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Controlling microbiological spoilage in floral waters

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.

Orange blossom. © INRA, CAIN Anne-Hélène
Updated on 06/27/2016
Published on 04/29/2016

The production of floral waters: seeking to improve the quality of a traditional process

Floral 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 populations

In 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 waters

The 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.

Contact(s)
Scientific contact(s):

Associated Division(s):
Microbiology and the Food Chain
Associated Centre(s):
Provence-Alpes-Côte d'Azur

For more information on this collaboration

The research work carried out in the context of the partnership between the INRA Joint Research Unit for the Safety and Quality of Plant Products (UMR-SQPOV) and Albert Vieille formed part of a CIFRE PhD project by Cécile Labadie.  Her thesis, entitled: "Chemical analysis and preservation of Rose and Orange blossom Hydrosols" was defended on December 4, 2015

. © INRA

Albert Vieille, the specialist in aromatic raw materials

Founded in the Grasse region nearly a century ago, Albert Vieille specializes in producing and distributing exclusively 100% pure and natural aromatic raw materials for professionals in the perfumery, cosmetics, food, and aromatherapy industries.
The company offers more than 200 aromatic products– essential oils, floral waters, absolutes, concretes, resinoids, and gum resins – for olfactory creations.
Company’s expertise is illustrated in the internal quality standards developed, which take the form of a 100% Pure and Natural Charter. It also lies in the control laboratory, which thoroughly analyses all materials to guarantee the quality of the Ingredients.
Its expertise is also found in the reliability of its network of agricultural partners in 40 countries, meaning the company can provide its customers with carefully monitored supplies of raw materials to ensure availability and reproducible quality.
Lastly, its production center in Spain puts into practice mastery of many different processing techniques for fresh and dried aromatic raw materials, gum-resins, and floral concretes, to meet customers’ varied needs.
As an expert in odorant fractions, the company contacted INRA for its expertise in the  microbiological control of foodborne micro-organims.  The CIFRE grant (Training through Research in industry project) was a highly  appropriate contractual agreement for the preparation of the PhD thesis.  With such CIFRE contracts PhD students conduct their research project for three years in a strong interaction in accordance with the scientific and technical objectives that the contracting company has defined. Hiring of the PhD student was entirely organised by the company's laboratory, and according to Elise Carénini, its manager, "our selection was very successful".  Moreover "the availability of the student's scientific supervisor (Frédéric Carlin) was particularly appreciated, as well as the original approach adopted by scientists who were initially more familiar with food products than with cosmetic products ".