Sugar-free extract is the latest unfamiliar expression to pass the lips of exporters of wine to China. This obscure test was the largest cause of wine being rejected by Chinese authorities last year. In this article Greg Howell, from Vintessential Laboratories, explains this test and make recommendations on what exporters should do to ensure that they have no technical problems getting their wine into China.
Wine Australia has advised Australian wine exporters of another technical issue in regard to wines exported to China. The latest issue coming from our great northern trading partner involves the obscure measure of Sugar-free extract.
To quote Steve Guy, Wine Australia’s general manager for regulatory affairs:
“A significant market access issue has recently emerged in China.
“A recent report in the Chinese edition of Decanter identified ‘sugar free extract’ as the leading reason for wine being rejected by Chinese Customs last year, accounting for nearly a quarter of all 165 rejected consignments. 10 per cent of these consignments were Australian.
“China applies minimum standards for a parameter described as ‘sugar-free extract’. This is determined by subtracting the sugar content from the ‘total dry extract’.
“White wines should meet the minimum of 16 g/l, rose wines 17 g/l and red wine 18 g/l.
“We have previously advised that China determines sugar levels in a manner that generally produces higher results than are obtained using the methods most commonly used in Australia. This partly explains why several Australian wines have been rejected for not meeting the minimum standard for ‘sugar free extract’.
“The problem is most apparent with sweet white wines…”
WHAT IS SUGAR-FREE EXTRACT?
Total Dry Extract (also known as Total Dry Matter or simply as Extract) is a measure of the non-volatile components of wine, determined under specified test conditions.
The main components making up this extract are sugars, glycerol, and the fixed (non-volatile) acids (3). The OIV (Organisation Internationale de la Vigne et du Vin) have an internationally accepted wine test method for analysing Total Dry Matter (4).
This has long been required on Export Certificates of Analysis for bulk wine exported to Europe and also for wine exported to Japan, and has been done in our labs for many years.
Sugar-free extract is determined using a modification of the Total Dry Extract method.
It is the amount of extract left when the content of all sugars (including sucrose) are subtracted from the Total Dry Extract.
It is defined in the OIV test method as the “difference between the total dry extract and the total sugars”.
WHY IS SUGAR-FREE EXTRACT IMPORTANT TO THE CHINESE AUTHORITIES?
A low value of Sugar-free extract can imply that excess water was added when making the wine and it appears this is the issue that is important to Chinese authorities.
This is especially the case in regard to domestically made wines, due to the practise of Chinese winemakers previously making “half-juiced” wine (5).
This was a longstanding technique of making a low alcohol product by adding water to wine prior to bottling! It was a popular product until it was banned in 2004.
Unfortunately the authorities are also applying the Sugar-free extract parameter to imported wine.
This adulteration issue was part of the original intent of extract measurements when first introduced in Europe many years ago.
According to one respected source (3), Sugar-free extract was used historically in Europe to detect wine adulterated with water or dissolved materials by using empirical values worked out in small districts with the same cultivar and very similar winemaking practices and in one season.
However, “the application of these empirical values to wines of today or to wines from different countries is far less valid.” (3)
Another respected source (6) states “Values for (sugar free) extracts range from 0.7g/100mL [7g/L] for low alcohol German wines to more than 3g/100mL [30g/L] for late harvest red wines, with an average value of about 2.0g/100mL [20g/L].”
As can be seen the figure of 7g/L for the above German wines is well below the level the Chinese apply for all white wines of 16g/L!
So the key issue is that the limits used by the Chinese for Sugar-free extract of 16, 17 and 18 g/L for whites, rosés and reds respectively are obviously not valid for imported wines from different countries using differing winemaking techniques.
HOW IS SUGAR-FREE EXTRACT MEASURED?
The original way to measure Total Dry Extract was to place a known amount of wine on a filter paper, let it evaporate under set conditions of temperature, time and pressure, and then measure the increased weight of the dry filter paper, results stated in gram per litre (g/L).
The latest version of the OIV Total Dry Extract method from 2009 (4) measures alcohol content and density, and then a calculation is performed.
To get Sugar-free extract, the total sugar content is subtracted from Total Dry Extract.
To quote the method:
“Sugar-free extract = Total dry extract – reducing sugars (glucose + fructose) – saccharose”
A couple of issues arise from this definition. The reducing sugars test used is not defined, and as we have previously published (7), this can be determined several ways with different levels of accuracy.
So if a reducing sugar method is used in China (say the older Rebelein or Lane and Eynon methods) and the more accurate and commonly used glucose + fructose by enzymatic analysis as used in Australia, the difference in results between these types of sugar tests can be 1-2 g/L, which in this scenario can be critical.
The reducing sugar test gives a higher result and this leads to a resultant lower Sugar-free extract, as noted in the Wine Australia bulletin.
Also, the last term in the equation – saccharose (an outdated term for sucrose) requires that sucrose has to be determined as well. Of course for Australian non-sparkling wines this should be negligible.
However as can be seen, by comparing typical Australian test results to the ones from the Chinese authorities it is very possible there will be differences in the level of Sugar-free extract for the same wine, with our results likely to be higher if the glucose + fructose test is applied here and a reducing sugar test used in China.
SO, WHAT SHOULD AN EXPORTER DO?
First, our strong recommendation is that Australian wine exporters measure Sugar-free extract before they send their wine to China.
Secondly, ensure the lab you use utilises the most appropriate test methods so that the results are as comparable as can be to the Chinese test results.
Finally, due to potential discrepancies between the testing practises in Australian wine labs compared to the Chinese labs, it would pay to have some safety margin in the Sugar-free extract result.
For example, the minimum limit for Sugar-free extract in white wine in China is 16 g/L. Do you export if you get a result from your lab of 16g/L, or 17g/L or say 18g/L?
This is a difficult decision to make but one that has to be kept in mind. Certainly if you get a result that is less than the limit imposed it is a risk sending the wine to China.
SCREENING OF WINE DESTINED FOR CHINA
Due to several recent issues with Australian wine being rejected in China, at Vintessential Laboratories we have implemented a Chinese Screen bundle of tests.
Note these are not required on the Export Certificate of Analysis. They are a few tests that we now know are used by the Chinese authorities to check wine and if any results are outside the limits set, the Chinese will reject the wine.
We are recommending our clients who export their wine to China get this screening bundle done and ensure all limits are passed, before going ahead with further testing to get an Export Certificate of Analysis.
Australian wine exporters now have another bizarre technical hurdle to get over in order to export their wine to China. The use of limits on Sugar-free extract by the Chinese authorities is causing more wines from around the world to be rejected for this parameter than any other.
It is strongly recommended exporters get their wines screened for this test before attempting to export their wine.
About the Author
Greg Howell founded Vintessential Laboratories in 1995. More articles on related oenological topics are available on the Vintessential website at www.vintessential.com.au/resources/articles/.
This article was first published in the October 2015 edition of the Grapegrower & Winemaker magazine.
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