Pulp Fiction or Fact The process of orange juice

The idea of juicing oranges has been in existence for

hundreds of years. Orange juice is such a common product

that one can incorrectly assume that the manufacturing

process is simple. The process is far from simple. Every day

thousands of gallons of orange juice are processed at many

different processing plants in order to satisfy consumer

demand. Many different varieties of oranges are blended to

make an orange juice with superior flavor. Oranges must be

graded, washed, and juiced. The juice must then be filtered,

pasteurized, and bottled before it is ready for consumers. The

manufacturers must be careful to ensure compliance with

many USDA and FDA regulations while providing

consumers with a likeable product. There are many

innovative uses for orange juice waste including using it as

animal feed or for ethanol production. This paper follows the

manufacturing process of orange juice in an attempt to give

the reader a holistic view of the process.

Lindsey Blanchard

Michael Dennis

Samantha Vallette

3/7/2008

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Table of Contents

ABSTRACT 1

OBJECTIVE 3

INTRODUCTION 3

BUYING ORANGES 5

PROCESS OVERVIEW 6

UNIT OPERATIONS 9

ORANGE PRESSING 9

FILTRATION 9

CENTRIFUGATION 12

CONCENTRATE V. FRESH 12

PASTEURIZATION 13

GRADING 14

WASTE 15

PACKAGING CONTAINERS 17

COST ANALYSIS 19

CONCLUSION 20

WORKS CITED 22

APPENDIX 26

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Objective

The objective of this project is to design a theoretical processing plant capable of

processing 500 oranges/minute into orange juice. This plan includes using only raw Valencia

oranges. Through this process, our plant should produce pulp-free, fresh (not from concentrate)

Valencia orange juice.

Introduction

Oranges are the bright, familiar fruits that stand out at the grocery store. However,

oranges make a long trip from the grove to the store shelves. Oranges are the fruits of

semitropical non-deciduous trees (Schultz). Oranges thrived in the 1820‟s when Florida became

a territory of the United States and by 1910 Florida was becoming the top citrus growing state

(Schultz, Oranges: Blood, Moro, Maltese and More). Oranges, in the U.S., are the third most

popular fruit, following bananas and apples (Schultz, Oranges: Blood, Moro, Maltese and

More). Today, there are five main categories of oranges: Round, Navel, Blood, Acid-less, and

Biter (Schultz).

Types of Oranges

There is a vast variety of oranges that are grown commercially. The most familiar to

juice making are Navel, blood/Moro, and Valencia. To make orange juice, different orange

breeds are mixed together to achieve the right taste (How is Orange Juice Made?). Navel

oranges are probably one of the more popular varieties; they are known for their secondary fruit

at the bottom of the other two halves. This is what makes the “navel” at the bottom of these

oranges (Sauls). They are grown through grafting a bud from an original navel. Valencia

oranges are best known for their amazing juice quality. Valencias tend to be large with a thick

peel and those sold as crops are typically seedless. Blood/Moro oranges are sometimes called

“blood” or “ruby” oranges, Moro oranges are known for the deep red coloration of their fruit

(Sauls). The pigment stems from high concentrations of anthocyanin. Anthocyanin is an

antioxidant known for combating against free-radicals (Our Fruit). A comparison of these types

of oranges can be viewed in Table 1.

Type of Orange Navel Valencia Blood

Seeds none Usually none Few

Appearance Have „navel‟, large Thick peel, large Blood red color

Taste/Quality Good Very good Good

Table 1: Comparison of orange types (Schultz and Huntrods).

Currently, Brazil and the U.S. over shadow all other countries in orange juice production

and 98% of the U.S. crop comes from Florida (Market Technologies, LLC.). Likewise, Brazil

makes up 80% of the FCOJ export market.

Health Benefits

Oranges are sold commercially for their delicious taste and obvious health benefits. For

example, a six-ounce glass of orange juice meets the following nutrient recommendations: more

4

than 100% vitamin C, 35% folate, 12% potassium, 34% thiamin, and a variety of phytonutrients

(FlordiaJuice.com). Other than these basic vitamins and nutrients, orange juice has been found

to provide other many health benefits

One example of a study done on the benefits of orange juice is its affects on kidney

stones. Kidney stones form due to minerals and other chemicals become over concentrated in

urine (Chang). These particles glom together to form painful stones in the body (Chang).

Potassium citrate supplements are often prescribed to aid in slowing the stones (Chang). Citrate

decreases the acidity of urine which prevents kidney stone formation (Chang). However, come

people cannot tolerate the supplements due to gastrointestinal side effects; these people can

drink citrus juices as an alternative, natural source of citrate (Chang). A daily glass of orange

juice has been shown to prevent recurrent kidney stones better than other citrus juices such as

lemonade (Chang). One reason orange juice may be more effective than other juices is because

the citrate is accompanied by a potassium ion; lemonade and cranberry juice contain a proton

which may counteract their acid-lowering effects (Chang).

History

Although anyone can squeeze an orange and produce orange juice, because it is a fruit

juice, orange juice does not stay fresh for very long. This first became a wide spread problem

during war time (The History Channel ). Nutritious foods were needed to supply the armies.

