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For orange juice, measures should be taken to protect vitamin C and flavour compounds, and to prevent microbial growth and colour changes. Vitamin C is the. The Orange Book - Ebook download as PDF File .pdf), Text File .txt) or read book online. The Orange form without the source being indicated (Tetra Pak). Packed with facts and knowledge about everything from orange plant origins to juice manufacturing and packaging, the Orange Book is the essential reference.

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A new edition of Tetra Pak's Orange Book is now available free online. The Orange Book is a comprehensive guide to orange juice production. The Orange Book is a comprehensive guide to orange juice production. Freshly updated, it concentrates our vast know-how and provides in-depth. Thanks to its rich taste and wholesome benefits, orange juice is the world's favourite juice beverage. The Orange Book is your comprehensive guide to orange.

History[ edit ] The most commonly applied technique to provide a safe and shelf-stable milk is heat treatment. However, without commercially available aseptic packaging systems to pack and store the product, such technology was not very useful in itself, and further development was stalled until the s. In , APV pioneered a steam injection technology, involving direct injection of steam through a specially designed nozzle which raises the product temperature instantly, under brand name Uperiser; milk was packaged in sterile cans. In the s APV launched the first commercial steam infusion system under the Palarisator brand name. They made a commercial breakthrough in the s, after technological advances, combining carton assembling and aseptic packaging technologies, followed by international expansion.

Long-term ascorbic acid administration reverses endothelial vasomotor dysfunction in patients with coronary artery disease. A Circulation. Online version available from www. Dietary carotene. Prentice Hall Press, NY. Chemical composition and organoleptic evaluation of juice from steamed cashew apple blended with orange juice. Plant Foods for Human Nutri. Development and quality evaluation of pineapple juice blend with carrot and orange juice.

Radical scavenging activities of Rio Red grapefruits and Sour orange fruit extracts in different in vitro model systems. Guide to body chemistry and nutrition. Keats Publishing, Illinois, U. Main organic acid distribution of authentic citrus juices in Turkey. Turkey J. The flavour profile. Stability of the vitamin C content of commercial orange juice.

Food Technol. Australia, 33 3 : Methods for determining the quality of citrus juice. Washington D. C: American Chemical Society. Multicollinearity and leverage in mixture experiments. Quality Tech. Human Nutrition and Dietetic. Status of the postharvest sector and its contribution to agricultural development and economic growth.

Universal, product and attribute specific scaling and the development of common lexicon in descriptive analysis. Carotenoid content in different varieties of pumpkins. Food Comp. A survey of cabbage production and constraints in Ghana. Ghana J. Citrus Production. BWIB claims some eco-cred for shipping its containers flat, while those who bottle in plastic send empties around the world. In fact, Nestle Waters, the largest springwater purveyor in the U. I could spend a lot of time looking at life cycle analyses of these products.

But the point I want to make is that these packages perpetuate the idea that it's okay to download water in single-use disposable packaging. In my humble opinion, we don't need to reduce our guilt for downloading convenience products, we need to download fewer of them in the first place. More from Elizabeth Royte in Is water in boxes better than water in plastic? This means that trees of the same cultivar are genetically identical and respond similarly to their environment, for example fruit.

The trees can grow in a wide range of soil conditions, from extremely sandy soils to rather heavy clay loams, although they grow best in intermediate types of soil. Local growing conditions, such as climate, type of soil and grove practices, have a large inuence on the quality of fruit produced and on the extracted juice.

An orange variety, for example Valencia, may have quite different properties when grown in different parts of the world. The major orange-growing regions are shown in Figure 1. Approximately 65 million tonnes of oranges are produced per year worldwide. Whenever possible, growers prefer to sell oranges to the fresh fruit market as their price is normally higher than for fruit sold for processing into juice.

In some countries this can lead to a signicant variation in the amount of fruit processed from one year to another. Florida and Brazil are the worlds largest fruit producing countries. Here the majority of fruit harvested is processed because the orange varieties in these regions are grown for processing rather than for direct consumption. Due to the planting of new trees, world orange production continued to increase into the early s mainly in Florida, Brazil and China.

