Articles scientifiques

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15 octobre 2018

A systems biology approach to explore the impact of maple tree dormancy release on sap variation and maple syrup quality

Auteurs : Guillaume Quang N’guyen, Nathalie Martin, Mani Jain, Luc Lagacé, Christian R. Landry et Marie Filteau

Cet article est disponible seulement en anglais (Scientific Reports, volume 8, Article number: 14658 (2018)).

Maple sap is a complex nutrient matrix collected during spring to produce maple syrup. The characteristics of sap change over the production period and its composition directly impacts syrup quality. This variability could in part be attributed to changes in tree metabolism following dormancy release, but little is known about these changes in deciduous trees. Therefore, understanding the variation in sap composition associated with dormancy release could help pinpoint the causes of some defects in maple syrup. In particular, a defect known as “buddy”, is an increasing concern for the industry. This off-flavor appears around the time of bud break, hence its name. To investigate sap variation related to bud break and the buddy defect, we monitored sap variation with respect to a dormancy release index (Sbb) and syrup quality. First, we looked at variation in amino acid content during this period. We observed a shift in amino acid relative proportions associated with dormancy release and found that most of them increase rapidly near the point of bud break, correlating with changes in syrup quality. Second, we identified biological processes that respond to variation in maple sap by performing a competition assay using the barcoded Saccharomyces cerevisiae prototroph deletion collection. This untargeted approach revealed that the organic sulfur content may be responsible for the development of the buddy off-flavor, and that dormancy release is necessary for the appearance of the defect, but other factors such as microbial activity may also be contributing.

06 juin 2017

Analysis of plastic residues in maple sap and syrup collected from tubing systems sanitized with isopropyl alcohol

Auteurs : Luc Lagacé, Carmen Charron et Mustapha Sadiki

Cet article est disponible seulement en anglais (Heliyon, Volume 3, Issue 5, May 2017, Article e00306). Le numéro de référence (Digital Object Identifier (DOI)) est le : 10.1016/j.heliyon.2017.e00306.

A plastic tubing system operated under vacuum is usually used to collect sap from maple trees during spring time to produce maple syrup. This system is commonly sanitized with isopropyl alcohol (IPA) to remove microbial contamination colonizing the system during the sugar season. Questions have been raised whether IPA would contribute to the leaching of plastic residues in maple sap and syrup coming from sanitized systems. First, an extraction experiment was performed in the lab on commercial plastic tubing materials that were submitted to IPA under harsh conditions. The results of the GC-MS analysis revealed the presence of many compounds that served has target for further tests. Secondly, tests were done on early and mid-season maple sap and syrup coming from many sugarbushes using IPA or not to determine potential concentrations of plastic residues. Results obtained from sap and syrup samples showed that no quantifiable (< 1–75 μg/L) concentration of any plastic molecules tested was determined in all samples coming from IPA treated or not treated systems. However, some samples of first sap run used as a rinse solution to be discarded before the season start and that were coming from non sanitized or IPA sanitized systems, showed quantifiable concentrations of chemical residue such as ultraviolet protector (octabenzone). These results show that IPA can be safely used to sanitize maple sap collection system in regards to the leaching of plastic residues in maple sap and syrup and reinforced the need to thoroughly rinse the tubing system at the beginning of the season for both sanitized and non sanitized systems. (4010110)

18 juillet 2016

Viability of probiotic bacteria in a maple sap beverage during refrigerated storage

Auteurs : Joseph Lupien-Meilleur, Denis Roy et Luc Lagacé

Cet article est disponible seulement en anglais (LWT - Food Science and Technology, Volume 74, December 2016, Pages 160–167). Le numéro de référence (Digital Object Identifier (DOI)) est le : 10.1016/j.lwt.2016.07.045.

There is an increasing demand for non-dairy probiotic foods made from raw materials. This study assessed the ability of maple sap concentrate diluted to 2, 5, and 8 ºBx to maintain the viability of probiotic bacteria inoculated at 108 and 1010 CFU/portion of 40 mL and stored for 12 weeks at 4 _C. Three two-strain and one three-strain combinations of Lactobacillus rhamnosus R0011, Lactobacillus helveticus R0052, and Bifidobacterium animalis subsp. lactis BB12 were analyzed. Survival was monitored by selective plate counting and viability was assessed by quantitative PCR following propidium monoazide treatment (PMA-qPCR). Results showed a lower survival of mixed cultures of R0052 and BB12 inoculated at 1010 CFU/portion than survival values obtained at 108 CFU/portion. Culturable and viable counts from sap inoculated at 1010 CFU/portion were significantly lower in sap diluted at 2 ºBx for every combination, highlighting the protective role of sap components at higher total soluble solids concentration. The ability of maple sap concentrate to maintain probiotic viability was readily and accurately determined by PMA-qPCR. According to this study, concentrated maple sap was able to maintain high viable and survival counts of carefully selected probiotics, demonstrating its potential as fluid for the production of a probiotic beverage. (432-4080026)

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