Détermination d’une méthodologie de lavage de la tubulure

543 Ko

Deux méthodes de lavage de la tubulure ont été comparées soit le lavage à l’eau et le lavage à l’hypochlorite de sodium. Ces lavages ont été effectués à l’érablière expérimentale à 50% et à 100% de la coulée. Les résultats ont permis d’observer l’évolution de la contamination durant toute la saison et ce en fonction de la nature des contaminants (bactéries totales, Pseudomonas, levures et moisissures). La flore contaminante était essentiellement constituée de bactéries du genre Pseudomonas. L’effet d’une coulée forte sur la charge microbienne est observé de façon évidente avec les suivis des populations. Cependant, la charge initiale de contamination étant élevée (environ 1x10⁷ UFC/ml), il a été difficile d’observer l’effet des méthodes de lavages proposées. Une légère baisse des populations a été observée après les traitements à l’eau et à l’hypochlorite de sodium sans toutefois déceler de différence entre les deux types de traitements. La présence de biofilm pourrait expliquer la reprise rapide de la contamination dans la tubulure. La formation du biofilm à la surface de la tubulure a été observée en microscopie électronique à balayage. Les photos au microscope électronique n’ont pas démontré que le biofilm s’installait de façon préférentielle sur la surface de la tubulure (bas versus haut du tube). Les effets des traitements de lavage n’ont également pas été démontrés grâce à la microscopie électronique. La poursuite des travaux sera consacrée à l’étude de différents produits de lavage et sur différents procédés pouvant limiter l’accumulation du biofilm à la surface de la tubulure.

Rapid Prediction of Maple Syrup Grade and Sensory Quality by Estimation of Microbial Quality of Maple Sap Using ATP Bioluminescence
(Source : IFT Institute of Food Technologists)

ATP bioluminescence was evaluated as a method for assessing the level of microbial contamination in sap and predicting maple syrup characteristics. This approach provided results that were strongly correlated with the standard plate count and took less time than the modified resazurin technique. ATP bioluminescence measurement of sap proved to be reliable for predicting physicochemical and sensory characteristics as indicated by the color and flavor of maple syrup. Most of the syrups made from saps with higher ATP bioluminescence values were darker in color and presented off-flavors. Based on these results, ATP bioluminescence could be used to improve sanitary practices associated with collecting and storing maple sap.

Identification of the Bacterial Community of Maple Sap by Using Amplified Ribosomal DNA (rDNA) Restriction Analysis and rDNA Sequencing
(Source : American Society for Microbiology )
 

The bacterial community of maple sap was characterized by analysis of samples obtained at the taphole of maple trees for the 2001 and 2002 seasons. Among the 190 bacterial isolates, 32 groups were formed according to the similarity of the banding patterns obtained by amplified ribosomal DNA restriction analysis (ARDRA). A subset of representative isolates for each ARDRA group was identified by 16S rRNA gene fragment sequencing. Results showed a wide variety of organisms, with 22 different genera encountered. Pseudomonas and Ralstonia, of the - and ß-Proteobacteria, respectively, were the most frequently encountered genera. Gram-positive bacteria were also observed, and Staphylococcus, Plantibacter, and Bacillus were the most highly represented genera. The sampling period corresponding to 50% of the cumulative sap flow percentage presented the greatest bacterial diversity according to its Shannon diversity index value (1.1). -Proteobacteria were found to be dominant almost from the beginning of the season to the end. These results are providing interesting insights on maple sap microflora that will be useful for further investigation related to microbial contamination and quality of maple products and also for guiding new strategies on taphole contamination control.

The bacterial microflora of maple sap and biofilms in collection system tubing were studied through the use of bacterial counts, scanning electron microscopy (SEM) of surfaces and the analysis of 16S rRNA gene by denaturing gradient gel electrophoresis (DGGE). Samples were taken at five times during the 2002 and 2003 seasons in order to follow the changes in the microflora of this complex ecosystem. Bacterial counts showed the growth of bacterial populations as the season advanced. These populations were mainly composed of psychrotrophic bacteria and Pseudomonas spp. SEM results confirmed the suspected presence of biofilms on the inner surfaces of tubing samples. Bacterial colonization and biofilm formation progressively increased during the season for both lateral and main line surfaces, and biofilms were mainly composed of rod shape bacteria. The bacterial microflora profiles obtained for sap and corresponding biofilm by DGGE showed up to 12 major bands. The Shannon-Weaver index of diversity (H) calculated from DGGE bands were statistically higher for sap samples compared to biofilm. The diversity index was relatively stable or increasing for lateral line sap and biofilm samples during the season while the diversity index for sap and biofilm samples of the main line showed a decreasing profile as the season progressed. Sequence analysis of major DGGE bands revealed the predominance of bacteria from the genera Pseudomonas, Rahnella and another, unidentified genus. The results describe the composition of sap collection system microflora as well as the formation of biofilms and will be useful for further studies on factors affecting maple product quality.

