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.

Single-spore isolates of Botrytis cinerea from commercially stored cabbage exhibited a broad range of virulence. Spore germination and hyphal growth required an exogenous source of nutrients. The ability of either spores or mycelium to cause infection of stored cabbage tissue was also dependent upon exogenous nutrients. Nutrients required for infection could be supplied in the form of glucose, cabbage leaf extract, potato dextrose agar (PDA), or by a wound at the site of inoculation. The concentration of nutrients and (or) spores influenced the ability of B. cinerea to cause tissue decay whereas spore age and bacterial populations did not. Spores on the surface of cabbage leaves germinated within 4 to 8 h in nutrient solution; an additional 8 to 16 h in nutrient solution were required for successful infection. The optimum temperature for fungal growth and for infection was 20 to 25C. The optimum relative humidity for decay was above 97%; decay did not occur at relative humidities below 93%.

In a study on container storage and syrup stability, when pure maple syrup was heated at the traditional minimum packing temperature of 82°C, 6.9% of syrups in all types of containers were surface-contaminated with a fungal mat; Penicillium and Aspergillus species predominated. Fungal growth was not found in syrups stored at 4°C for 12 months, only in syrups stored for the same length of time at 24 and 30°C. In a second container study, heating the maple syrup before packing at 93°C resulted in no detectable fungal growth. This higher-than-recommended reheating temperature successfully minimized the effect of cold ambient temperatures during syrup packing, so that the reheated syrup was hot enough to sterilize the container and the air space between syrup and cap.

Cabbage cultivars which differed in ability to withstand storage showed differential susceptibility to Botrytis cinerea. For a given cultivar, outer leaves on the head were less susceptible than inner leaves, thick areas on leaves were less susceptible than thin areas, and adaxial surfaces of leaves were less susceptible than abaxial surfaces. Uncontrolled variability in rate of decay was reduced by standardizing these parameters. Susceptibility was not related to the location of tissues within individual leaves and appeared to be independent of the dry matter content of tissues.

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.