The Storage Temperature of Beer

We know the light and oxygen is the enemy of beer storage, the finished beer must be stored without light (especially sunshine) and oxygen; but also some people talking about that the finished beer must be kept under low temperature, even with some data for explaination, talking about, for every 10°C (50°F) increase in temperature, the related chemical reaction rate doubles, beer stored at 100°F for one week tastes as old as beer stored at 70°F for two months, or as old as beer stored at 40°F for one year……but also some different opinions, the typical one is for the IPA, it was designed in the late 1700’s to withstand the long journey by ship from Britain to India, which meant spending up to six months in hot climates. Rumor has it that this “hot maturation” process created a beer that was so good, it became popular back in Britain, is it possible that the technologies of beer brewing and storage now even not as good as the one of IPA in the late 1700’s? also some people did relative tests and investigation proved with relative data that the temperature influence to the beer is not as so big as some people talked about.

then, does the storage temperature really affect the taste/flavor stability of beer and/or how big influence of it? based on our relative tests and relative investigation data, it shows that the temperature has some influence to the beer quality/shelf life, mainly on the oxidation of beer (or old beer), but it’s not an inherently damaging factor or a direct factor of beer flavor and/or taste stability, if the quality of finished beer is good enough, the quality control of filling process, the beer packaging method/control is good enough, then, it’s completely not necessary to worry too much about the influence of beer storage temperature to the beer flavor/taste stability; the information of beer must be stored under low temperature or even transported under low temperature could be persistently and irrationally overstated, it’s possible that the beer is not brewed good/healthy enough, especially not packed/filled good enough, and then overstated the affects of the storage temperature to the taste/flavor stability of beer.

we know the heat/temperature influence to the beer is mainly on the taste/flavor stability – the oxidized taste or old beer taste, there are hundreds chemicals affects the flavor/taste of the beer, but the chemicals related to the old beer taste, whether it’s from Trans--2 nonenal, or 2-methylpropionaldehyde, 2-methylbutyraldehyde, 3-methylbutyraldehyde, benzaldehyde, phenylacetaldehyde, Mercaptoacetaldehyde, or from other low flavor threshold Long chain unsaturated carbonyl compounds, etc., relative research indicates, the old taste (or oxidized taste) of beer is from saturated or unsaturated carbonyl compounds which is reacted from precursor including  aliphatic acid, reducing sugar, melanoid pigment, polyphenol, amino acid, etc., with oxygen, the temperature only speed or slow down such reaction, not the inherent or direct factor of such old/oxidized taste of beer.

so, the direct factors of old/oxidized taste of beer are from the inherent precursor in the beer (aliphatic acid, reducing sugar, melanoid pigment, polyphenol, amino acid, etc.) and oxygen, the ultimate way to prevent old/oxidized beer taste should be to control such precursor in the beer and/or the total content of oxygen in the beer, or prevent such reactions; but the threshold of precursor which affects the old/oxidized taste of beer is very low, it’s very difficult or even not possible to control them (especially for the microbreweries and/or home breweries), and although the filtered and pasteurize beer is more easy for storage and have more long shelf life, but such beer also lose a lot of peculiar flavor, that’s why the draft beer is more fresh and is better on flavor but more difficult for storage and more short shelf life.

also some method to add antioxidant, e.g. sulfur dioxide and/or sulfite into the beer to Improve the endogenous antioxidant ability of Beer, to prevent relative oxidation reaction and old/oxidized taste of beer, but it’s not so easy to control the content, the side-effect of such material (especially the sulfide) to the beer flavor, especially for small/micro breweries and/or home breweries.

in comparison, to control the total oxygen content in the beer (include the dissolved oxygen from the brewing process and the oxygen goes into the beer in filling process, and the air/oxygen in the head space) could be more easy from the cost as well the process control, if the total content of oxygen in the beer can be controlled very low, relative oxidation reaction will be not possible, even normal storage temperature or even high storage temperature for the beer, it’s not possible to speed up relative oxidation reaction and no relative chemicals in the beer form the old/oxidized taste.

relative research and test data indicates, if the total content of oxygen in the beer can be controlled within 1000ppb, even under high temperature, the beer will not have obvious old/oxidized taste. we have tried to fill the fresh beer into our kegs without filter and pasteurization, and make sure that almost zero air (oxygen) goes into the beer in filling process and after filling process, put the filled kegs under 35°C, every month check the oxygen and CO2 content in the beer, to compare with the one of the beer filled into keg but stored under low temperature, at the same time, do blind taste test for the beer filled in the keg which stored under both high temperature and low temperature, 3~6 months (even more long time), almost no difference on old/oxidized taste for the beer stored under on both temperature conditions.

of course, within the whole shelf life, total 1000ppb of total oxygen content inside the beer is very difficult for the breweries, especially for the small breweries or even the home breweries, as means for 500ml glass bottle or beer can, it only can have less than 1.7ml air (only less than 1.2ml air for 350ml glass bottle or beer can), or less than 100ml air (not pure oxygen) in 30L beer keg, it’s really not so easy for most of breweries especially small or even home breweries under cost control; e.g. for draft beer into the beer keg, after cleaning/drying/sterilization for the keg, it needs a lot of pure CO2 to flush the keg so that the air inside the keg can be completely replaced, even after filling, it’s difficult to guarantee the air inside the head space is less than 100ml. for draft beer, if possible, could be better to choose keg like the Gprokeg plastic beer keg (one-way and reusable kegs), the beer bag inside the keg is vacuumized for several times and with air replacement by inert gas, it can guarantee that the air goes into the beer during and after the filling process is almost zero.

so, for our opinion, talking about the heat/temperature will kill the beer, and the beer must be stored at low temperature or even has to be transported under low temperature, is not complete; for the beer without good enough quality control and/or process control, if the content of the inherent precursor in the beer (aliphatic acid, reducing sugar, melanoid pigment, polyphenol, amino acid, etc.) is high, the endogenous antioxidant ability of beer is not good enough, and the total content of oxygen in the beer is too high, then, it’s better to store and transport the beer under low temperature, to slow down the relative oxidation reaction and old/oxidation taste, to extend the shelf life of beer; but if the beer quality is good enough, especially good quality beer filled in premium keg like the Gprokeg plastic keg (reusable and one-way plastic kegs), to control the total content of oxygen in the filled beer to very low, then, don’t need to worry about the storage temperature too much, if possible, can store the beer under low temperature, but even if normal temperature or high temperature in transportation will not have obvious affects to the beer shelf life.