Aseptic tapping of sugar maple (Acersaccharum) results in light color grade syrup

Abstract

An aseptic technique was used to collect 227 sap samples from 84 tapholes, including several initial and successive collections, of 27 sugar maples (Acersaccharum Marsh.) over six sap flow seasons (mid-February to late April). In this technique, all material used is sterilized, and the bark as well is sterilized with alcohol. Of the 227 sap samples, 62.5% were sterile or essentially sterile (0–10 colony forming units of microorganisms per millilitre), and of the 74 sap samples from initial collections, 83.8% were sterile or essentially sterile, in contrast with successive collections from the same taphole (P = 0.001). The 35 composite sap samples collected from 1800 nonaseptically tapped tapholes on 900 trees, which were our control, were all contaminated with greater than 800 colony forming units of microorganisms per millilitre. Sap obtained with the aseptic tapping technique produced 92.8% light amber grade syrup and 7.2% medium amber grade syrup. Sap obtained with the traditional tapping technique produced 61.8% light amber syrup, 11.8% medium amber syrup, 14.7% dark amber syrup, and 11.8% syrup that was darker than the dark amber grade. The grade was determined both visually and by a spectrophotometric method. We have substantiated that maple sap is sterile in maple xylem. If sap microbial contamination is minimized and cold sap storage is used, lighter color grade syrup than what is achieved with traditional practices (P = 0.001) can be produced to the end of the season. To avoid the usage of a chemical taphole sanitizer, we recommend cleaner ways for tapping maple trees.

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.…”

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

“…Research in this field has already demonstrated that the sanitary quality of maple sap has an effect on the physicochemical and sensory quality of maple syrup (Edson 1912). Some of these effects are undesirable and result in syrups that are dark in color (Morselli and Whalen 1991), present off-flavors or have a "ropy" texture (Fabian and Buskirk 1935;Holgate 1950). The microorganisms in maple sap play a role in the enzymatic hydrolysis of sucrose-producing reducing sugars (glucose and fructose), and these sugars are responsible for the dark color and the intense caramel flavor that arise during evaporation, masking the characteristic maple flavor of syrup (Naghski and Willits 1957).…”

“…Table 1 shows the evolution during the tapping season of the respective types of microbial contamination. Since maple sap is sterile in the xylem of maple trees (Morselli and Whalen 1991), it follows that these microorganisms must be introduced into the sap after tapping through unsanitary tapping procedures and/or the contaminated surfaces of collection tubes, reverse osmosis Figure 3Number of sap samples found for each sap contamination class according to the invert sugar content systems, and storage tanks. This contamination depends on time and weather conditions.…”

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

“…Unlike honey, that gets much of its character from the floral species in surrounding fields (Corbella and Cozzolino, 2005), maple syrup quality is influenced by the timing of sap harvest. Early season syrups tend to be light-colored, while late season batches are much darker, with a more robust taste (Morselli and Whalen, 1991). Optical spectroscopy is of interest not only for routine physico-chemical testing, but also to highlight characteristics 0260-8774/$ -see front matter Ó 2009 Elsevier Ltd. All rights reserved.…”