World orange production is also expected to increase further in other regions as a result of improved planting programmes, cultivating techniques, and support given to orange growers. Nevertheless, unwanted climatic effects like frost and storms, along with uncontrolled diseases of fruit trees, could reduce crops and juice yields signicantly. Recent years have seen notable uctuations in world orange production. In Brazil surpassed Florida as the worlds number one orange producer.

However, new trees that were planted further south in Florida in areas less affected by frost are now bearing fruit. This has boosted Floridas orange production signicantly and in years with good yields the state meets most of the US demand for juice. Figure 1. China has the fastest growth in citrus fruit production as a result of the intensive planting of new trees. So far, most oranges in China are consumed fresh, with only a small amount of fruit being processed. The Mediterranean is an important region for growing high-quality fruit.

As more and more Mediterranean oranges are being eaten fresh, juice production is gradually declining in this region.

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Commercial cultivation of oranges intended for large-scale processing into fruit sections and juice began in Florida in the s.

In the late s, frozen concentrated orange juice for home dilution was developed in the USA. This led to a rapid growth in orange juice consumption. As a result, the cultivation and processing capacity of oranges in Florida grew rapidly. However, severe frosts in Florida drastically reduced fruit yields and killed many trees during the s, 70s and 80s.

To secure the supply of orange juice for the US market, trees were planted and large processing plants were built for orange concentrate in Brazil. The rst concentrate plant was built in Brazil in the early s and the large expansion in production capacity took place during the 70s and 80s. Orange processing in Brazil was established by US companies.

Like any other fruit, orange trees are susceptible to diseases. These may affect the leaves or fruit and even kill the trees.

Because diseases have a large economical impact on the citrus industry, many orange-growing regions allocate large funds for research on citrus diseases, and develop more resistant fruit cultivars and cultivation methods to limit their effects.

The characteristics of a disease will determine the appropriate response to control it. Control methods include the eradication of infected trees, chemical suppression of disease-transmitting insects and using resistant rootstock for grafting.

New trees should come from controlled nurseries where seedlings are protected from airborne or soil contamination. The inspection of groves and follow-up of measures taken are important for successful control of a disease. Large eradication programmes may require special funding.

New plantings were made using a different rootstock Rangpur Lime resistant to this virus. Among the serious citrus diseases found today is Citrus Canker, caused by Xanthomonas bacteria, that results in premature leaf and fruit drop.

There is no treatment but the disease is limited by removing all trees within a 60 m radius of infected trees. CVC Citrus Cholorosis Variegated , caused by a bacterial pathogen transmitted by the sharpshooter insect, leads to spotted leaves and small fruit. The fungal disease Citrus Black Spot causes lesions on the fruit skin, which make fruit unsuitable for consumption although it can still be processed.

In , a new disease was discovered in Brazil called Citrus Sudden Death CSD because it caused the rapid decline and death of trees with fruit and leaves still on them. It is caused by an insect-transmitted virus similar to Tristeza and in just a few years it has spread to important citrus areas of So Paulo State.

Certain rootstocks are resistant to the Sudden Death virus. Now there is intensive replanting using resistant trees as well as in-arching, where resistant seedlings are planted next to an existing exposed tree and a by-pass is grafted onto it above the bud union.

However, since these alternative rootstocks are less resistant to drought, they may require more irrigation or be used to plant groves in areas having a wetter climate. Therefore, the time between picking fruit and processing it into juice and other products should ideally be as short as possible less than 24 hours although longer periods are not uncommon.

Because the orange is a seasonal fruit, each region strives to grow orange varieties with different ripening periods see Figure 1. This prolongs the total harvesting period in a region and allows greater utilisation of processing equipment.

To provide a year-round supply to consumers, juice must be stored to bridge the gap between seasons. Most of the juice is stored frozen as concentrate. For the same amount of ready-to-drink RTD juice, concentrate requires 56 times less volume for storage and shipping than singlestrength juice. Thus shipping costs over long distances are signicantly higher for single-strength products like not-from-concentrate juice NFC.

Juices from early and late fruit varieties differ in quality as regards colour, sugar content, etc. To deliver products of specied and consistent quality throughout the year, concentrate suppliers blend concentrates produced from different orange varieties.