During the late 1700‟s, the Emperor Napoleon Bonaparte had problems keeping his troops fed

and offered a prize for anyone who could find a way to preserve food (Chesswood). People tried

pickling and drying but both altered the taste and were undesirable options (The History

Channel ). Nicolas Appert, a French confectioner, found that if you seal food in glass jars and

then boil it for several hours, the shelf life increased drastically (Chesswood) (The History

Channel ). He won the prize, and around 1806 his methods were implemented by the French

Navy on a variety of foods (Chesswood) (The History Channel ). However, it wasn‟t until 50

years later that Louis Pasteur explained why Appert‟s method of heating food stopped it from

spoiling (Chesswood). He demonstrated that the growth of microorganisms caused food to spoil

(Chesswood). During WWII, scurvy, which is caused by a lack of vitamin C, was a major

problem for troops worldwide (The History Channel ). The army approached Florida scientists

for help (The History Channel ). From this, frozen concentrated orange juice (FCOJ) was born

in 1947 (The History Channel ). In 1948, a patent was filed by Florida researchers who added

10% fresh juice to the final product instead of water to help restore the fresh orange juice flavor

(Matthews, Frozen Concentrated Orange Juice From Florida Oranges). The juice was

pasteurized under low heat and a high vacuum and then water was added to return it to juice

(The History Channel ). This also enabled orange juice to be available in the U.S. year round

(The History Channel ).

This method was improved upon by Anthony Rossi in 1954 when he created flash

pasteurization for the Tropicana Orange Juice company (Tropicana). This process raises the

temperature of the juice for a much shorter time, therefore, making it safe for an extended shelf

life (Tropicana). This new, faster method allowed consumers to taste the first pure, not-from-

concentrate orange juice (Tropicana).

5

Buying Oranges

Oranges are sensitive to weather conditions and since they are grown in semi-tropical

regions, hurricanes, drought in Brazil, and frost and freezes in Florida can be disastrous to the

crop (Market Technologies, LLC.). When impending weather occurs, orange juice prices rise.

For example, in 2006, the average price of a gallon of orange juice was 14% higher than

previous years when the prices had been relatively steady (MARTIN). This was due to the

hurricanes Charley, Frances, and Jeanne which bludgeoned the state; they uprooted trees and

nearly ripened fruit was flown off the trees or damaged in almost every grove across the state

(MARTIN). To make matters worse, citrus canker disease spread across the state from Dade

County due to the winds and about 10% of the state‟s groves have had to be burned to stop the

spread of the disease (MARTIN). Normally, the industry plants new trees in response to

weather disasters; however, that year, the numbers could not be salvaged on such a large scale

(MARTIN). See Chart 1 for the orange production by year in the U.S. for the last ten years.

Chart 1: Orange production in the U.S. (United States Department of Agriculture).

The dip in production between 2005 and 2007 was due to hurricanes and other weather

conditions. The effect of weather can also be illustrated by Chart 2 which shows the acreage

used to grow oranges on a per year basis. One reason the acreage tapers off between 2005 and

2007 is because of damage and disease. Besides weather and disease problems, other factors

such as processing capacity and strength of the U.S. Dollar affect FCOJ supplies (Market

Technologies, LLC.).

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Chart 2: Acres used for orange growth in the U.S. per year (United States Department of

Agriculture).

Oranges for juice processing plants are typically bought directly from the grove. The

price is agreed upon by the grower and plant depending on the quantity being purchased and

their personal standings. Usually, a contract is agreed on to purchase however many oranges per

season and the price is negotiated for each shipment. The price of oranges varies from season to

season due to weather effects. Harsh freezes cause fewer oranges to bloom and therefore the

prices will rise. Because of this unstable market, it is difficult to make a budget and accurately

account for the cost of oranges. Assuming Valencia or Navel oranges are used, plants can

expect to pay between $7 and $10 per carton (a carton is about 40 oranges depending on fruit

size) (Muzzi) (Blake). Therefore, to meet a 500 oranges/min processing rate, 12.5 cartons are

needed for an approximate price of $125 (this is rounded up to account for variation in cost,

size, and damaged fruit).

Processing Overview

Oranges sold in the U.S. come from two main locations: Brazil and Florida (Market

Technologies, LLC.). This is due to the fact that they have inverse growing seasons and,

therefore, can supply the market year round (Market Technologies, LLC.). Florida oranges

typically bloom between March and April and must ripen on the tree; although, there are early

and late varieties, oranges typically mature between December and February (Townsend).

Orange groves are tested for quality by taking samples. About 40 oranges per 40 acre section

are tested (Townsend). The first step of extraction is removing the oranges from the orange

trees. This is a delicate process. Harvesters must find a way to remove tons of oranges in a short

amount of time. They must also not harm the orange tree so that it can be used again in the next

season. Oranges must be picked up directly from the tree. Any fallen fruit cannot be used

because of pathogen risk and must be discarded ( U.S. Department of Health and Human

Services). Growers harvest oranges by two main methods: handpicked or mechanically picked

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(Townsend). Those that are handpicked are done so by a crew of harvesters using ladders and

canvas sacks (Townsend). This procedure requires the cost of labor as well as time. Yet, human

workers can pick oranges of precise size and maturity levels. They can reach to get oranges

close to the tree trunk. They do not require work or maintenance. Even though this is not

entirely economically efficient for commercial use, in Florida, 96% of oranges are still

handpicked (Townsend). This may be because human laborers tend to damage far less fruit than

their mechanical counterpart (California). There are three types of machines used for

mechanical picking: continuous canopy shake and catch system, trunk shake and catch system,

and tractor-drawn continuous canopy shaker (Townsend). All of these methods gently shake the

fruits out of the trees and are caught gently by cloth catchers. Using machinery to pick oranges

can be advantageous. Machines are used because they can work much faster than human

pickers. In fact, the Oxbo 3220, a harvesting machine, can harvest at a rate of eight seconds per

tree. A pair of machines can collect about a million pounds of fruit in one day. The Oxbo 3220

and other Oxbo harvesters use 12 sets of tines that are about 6 ft in length. A conveyor belt is

uses to transfer the oranges to a catcher in the back of the vehicle. Also, on the Oxbo 3210

model, there are 4 powered sweeps that allow the tires to pass without ruining the fallen oranges

