Search

Hop cones, the immature inflorescences of the female plant of Humulus lupulus L., have been used for centuries to improve the flavor of beer and can be also used for a great variety of other products. Four samples of hop, belonging to three different cultivars (Nugget, Saaz and Perle), were studied in the present work. Headspace solid-phase microextraction and hydrodistillation techniques were used to obtain the volatile profiles of the samples.Independent of the technique employed, over 40 volatile compounds were detected in the hop pellet samples (esters, monoterpenes, monoterpenoids, sesquiterpenes and sesquiterpenoids). Sesquiterpenes and sesquiterpenoids represented the majority of the total aromatic compounds. The main compounds for all cultivars were myrcene, β-caryophyllene and humulene, but the presence of high amounts of β-farnesene in Saaz cultivar was highlighted.Both techniques were suitable for studying qualitatively the volatile composition of hop pellets, but some differences were shown when studying the proportion of the main constituents of the volatile profiles. Understanding these differences may help researchers design future studies to advise the industry how to exploit the potential of each hop cultivar.

The volatile compounds produced by Debaryomyces hansenii NRRL Y-7426 during the fermentation of detoxified concentrated distilled grape marc hemicellulosic hydrolysates was analysed by GC–MS. Thirty-five compounds corresponding to ten groups of volatile compounds: terpenes, higher alcohols, C6 alcohols, aldehydes, volatile acids, acetates, ethyl esters, volatile phenols, sulphur compounds and hydrocarbons were identified. The supplementation with commercial nutrients increased the concentration of 2-phenylethanol, a commercial flavour and fragrance compound, with a rose-like odour, employed in cosmetics and food industries; and other positive compounds to the aroma such as terpenes and ethyl esters. Non-supplemented media produced the highest content in higher alcohols, volatile acids, sulphur compounds and in the majority of hydrocarbons detected, meanwhile supplementation with vinasses hardly produced volatile compounds. Only four volatile compounds contributed directly to the aroma according to the OAVs values higher than 1. Finally, a PCA analysis allowed accounting for 100 % of the variance.