Most NFC products also consist of a blend of juices extracted at different times of the season. Blending of NFC may take place within the producing country or in the importing market. The difference in quality and yield between different orange varieties is reected in the range of market prices. In plants where NFC is produced, concentrate should also be produced to make use of the nonoptimal fruit. In most regions, fruit best suited to NFC production is available for only part of the season.

The proportion of NFC and concentrate produced in a certain region will depend on the availability of suitable fruit. The rejected fruit is used for processing into juice.

This is why juice processing facilities are also found in regions which specialise in producing oranges intended for the fresh fruit market. In Florida, oranges are usually processed from late October to early June. Good quality fruit is harvested for the greater part of the season. In the Mediterranean, the period yielding fruit of quality suitable for processing is shorter than in Florida and Brazil.

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NFC is essentially juice as it is extracted directly from the fruit. Regulations and the production process allow for very limited, if any, adjustments to product characteristics other than blending NFC from different varieties. Therefore careful selection of the fruit is necessary for NFC production. In concentrate production it is possible to adjust certain quality parameters. Careful control of the evaporation step, essence recovery and the possibility of blending concentrates that differ in character enable the processor to meet many different product specications.

Hence, variations in fruit properties are less critical for concentrate production. The peel consists of a thin outer layer called the avedo and a thicker, brous inner layer called the albedo.

Orange-coloured substances called carotenoids in the avedo give the fruit its characteristic colour. Vesicles a small sac or cavity containing peel oil also present in the avedo contribute to the fruits fresh aroma.

The white spongy albedo contains several substances which inuence juice quality, often negatively, if they nd their way into extracted juice. These substances include avonoids, d-limonene, limonin and pectin. In theory, the aim of the juice extraction process is to remove the maximum amount of juice from the fruit without including any peel. In practice, a compromise is made between the possible juice yield and the desired product quality.

Valuable oil from the peel is recovered during juice extraction. Volatile avours from the juice are also recovered during juice processing. The remaining material is mainly pulp, peel, rag and seeds. Some pulp is recovered for sale as a commercial product.

Soluble solids are reclaimed from the remaining pulp stream by washing with water. Other by-products such as pectin and clouding agents are sometimes recovered. Peel and other residual waste can be dewatered and dried as pellets for animal feed.

Because orange waste is very biodegradable, small plants may dispose of it as landll. Increased cost-efciency is important for the orange juice industry.

The development of equipment within the citrus processing industry is aimed at increasing juice yields while maintaining juice quality. It is also very important to reduce energy costs and to further rene by-products and nd new uses for them. The edible portion of the fruit is known as the endocarp.

It consists of a central brous core, individual segments, segments walls and an outer membrane. The segments contain juice vesicles, or juice sacs, that are held together by a waxy substance. Seeds may also be present within the segments. See Figure 1. Apart from the juice itself, droplets of juice oil and lipid are also present in the juice vesicles.

The juice contains sugars, acids, vitamins, minerals, pectins and coloured components along with many other components. These are discussed in more detail in subsection 2. After juice is extracted, pieces of ruptured juice sacs and segment walls are recovered as pulp. When these particles are large, they are referred to as oating pulp because they rise to the surface of the juice.

Very ne particles and suspended solids that gradually accumulate at the bottom of the juice are called sinking pulp. This product is produced either: The orange is one of natures gifts.

The two primary products whole fruit and juice are enjoyed worldwide.

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Various secondary products, the by-products, help to maximise prots and minimise waste. No part of the fruit is unused after the juice is extracted if fruit throughput justies investment in equipment needed to turn pulp and peel into commercial products.

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A range of products that can be obtained from oranges is summarised below, many of which are discussed in greater detail in other sections of this book. Yields of the various products derived from Florida Valencia oranges are shown in Figure 1. A by-product made either by milling the whole fresh fruit or by mixing juice concentrate with milled peel. This product is used as an ingredient for fruit drinks. Because comminuted citrus base has a stronger avour and provides more cloud than pure orange juice, it imparts a good orange avour to fruit drinks of low fruit content.