(Oxbo Citrus Harvester Features). There are a few disadvantages. The machinery does not

collect all the orange available for picking. Also, there are few, if any, machines that can

distinguish between mature and rotten fruit. As of now Oxbo is working on another Citrus

harvester, model 3200, that will separate ripe oranges from bad oranges (Oxbo Citrus Harvester

Features). The cost of using machinery is also an issue. Even though they are expensive, their

upfront high cost eventually pays for itself. Each type of mechanical picker deposits the oranges

into plastic tubs that can hold approximately 900 lbs of oranges (Townsend). The tubs are then

emptied into a special truck called a “goat” by a hydraulic boom (Townsend). The oranges are

then hauled off to a processing plant (Townsend).

Of all the oranges harvested in the U.S., 70% of them are processed for orange juice

(brokersXpress, LLC.). When the fruit leaves the groves and it brought to the processing plants

they are weighed on scales to determine payment to the grower (Townsend). The oranges are

then funneled onto a conveyer belt for inspection (Townsend). There are three agencies that

directly regulate the Florida orange juice industry: the Florida Department of Citrus (FDC), the

Florida Department of Agriculture and Consumer Services (FDACS), and the U.S. Department

of Agriculture (USDA) (Matthews, Frozen Concentrated Orange Juice From Florida Oranges).

A representative sample of about 40 lbs (roughly 18 kg) is taken from the belt to test for juice

content, maturity, and to certify the pounds solid per box (units used to determine grower‟s

payment) (Townsend) (How is Orange Juice Made?).

In order to maintain consistency, a brix measurement is taken at the grove, once the

oranges enter the plant, and during processing (Townsend). Brix is the total soluble solids

measurement which primarily includes: sugars such as sucrose, fructose, and glucose, citric

acid, and minerals (Matthews, Frozen Concentrated Orange Juice From Florida Oranges).

Measurements are taken by hydrometers which measure specific gravity which is then reported

in “degrees Brix” and is equivalent to the percentage of soluble solids (Matthews, Frozen

Concentrated Orange Juice From Florida Oranges). Generally, FCOJ is kept at about 65° brix

(65% solids) whereas NFC is at 12°. FCOJ is usually stored and separated by variety and ratio

of brix to acid range (which determines the flavor of the juice) (Townsend) (Townsend). Acid

measurement is the total titratable acidity or the total acid in the juice which is found by using a

titration method using sodium hydroxide and phenolphthalein indicator (Townsend) (Matthews,

8

Frozen Concentrated Orange Juice From Florida Oranges). These acids include: citric acid (the

majority), malic acid, and tartaric acid (Matthews, Frozen Concentrated Orange Juice From

Florida Oranges). The brix to acid ratio is simply the brix value divided by the acid content and

can be viewed in Equations 1, 2, and 3; this ratio must lie between 12.5 and 19.5 (Matthews,

Frozen Concentrated Orange Juice From Florida Oranges).

Equations [1], [2], and [3]: These equations are used to calculate orange juice quality.

Once the sample is approved, the rest of the oranges are loaded onto the conveyor belts.

These transporters come in different materials but basically do the same function. Black 150

RMA Grade, White 150 RMN Grade, Black and White PVC, and White Nitrile are a few types.

Most importantly, for food handling, these materials are resistant to food oils (Food Products

Applications). From the conveyor belt, the oranges go through the washer. A washer rinses fruit

to remove impurities such as pesticides, dirt, and bacteria (How is Orange Juice Made?). They

are usually made of stainless steel and are composed of a trough attached to the conveyor belt

(Veenu Hitech). The rinse is made of a general detergent. Human graders watch the conveyor

belt and pick off bad, rotten oranges that do not meet standards. The healthy oranges go on to

get separated by size for extraction where, during juicing, the peel is pricked to extract natural

oils (Townsend) (How is Orange Juice Made?). Then, by some various process, the juice is

extracted. Only about 50% of the fruit is actually juice, the rest is peel, pulp, and seeds

(Matthews, Frozen Concentrated Orange Juice From Florida Oranges). Next, the juice and pulp

mixture is filtered and the waste products are diverted to be used for by-products (Townsend).

Here, the juice is separated depending on whether it is to be FCOJ or Not From Concentrate

(NFC) (Townsend). If the juice is to be FCOJ then it goes to the evaporators which remove

most of the water by vacuum heating, the remaining juice sugars and solids are then stored and

chilled (Townsend) (Matthews, Frozen Concentrated Orange Juice From Florida Oranges).

Otherwise, the orange juice enters the pasteurizer the juice is heated to deactivate natural

enzymes which aids in maintaining quality of the juice (Matthews, Frozen Concentrated Orange

Juice From Florida Oranges).

The juice is then packaged into cardboard cartons, glass, or plastic jugs to be sold

commercially (Townsend). All forms (FCOJ, RTS, and NFC) of orange juice are always

pasteurized before sale to prevent contamination (Townsend). FCOJ has very little loss of

nutrients, such as vitamin C (only about 2%), which is lost during extraction, concentration, and

freezing due to maintaining its high brix level (Matthews, Frozen Concentrated Orange Juice

From Florida Oranges). FCOJ is produced in about 35 Florida processing plants which have

extremely efficient machinery (Matthews, Frozen Concentrated Orange Juice From Florida

Oranges). A typical extractor machine processes 400 to 700 oranges per minute and go through

over 100,000 boxes (one box is 90 pounds of oranges)of oranges each day (Matthews, Frozen

Concentrated Orange Juice From Florida Oranges) (MARTIN). This is around 517,000 gallons

of orange juice per day, which could supply 17,000 people with orange juice for a year

(Matthews, Frozen Concentrated Orange Juice From Florida Oranges).

