Hop, Humulus lupulus, ext.

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Hop extract is a multi-component UVCB. Hop extract has a long history of use as an food ingredient in the manufacture of beer, and it has GRAS status in the USA. It has therefore been used safely, both in the EU and worldwide, for a considerable number of years. Since it is a UVCB, the precise composition can vary, but detailed compositional information is given in the boundary composition. Briefly, the major components of hop extract are the alpha acids, the beta acids and the hop essential oil. The hop essential oil is the only component for which there is a predicted significant vapour pressure. Hop essential oil makes up 0 - 40% of a hop extract. Hop oil itself made up of a very large number of components, but the major three components are myrcene, humulene and caryophyllene. Even an essential oil-rich hop extract has a viscosity of 1 - 3 Pa.s at 30 - 40 oC (Barth Haas Group internal company data), that is, a viscosity substantially above that of water. A hop extract is not therefore likely to pose an inhalation hazard risk. The other safety hazard pertaining to vapour pressure is the environmental fate and biodegradation of hop extract. Hop extract is produced by ethanol or carbon dioxide extraction of hop cones – this is a “natural” extract under food legislation, although solvent extracts are not considered as “natural” under REACH, unless extracted simply by water, hence the REACH registration. Nevertheless, hop extract is effectively a natural extract. Taking into account the compositional and potential safety data, it is reasonable to estimate the vapour pressure of a hop extract based on its most volatile component, namely myrcene. This has been done for this end point.

Qualifier:

according to guideline

Guideline:

other: Gas chromatography based retention index method

Version / remarks:

Details are given in the reference A van Roon et al (2002) J. Chromatog. A vol 955, pp. 102-115. A gas chromatography method was used, with n-alkanes as reference compounds, determining Kovats retention indices, and using an equilibrium fugacity model. The results obtained were compared with published literature values.

Principles of method if other than guideline:

Details are given in the reference A van Roon et al (2002) J. Chromatog. A vol 955, pp. 102-115. A gas chromatography method was used, with n-alkanes as reference compounds, determining Kovats retention indices, and using an equilibrium fugacity model. The results obtained were compared with published literature values.

GLP compliance:

not specified

Type of method:

other: See A van Roon et al (2002) J. Chromatog. A vol 955, pp. 102-115. A gas chromatography method was used, with n-alkanes as reference compounds, determining Kovats retention indices, and using an equilibrium fugacity model.

Key result

Temp.:

298.15 K

Vapour pressure:

ca. 1.38 < mm Hg

Conclusions:

The vapour pressure can be taken to be equal or less than that of the UVCB's principal volatile component, namely myrcene.

Key value for chemical safety assessment

Vapour pressure:

0.184 kPa

at the temperature of:

298.15 K

Additional information

Based on the most volatile component on this UVCB, namely myrcene.