It was originally developed in the UK. This is ruptured juice sacs and segment walls recovered after the extraction process. It can be added back to juice and juice drinks to provide mouthfeel and give a natural appearance to the product. Pulp, also traded as cells, is usually distributed frozen but also in aseptic bag-in-box containers.

After picking, fruit intended for the fresh fruit market is sent to packing stations where it is normally graded by visual inspection, washed, coated with wax and packed. The detergent used in washing may include fungicides. As traces of fungicide could nd its way into juice, fruit from packing houses may not be processed into juice for sale to, for example, the European Union countries.

SunBase, Florida. A product reclaimed from washing the pulp stream. Pulp wash contains soluble fruit solids and is often used in fruit drink formulations as a source of sugars and fruit solids.

It is also used as a clouding agent to provide body and mouthfeel because of its pectin content. If the law permits, pulp wash is sometimes added to juice in-line before concentration. The major component of peel oil. Industrial d-limonene is recovered as a by-product from waste peel in the feed mill.

It is sold for use in the plastics industry as a raw material for the manufacture of synthetic resins and adhesives. It has also found use as a solvent, e. Animal feed. Dry pellets made from the material left over from juice processing. The waste stream consists of peel, rag, unrecovered pulp and seeds. This residue is dewatered and dried to form concentrated fodder for cattle and sheep. The oil extracted from orange peel. Some peel oil is added to concentrate after evaporation prior to long-term storage.

It masks or slows down the development of a cardboard off-taste during storage. Peel oil is sometimes used by blending houses and juice packers for extra additions to concentrate.

It is sold to avour manufacturers for the production of various avour compounds used in the beverage, cosmetics and chemical industries. The syrup produced from the concentration of liquor pressed from the wet waste stream. It is used in producing animal feed pellets or as raw material for the production of citrus alcohol by fermentation. A less common by-product of fruit peel.

Pectin can be extracted from the peel for use in jam, marmalade, jelly and preserve production. Essence comprises the volatile components recovered from the evaporation process. These are separated in an aqueous phase and an oil phase. The water-soluble compounds essence aroma are sometimes added back to the concentrate or juice product. The oil phase essence oil is different from peel oil and contains more of the fruit avour.

Essence oil is also used as add-back to concentrate. Both aroma and essence oil are raw materials used by avour companies for the manufacture of avour mixtures for the beverage and other food industries.

Mexico 1. Regions contributing to the majority of world orange juice production are shown in Figure 1. The export of orange juice onto the world market is dominated by Brazil. US exports are quite small as a consequence of the large domestic market for orange juice.

The USA has been a signicant net importer of juice. However, as juice production in Florida increased as a result of new tree planting, US net juice imports have gradually declined to a low level, the quantities depending on the size of the Florida harvest. Thus more juice available on the world market must nd new or existing markets. Almost all commercial groves and processing plants are located in the state of So Paulo, where million boxes were produced.

The majority of Brazilian oranges goes into processing. Nevertheless, the domestic fresh fruit market, selling for home-squeezed orange juice, makes up a signicant share of the total production resulting from the increase in per capita income. Florida Department of Citrus. Sweet oranges comprise the bulk of the Brazilian crop. The most important varieties are: Pera Rio Pera Natal Valencia.

Brazilian fruit tends to be smaller, less round and to have a thicker peel than oranges grown for processing in, for example, Florida. The normal processing season for Brazilian juice plants is from late June through to early February. Groves are not normally irrigated and climatic variations, including drought, can have a strong inuence on fruit yield and juice quality.

Some citrus varieties Hamlin and Valencia have a biennial cycle which leads to cyclic uctuations in orange output. The variation in yield per tree obtained during recent harvest seasons is shown in Figure 1. In Brazil, the bloom the time when the tree owers and becomes pollinated before the new crop of fruit starts to grow does not occur at the same time for all the trees in a grove or plantation. As a consequence, trees in a grove bear fruit of differing ripeness at any given time. Since fruit in a specic grove is gathered at one picking, the harvested crop will therefore vary in maturity.

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This variation in fruit ripeness forces the processor to make compromises in the juice extraction process that affect both the quality and yield of juice produced. Nevertheless, the processor can modify process conditions and use essence recovery and juice blending to compensate for variations in fruit to produce juice concentrate of consistent uniformity.