]3[Acid

BrixRatio [2]

juice

acidsother acid citricAcid [1]

solution total

solids soluableBrix

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Processing Unit Operations

Orange Pressing

Extraction, for oranges, involves the separation of the liquid juice from the solid pulp

and peel. The process must be done correctly or the juice may become infected with pathogens

from the exterior peel ( U.S. Department of Health and Human Services). There are different

ways to extract the juice. For industrial use quick, effective and low maintenance extractors are

best.

One procedure in industrial use is taking two metal cups and squeezing the orange.

There are metal tubes on the bases of these cups that will collect the solid pulp and peel as the

squeezed juice will run over into holes in the bottom tube. Also, water is sprayed to wash away

usable oil on the orange peel at that exact moment. Another type of industrial juice extractor

cuts the orange in half with a knife on the conveyor belt then grabs the oranges with rubber

suction cups. The oranges are juiced using plastic serrated reamers. In this method, oil from the

peel is extracted by pricking on the surface and washed out by water. Peelings can be cut off

and cleaned in about 3 seconds (How is Orange Juice Made?).

Even though they are effective, equipment can be expensive. For instance, Zama

Enterprises has an extractor known as the Zumex 450 that turns out at least 300 - 350 liters/hour

for a fruit diameter of 60 to 70 mm. It includes an automatic orange feeder, peel collections

stand, adjustable juicing head, and nine-cavity pressing unit set (Zama Enterprise). A typical

goal for a processing plant is 500 oranges processed per minute. Yet, this machine is not fast

enough for the 500 oranges per goal. In fact, the process calls for 7,981.58 liters/hour output. At

least 23 Zumex 450‟s would be needed to accomplish this goal. At about a retail price of

$50,000 per juicer, the cost would be around $1.2 million.

Once the juice has been extracted, the process has only just begun. From the extractor,

the juice must be separated from solid pulp, seeds, and left-over peels to liquid juice. There are

two ways to accomplish this – filtration and centrifugation. Both methods separate juice from

pulp and seeds, but in very different ways.

Filtration

Filtration is used to take insoluble solids and separate them from a liquid mixture

through a membrane (or septum) that allows the liquid to pass through but not the solid

(Sabliov). Filtration of orange juice will allow the liquid juice to be absent of pulp, leftover

seeds, and peels from extraction. Pure liquid juice is needed for purification steps such as

pasteurization. Even if pasteurization does not occur, the pulp should be added later so that it

can be measured to the correct percentage of orange juice for consumers.

Mesh screens, sometimes called finisher screens, are a very direct and simple way of

filtering out seeds and pulp (Morris). The screen contains tiny holes about 0.5 to 2.5 mm in

diameter. The holes must be this small or seeds will seep through into the liquid (Strobel). The

pulp and seeds that are not used for juice are usually made into citrus pulp pellets that are used

for animal seed. If the pulp is of high quality, it is called “orange cells” and is used to make

pulpy orange juice after pasteurization (Orange Processing Industry).

Ultrafiltration is a pressure driven type of filtration (Sabliov). It involves forcing

molecules of small molecular weight (i.e. <10³ Da) through a semipermeable membrane

10

(Ultrafiltration). Molecules with molecular weights of 103 to 10

6 daltons do not pass through

and form a layer on the top of the membrane known as filter cake. For biological materials such

as orange pulp, the cake is known as compressible cake and the time it takes to filter a certain

volume of orange juice depends on the pressure used during the process (Sabliov). For

clarification, pure juice is called filtrate during ultrafiltration. The time it takes to filter can be

found using Equation 4.

𝛼 = 𝛼 ′ ∗ (Δ𝑃)𝑆 𝑡 =𝜇𝛼 ′

2Δ𝑃∗ 𝜌0 ∗

𝑉2

𝐴2 [4]

where: α‟ = average specific cake resistance constant. It is dependent on the size

and shape of the particle.

ΔP = change in pressure

s =compressibility of the cake (between 0.1-0.8)

µ = dynamic viscosity

ρo = mass of the solid cake/volume of the filtrate

V = total volume of the filtrate

A = cross-sectional area of bed (membrane)

T = time

Equation [4]: This equation is used to find the filtering time for any given material.

After a certain amount of time, the filter cake must be removed. For batch processes

which stop production after a certain amount of material is finished a step, this can be done once

filtration is completed. For continuous processes, the cake must be removed constantly. This

can be done using a blade that scrapes the cake off after a given amount of orange juice has

been filtered. Currently, ultrafiltration is mostly used in labs (Ultrafiltration

(Industrial)).Therefore, batch processes are common.

Ultrafiltration has many good qualities. Processes using membrane tend to be cheap and

easy to clean. They refrain from altering the chemical and physical composition of the material.

Enzymes utilization is lowered and there is no need to use gelatins, absorbents or other filtering

aids. Also, the amount of juice produced in higher than most juice production methods. Faulty

characteristics of ultrafiltration include the build-up and clean-up of the cake on the membrane

and pore-clogging on the membrane which lead to concentration polarization. This refers to the

time when the permeate flux decreases and a steady-state value is reached. This effect can

decrease the re-use value of the membrane (Cassano, Marchio and Drioli). Permeate flux is

determined by a derivation of the Darcy model equation (Equation 5) as seen in Equation 6 for

membrane flow. The general index ranges from 2 to 0. A 2 refers to complete poor blocking

whereas a 0 means that the pores are not blocking and instead a cake is forming with good flow

of the filtrate (Cassano, Marchio and Drioli). The reason this method is usually used in labs and

not in high production may be that the cake is too hard to control during large amounts of juice

manufacturing.

