Citrus Juice Production Technology
Fresh Market Extension Technologies
The 1999/2000 Citrus production reached 70.8 million tons globally. Brazil, the United States and China continue to lead production and their combined output represent close to 60% of the world's total. The 2000/01 forecast for the Northern Hemisphere at 45.9 million tons is down by 10% relative to the previous season. Preliminary forecasts indicate that the Southern Hemisphere may have a reduced crop as well, primarily because Brazil's crop may be adversely affected by unfavorable weather conditions. Of the total Citrus production close to 60% is consumed in the fresh market, and approximately 40% is processed.
Citrus juice products enjoy a significant share of the retail beverage market and have evolved over the years from fresh juice to the popular Not-From-Concentrate (NFC) juice, which today outperforms all other citrus juice categories. NFC sells in the premium chilled juice market segment and its growth rate year-over-year has been phenomenal for the past decade. Season to date sales of NFC orange juice in the United States are up 10.5% from last season figures. The total world orange juice production for 1999/00 was close to 2.4 million tons at 65o Brix equivalent. The main producers of orange juice are Brazil and Florida and their combined production account for close to 90% of the world supply. China has emerged with a significant orange crop production and will continue to grow at an accelerated pace as new groves are installed and trees come into production.
As indicated, over half of the world's production is consumed in the fresh market. The commercial packing of fresh citrus utilizing the most modern post-harvest handling procedures plus efficient distribution channels makes fresh citrus available to consumers in all corners of the world. The chart below illustrates production trends in the 1999/00 season and shows that most countries produced fruit primarily for consumption in the fresh market.
1999/2000 World Citrus Production and Utilization
Some fluctuation from season to season is expected as producers may take advantage of favorable world pricing and divert fruit to the most lucrative market. On the other hand, Brazil and the USA traditionally have a large portion of their crop converted into juice products, which typically reaches well over 50% of the total production.
The popularity of orange juice is certainly due to its pleasant and refreshing flavor plus consumers know they get the nutritional benefits from vitamin C, folic acid and the dietary fiber in one serving. Processes of pasteurization and concentration preserve the product's quality and high nutritive value. Continuous technology improvements have enabled the industry to excel on quality with the result that today orange juice is better tasting and more like fresh squeezed juice than ever before.
The "Whole Fruit Extraction Principle" of juice extraction is a technology that extracts over 75% of the world's citrus juice production. This principle relies in the unique design of the extraction juicing components within the machine. These components interact in a manner that peel the orange and squeeze the juice out from the peeled orange through a strainer, all within a few fractions of a second. The result is a juice of extremely high quality that is ready to be consumed as fresh squeezed juice or it can be further processed into NFC or FCOJ.
The production of Frozen Concentrated Orange Juice (FCOJ) starts at fruit receiving and unloading. Fruit is brought to the plant in trucks with trailer capacities up to 20 tons. The unloading step can be relatively simple or it may employ hydraulic ramps to discharge fruit by gravity into conveyor belts. Typically, fruit is sampled during this operation to determine maturity level and juice content. The sugar and acid level are determined and are often used as a basis for fruit buying and for selective blending of loads to achieve specific quality parameters, such as Brix, a measure of sugar content, and acid ratio. Sugar and acid ratios ultimately establish product quality standards together with flavor and color. The illustration below shows a typical citrus processing plant layout. The process flow outlines the steps involved in production of citrus juice concentrate.
Frozen Concentrate Orange Juice Production
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Unwholesome fruit is removed during unloading before the oranges are conveyed to storage bins. Wood and metal bins are commonly used, and are designed with baffles to minimize impact as fruit descends through to the base of the bin. As the plant begins the day's operation the oranges roll out of the bins into conveyor belts, and are transported to the main extraction line via a bucket elevator and on to a surge bin. The surge bin serves as a buffer to control and maintain an adequate fruit flow for the extraction line. The oranges are pulled from the surge bin into a brush washer, washed, sanitized and graded again before juice extraction. Detergents and a chlorinated water rinse can be used. Cooled condensate water from juice evaporation may also be used in the washing step.
After washing and grading, fruit is sized and goes to juice extractors, the extracted juice is then conveyed to finishers to separate juice sacs from the juice. The finished juice may be centrifuged to reduce pulp and defects level; it is further collected in large cold wall tanks and next concentrated in a TASTE evaporator. The acronym stands for " Thermally Accelerated Short Time Evaporator " because water is removed from citrus juice in a vapor form in a very short time as it passes through the unit once. The multi-stage, multi-effect design used to construct the unit provides outstanding steam economy. Today, the TASTE is the standard concentration unit for the citrus industry.
