distillation.

Raw material (fruit)

Selling

FTNF aromas

Analytical evaluations

Juice addition

Shelf-life study

Shelf-life study

Folded oils/folded essences

Light fractions Terpenes

Volatile compounds - peel oil, oil phase, water phase

Distillation/fractional process

FTNF = From the named fruit




167

concentration of each component of single, 5-fold, 10-fold oils and terpene can beseen in Table 6.1.

The values of the components as area percentage

(area %) were analyzed byHRGC, using the following analytical conditions:

Gas Chromatograph Shimadzu, 14BPFSC, 115/220 V AC (50/60 Hz) and 2KVA max. capacity. Detector: Flame Ionization; T = 220ºC. Injector: Split / splitless(Split = 1:100);T = 200°C. Column: Capillary – Shimadzu, Type bonded phase.Phase: CBP1 (nonpolar). Size: 30m

×

0.25 mm. Film thickness: 0.25 micron. Mate-rial: Fused silica. Temperature program = 40ºC to 190ºC (4ºC/min).

The area percentage (HRGC) of each identified component of the orange essenceoils, single, 5-fold, and 10-fold products, is listed in Table 6.2. There are morearomatic or fragrant components in the essence oil as compared to peel oil, as canbe seen in Tables 6.1 and 6.2. It is therefore advisable to remember that the peel oilis obtained from the orange peel while the essence oil is from the concentration ofthe orange juice. The latter has fresher compounds than the former . Special attentionmight be given to the valencene content in the folded oil phases. This componentis very important for the fruit taste characteristic. During the concentration processof the essence oil, special light fractions can be obtained, if processed under idealconditions. Table 6.3 shows the concentration of one of these fractions, obtainedfrom the essence oil (oil phase). It is a very light fraction because it is rich with top

FIGURE 6.3

Vacuum fractional distillation at Flavor Tec.



168


note components, for example, ethyl-butyrate and octanal, as can be seen in Figure6.6.

Special attention might also be given to the high level of the light components,for example, hexanal and ethyl-butyrate, which are very important for the top notesof a flavor. The FTNF aromas are produced by blending the folded oils and oilphases plus the special light fractions, as show in Figure 6.2.

At Flavor Tec, this blending is done with different fractions, as show in Figure6.2. The FTNF aromas are produced by blending the folded oils and folded oilphases.

It depends on the desired characteristics of the final flavor, for example,fruity, fresh, green, and so forth. As an example, Table 6.4 shows the concentrationof some components of two different FTNF aromas called A and B. They are productsof Flavor Tec, after concentration of the raw materials and blending with lightfractions.

The main differences between the aromas A and B are: A is fresher than B, asdemonstrated by its ethyl-butyrate content, and B has more juice note, as shown inits valencene content.

These special characteristics of each component will give unique flavor noteswhen added to the final food product.

FIGURE 6.4

Chromatographic profile of 10-fold orange oil (HRGC).

1 α - Pinene 2 Sabinene 3 Mircene + Octanal 4 Phelandrene 5 D – Limonene 6 Nonanal 7 Linalol 8 Citronelal 9 Decanal 10 Neral 11 Geranial 12 Valencene

12

46

8

9

3

57

12

11

10




169

FIGURE 6.5

Chromatographic profile of orange terpene (d-limonene) (HRGC).

TABLE 6.1Area Percentage by HRGC of the Identified Components of the Orange Peel Oils in Several Concentrations

Evaluated Products (area %)

Pick No. Components Single Oil 5-Fold Oil 10-Fold Oil Terpene

1

α

-Pinene 0.49 0.31 0.13 0.532 Sabinene 0.32 0.20 0.13 0.433 Mircene + Octanal 2.19 1.54 1.08 2.354 Phelandrene 0.15 0.10 0.05 0.165 D-limonene 95.36 91.92 81.71 96.306 Nonanal 0.03 0.11 0.10 0.027 Linalol 0.38 1.01 2.08 0.138 Citronelal 0.04 0.13 0.35 0.019 Decanal 0.24 1.15 3.07 –

10 Neral 0.06 0.29 0.92 –11 Geranial 0.10 0.50 1.51 –12 Valencene 0.04 0.14 0.58 –

1 α-Pinene2 Sabinene3 Mircene + Octanal4 Phelandrene5 D-limonene6 Nonanal7 Linalol8 Citronelal

1

53

2

8

76

4



170


6.3 CONCLUSIONS

Fractional distillation has been shown to be an efficient process. At high vacuum, itis a safer process from an operational point of view, but also much gentler on theraw materials, because of the short residence time and low distillation temperature.This results in better fragrant characteristics in the final products. To obtain top-quality products, the raw materials, orange peel oil and oil phase, need to be wellpreserved from harvest until their use in the process.