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(5) Darcy‟s Equation of Membrane Operations (6) Field Model for permeate flux in

orange juice

𝐽 =∆𝑃 − ∆𝛱

𝜇 𝑅𝑓 + 𝑅𝑚 5 −

𝑑𝐽

𝑑𝑡= 𝑘 × 𝐽 − 𝐽𝑙𝑖𝑚 × 𝐽2−𝑛 [6]

where: J = volumetric flux (m/s)

ΔP = hydraulic pressure difference between the feed and permeate sides

of

the membrane (Pa)

ΔΠ = osmotic pressure difference between the feed and permeate sides of

the membrane (Pa)

μ = dynamic viscosity (Pa-s)

Rf = fouling resistance (m − 1)

Rm = membrane resistance (m − 1) (Darcy's Law)

t = time (s)

J lim = limit value of permeate flux at steady-state

K = phenomenological coefficient

n = general index

Equations [5] and [6]: The equation for permeate flux in orange juice as derived from the Darcy

Equation.

Reverse osmosis is another pressure driven membrane filtration process. However,

instead of having a cake with particles of large molecular weight, light molecules are kept back

using a concentration gradient. The procedure uses reverse osmosis, a process in which high

concentration regions go toward low concentration regions (Sabliov). A membrane is placed

between the orange juice and the low concentration area in a plate and frame set-up. Due to high

osmotic pressure in orange juice, a large pressure (between 10 and 200 bars) is used for reverse

osmosis to occur. Permeate flux in reverse osmosis also uses a derivation of Darcy‟s Law

(Equation 7).

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𝐽 =𝑉

𝐴×∆𝑡 [7]

where: J = volumetric flux (mm/s)

V = volume collected during a time interval (mm³)

t = aforementioned time interval (s)

A = area of the membrane surface (mm²)

Equation [7]: Darcy‟s Law

The process has the advantage of low temperature use. High temperatures can denature the

nutrients in orange juice as well as alter the taste and smell. However, reverse osmosis requires

high pressure and even then, may not be able to overcome the juice‟s osmotic pressure.

Normally, reverse osmosis is used with other processes, such as ultrafiltration, described above,

or microfiltration (Jesus, Leite and Silva) which uses pore size to filter orange juice (Sabliov).

Centrifugation

Centrifugation is usually used after filtration as a way of purifying the orange juice. It

lowers the pulp content even more, solidifying a pure liquid product (Orange Processing

Industry). More dense content in a centrifuge gravitates toward the outside of a cylinder while

less dense product stays proximal to the centrifuge‟s rotating axis. The heavy material, like

pulp, will cake together on the outside of the cylinder for prompt removal. For orange juice, the

mostly likely use of a centrifuge is a basket centrifuge. They are comprised of a deep cylindrical

bowl that rotates around a horizontal or vertical axis. The rotation causes a solid cake to form on

the perforated sides of the cylinder. The cake is scraped off periodically with a knife and water

is sprayed inside to keep the process continuous (Singh). An example of a basket centrifuge is

the Mitsubishi Vertical Basket Centrifuge Model VZ-T. It is a top-direct driven centrifuge

which means the top descends into a basket cylinder and can come up for cleaning and

maintenance. The centrifuge has a changeable inner diameter and a raking knife that removes

the cake in one sweep. The change in diameter and its effects on other parameters are seen in

Table 2 (Mitsubishi Vertical Basket Centrifuge).

Model Inside

diameter

(mm)

Capacity

(L)

Filtration

area (m2)

Speed(rpm) Centrifugal effect

(G)

VZ20T 535 35 0.59 1800 950

VZ42T 1070 260 2.4 1160 800

VZ48T 1220 600 3.8 1080 800

Table 2: Basket centrifuge specifications.

Concentrated v. Fresh Orange Juice

After filtration, orange juice can take two different paths – concentrate or non-

concentrate. Bulk frozen concentrated orange juice, also known as FCOJ, is a highly used form

13

of concentrated orange juice. It allows for storage of orange juice for a large amount of time.

Yet, much of the taste of fresh orange is lost during evaporation in order to get the concentration

form. Therefore, a small amount of fresh orange juice is added to the concentrated frozen form,

allowing the fresh taste to be restored (Matthews, Frozen Concentrated Orange Juice From

Florida Oranges). The process takes several steps. First, the pure liquid orange juice is put in an

evaporator which will remove most of the water content. The orange juice goes from a soluble

solid concentration of 12°Brix to 65°Brix (Matthews, Frozen Concentrated Orange Juice From

Florida Oranges). The concentrated juice is then frozen at less than or equal to 20 °F in a tank or

55 gallon drums. When concentrate is needed to make juice for sale it is mixed with fresh

orange juice or water and flavor oils to bring it to about 42°Brix. It is then packaged and frozen

for sale in 6, 12, or 24 ounce cans. For consumer use, frozen concentrate is turned into chilled

reconstituted ready-to-serve orange juice or recon RTS OJ as it is known (Morris). The frozen

concentrate is combined with 3 volumetric servings of water to bring the mixture to 11.8°Brix

(Matthews, Frozen Concentrated Orange Juice From Florida Oranges). FCOJ must meet strict

standards. The rating is called grading and includes scoring on appearance, defectiveness, flavor

and color. For Grade A FCOJ must not have an added sweetener and the ° Brix must be from

the orange juice only (Matthews, Frozen Concentrated Orange Juice From Florida Oranges).

