Wednesday, November 17, 2010
Boilers In Kosher Production
A "Boiler" is a closed vessel containing water. The water in a steam boiler is pressurized and turned into steam when heat is added. The steam is then directed to different locations for use in processing food or food ingredients. The water that is lost in the steam cycle must be replaced. It takes one pound of water to produce one pound of steam.
The boiler does different functions, it holds the water, transfers heat to the water to make steam, and collects the steam that is produced. The fire heats the water to about 212F and the water begins to boil and turns to steam. A pipe is put on top of the lid of the container (boiler) so the steam flows up through the pipe and leads the steam to where it is needed.
The most efficient way to operate a boiler is to minimize the cost of producing the steam, or increasing the amount of steam while using the same amount of fuel. One way is by increasing the heating surface of the boiler, so that more heat is transferred to the water to produce steam. Some boilers use a large heating surface, it would be like laying the boiler on its side (the scotch marine type).
Some boilers will use "fire tubes" (pipes), where the fire passes through the pipes and the water is on the outside of the tubes. Others will have the "watertube" where the water passing through the pipes and the heat is on the outside of the pipes. The container, heat & water are still present, the only difference is that more water is put next to the heated metal.
Water in the boiler is heated and turns to steam. The steam leaves the boiler by a pipe or pipes called the "Main", where it enters the "Header". From the header the steam enters branch lines, & is carried into risers & then to the steam heating equipment, usually a double walled vessel. The food /ingredient is in the equipment on one side of the wall & the steam is on the other side of the wall of the equipment.
At this point the steam in the heating unit cools and turns to water called "condensate". The condensate is separated from the heating equipment by a "steam-trap" that allows condensate (water), but not steam, to pass through. The condensate goes into a "condensate-return-line", to a vacuum tank. A vacuum pump creates a vacuum that helps draw the water out of the condensate return line & in to the vacuum tank. The vacuum pump returns the water condensate to the boiler through the feed-water line. Once it has returned to the boiler, the water/ condensate again is turned into steam and the process repeats itself. Usually some additional (pre-heated) city water will also be required, as not all of the steam can be recaptured & returned as condensate.
Steam is used to heat product by direct injection of live steam directly into the product. Our discussion is on low-pressure steam boilers, up to 15 psi =(pounds per square inch). There is also the cast iron sectional boiler. A steam boiler is not filled with water to the top, so to leave room for the steam and for expansion. As the steam pressure increase there is a corresponding increase in the steam temperature.
As an example steam at 10 psi is 240F, steam at 15 psi is 250F. There will be a number of parts on a boiler to distinguish the steam boiler from the water boiler. We will list some of them; on the steam boiler: there will be a sight glass (attached to a water column) on the boiler to see the level of the water in the boiler. A pressure gauge 0-30 psi, connected to the highest part of the steam side of the boiler via a siphon (either a U-tube or a pigtail siphon). A safety valve (15 psi maximum).
A low water cut-off, if the water in the boiler drops too low & there isn't sufficient make-up water from the condensate & or fresh water the boiler will shut down. A pressure control will be installed to control the boiler pressure. A number of blow-down valves to clear out the dirt & sludge from the boiler parts & from the water column. Fresh water that is added to the boiler contains minerals, impurities etc. which will settle on the tubes in the boiler and cause deterioration of the boiler so chemicals are usually added to the boiler overcome these and other problems. Most of the chemicals do not travel with the live steam but remain in the boiler or condensate. There will be additional fittings near the heating unit. Some of them are, a strainer, a trap, a condensate return line, a pump & a condensate holding tank.
High temperature or high pressure cutoff, is rest manually by a rest button. So even if a Mashgiach seals the boiler switch to accomplish bishul yisroel (not Bais-Yosef) it does not work, because there always another shut off swith for safety, and the manual rest for high pressure cut off.
Some of the kosher concerns: The steam/condensate that comes in contact with the wall of the vessel heating the food product that is on the other side of the wall will absorb the taste of the product in the kettle. If the product is a non-kosher product it will render the steam/condensate non-kosher as it has absorbed the non-kosher taste. If the product is meat or dairy the steam/condensate will absorb the taste and become either meat or dairy.
The steam condensate returns to the boiler and is reused, but we can only use it for the same type of product meat/dairy/non-kosher. To complicate the matter we may have many different kettles receiving their steam from the same source. The question remains how can we cook at the same time utilizing the same steam heat source? Solutions?
One possibility is to drain the water from the boiler, the condensate tank and all of the lines. We would then leave it empty for 24 hours before filling up with fresh clean water. We would of course kosherize if need be. It would still not solve the problem of using the boiler for incompatible (=meat & dairy, non-kosher) product at the same time.
We can disconnect the condensate return line from the non-compatible product, so the condensate will not return to the boiler. Some kosher certifiers will not use steam to heat incompatible product even when the condensate does not return to the boiler. In certain cases with some modifications they may allow the use. The goal is to introduce some way to make the boiler water / condensate unpalatable to humans (an unpleasant/or bitter taste). When the condensate water is unpalatable to humans, the condensate does not become meaty/dairy or non-kosher.
We can introduce to the boiler chemicals that will achieve that goal. Most chemicals that are added to the boiler water do not travel with the steam. As the water turns to steam the chemicals and the impurities remain in the boiler water. Some of it eventually turn to sludge which has to be cleaned out. We need a chemical or product that will render the water unpalatable to humans and will also travel with the steam.
There are a number of chemicals available, 2 of the chemicals that are commonly used are pine-oil & Bitrex. (Bitrex is the most bitter substance known). The exact amount of chemical to put in would depend on a number of factors. In the event that the manufacturing process uses live injected steam in some of their products we can not use the above solution. In the event that we can not introduce to the condensate water a chemical to make it unpalatable, and we can only introduce a chemical that remains in the boiler it will have to be unfit for even a dog's consumption, which is a much higher concentration than for humans.
Some kosher certifiers have introduced certain other chemicals to alleviate the above concerns, while other certifiers do not agree to accept those chemicals as satisfying the requirements. We can encounter the same problems in non-steam systems also. The circulating hot water system and the heat exchanger type system. Some of these are used in chocolate manufacturing systems. Many of the chocolate manufacturers do dark chocolate and milk chocolate as well. The same water used for heating the chocolate product may go from a dark chocolate conch or holding tank to one holding a milk chocolate, and vice versa.
Kosher Alert: When a kosher certifier removes its kosher supervision from an establishment/product, & publicizes a kosher alert-it is (sadly) all too common for another kosher certifier to thereafter certify the establishment/product. It would be incumbent upon the kosher consumer to check with the first certifier as to the reason that the kosher certification was removed. If a satisfactory response is received that there are legitimate kosher concerns then the establishment/product should of course not be patronized.
There are a number of items that the Code of Jewish Law requires them to be purchased with seals on them if purchasing from a non-religious Jew, even if the store is owned by a Jewish person. Those items are fish, meat, dairy, cheese & wine products. We have seen locally that the kosher consumers & establishments are not fully cognizant of these requirements.