Because the monetary value of the fruit juice mar- ket is so enormous, juice adulteration is a common feature of commercial life. For orange juice, the term “adulteration” means the addition of non- orange materials to products that are labelled and sold as orange juice. The value of orange juice is such that even modest adulteration can result in large profits, something which encourages fraud among both producers and those handling con- centrate for reconstitution and packaging. Any importing country can be affected, particularly when there is a shortage of orange juice supply.
The problem of juice adulteration is seldom related to health risk, but primarily related to fraudulent practices. Although there may be a slight reduction in juice quality, the same decline in quality can result from poor processing condi- tions. The issue at stake is that someone is making a lot of money by adding cheap materials such as sugar, acid and colour to juice in order to cheat the consumer into paying too much for what is thought to be a premium product. When checks on quality are inadequate or unenforced, this inevitably leads to a greater degree of adulteration.
Consumers should be protected from such fraud by regulatory authorities using their power to ensure that the composition, quality and la- belling of orange juice are strictly controlled. Re- sponsible authorities in every producing country and importing country deplore adulteration. Therefore, most take active steps to discover and
prevent it, and to ensure that orange juice com- plies with the relevant standards applicable. The aim of most work on safeguarding the authenticity of orange juice is essentially to make adulteration so expensive that it is no longer attractive.
It should also be noted that adulteration cannot be considered contamination. Unlike contamination, which is often harmful to health, the materials unlawfully added to juice are so like the juice’s natural constituents that they cannot be regarded as contaminants in the accepted sense.
The term “adulteration” is used to describe the addition of materials not derived from citrus fruit. This includes the addition of water, sucrose and
citric acid to maintain the soluble-solids content. On the other hand, the term “sophistication” is used to describe the use of other citrus products to extend or attempt to mimic genuine juice. Non- orange citrus juices, orange pulp wash and other matter derived from peel, rag or seeds constitute sophistication.
11.2.1 PROTECTING THE CONSUMER
A number of measures are taken to prevent the adulteration of orange juice and check its au- thenticity, that is, its declared origin and content. Producing countries, aware of the damage that adulteration can do to the legitimate trade, carry out various inspection and control procedures. Companies buying orange juice products try to purchase only through reliable suppliers known to have a good reputation. Voluntary organi- sations with declared self-control are estab- lished in Europe. Both suppliers and buyers are members. They are committed to carrying out self-control and following certain agreed rules. Examples of such organisations are SGF/IRMA, originating in Germany, and EQCS, European Quality Control System for juices and nectars. EQCS was founded by AIJN and its EU-based participants produce more than 85 % of all the fruit juices and nectars in the EU.
The basis for testing quality and authentic- ity parameters by the EQCS and its European members, and SGF/IRMA for their members (raw material suppliers in more than 50 countries), is the AIJN Code of Practice.
Due to intensive collaboration directed by the AIJN, local standards such as the RSK values in Germany, old AFNOR standards in France and the quality criteria in the Netherlands are incorporated in the AIJN Code of Practice. This means that the old, and sometimes still available standards, are not updated anymore and therefore no longer applied.
11.2.2 TELLING WRONG FROM RIGHT
As the adulteration of orange juice has become increasingly sophisticated, the analytical methods needed to detect fraud have been developed to re- veal specific types of adulteration. These analytical methods can be divided into four main groups. 1. Simple physical measurements such as
weight, volume, density, acidity, purity and sample concentration. Although these meas- urements do little to prove the authenticity of the product, they do give an indication of the value or price of the commodity tested. 2. Comparing the analytical composition of
samples with reference standards. Typical parameters include the content of sugars, or- ganic acids, amino acids, trace elements, etc., and flavour profiles. Spectrographic adsorp- tion patterns derived from visible light, ul- traviolet light and fluorescent measurements are important for providing “fingerprints” of orange juice samples. Although useful, the main disadvantage of this method is that the pattern for authentic products varies to an un- acceptable degree and can often be matched by adulterators adding appropriate “cocktails” to adulterated orange juice.
3. Testing for components that are not normally present in orange juice, or only present in trace amounts. Such components include natural or artificial flavours, D-malic or D-amino acids (as opposed to their common L-counterparts), synthetic intermediates or catalysts, preservatives like benzoates, etc. If these substances are found in amounts above accepted levels, then this is usually good proof of adulteration. Nevertheless, skilled adulterators are known to use pure or modified additives that can mislead both analysts and their instruments.
4. Isotopic fingerprinting of sugar content. Because of the high price of natural juice, the economic temptation to adulterate or- ange juice by adding sugar from sugar cane and sugar beet, or in the form of corn syrup, is considerable. Fortunately, isotopic tech- nique can now tell the differences between these different sugars by analysing their carbon content.
Isotope analysis
The carbon atom exists in two different isotopes,
12C, which has a natural abundance of 98.89 %,
and 13C, the heavier isotope with a natural abun-
dance of 1.11 %. During photosynthesis, plants discriminate against 13C. The degree of depletion
of 13C in plant tissue as a result of this depends on
how a plant extracts carbon dioxide, CO2, from
the air. As the orange plant extracts its carbon in a different way from sugar cane and maize, the relative proportions of 12C and 13C in these
plant tissues also differ. This fact can be used to trace the origin of sugar with the help of carbon stable isotope ratio analysis (CSIRA), and hence to determine whether juice has been adulterated by adding either cane sugar or high fructose corn syrup (HFCS).
“The value of juice is such that
even modest adulteration can
result in large profits
”
A trickier problem is to tell the difference between natural orange sugars and sugar from sugar beet, as both these plants extract carbon dioxide from air in exactly the same way. However, the posi- tion of the 13C atom in the sugar molecule does
differ between the two sugar sources. This can be detected using SNIF-NMR analysis (Site-spe- cific Natural Isotopic Fractionation measured by Nuclear Magnetic Resonance). Thus all three of the most commonly used sugar adulterants can now be detected.