If the orange juice is chosen for non-concentrate use, it is brought to a centrifuge after

filtration to remove oils. The levels of oil are then between 0.02% and 0.4%. After the

centrifuge, the not-from-concentrate, also known as NFC, orange juice is pasteurized and/or

chilled, then packaged. Sometimes, the juice is frozen in 55 gallon drums for storage. Yet, it can

also be chilled in stainless steel aseptic tanks or even chilled in plastic bags with a capacity of

around 300 gallons that are in 4ft by 4ft wooden boxes (Morris).

Pasteurization

One of the most important steps in orange juice manufacture is pasteurization. Because

orange juice is usually consumed directly without any cooking, it is important that the bottled

product is safe for human consumption. All processes regarding orange juice produced and

distributed in the United States are regulated by the Food and Drug Administration (FDA). In

2005, Orchid Island Juice Company of Fort Pierce, Florida recalled all of their unpasteurized

orange juice after it was suspected to be contaminated with Salmonella Typhimurium. (Orchid

Island Juice Company) The term “pasteurization” is used loosely to indicate the killing of

pathogens, but the FDA refers to this process as “Pathogen Reduction.” (FDA 21CFR120)

The FDA requires that all orange juice manufacturers achieve a 5-log (105)

pathogen

reduction standard. In order to reach this standard, the company must first do a thorough

inspection of its product to determine the types of pathogens that may be in the product. The

company must then take steps to insure that a 5-log pathogen reduction is met and kept for as

long as the product will be on retailer shelves. The FDA requires that the 5-log reduction is

accomplished in at least one of two ways. The first type of reduction can be accomplished with

direct thermal processing of the orange juice in one step. (FDA 21CFR120) This is usually

called pasteurization. In this step, the orange juice is directly heated to a temperature that will

kill the pathogens but not hurt the product. Many manufacturers “commonly pasteurize for 16

seconds at 165°F or 1 second at 185°F.” This method is has a large production capacity and is

well known and understood. However, pasteurization can give some orange juice a “cooked”

taste. For this reason, some manufacturers prefer not to pasteurize their product. (Kuntz)

14

Another pathogen reduction technique allowed by the FDA is the treatment of fruit

surfaces. Because most pathogens are found on the surface of the fruit, treatment of the fruit

surfaces can also be effective in reducing pathogens. The manufacturers must ensure that their

product is safe for human consumption. The FDA mandates that processing facilities test their

final products on ensure safety. The following test, or one of equal accuracy, must be

performed for every 1,000 gallons of orange juice produced. The samples are taken from

random juice containers that are ready for consumers. The following steps are then performed:

“(1) Sample size. Total-20 mL of juice; perform analysis using two 10 mL aliquots.

(2) Media. Universal Preenrichment Broth (Difco, Detroit, MI), EC Broth (various

manufacturers).

(3) Procedure. Perform the following procedure two times:

(i) Aseptically inoculate 10 mL of juice into 90 mL of Universal Preenrichment Broth (Difco)

and incubate at 35 deg. C for 18 to 24 hours.

(ii) Next day, transfer 1 mL of preenriched sample into 10 mL of EC Broth, without durham

gas vials. After inoculation, aseptically add a ColiComplete SSD disc into each tube.

(iii) Incubate at 44.5 deg. C for 18 to 24 hours.

(iv) Examine the tubes under longwave ultra violet light (366 nm). Fluorescent tubes indicate

presence of E. coli.

(v) MUG positive and negative controls should be used as reference in interpreting

fluorescence reactions. Use an E. coli for positive control and 2 negative controls--a MUG

negative strain and an uninoculated tube media.

If either 10 mL subsample is positive for E. coli, the 20 mL sample is recorded as positive…”

(FDA 21CFR120)

If a positive result is recorded. The processing plant must halt operations and trace the

contamination to its source. Only after the problem has been diagnosed and fixed, can the plant

resume operations. Strict guidelines such as those above help to ensure the safety of the product

for consumers. A number of new pathogen reduction processes are being researched to possibly

improve flavor while retaining safety. (FDA 21CFR120)

Grading

The USDA has set guidelines to help consumers determine the quality of the orange

juice that they are purchasing. Every orange juice processing plant has an overseer from the

USDA who monitors all of the plant‟s operations. This official is responsible for monitoring

the quality and safety of the orange juice. One way that the official does this is by grading the

orange juice that is processed. The official inspects all aspects of the orange juice to determine

the grade. The orange juices can be graded as grade A, grade B, or substandard. Table 3 is an

example of specifications used to grade frozen concentrated orange juice.

15

Table 3: Grading specifications for FCOJ (United States Department of Agriculture).

Waste

In any manufacturing process, there are waste products. In orange juice manufacturing

there is a large amount of waste since only 50% of the orange is juice. This waste consists of

the orange peel, inner fibers, seeds, and often the pulp (see Figure 2). While the pulp can be

gathered and put back into the juice for pulpy juice, the other waste products cannot be used for

the juice manufacture. Luckily, the wastes are biodegradable and generally do not pose

16

environmental hazards. However in order to offset costs, and in some instances generate

profits, orange juice manufacturers must find good uses for their waste products. Currently,

approximately 3 million tons of this waste is produced each year by citrus-processing

companies (Society).There are two main options for disposing of this waste material. The first is

to burn or throw it away. This method, however, is wasteful and beneficial to no one because

burning it produces potentially harmful gasses and throwing it away just adds to buildup in

landfills. The other option is to sell it for practical uses.