The evaporator typically contains an essence recovery unit to collect aqueous and oil phase flavor components that are removed with the water vapors, as juice is concentrated. The essences can be added back to concentrate during the blending operation or may be sold to the flavor industry. Concentrate from the evaporator is flash cooled to 5o to 10o C, further chilled to -5o to -10o C and stored in large bulk storage tanks. These tanks are housed within a cold room at -10o to -18o C and the site is commonly referred to as a tank farm. Capacities of these tanks can be up to 250,000 gallons. Concentrate storage in tank farms is the norm for the industry as well as bulk transportation and distribution to the markets. Concentrate in polyethylene-lined steel drums may be used to meet the requirements of markets that are not set up for bulk handling or for special orders. The drums are stored in cold rooms under the same temperature conditions as the tank farm operations.
The recovery of citrus by-products is an important economical aspect in citrus processing operations and it is particularly appropriate when a large volume of fruit is processed. The most common by-products derived from citrus are peel oil, aroma and essence oil, frozen pulp cells and cattle feed pellets. Recovery of soluble solids from the pulp material commonly referred to pulp wash liquor, could be a source of juice solids for production of juice based beverages and may be the one of the best choices when juice prices are high.
Not-From-Concentrate (NFC) juice is a product that today is the closest match to fresh juice in a convenient ready-to-serve package. It meets consumer's desires for improved flavor, for less-processed products, and for more natural juicy bits of orange. Furthermore, increased consumer health awareness and knowledge of citrus's nutritional value has played an important role in NFC's growth rate. Today, NFC has a significant market share and continues to grow taking share away from retail concentrate and reconstituted juice. The product is made by a closely controlled pasteurization process to minimize juice exposure to heat. Excessive heat contributes to cooked flavor development and undesirable changes to delicate aromatic components. Year round supply of the product is possible as a large volume of juice is stored utilizing various storage technologies. Aseptic bulk storage in tank farms, Bag-In-Drum and Bag-In-Box systems, and frozen storage are commonly used.
Aseptic storage of NFC became a necessity in the industry as the market expanded. NFC was first stored in frozen block form. For large volumes, aseptic storage is more viable economically because of ease of handling and energy gains as compared to frozen storage. Many plants in the industry have installed bulk aseptic storage tanks, some with capacities to hold one million gallons of single strength juice per tank. Aseptic juice handling technology will continue to grow, as new applications are required in juice blending and transfer operations.
Other important factors in the production of NFC are the control of peel oil and bitterness level in the juice. Excessive peel oil contributes to the undesirable flavor changes that can occur in citrus juices during processing and storage. Furthermore, because of its burning sensation when present at high levels, it can overwhelm consumer's ability to discern the delicate flavor components.
Valencia oranges are best suited for NFC production as they have very low levels of limonin, a natural component of citrus known for its bitter taste. Navel oranges on the other hand, are recommended for use in blended juices.
Application of process control for every aspect of a citrus operation, rapid access to information and networking, and access to technical support via the Internet is common today in the industry. Information and communication systems are enabling the industry to stay competitive and to achieve total quality management, cost effectiveness and better business management.
Hazard Analysis Critical Control Point (HACCP) procedures are required by the U. S. Food and Drug Administration to help producers achieve their quality and food safety and protection goals. The European ISO 9000 series certification has become a standard for the industry.
The citrus industry is rapidly adopting process control technologies to fully automate all aspects of plant operations. The intent is to improve plant efficiency, reduce costs, and provide the tools for better operations management The most modern plant installations in recent years have a modular control package fully integrated into a management information system with an advanced network. Management has the capability to review any operational data and identify areas of concern very quickly. Corrective measures can be implemented and the processes realigned.
Automation can start at the plant's gate, beginning with documentation of truck weight and fruit identification at the scale house, and integrated with maturity/quality data information (State Test) for the corresponding load of fruit. Next, it continues through fruit handling, bin blending and juice room control. The system operates based on juice demand from downstream processes and makes adjustments to fruit flow through the line to deliver juice as required. Evaporator automation assures the juice is within a set range of concentration according to pre-determined values. Finisher operation, by-product recovery systems, and clean-up operations can be automated to assure consistent results
Production of premium quality citrus juices requires tighter sanitation control relative to concentrate production since heat treatments are less severe to minimize changes to flavor. The application of dairy standards for the equipment line and operations is not unusual today. Stainless steel fruit handling/conveying equipment such as fruit storage bins, bucket elevators, conveyor belt side rails, and other equipment are more common. Washed fruit may be sanitized before leaving the washer. Furthermore, conveyor belts may be sprayed with a sanitizing solution to minimize surface mold growth.
Automatic clean up systems are instrumental in consistently keeping extraction lines clean and sanitary especially for NFC production. Frequency of cleaning may be higher than for concentrate production and could vary based on fruit condition.