TABLE 6.2Area Percentage by HRGC of Some Components of the Orange Essences or Orange Oil Phases in Several Concentrations

Evaluated Products (area %)

Pick No. Components Single Oil Phase 5-Fold Oil Phase 10-Fold Oil Phase

1 Hexanal 0.01 0.29 0.712 Ethyl-butyrate 0.03 0.14 0.333 T-2-hexanal 0.01 0.02 0.064

α

-Pinene 0.38 0.93 2.105 Sabinene 0.34 0.34 0.676 Mircene + Octanal 2.17 1.46 2.307 Phelandrene 0.08 0.09 0.128 D-limonene 94.57 85.75 68.209 Nonanal 0.10 0.09 0.1410 Linalol 0.70 2.13 2.7811 Citronelal 0.01 0.13 0.5712 Decanal 0.30 1.21 3.7013 Neral 0.11 0.54 2.0414 Geranial 0.10 0.49 1.0015 Valencene 0.23 2.31 4.08

TABLE 6.3Area Percentage by HRGC of the Main Components of the Light Fraction of the Orange Oil Phase

Pick No. Components Oil Phase Light Fraction (area %)

1 Hexanal 5.382 Ethyl-butyrate 2.543 T-2-Hexanal 0.414

α

-Pinene 13.845 Sabinene 4.346 Mircene + Octanal 12.767 Phelandrene 0.648 D-limonene 57.51




171

FIGURE 6.6

Chromatographic profile of special light fraction of orange oil phase (HRGC).

TABLE 6.4FTNF Orange Aromas (A and B) HRGC Data

Pick No. Components Sample A (area %) Sample B (area %)

1 Acetaldehyde TR TR2 Hexanal 0.27 0.103 Ethyl-butyrate 0.18 0.054 T-2-hexanal 0.10 0.055

α

-Pinene 1.23 0.746 Sabinene 0.60 0.287 Mircene + Octanal 2.98 1.918 Phelandrene 0.17 0.099 D-limonene 87.36 86.08

10 Nonanal 0.05 0.1011 Linalol 1.02 1.7012 Citronelal 0.12 0.1713 Decanal 1.38 1.8014 Neral 0.40 0.5415 Geranial 0.52 0.8016 Valencene 0.53 1.17

1 Hexanal2 Ethyl-butyrate3 T-2-hexanal4 α-Pinene5 Sabinene6 Mircene + Octanal7 Phelandrene8 D-Limonene

123

4

5

6

8

7



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It is well known that single citrus oils and essences can come in large volumesfrom the industry. The storage and transportation costs of these products are high,which is another reason why more interest is been shown in the concentratedproducts. Research results have shown limonene to be a good candidate for humanclinical chemoprevention trials. Figure 6.4, Figure 6.5, and Figure 6.6 with chro-matograms and Table 6.1, Table 6.2, and Table 6.3 of the main components thatwere obtained from this work at Flavor Tec, show that the folded oils, essences, andthe aromas, besides their fragrant components, also maintain good levels of d-limonene concentration when added to juice and other beverages. Although consid-erable differences have been observed with these preparations, wide acceptance bysensory panels has been achieved. It is very important to note that these folded oilsand aromas are useful in both aspects: (1) as functional foods, because of thelimonene content, and (2) the taste and fragrance, because of their fragrant com-pounds such as esters, aldehydes, and so forth. It is very important to bear in mindthat the aroma is not a curative but will in general enhance food products.

REFERENCES

1. PE Chemical Engineering Review by Wagar Ahmad, PhD. Binary distillation weightand mole fractions, www.reviewpe.com/pe/samples/b6_7htm, (retrieved October 5,2004).

2. Steam distillation. Infuse your life with excellence, www.serene-aromateraphy.de/steamdistillation.html, (retrieved October 28, 2004).

3. Redd, J.B., Hendrix, D.L., and Hendrix, C.M.Jr., Process procedures,

Quality ControlManual For Citrus Processing Plants

, Ag Science, Inc., Auburndale, Florida vol II,section I, division B, 1992.

4. Myers Vacuum, Molecular distillation: the unique principle behind a unique process,www.myers-vacuum.com/mv1.html, (retrieved November 3, 2004).

5. Bettini, M.F.M., Orange concentrated essences by fractional distillation, presented at25th IFU – Symposium, Stuttgart, Germany, May , 2004.

6. Formacek, V. and K.-H. Kubeczka, Orange oil, sweet,

Essential Oils Analysis byCapillary Chromatography and Carbon-13 NMR Spectroscopy

, John Wiley & Sons,New York, 185, 1982.

7. Kesterson, J.W., Hendrickson, R. and Braddock, R.J., Introduction, review of litera-ture,

Florida Citrus Oils

, technical bulletin 749, Gainesville, FL, 3,1971.8. Heath, H. B, London, England and Reineccius G., Dept. of Food Science and Nutri-

tion, University of Minnesota, St. Paul,

Minnesota, Flavor Chemistry and Technology

,England, 1986.

9. Florida Chemical Company, Inc., Folded orange oil, www.d-limonene.com/datasheets/foldedorangeoil.html, (retrieved October 6, 2004).



http://www.reviewpe.com/

http://new-list.com/?Serene-Aromatherapy:-Infuse-Your-Life-With-Excellence&id=4519

http://www.myers-vacuum.com/

http://www.d-limonene.com/

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