Figure 2: Parts of an orange (Mathews).

The most popular use for orange juice waste is animal feed. The waste is grinded,

dehydrated and pelletized in a fairly simple and cheap process. The feed can then be sold to

livestock farmers. “It is, in fact, for this reason alone that Florida has long been one of the

states with the most beef cattle finished in feeder lot operations in the United States.” The Tico

Fruit processing plant in Costa Rica is another example of a processing plant that makes a profit

by processing its waste in this manner. (WWF) The liquid portion not used for cattle feed is

converted to molasses which can be sold to beverage companies (Society). Since orange juice

waste is worth approximately 2-4 cents/lb this is much more profitable than simply discarding it

as waste since the plant would have to pay to have the waste removed anyway (Society).

With the current demand for fuels such as ethanol steadily increasing, it makes sense

that some companies would try to use orange waste products for ethanol production. In 2007,

Florida Power and Light (FPL) announced that it would be building an ethanol production plant

in Hendry County, Florida that utilized orange waste. The plant will be using technology

developed by Citrus Energy. Yeast will be used to ferment the waste and ethanol will be

extracted. This method is more efficient and therefore cheaper than producing ethanol using

corn. FPL estimates that the plant will produce four million gallons of ethanol every year. That

ethanol will be blended with gasoline to produce an estimate 60 million gallons of fuel yearly.

FPL believes that the plant would make the company “a national leader as it relates to ethanol.”

(Klas) Ethanol production is currently being researched as an alternative to petroleum fuels

(Society). Using just citrus waste products, 50 million gallons of ethanol could be produced per

17

year (Society). Since this process is still being developed and refined, most processing plants

opt to sell their waste to cattle feed production.

Pectin, which is used to manufacture jellies and jams, can also be extracted from pulp

waste. Also, a number of oils can be extracted. For example d-limonene has good solvent

properties and can be sold as an industrial cleaner. Hesperidin and other flavonoids along with

anthocyanins and hydroxycinnamates are found in orange peel. These compounds are highly

sought after by the pharmaceutical industry for possible uses. They are also used in health

products as antioxidants. The seeds also have antibacterial and fungicidal properties. Research

is currently ongoing to determine the best ways to extract such products in order to maximize

yield and profits. (Grohmann) (Scordino)

Currently, during the orange pressing phase of orange juice processing, the peels are

pricked and oil is removed by the pressing machines. This oil is a combination of a-pinene,

sabinene, myrcene, limonene, linalool, citronellal, neral and geranial (Concepts). The raw oil is

then cold pressed, distilled, and extracted using first solvent and then supercritical fluid

extraction (Services). This isolated oil can then be sold for perfumes and other scent uses such

as candles, shampoos, or aromatherapy. Since plants usually only yield between 0.01% and

2.0% essential oil and isolation requires many steps, essential oils sell for about $3.00 per ounce

but price varies with purity (Services) (Sourcing). Because of this high price, it is in an orange

processing plant‟s best interests to collect and sell the essential oil. Therefore, most

commercially sold juice extractors come with built in components that collect the oils. Sale of

this oil can be done in the raw or processed form. The difference between the two sale varieties

is the amount of money and work that the plant wants to spend. If the plant sells the oils raw

then they will not be able to sell it for as much as if they spent the money on processing

equipment and man power to isolate it and sell it.

For the purposes of this process, the dried wastes will be sold for cattle feed production,

the liquid will be sold for molasses production, and the essential oils will be sold raw. It will be

assumed that no further processing of waste products will be done on site further than waste

removal. The waste products will be sold in their raw form to be processed at another plant.

This is due to the excess equipment, man-power, and other considerations that these extra

processes entail. Therefore, for cost analysis purposes, the raw prices will be used.

Containers/Packaging

The type of packaging used to store orange juice is an important factor in preservation of

quality. The most popular types of packaging for refrigerated orange juice include glass,

plastics, and lined cardboard. Ideally, a number of different qualities should be preserved in

the orange juice. The most important factor in packaging is maintaining a sterile environment.

A sealed container must not allow the introduction of microbes into the juice. Such an

occurrence would lead to spoiled and contaminated product and would be potentially

dangerous. All modern containers are filled and sealed in sterile environments to ensure that the

product is not contaminated. These containers are good barriers against microbes as long as

their integrity is maintained. Another factor to be considered is vitamin and color degradation.

Vitamin C is very fragile and will degrade easily after exposure to light, heat, and oxygen.

(Cisneros-Zevallos) The color of the orange, an important selling point, will also degrade under

similar conditions. In order to maintain vitamin C levels opaque plastic or cardboard containers

18

are generally preferred. Glass containers tend to allow too much light to pass through and

degrade the vitamin C as well as degrade the color of the orange juice to a brown color.

(Sajilata)

The loss of flavor compounds is also an important consideration. Glass containers

generally do not adsorb flavor compounds in the orange juice. The same cannot be said for

plastic containers. Over time, the flavor compounds interact with the plastic and are lost. This

of course is not good for consumers. PET (polyethylene terephtalate) is a plastic that has shown

good qualities regarding the preservation of flavor compounds. (Ducruet) Another factor to

study is the cost of packing. Glass is generally the most expensive with plastic and cardboard

being less expensive.

