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 ÒbuddyÓ, 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.
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Buddy maple syrup is characterized by an unpleasant cabbage?like flavor occurring generally toward the end of the sap harvest season. Occurrence of buddy off?flavor leads to a decrease in syrup value and economic loss for the industry. It is therefore relevant to characterize the off?flavor in order to apply corrective treatments. HS?SPME combined with GC/MS was applied to analyze volatile aroma compounds in buddy maple syrup samples. Two novel volatile sulfur compounds were found in maple syrup: dimethyl disulfide (DMDS) and dimethyl trisulfide. A 3?alternative forced choice in ascending concentration of different buddy syrups diluted in good quality syrup was conducted in triplicate to assess buddy syrup concentration thresholds leading to detection and recognition of the off?flavor by 16 panelists while monitoring volatile aroma compounds in diluted samples. Results showed that DMDS was associated with the flavor defect. The recognition threshold concentration of buddy syrup varies depending on the syrup sample and the off?flavor can be detected in syrups containing very low DMDS content. Application of a continuous heat treatment on buddy syrups for 2 hr at 104.5 ¡C led to a removal of the buddy off?flavor as well as a significant reduction in DMDS content.
Techniques used to produce maple syrup have considerably evolved over the last decades making them more efficient and economically profitable. However, these advances must respect composition and quality standards as well as authenticity of maple products. Recently, a new and improved high vacuum technology has been made available to producers to achieve higher sap yields. The aim of the present study was therefore to evaluate the effect of this new system on the yield of sap and on the sap and syrup chemical composition.
The use of air injection technology in the maple industry can be defined as: the forced introduction of air through a series of perforated pipes submerged in the boiling sap in the front and /or back pan of a maple syrup evaporator. Several studies conducted in recent years have investigated aspects of the use of air injection technology in the process of maple syrup production.