Characteristics of Maple Syrup Processed from Bleach-Treated Sap ¹

Recently an undefined off-flavor was detected in syrup produced from sap flowing from tubing systems cleaned with bleach. To identify if bleach was the source of the off-flavor, samples of maple sap, to which various concentrations of sodium hypochlorite (a common sanitizing solution) were added, were processed to syrup. Three tasters detected off-flavors in all experimental syrups, except the control, and associated them with the sodium and chloride level. An off-flavor was described as "salty" with a minimum sodium level of 2,500 ppm and a minimum chloride level of 3,930 ppm and an off-flavor called "undefined" was detected in syrups with a minimum sodium level of 139 ppm and chloride level of 380 ppm. A dramatic two-color-grade change occurred in syrup produced from sap with the highest bleach-to-sap ratio, and was associated with a pH decrease and invert sugar increase.