As far as maintaining the ideal temperature, heat flux must be considered when choosing

a packaging material. Heat flux is a property of a material that considers the thickness and

thermal conductivity. Thermal conductivity is a variable which corresponds to the amount of

heat a material can pass from one side of it to another. Heat flux can then be multiplied by the

total area of a package to determine the amount of heat that will transfer through that packaging

and infiltrate the product. The lower the heat flux, the less heat will damage the product. It was

found during an experimental procedure that glass has the lowest heat flux when compared to

clear plastic, wax paper, and aluminum (L. Blanchard). Plastic, wax paper and finally aluminum

followed behind respectively. However, glass is fragile and expensive. Therefore, for this

process, plastic will be used as a packaging material since it is relatively inexpensive and had

the second lowest heat flux. It is important to note that the aluminum had a heat flux of

significantly higher; this is because it is a metal, and therefore, a good conductor. For this

reason, FCOJ is typically stored in aluminum packaging. This is because heat travels very well

through it. Therefore, when placed in a freezer it will freeze very quickly and maintain its

quality while frozen. Likewise, when removed from the freezer to thaw for consumption, it will

thaw fairly quickly since the heat will penetrate the container well.

The FDA also restricts the labeling that appears on the containers. The following rules

must be followed in regards to labeling:

“100% Pure or 100% Juice

Guarantees only 100 percent fruit juice, complete with all its nutrients. If it's not there,

it's not all juice.

"Cocktail," "Punch," "Drink," "Beverage"

Terms which signify diluted juice containing less than 100 percent juice, often with

added sweeteners.

Fresh Squeezed Juice

Squeezed from fresh fruit. It is not pasteurized and is usually located in the produce or

dairy section of the grocery store.

From Concentrate

Water is removed from whole juice to make concentrate; then water is added back to

reconstitute to 100 percent juice or to diluted juice such as lemonade.

Not From Concentrate

Juice that has never been concentrated.

Fresh Frozen

19

Freshly squeezed, and packaged and frozen without pasteurization or further processing.

It is usually sold in plastic bottles in the frozen food section of the grocery store and is

ready to drink after thawing.

Juice on Unrefrigerated Shelves

Shelf-stable product usually found with canned and bottled juices on unrefrigerated

shelves of your store. It is pasteurized juice, or diluted juice, often from concentrate,

packaged in sterilized containers.

Canned Juice

Heated and sealed in cans to provide extended shelf life of more than one year.” (Lewis)

Cost Analysis

The major expenses of orange juice production come from the upfront cost of the

equipment, labor, and purchasing oranges. As far as the equipment, it is estimated that the

equipment costs are as follows in Table 4.

Item Description # required Cost/unit Total Cost

Orange Presser Model 291B/391B 1 250,000 250,000

Plate and Frame Filter Filter Area = 39.70 m^2 1 114,000 114,000

Electric Heater Power = 192.15 kW 2 100,000 200,000

Electric Cooler Power = 189.09 kW 6 100,000 600,000

Bowl Centrifuge Sigma Factor = 151.75 m2 1 94,000 94,000

Unlisted Equipment piping, etc. 315,000

TOTAL: 1,573,000 Table 4: Cost of equipment required for processing plant (SuperPro). (costs are in

U.S.D.)

These values came from manufacturer quotes and the computer software SuperPro‟s data base.

It is assumed that the plant will be open 24hr/day and approximately 330 days/year (taking into

account holidays). Labor estimates will be approximately $2,628,309 per year; this is assuming

a $60/hr pay (SuperPro). The cost of oranges is the most important expenditure. However, since

orange prices vary from season to season and also depending on the contract set up with the

grove, it is difficult to budget for orange prices. An approximate value of $48,133,697 per year

is expected (SuperPro). Therefore, the total for equipment, labor, and oranges is about

$52,335,006 annually.

Other costs must also be considered. For example, the direct fixed capital costs will be

around $9,780,000 (SuperPro). These are mostly one time costs which include contracting,

installation, engineering, and other equipment fees. Also, utilities must be taken into account.

Since orange juice processing includes pasteurization and cooling, heating bills are high.

Therefore, the total utility bill would be approximately $41,616,719 per year (SuperPro). It is

important to note that this is almost as much as will be spent on oranges.

As far as profits go, there is money coming in from the sale of the orange juice as well

as the sale of waste products. The summation of waste product income can be viewed in Table

5.

20

Product Amount produced Price/unit Profit ($/yr)

Orange Juice 15,648,844 gal/yr 6.31 $/gal 98,813,000

Solids for Cattle Feed 788,009 kg/yr 0.08 $/kg 63,000

Liquids for Molasses 413,491 kg/yr 0.08 $/kg 33,000

Oils 3,089,998 kg/yr 0.08 $/kg 247,000

99,156,000 Table 5: Profits from orange juice and waste sales (SuperPro).

For these values, it is important to notice that the waste sale prices are variable. These prices

depend on the amount of processing and isolation that the plant does before selling them, as

well as the contracted price agreement with the purchaser. Also, the orange juice profit is based

on a $6.05/gal cost to process the oranges (SuperPro).

Overall, the start up cost of the plant is approximately $18,667,000 (SuperPro). The

operating costs (labor and utilities) are $94,610,000 /yr (SuperPro). The total revenue is

99,156,000/yr (SuperPro). And therefore, the net profit after taxes would be $3,657,000/yr

(SuperPro). Using this figure, the plant would be able to pay back all initial debt after 5.1 years

(SuperPro).

Conclusion

This paper has followed oranges as they have been picked, graded, washed, and juiced.

The juice is then filtered, pasteurized, and bottled. In this paper, the orange juice manufacturing

process has been closely followed in an attempt to give the reader a greater appreciation of the

process. It also serves to give the reader an in-depth overview of the process so that he/she may

be able to apply this knowledge. It is believed that using this process, the objective to process

500 oranges/minute will be reached.

21

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