Rapid Prediction of Maple Syrup Grade and Sensory Quality by Estimation of Microbial Quality of Maple Sap Using ATP Bioluminescence

Abstract

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

“…Results obtained emphasize the need to elaborate strategies to control microbial contamination of the taphole, since this contamination will serve as inoculum for the sap collection and holding system. Research in the past has demonstrated that microorganisms can adversely affect the quality of maple syrup (5,15,18,21). This quality is primarily based on the color, flavor, and texture of maple syrup.…”

“…The sap is a solution containing between 1 and 5.4% solids composed of different organic compounds, such as sucrose, glucose, fructose, organic acids, and nitrogenous and phenolic compounds, as well as different minerals (19). This solution is known to be a good nutrient medium for microorganisms, and their growth in the sap will eventually affect the quality of maple syrup and other end products (15,18,21). These microorganisms can enter the sap, notably by unsanitary tapping, since the taphole constitutes their first point of entry into maple sap.…”

“…Solutions to control this contamination have been proposed without any real success. Nevertheless, bacteria have already been found to be predominant in the sap compared to yeasts and moulds (15), and efforts have also been made in the past for their identification. The most significant work was reported by Sheneman and Costilow (25), who found several species of bacteria in the tapholes of maple trees, consisting mainly of gram-negative rod-shaped aerobic bacteria identified as Pseudomonas, Achromobacter, and Flavobacterium.…”

Assessment of maple syrup physico-chemistry and typicity by means of fluorescence spectroscopy

“…Hence, at the beginning of the season, sap had lower microbial populations that increased with time, as average air temperature tended to increase. Sucrose, the major sugar in sap, was thus degraded to reducing sugars through microbial activity (Lagacé et al, 2002). This generally results in syrups going from a light to a darker shade as season progresses, as observed in 2003.…”

“…Prediction of the moment of harvest opens the possibility for maple syrup classification according to flavour categories. Early season syrups tend to have a mild or woody flavour, mid-season syrups a more sugary/confectionery or typical maple flavour, whereas late season syrups have a much stronger empyreumatic flavour (Lagacé et al, 2002;Morselli and Whalen, 1975). However, a common industrial practice of syrup lot mixture would break the traceability linkage with initial sap timing of harvest.…”