Vapor Analysis of Fermented Spanish‐type Green Olives by Gas Chromatography

Abstract

SUMMARY: Five major components were detected gas chromatographically in the head‐space vapor (HSV) of Spanish‐type green olives fermented by pure cultures of Lactobacillus plantarum, Pediococcus cerevisiae and Leuconostoc mesenteroides. Three of these compounds were identified as acetaldehyde, methyl sulfide, and ethanol. The same compounds were present in unfermented olives but in different amounts. Olives that had undergone a natural fermentation contained the above five compounds, and, in addition, a varying number of other compounds. These results indicated that HSV analysis may be a rapid method for detecting volatile end products resulting from the metabolism of various microorganisms. A high ethanol content was found in olive brines that contained a predominance of yeasts. Abnormal fermentations gave unique HSV profiles, one of which indicated a high level of 2‐butanol. Methyl sulfide was found to be a major odor component of fermented as well as unfermented olives. Acetaldehyde and ethanol contributed secondarily to the odor. Primary contributions of fermentation by the above lactic acid bacteria to the flavor of olives were: (1) production of a desirable level of acidity, and (2) utilization of fermentable sugars to the exclusion of microorganisms which produce metabolic end products with undesirable flavor characteristics.

Table olives volatile fingerprints: Potential of an electronic nose for quality discrimination

“…lactic acid bacteria, the major group responsible for olive fermentation or any other group (e.g. yeasts, filamentous fungi, clostridia) associated with spoilage of these fermented products [2]. It is thus clear that volatile compounds have a decisive role in the characterisation of the flavour pattern of a given olive sample.…”

“…In the last decades many efforts have been made to study the aromatic fraction of fermented olives based mainly on chromatographic determinations [2][3][4][5][6][7][8][9]. However, these analytical techniques are also time-consuming and require sophisticated equipment and skilled personnel.…”

An investigation on molecular partition of aroma compounds in fruit matrix and brine medium of fermented table olives

“…The combination of high salt and low pH greatly reduces the risk of microbial spoilage of the olives (Zervakis, 2006). Moreover alcohols, esters, aldehydes, and ketons as well as other acids are known to be formed by microorganisms which are competitive with lactic acid bacteria in brined olives (Fleming, Etchells, & Bell, 1969). The lactic acid bacteria belong to two main groups the homofermenters and the heterofermenters.…”

Transformaciones bioquímicas durante la fermentación de productos vegetales

“…Aunque se han publicado algunos trabajos sobre análisis de componentes volátiles responsables del aroma en aceitunas (Fleming et al, 1969) y pepinillos (Aurand et al, 1965) se desconoce cuál es la contribución relativa de cada uno de estos componentes, así como su evolución a lo largo de la fermentación. Uno de los pocos trabajos completos publicados al respecto es el de Karki et al (1983), quienes realizan el estudio con una preparación típica oriental, mezcla de diversos vegetales fermentada por bacterias acidolácticas, conocida como Gundruk.…”