Stability of floral waters: distillation produces nearly sterile hydrosols when collected in the essencier

Study of the microbiota of two floral waters (rose and orange blossom) is a key-issue in ensuring their optimal preservation. Appropriate and adapted protocols for stability tests have been developed and have improved the production processes? applied by the industrial partner, Albert Vieille.The production of floral waters: seeking to improve the quality of a traditional processFloral waters (or hydrosols) are co-products from the steam distillation or hydrodistillation of aromatic plants in the production of the much less abundant but highly valuable essential oils (EOs). These are mainly used in the food and cosmetic industries, perfumery and aromatherapy. Orange blossom (Citrus aurantium L. ssp. amara L.) and rose (Rosa damascena Miller and Rosa centifolia L.) hydrosols are the most commonly used hydrosols worldwide, with an estimated annual production of 1500 t and 1000 t, respectively, not accounting for local and family production. The steam distillation or hydrodistillation process of aromatic plants produces two non-miscible phases: the EO phase containing the major part of volatile compounds, and the hydrosol phase composed of condensed water and a small amount of dissolved EO (usually less than 1 g/L) that confers their organoleptic properties.These two floral waters sometimes suffer from microbiological instability, which producers need to control in order to comply with industrial specifications and standards.? Until recently, the causes of these microbiological instability issues were generally little? studied and only partially understood.A microbiota dominated by four bacterial populationsIn the context of a collaboration with the company Albert Vieille, 22 samples of orange blossom water and rosewater from different producers around the Mediterranean basin were analysed.? The dominant microflora in these products were Gram-negative bacteria which mainly belonged to four separate phylogenetic? branches : Pseudomonas sp., Burkholderia cepacia, Rhodospirillaceae and Acetobacteraceae. These bacteria are not particularly demanding and can directly metabolise components of the volatile fraction, or use for their growth the rare nutrients solubilised in hydrosols.The hydrosols were shown to be markedly susceptible to microbial contamination, which could reach high levels (up to 6-7 log10 CFU/ml), but without displaying any signs of spoilage (cloudiness, off-odour, or off-colour) in many instances.Options to improve the stability of floral watersThe air transport of micro-organisms was the most likely source of hydrosol contamination, which could occur during decanting, sampling or other storage operations? performed in open air and using clean, but not sterile, containers.? Distillation (by steamed? water at 100?C for about 4 hours)? produces nearly sterile? hydrosols when collected in the essencier (or florentine separator).? Aseptic packaging is too expensive for this type of product with low added value, so packaging in sterile and hermetically sealed containers at the essencier outlet offers a potential opportunity for improvement.Similarly, various chemical preservatives were tested and efficient conditions were determined at the laboratory scale.? However, further research is now necessary to identify preservatives that respect the natural image of hydrosols.Knowledge to enable the revision of processes Methodological developments in the context of this collaboration between Albert Vieille and INRA offer new opportunities for the commercial development of this company.? A specific protocol has been compiled to evaluate stability during the storage of floral waters at different temperatures and pH levels. This could easily be applied to hydrosols other than orange blossom or rose hydrosols.Finally, the quality system of the company was reviewed and the control plans were revised to enable the monitoring of product stability from? the end of production to the end of storage. Sources (text and picture):