|Characteristics and fitness for container transport
This section will look at beverages which are primarily transported as liquids in containers of glass (bottles), metal (cans, jerricans, barrels), plastic (jerricans, bottles) or wood (barrels).
A distinction is made between alcoholic beverages and non-alcoholic soft drinks. Alcoholic beverages contain ethyl alcohol, generally at a dilution of less than 50%. They include wines, beers, spirits and wine-containing/wine-like beverages. Non-alcoholic soft drinks include, among other things, fruit juices, table water, mineral water and lemonade.
Beverages are goods displaying 4th order biotic activity (BA 4), i.e. they are goods in which biochemical and microbial processes have stopped and which are isolated from the external environment, e.g. sterilized and pasteurized goods in hermetically sealed packaging (liquids in bottles, jerricans, cans, barrels).
Owing to this packaging, they are assigned to water content class 0 (WCC 0).
Beverages require particular temperature, humidity/moisture and possibly ventilation conditions (SC VI), since they suffer in particular from temperature-determined physical changes, such as ice expansion rupture or heat expansion rupture of the containers due to thermal expansion (dilatation). Excessive humidity leads to damage, especially to labels. If the product, packaging and pallets are container dry, they do not need to be ventilated, and can be transported in standard containers.
Transport instructions and damage
Ice expansion rupture
From a chemical standpoint, beverages are aqueous solutions or water-containing mixtures of substances, with significant factors for their storage being the physical properties of the water, in particular its temperature-determined volume changes and expansion (dilatation) on freezing.
The anomaly of water is that, after reaching maximum density at 4°C, it continues to expand when cooled further until freezing point is reached at 0°C. The decisive factor, however, is dilatation upon transition from the liquid to the solid phase. Its volume increases by approximately 9%. This leads to elevated pressures in the contents, resulting in bursting of the container. This phenomenon is known as ice expansion rupture.
In the case of non-alcoholic soft drinks, the freezing point is lower than that of pure water, depending on the concentration of these dissolved substances in the water. An increased concentration of a solution is associated not only with a reduction in the freezing point but also a smaller increase in volume on freezing, since dilatation of the water is countered by contraction (reduction in volume) of the accompanying substances (sugar, fruit concentrate, acidulating agents etc.) (see Table. 22).
Table 25: Freezing point reduction and change in volume on freezing
of sucrose solutions;
With increasing cooling below freezing point, ice continually precipitates out, accompanied by segregation processes, and an ice layer a few centimeters thick is sufficient to cause ice expansion rupture of conventional glass bottle packaging, without its contents having to be completely frozen. Water-containing goods whose freezing point is just below 0°C are at particular risk of ice expansion rupture (see Table 26). With most non-alcoholic soft drinks, freezing point is between -0.3 and
Table 26: Freezing points of certain beverages;
Ice expansion rupture is observed particularly frequently and severely with carbon dioxide-containing beverages contained in bottles (mineral water, fizzy drinks etc). The internal pressure arising due to the increase in volume on freezing of the water is increased still further in this beverages as a result of release of the dissolved carbon dioxide.
In contrast, ice expansion rupture is seldom observed in alcoholic beverages, especially wines and spirits, due to their lower freezing points. In addition, when wines and spirits freeze, dilatation of the water is accompanied by contraction (reduction in volume) of the alcohol, which at 35 vol.%, is so considerable that the overall volume does not expand on freezing of the water. In vollbiers, the increase in volume generally results in liquid escaping through the bottle closures.
Heat expansion rupture
In the case of liquids in glass containers, high temperatures and a high coefficient of thermal expansion may cause the containers to burst, given the considerable pressure then exerted by the contents. The risk of heat expansion rupture increases, the greater the coefficient of thermal expansion. For example, at 18°C the coefficient of cubic (thermal) expansion is 0.00018/°C for water, but 0.00110/°C for ethyl alcohol. As a consequence, in the case of ethyl alcohol the risk of heat expansion rupture is six times that of water. Alcoholic beverages are thus more at risk from heat expansion rupture than non-alcoholic beverages.
Because of the risk of ice expansion rupture, transport temperatures of less than 2°C are inadvisable for beverages, while the risk of heat expansion rupture means that temperatures of > 20°C should be avoided.
Tank containers should be loaded in such a way that sufficient ullage space is left for heat-induced expansion. Some liquids are subject to filling regulations. The shipper must state that these have been complied with.
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