Most juice in Brazil is processed into concentrate that is exported in large volumes. There is a small but growing production of NFC. This is intended for the South American market, as well as overseas export to North America and Europe.

Seasonal variations occur from year to year depending on the weather. Climatic conditions in Florida are such that the bloom occurs uniformly and during a very short period of time, usually two or three weeks. The high level of grove management includes irrigation and intensive pest and weed control.

This combination of favourable climate and procient grove management enables the fruit to ripen uniformly for efcient harvesting. Moreover, the uniform fruit quality enables the processor to select the optimum processing conditions for the fruit harvested each day. A combination of climatic conditions, tree variety and soil conditions results in fruit that has a low appeal to the fresh fruit market, but produces a very high quality of juice.

The skin is not uniform in colour and it is often quite green or yellow. The peel is fairly difcult to remove, which contributes to consumer rejection. However, the round shape and thin peel of Florida oranges make them ideal for mechanical extraction systems.

The main varieties of sweet oranges are: During the early part of the season the orange juice is light in colour and has a low oil content, whereas during late season the juice has a stronger colour and higher oil content.

There are relatively short distances between juice production and consumption. This region includes several areas of small but increasing orange cultivation and orange juice production. Valencia is the most common variety of sweet orange. Grove management is not intensive and irrigation is rare. Climatic variations lead to differences in crop yield and juice quality between seasons. The main product in this region is frozen concentrate, although NFC is also produced for export markets.

The orange processing capacity has been consolidated in Belize and Costa Rica, whereas capacity has expanded in Cuba, the largest producer in the region. Cubas citrus production increased steadily in the s. However, in a hurricane damaged a large part of the citrus-growing area. Cuba is among the worlds most important grapefruit producers, but output was dramatically reduced by the hurricane.

Valencia oranges are harvested from December to June. Fruit harvested from March onwards tends to be high in sugar and low in acidity, which leads to very high Brix: This juice therefore requires blending.

California is the second largest orange-producing area in the US as regards quantity of fruit, but is the leading supplier of oranges to the fresh fruit market. The dry climate results in oranges with thick skin and good appearance that appeal to consumers.

The dominant sweet orange variety in California is Navel, a seedless variety, followed by Valencia. Both are grown primarily for the fresh fruit market.

Navel orange juice has the peculiarity of developing a bitter taste after processing. In small amounts, Navel juice can be used for blending with other juices or, alternatively, the bitterness can be removed in a debittering process.

The majority of groves are small, a result of Mexican land reform and regulation that limit the size of farms. In the orange-growing areas there is often a shortage of investment money and difculty in achieving effective grove management. This leads to variations in crop size and fruit quality from year to year.

In years with short orange supply, prices are high in the domestic fresh fruit market and so less fruit goes to processing. Citrus production in Argentina was about 2. However, lemon is the most important citrus crop, with Argentina being the worlds largest producer of lemons, yielding about 1 million tonnes annually. Most lemons are grown in the northeast province of Tucuman.

One third is exported as fresh fruit, whereas about two thirds are processed into lemon juice. Local consumption of lemons is small, and the main markets for lemon export lie in the Northern Hemisphere. Fresh fruit export to some regions has been constrained by the required protocols and phytosanitary standards, but these demands are now being increasingly met.

China has the highest growth in citrus fruit production, with the provinces Sichuan, Guangdong and Zheijang accounting for the largest yields. Nevertheless, compared with other large citrus-producing regions, fruit yields are relatively low because of poor cultivar availability and grove practices. Mandarins account for more than half of citrus harvests in China, although the trend is to reduce mandarin planting in favour of sweet orange cultivars.

Most oranges are consumed fresh with very little being processed into juice; the predominant processed product is canned mandarin. At present, the majority of oranges are harvested during a short period. Since fruit quality deteriorates rapidly after harvesting, there is only a short fresh fruit consumption period of 34 months. In comparison, Brazil and Florida have typical harvesting cycles with balanced yields over 7 months.

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Therefore there is a strong desire in China to change to fruit varieties that result in longer consumption and processing periods. The per capita growth in income has led to the rapidly increased demand for orange juice, especially in large cities. But until greater orange production can support efcient processing, this demand will continue to be satised by juice imports over the next few years.

