The compliance of the declared filling volume is an important topic for all bottlers. On one hand the legal minimum values must be met and on the other hand overfilling means considerable economical loss.
The simple transfer of the juice in a graduated cylinder is quite inaccurate as the scale of such a cylinder is too wide and do not give an exact result. Additionally there will always be some remains in the bottle. Therefore this method is not precise enough for this task.
The usual continuous check of the filling volume in a filling line is done by weighing the full bottle and subtracting the average weight of empty bottle and cap. The weight of the juice can be transferred into volume by the division with the average density of the juice. This can be done automatically, but contains the risk of slightly incorrect results, as the weight of the packaging and the density of the juice normally vary within a predefined range.
This new method describes a more exact way to determine the filling volume (net volume) in a laboratory.
It is now available in the Methods of Analysis section of the IFU Website!
This recommendation has been revised and is available via the IFU website under Methods of Analysis
General information
Patulin is a mycotoxin produced by particular forms of moulds typically from the genera aspergillus, penicillium and byssochlamys. Patulin is normally found in apples or pears that shows areas of rot but has also been detected in small amounts in other fruits. It can be a significant problem in fruits that are suspectable to “core rot”, e.g. Bramley apples, where the fruit might look quite sound “on the outside” but may actually contain a very high level of contamination with patulin in the centre of the fruit.
Since this recommendation was first published there have been a number of new methods developed to assist in the analysis of patulin, which are discussed in this revised recommendation.
Access to IFU publications
Available to Corporate and Association members and subscribers to all publications by logging onto the website. Individual publications can be purchased via the on line store. Friend members (cat 2) have access to 5 publications per year.
Determination of Acetic Acid (enzymatic method)
This method has been revised and has been loaded onto the IFU website. It now includes precision data.
General information
This method serves to determine the acetic acid content of a fruit and vegetable juices & purees. Provided that it meets characteristic performance, this enzymatic method can also be carried out using an automatic analyser.
Principle
Acetic acid (acetate) is converted in the presence of the enzyme acetyl-CoA synthetase (ACS) with adenosine-5′-triphosphate (ATP) and coenzyme A (CoA) to acetyl-CoA.
Acetyl-CoA reacts with oxaloacetate to citrate in the presence of citrate synthase (CS).
The oxaloacetate required for reaction (2) is formed from malate and nicotinamideadenine dinucleotide (NAD) in the presence of malate dehydrogenase (MDH) (3). In this reaction NAD is reduced to NADH.
The determination is based on the formation of NADH which is measured by the increase in absorbance at 340, 334 or 365 nm. Since a preceding indicator reaction is used, the amount of NADH formed is not linearly proportional to the acetic acid concentration.
Determination of Sulphur Dioxide
IFU Method 7a – The determination of total sulphur dioxide has been revised and is available in the catalogue of methods which can be accessed via the IFU website www.ifu-fruitjuice.com.
The revision includes an addendum for the determination of SO2 is via ion chromatography. This is useful when a confirmation of very low concentrations is needed or when false positive results must be ruled out. This can be the case for example in vegetable juices from Brassica (cabbage) which contains high levels of endogenous sulfur compounds. An analysis on sulfate from the solution of the first receiver flask can be performed using this procedure.
