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!
Detection and Enumeration of Spore-forming Thermo-Acidophilic Spoilage bacteria (Alicyclobacillus spp.)
This third edition cancels and replaces the second edition (IFU Method No. 12: 2007), which has been technically revised.
The main changes, compared to IFU Method No. 12:2007, are the following.
- The tittle of the method has been changed.
- The optional usage of several media has been changed to the usage of one liquid (BAT broth) and one solid medium (BAT agar).
- A new pour plating technique is introduced for enumeration in 1 g.
- Performance testing for the quality assurance of the culture media has been added to Annex B.
- Performance characteristics for this method have been added to Annex D.
- Optional pre-incubation of packed ready-to-drink products has been added to Annex E.
- Matrix-dependent special processes have been added to Annex F.
This method has been revised and has been loaded onto the IFU website. Please select the heading Methods of Analysis and the drop down menu Microbiological Methods. The method is available to corporate members as part of the subscription. Non members can buy the method via the store link on the website
Determination of Acetic Acid (enzymatic method)
This method has been revised and has been loaded onto the IFU website. It now includes precision data.
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.
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.
Mesophilic & Thermoduric – Thermophilic Bacteria: Spore Count
Please note that this method has been revised with a corrected thermal treatment step in sections D- IV and D-V. Thermophilic aerobic and anerobic sporeforming bacteria – spore count.
The revised method can be access via the methods section of the IFU website www.ifu-fruitjuice.com.
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.