MAPLE SIRUP PRODUCERS MANUAL 



13 



PN-4716 



Figure 20. — Cross section of a maple log showing stained 

 area caused by fungus growth in old tapholes. The 

 stains show the exact contour of the holes including the 

 area entered by the screw of the bit, but do not indicate 

 whether the holes lie above or below the plane of the 

 cut. Note that the stain is confined to the width of the 

 taphole, which indicates that the lateral damage to the 

 tree is restricted to within one-half inch on each side of 

 the hole. But damage may extend several inches above 

 and below the hole, as shown in figure 19. 



pellet will keep the hole essentially sterile 

 throughout the sap season (6 to 10 weeks) and 

 therefore will permit flow of sap H, 5, 6) each 

 time the weather is favorable. If large early 

 flows of sap occur, a second pellet may be 

 needed after 4 weeks. The active ingredient of 

 the pellet is paraformaldehyde which, because 

 of its germicidal effect and low solubility, makes 

 it ideally suited to this use. Each pellet must 

 contain a minimum of 200 milligrams of availa- 

 ble formaldehyde at the time it is placed in the 

 taphole. 



The function of the pellet is to contribute 

 enough formaldehyde to the 1 to 5 milliliters of 

 sap remaining in the taphole between flow 

 periods to keep microbial growth to a minimum. 

 When the sap is flowing, the short time it is in 

 contact with the pellet permits only a trace of 

 formaldehyde (less than 5 p.p.m.) to be dis- 

 solved. This small amount of formaldehyde is 

 removed from the boiling sap while it is being 

 concentrated to sirup in the evaporator pan. 



The very low concentration of formaldehyde in 

 the sap in the storage tanks will not maintain 

 the sap in a sterile condition {133, 13 Jf). This is 

 fortunate because it is sometimes desirable to 

 culture the sap with specific micro-organisms or 

 enzymes. Sap is cultured as one step in produc- 

 ing high- flavored maple sirup; it is also cultured 

 to destroy substances that are responsible for 

 the buddy flavor in "buddy" sap («). Other 

 germicides are under investigation (W, AD- 



Because of the very low residue of formalde- 

 hyde in sirup, the U.S. Food and Drug Adminis- 

 tration issued in February 1962 a regulation 

 governing its use {130). 



However, under no circumstances should 

 more than one paraformaldehyde pellet be 

 placed in a taphole, nor should formaldehyde be 

 added to the storage tanks. To do either might 

 raise the concentration of formaldehyde in sap 

 and contribute to a high concentration in the 

 sirup. This would produce sirup containing 

 more formaldehyde than specified in regula- 

 tions of the U.S. Food and Drug Administration 

 or of the State in which the sirup is made. 



PN-4717 



Figure 21. — A germicidal pellet is inserted in a taphole 

 immediately after the taphole has been drilled or after 

 it has been flushed with hypochlorite solution. 