Fresh fruit will continue to be the main market for domestic oranges. When China joined the WTO in it agreed to reduce tariff rates, a measure that promotes higher imports of fresh fruit and orange juice. Citrus fruit grown in Japan consists primarily of mandarin varieties, some of which are processed into juice. However, since the strict restrictions governing fruit juice imports into Japan were lifted at the end of the s, production of mandarin juice has decreased to a low level.

Imported orange juice concentrate now meets the needs of the rapidly expanding domestic juice market. Japan is also a large importer of fresh grapefruit and orange fruit, mainly from the US. Periods of economic downturn also show in declining imports.

Sweet orange varieties in Australia are Navel and Valencia. Because of the high popularity of Navel it is easy to peel and enjoyable to eat and new plantings replacing old Valencia trees, it now accounts for about half of the crop and supplies the fresh fruit market.

The orange production in Australia was about 0. It is difcult for Australian producers to compete at world market prices for concentrate in the domestic market. Frozen concentrate now accounts for half of the juice market, mainly imported from Brazil. There is also a drive to increase the export of fresh fruit, primarily Navel, to Far East markets and increasingly to the US.

As Australia has an alternate season to the US, it can supply the US market with high-quality fruit during the California Navel off-season. Oranges in the Mediterranean region are primarily grown for the fresh fruit market, both domestic and for export to European countries. The Mediterranean is also important for other citrus fruits.

Mandarin production is about 4. Spain is the largest Mediterranean producer of oranges and mandarins, the most important sweet orange varieties being Navel and Valencia. Exports to fresh fruit markets dominate. Production of orange concentrate has been reduced drastically in Spain because production costs are not competitive with world-market concentrate prices. This is despite the fact that processors in European Union countries are entitled to a signicant subsidy for downloading fruit for juice production.

NFC is produced for the European market from high-quality Valencia fruit but volumes are limited by fruit availability. The cultivation of seedless clementines in Spain has met with success and is much appreciated by consumers. In Italy, orange concentrate production has also dropped drastically because of strong international competition as regards price. However, several types of blood orange unique to Sicily are grown on the island.

Juice from these oranges has created a niche market for export of both NFC and concentrate. In other cultivation areas, replacement of blonde oranges with more protable pink grapefruit is taking place.

About 11 million tonnes of oranges are grown in this region Citrus production in Israel has been declining for many years.

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Orange production was less than 0. The drop in concentrate production has caused the closure of processing plants. Uprooting of orchards is carried out because of low protability, urbanisation and an increasing water shortage.

The main varieties of sweet oranges grown in Israel are Shamouti early and Valencia. Jaffa is not a fruit variety but a trade name used for fruit and juice exported from Haifa harbour. The CMBI Citrus Marketing Board of Israel , which encouraged the production and marketing of citrus for more than 65 years and actively built up the European juice market, closed in South Africa has an expanding citrus industry, the main orange varieties being Valencia and Navel. Most of the orange production, some 1.

Traditionally, the main export market for orange fruit was Europe, but deregulation in opened up new opportunities that led to Japan and the Middle East becoming important markets. South Africa has good potential for exporting fresh fruit to the northern hemisphere because of its alternate season. However, increased trade depends on South Africa meeting the phytosanitary requirements and production protocols of the importing regions. Changes in the organisation of the South Africa citrus industry have taken place aimed at enabling producers to meet importers demands more efciently.

In section 2 you will read about: How quality is assessed in objective and subjective ways. Substances and factors that are important to juice quality, such as sugars and acids, cloud, pulp, avour and colour components, and vitamin C.

How the different quality parameters are measured. Orange juice categories and the terms used to describe the various types of orange juice. An introduction to regulations governing juice quality. Orange juice quality and categories Juice categories and relevant terms Many special terms are used for the two main categories of orange juice products, ready-to-drink orange juice and juice concentrate.