Biofilm formation and Biocides sensitivity of Pseudomonas marginalis isolated from a Maple Sap Collection System
L.Lagacé, M. Jacques, A.A. Mafu and D. Roy
(Journal of Food Protection, Vol. 69, No 10, 2006, Pages 2411-2416)

The susceptibility of planktonic and biofilm cells of Pseudomonas marginalis toward four commonly used biocides at different temperatures (15 and 30°C) and biofilm growth times (24 and 48 h) was assessed. Using the MBEC biofilm device, biofilm production in maple sap was shown to be highly reproducible for each set of conditions tested. Biofilm formation was influenced by growth temperature and time. A temperature of 15°C and incubation time of 24 h yielded fewer CFU per peg and showed fewer adhered cells and typical biofilm structures, based on scanning electron microscopy observations as compared with other conditions. Minimal biofilm eradication concentration values for P. marginalis were significantly greater (P < 0.001) than were MBCs for planktonic cells and for every biocide tested, with the exception of minimal biofilm eradication concentration values for peracetic acid at 15°C and 24 h. Sodium hypochlorite and peracetic acid sanitizers were able to eliminate P. marginalis biofilms at lower concentrations as compared with hydrogen peroxide- and quaternary ammonium-based sanitizers (P < 0.001). According to the results obtained, sodium hypochlorite and peracetic acid sanitizers would be more appropriate for maple sap collection system sanitation.

Évaluation des principaux facteurs associés à la détérioration microbienne du sirop d’érable en vrac
Luc Lagacé, Ph.D., Centre de recherche, de développement et de transfert technologique acéricole Inc. 3600 boul. Casavant Ouest, St-Hyacinthe, QC, Canada. J2S 8E3.

Résumé

L’importance de différentes variables sur la conservation du sirop d’érable en barils a été étudiée dans le cadre de ce projet. Premièrement, une comparaison de 4 types de barils et de 2 techniques d’échantillonnage (standard et Morneau) a été effectuée à partir de 9 lots de sirop et en utilisant des conditions rigoureusement contrôlées de mise en contenant. Les résultats obtenus ont démontré que la couleur du sirop a été influencée par le type de barils durant la période d’entreposage de 24 mois.  Les barils Barinox et Vulcan ont permis une meilleure conservation de la couleur du sirop comparativement aux barils Morneau et CDL (sac laminé d’aluminium). Les conditions contrôlées de mise en contenant ont permis d’obtenir un faible taux (2%) de détérioration microbienne du sirop durant l’entreposage. Cependant, l’échantillonnage à l’aide de la technique standard a fait augmenter considérablement ce taux (16,6%) notamment pour les barils Morneau et CDL.  L’échantillonnage à l’aide de l’échantillonneur Morneau a permis un taux réduit de détérioration de 3,7%.  Deuxièmement, une analyse a été effectuée de la population de 53206 barils reçus des producteurs après la récolte et entreposés environ pendant 6 mois avant d’être reclassés à l’automne 2004 en vue d’être pasteurisés. Cette analyse a permis d’évaluer l’importance de différentes variables sur l’apparition de la détérioration microbienne du sirop à l’entreposage. Les résultats révèlent notamment que les pratiques de mise en contenant sont considérablement importantes pour la conservation du sirop. Une concentration en solides solubles inférieure à 66°Brix ainsi qu’un taux de remplissage inférieur à 90% sont parmi les variables qui sont les plus fortement corrélées à la détérioration microbienne. De plus, une certaine catégorie de sirops venant d’entreprises de plus petite taille semblent plus fortement associés à la détérioration microbienne du sirop à l’entreposage. Finalement, le baril de plastique Morneau s’est révélé plus susceptible aux pratiques défavorables à la conservation du sirop faisant en sorte qu’il est associé à une proportion importante de barils présentant une détérioration microbienne (43%).  Ces résultats révèlent l’importance de contrôler les pratiques de mise en contenant à l’érablière ainsi que l’échantillonnage et l’entreposage afin de prévenir la dégradation de la qualité du sirop en vrac et d’éviter des pertes monétaires importantes pour l’industrie acéricole.

Mots clés : sirop, érable, barils, entreposage, conservation,  fermentation, saveur

Abstract

The importance of different variables on the stability during storage of bulk maple syrup was investigated in this project. First, 4 types of 32-gallon drums and 2 sampling techniques (standard and Morneau) were evaluated for 9 different lots of maple syrup produced in rigorously controlled packaging conditions. Results obtained demonstrate that the colour of maple syrup was influenced by the type of drums over the storage period of 24 months. Metal drums from Barinox and Vulcan showed a slightly better colour stability of maple syrup compared to Morneau and CDL (aluminium barrier bag) plastic drums. Under controlled packaging conditions, the rate of microbial spoilage of maple syrup during storage was low (2%). But after sampling of containers using the standard method, the rate of microbial spoilage considerably increased (16.6%) especially for the Morneau and CDL containers. Sampling with the Morneau device
permitted to control the microbial spoilage rate to 3.7%.  Second, an analysis was performed on the population of 53206 maple syrup drums that were received from Quebec producers following the 2004 season and kept in storage for approximately 6 months before being re-inspected and
pasteurized for long period storage. From this analysis, some variables showed to be highly related to microbial spoilage during the 6 month storage period. Results showed that the packaging operations performed by the maple syrup producers are critical to maple syrup stability during storage. A total solid concentration lower than 66°Brix and a percentage of drum filling lower than 90% were among the variables that most strongly correlated with microbial spoilage. Furthermore, a category of syrup coming from smaller sugarbushes was also highly related to microbial spoilage during storage. Finally, a certain type of drum (Morneau plastic
drum) showed to be highly susceptible to improper packaging operations and was related to a high proportion of syrups (43%) that had microbial spoilage.  These results reveal the importance of appropriate packaging operations at the sugarhouse and of good sampling practices for inspection to prevent microbial spoilage of bulk maple syrup during storage and avoid important economical loss for the maple syrup industry.

 Key words: maple, syrup, drums, storage, conservation, fermentation, flavour