MAPLE SIRUP PRODUCERS MANUAL 



79 



as the temperature of the sirup solution in- 

 creases and as its concentration increases. 

 Sugar sand occurs in various forms, ranging 

 from an amorphous black, oily substance to a 

 fine, white, crystalline material. Dark sugar 

 sand will usually cause the sirup to appear a 

 grade or two darker than normal, whereas 

 white sugar sand will often cause it to appear 

 lighter. 



The amount of this precipitate in the sirup is 

 not always the same. Sap from the same sugar 

 grove varies from year to year and even within 

 the same season. 



Studies at the Ohio (Wooster) Agricultural 

 Experiment Station' indicate that trees at high 

 elevations tend to produce more sugar sand 

 than do those at lower elevations. The Ohio 

 workers were not able to show any relation 

 between climatological data or soil types and 

 amounts of sugar sand formed. 



Sirup to be sold for table use must be clear 

 (free of suspended matter) to meet Federal and 

 some State specifications. Sirup can be clarified 

 by sedimention, filtration, or centrifugation. On 

 the farm, sedimentation and filtration are the 

 methods generally used. 



Sediiiieiitatioii 



Sedimentation or settling is the simplest 

 method of clarifying maple sirup, but it has 

 several disadvantages. It cannot be used to 

 clarify all sirup. Some sirup contains suspended 

 particles so fine that they resist settling. Clari- 

 fication by sedimentation requires a long 

 time — days and sometimes weeks. After set- 

 tling at room temperature, the sirup must be 

 reheated to 180" F. before packaging to insure a 

 sterile pack. This reheating may darken the 

 sirup enough to lower its grade. 



To clarify by sedimentation, the hot sirup is 

 first put through a coarse filter, such as several 

 layers of flannel or cheesecloth, to screen out 

 large particles of foreign matter. It is then 

 transferred to the settling tank. The tank 

 should be of noncorrosive metal, and its height 

 should be at least twice its diameter. It should 

 have a dustproof cover and a spigot or other 

 means of drawing off the sirup about 2 inches 

 above the bottom of the tank. The sirup should 



Unpublished data. 



be left in the tank until samples that are 

 withdrawn show it to be sparkling clear. It is 

 then drawn from the tank, standardized for 

 density, heated to 180° F., and packaged. Sirup 

 that has failed to clarify after several weeks of 

 standing must be filtered. Because of the un- 

 certainty of the sedimentation method, it is 

 rapidly losing favor. 



In large operations, the sirup can be kept 

 sterile if it is added to the settling tank while it 

 is hot (above 180° F.) and if the entire surface of 

 the sirup is continuously irradiated by germici- 

 dal lamps. 



Filtration 



Filtration of maple sirup is not a simple 

 procedure. As with sedimentation, the success 

 and ease of clarifying sirup by filtration depend 

 on the nature of the suspended particles that 

 are to be removed. It is best to use two filters — 

 a prefilter to remove the coarse material and a 

 thicker filter to remove the fme. In the past, 

 the most commonly used prefilter was several 

 layers of cheesecloth, outing flannel, or similar 

 cloth. Today, a nonwoven rayon material called 

 miracle cloth or maple prefilter paper is used 

 with considerable success. After prefiltering, 

 the sirup is run through a thicker filter. For- 

 merly these filters were made of wool, but now 

 they usually are a layer of synthetic felt (Or- 

 ion). 



Synthetic felt filters have many advantages 

 over wool felt filters. They do not impart a 

 foreign flavor to the sirup, shrink very little or 

 not at all, do not pill, resist abrasion, stain only 

 slightly, and have a long life. Synthetic filters 

 that have been in use more than 5 years show 

 little evidence of wear. 



The disadvantage of the two-filter system is 

 that the large particles are removed on the 

 coarse prefilter. The fme particles are collected 

 on the finishing filter, and they may form a 

 compact bed that resists flow of the thick sirup. 



The most common filtration assembly in the 

 past was a large milk can in which was inserted 

 a cone-shaped, felt bag supported at the top of 

 the can. However, this is little used today. 



Hat Filters 



A flat filter consists of a felt sheet for a 

 filtering surface (fig. 95) instead of a cone. It 



