Either way, this article was clever and I thought I'd share it.


The science of ageing wine

Box clever
Jun 10th 2009
From The Economist print edition

Some wine can improve if stored in a carton rather than in a bottle



AMONG snobs and sommeliers, nothing can compete with wine in a glass
bottle sealed with a cork stopper. Yet as cheap alternatives to cork
have become available and high fuel prices have made transporting
glass more expensive, some winemakers have adopted an alternative
method of storage: putting wine in cartons, like those used for milk,
made from layers of polythene, paper and aluminium foil. Admittedly,
serving wine from a carton lacks the aesthetic appeal of a bottle, and
cartons have also been criticised for allowing flavour-destroying
oxygen to seep in during storage. A new study, however, reveals that
although the criticism of wine cartons for allowing oxidation is
valid, they have the advantage of soaking up chemicals that can ruin
the flavour in other ways.

High levels of chemicals called alkyl-methoxypyrazines can make wines
taste as though the fruit from which they were made was under-ripe or
low-quality. Originally grapes themselves were thought to be the only
source of this class of compounds in wine, but recent research has
shown that invasive Asian lady beetles (also known as Harlequin
ladybirds) are also involved in the process. These beetles eat grapes
and can accidentally get mixed into the winemaking process. They then
contribute to the formation of these undesirable chemicals in some
North American and French wines.

The wine industry has tried various ways to remove alkyl-
methoxypyrazines, but none has been particularly successful. To make
matters worse, the Asian lady beetle is becoming more prevalent in
Italy, Spain, Argentina and South Africa, which means winemakers from
those regions could soon face the problem of dealing with these
chemicals, too. But it has long been known that packaging plays a role
in controlling wine chemistry and taste by absorbing some volatile
compounds in a process known as “flavour scalping”. A team led by Gary
Pickering at Brock University in Canada decided to investigate the
impact of different forms of packaging on the concentration of alkyl-
methoxypyrazines in wines.

The researchers added three types of alkyl-methoxypyrazine to red
(cabernet franc) and white (riesling) wines, some of which were stored
in cartons, and others in bottles. Natural cork, synthetic cork and
screw caps were used to seal the bottles. The researchers then
monitored chemical levels in the wines for 18 months.

They report in the Journal of Agricultural and Food Chemistry that at
the end of the study the levels of the different types of alkyl-
methoxypyrazines, known as IBMP, IPMP and SBMP, had fallen by 45%, 32%
and 26% respectively in the wines stored in cartons. In wines stored
in bottles, the levels of IBMP (which produces a characteristic “sweet
pepper” taste) did not fall as much: by 37% for synthetic cork, 36%
for screw cap and 31% for natural cork. When it came to IPMP
(associated with “green pea” and “earthy” flavours) the level
increased by 2-3% for natural cork, but fell by 7% for screw cap and
19% for synthetic cork. The levels of SBMP (which is thought to help
determine aroma) rose in all the bottled wine, but fell in that kept
in cartons. The results were similar for both types of grape.

Why the cartons have this effect is not entirely understood, but Dr
Pickering speculates that the wine may be seeping through the inner
polythene layers and making contact with the aluminium layer beyond.
He suggests that the alkyl-methoxypyrazine molecules may be sticking
to the aluminium and thus being segregated from the wine. If his
theory is correct, fiddling with the composition of box interiors
could be a good way for the wine industry to control the concentration
of unpleasant chemicals.

Cartons might thus assume an important role in the wine market. They
could be ideal for storing wines that are inclined to be high in alkyl-
methoxypyrazines but will be drunk relatively soon after purchase,
before oxidation can become a significant problem. For grand wines,
however, bottles with natural corks are likely to remain the packaging
of choice.