Some of these terms are referred to in the regulations of certain countries, other terms are merely used in juice marketing and trading. Standards and regulations governing product origin, juice processing, juice quality and product labelling are implemented by a number of regulatory bodies in different trading blocs. There is a general desire worldwide to harmonise the standards in force. Summary The most important compounds that inuence the quality of orange juice are sugars and acids, avour and colour components, and vitamin C.

These compounds, plus cloud, are analysed to dene and grade juice. The Brix scale is used to measure sugar concentration, and juice acidity is measured by titration. There are several methods for measuring cloud and colour. Flavour is evaluated using subjective methods and is thus difcult to dene and measure. The deterioration of juice quality is mainly related to avour degradation, nonenzymatic browning and nutrient loss.

Enzyme activity affects the mouthfeel of juice, and the formation of limonin makes juice taste bitter. For food products, quality is subjective and what is good quality must ultimately be determined by the consumer.

This is also true for orange juice. The quality of orange juice as perceived by the consumer is made up of: TABLE 2. However, because orange juice is traded and consumed worldwide, its quality cannot be determined solely by subjective assessments.

To make assessments more objective, several quality parameters have been dened. Some of these parameters are used to classify grade orange juice, while others are used to specify the product for trading.

Table 2. All the parameters listed in Table 2. Orange juice avour can only be evaluated by sensory means, usually by groups of panellists.

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These analysis methods have been collected and published in books by, for example, Redd et al. All processing and storage of juice on its way to the consumer should aim at maintaining the initial quality as much as possible. The effects of processing on quality are mainly related to avour degradation, while nonoptimal storage conditions can result in juice browning, loss of vitamin C and avour changes.

Properties L-ascorbic acid vit. Guidelines for quality standards for fruit juices for the European Union are specied in the Code of Practice for the evaluation of fruit and vegetable juices, published by the AIJN see Section The absolute quality requirements dened in the reference guideline for orange juice are given in Table 2.

The quality factors are measured on a point scale. If the total score is above the limit but just one of the quality factors does not meet the Grade A requirements, the juice still may not be labelled Grade A.

The most important properties of orange juice that are directly related to these quality parameters are discussed in the following subsections. The basic quality of orange juice is determined at the fruit processor, i. Subsequent processing steps cannot improve the main quality parameters of a given production batch. This can only be achieved by blending a particular juice with superior quality orange juice or concentrate.

This is commonly done. The Brix scale is based on standard measurements at 20 C. To obtain the corrected Brix value, the acid content must be determined by titration in order to read the right correction value from a table. The most important properties of orange juice are its sugar content and ratio of sugar to acid content.

This ratio indicates the balance between sweetness and acidity in the juice. When the fruit matures, this ratio increases as sugars are formed and the acid content decreases. The sugars are mainly sucrose, glucose and fructose in a ratio approximating to 2: The sugar content of juice is normally expressed as Brix. In extracted juice, the concentration of sugar typically varies from 9 Brix for early season varieties to 12 Brix for fruit harvested late in the season e.

The Brix degree Brix scale, which was developed by the sugar industry, relates the sucrose concentration of a pure sucrose solution to its density at 20 C. Brix for orange juice not only includes the concentration of dissolved sugars but all soluble solids.

Dissolved substances other than sugars will inuence the result of Brix measurements. Thus, the level of acid, the second most abundant dissolved material, is often measured and a correction of the Brix value is made. For single-strength orange juice, acid correction is small and the term Brix is commonly used without correction to mean only the sugar content. However, in measuring Brix of orange juice concentrate, the acid correction is important due to the much higher acid content of concentrate.

Here, the term Brix, cor rected is used. Density measurements: The buoyancy of a hydrometer in a liquid is directly proportional to the density of the solution. Therefore a scale on the neck of the hydrometer can be calibrated to a Brix scale. The Brix is read on the scale at the point where the liquid meniscus intersects the hydrometer neck.

Before measuring it is important to deaerate the juice since air in the sample can affect the result. Hydrometers are mostly used for singlestrength juice. Although a hydrometer is an inexpensive instrument, it is not very fast and requires up to ml of sample. For in-line Brix measurements, one common method of measuring density is to feed the sample through an oscillating tube. When the liquid enters the tube, the frequency of the oscillations decrease. From this deviation the density can be calculated.

Read more about inline density measurements in subsection 7.