Pasteurization is the process of heat treatment to achieve inactivation of the natural enzymes and microorganisms. As heat can damage the delicate flavor components, improvements in process technologies are being investigated to minimize and fine-tune the juice exposure to heat in terms of time and temperature. Most of the technologies known to have some degree of success in inactivating microorganisms and enzymes are not commercialized, such as, high-pressure pasteurization, electric-pulse and microwave technologies. High-pressure pasteurization of juice, although technically successful, was a commercial process for a short time, but its use was discontinued as the process proved to be not viable economically.
The application of technically sound and advanced packinghouse processes is very important to bring wholesome fruit to consumers. Most citrus fruits could be packed in a given packing line, but some variations of post-harvest handling processes are used to pack oranges, grapefruit, mandarins and lemons and may require that lemons be packed exclusively in one line, while the delicate mandarins may be packed in another. Oranges and grapefruit are often packed in the same line. The chart below illustrates the steps and process flow during a fresh citrus packing operation.
Typical Fresh Citrus Packing Operation
The commercial packing of citrus begins with careful picking and hauling to the packinghouse. Some fruit may be treated with post-harvest fungicides and stored for a period of time until ready for packing. A truckload may also be treated with fungicides soon after the fruit arrives at the packinghouse. Many commercial operations have truck or bin drenching systems to immediately treat fruit following harvest. This early treatment step is very important to control infection by Penicillium and to control latent infections by stem invading organisms and others.
When ready for packing, fruit from field containers roll on to conveyor belts as the bins are tipped over. The fruit can go through a dip tank for treatment with a chlorine solution or carbonates or a chlorine spray may be applied as the fruit progresses through the line. The very small and very large fruit can be removed to meet size standards as fruit goes through a pre-sizer. After the pre-sizer, fruit is washed with detergents that may contain sanitizers as an option. A high pressure washing system may be used to remove scale insects and debris. This technology allows more fruit to meet quality standards and quarantine requirements as insect bodies and other heavy film deposits from mold growth are removed. It also improves fruit appearance and facilitates identification and removal of unsound fruit at the grading stage. At this point unwholesome fruit and other fruit that do not meet external quality standards are removed.
A fungicide treatment usually follows and the application method used may be as an aqueous spray, a drip or by a control droplet application (CDA). The fungicide may also be applied together with the protective wax coating. The choice of fungicides is dependent on regulatory approval and is different for each country. In the U.S., Thiabendazole (TBZ) and Imazalil are approved fungicides for post-harvest application. Orthophenylphenol (SOPP) and carbonates are approved as fruit sanitizers. Immediately after fungicide treatment, a water based wax emulsion is applied to protect fruit from water loss and improve appearance. The application methods are basically similar to a fungicide treatment. The protective coating and fungicide treatment procedure are very important to not only assure that fruit arrives in very good conditions at the consuming markets, but that they stay fresh longer. Citrus protective coatings are formulated with various natural waxes and resins that have been approved for use as a coating material by appropriate regulatory agencies. They are formulated to achieve a maximum reduction in moisture loss through the peel while allowing the exchange of oxygen and carbon dioxide as the fruit continues to breathe. Excessive reduction in respiration may result in off-flavor development. An effective protective coating can reduce weight loss by 30 to 40%.
Post-harvest fungicide treatments follow the prescribed procedures according to the regulations established by each country where they are used. The following table lists post-harvest fungicides in use and effectiveness against the most common spoilage causing organisms.
Effectiveness of Citrus Post-harvest Fungicides
Fungicide |
Stem End Rot |
Mold |
Alternaria |
Sour Rot |
SOPP |
Some effect |
Effective |
No effect |
Some effect |
TBZ |
Effective |
Effective |
No effect |
No effect |
Imazalil |
Effective |
Effective |
Effective |
No effect |
Guazatine |
No effect |
No effect |
No effect |
Effective |
After further selection by sizes, fruit is packed in wholesale containers at the packing stations. In the United States, citrus may also be labeled to identify the place of origin, the variety, and the quality and for pricing (PLU) information. This step usually is done after fruit is graded for quality and sizes. Packed containers may vary in size and form depending on the market and can be cardboard boxes, plastic mesh bags, or large fiberboard bins. Packed fruit is maintained under cool and high humidity conditions during storage, transportation and distribution.
The above are some of the more important processes available to control post-harvest losses. Management should select a program that can best meet the conditions from the specific geographical area in which citrus is produced, the distribution channels and the consuming market. Some of the points to consider for selection of a good basic program are:
In all cases, good packing house cleaning and sanitation programs should be maintained, including equipment sanitation with appropriate quaternary compounds, periodic assays for the presence of resistant organisms and provisions should be made to enable substitution of the fungicide as required.
The ability to utilize the most advanced technologies for production of citrus juice products and the available processes for post-harvest handling of fresh citrus have contributed to providing consumers in most markets with high quality juice products and a wide range of citrus fruit that are attractive, wholesome and reliable.
