Many consumers would be quite surprised to know that the pareve-certified orange juice and iced tea that they enjoy are often manufactured on dairy equipment, and that this equipment was kashered to be rendered pareve for the production of these beverages. The fact is that the pasteurization and filling equipment used in dairies for milk is ideal for all types of drinks, and dairy factories therefore frequently produce a wide variety of non-dairy beverages. There are actually very few types of pareve beverages that can be assumed to be manufactured exclusively in pareve plants; fruit juice, punch, iced tea and coffee, plus lemonade – whether made as ‘national’ brands or as ‘heimishe’, Jewish brands – are all prone to be processed on dairy equipment which was kashered under the supervision or direction of a kashrus agency.

In order to get a closer look and try to understand what is going on, we need a brief introduction to basic dairy plant equipment.

In order to kill harmful bacteria, milk (and many other beverages) must be pasteurized, which involves heating the milk to a high temperature and then cooling it down. The most common arrangement of pasteurization/production systems in dairy plants goes something like this:

The raw, liquid milk is first stored in silos (large tanks), from whence it may travel to a batch tank, where additives are incorporated. (For example, raw milk which is being made into chocolate milk will flow from the silo to be treated in a batch tank with chocolate powder and sugar.)

The milk then proceeds to the pasteurization system.

The initial phase of this system is the entry of milk to a balance tank. The balance tank is a small vessel which serves as the intermediary between the silo or batch tank and the actual pasteurization equipment, metering and controlling the flow from the silo or batch tank to the pasteurization equipment to assure steady volume and processing.

The heating techniques utilized for dairy (and almost all) pasteurization are unlike anything one would find in a domestic kitchen. When we heat food in our homes, the food is cooked directly in water, fried directly in oil, or roasted in the presence of a direct flame or heating element. By contrast, almost all pasteurization systems utilize indirect heat, such that the product never contacts or has direct exposure to the actual heat source. Rather, heat is transferred to the product through many mediums, all totally unheard of in our home kitchens. In fact, as we’ll see in a moment, industrial pasteurization systems often use food itself as heating and cooling mediums! Let’s take a look.

The actual pasteurization protocol in dairy plants involves a five-step process: (1) The milk is pre-heated to about 140 F degrees by entering a plate heat exchanger. Plate heat exchangers (herein referred to merely as ‘heat exchangers’ ) are machines with many, many metal plates which are used to heat and cool liquids in amazing ways. As we will see, liquid that is being pasteurized travels on one side of the plates of the heat exchanger. On the other side of the plates, a hot or cold substance , which has absolutely no contact with the liquid on the first side of the plates, heats or cools the liquid on the first side of the plates by transferring heat or coolness through the metal plates.
The heating or cooling medium in this pre-heating stage, IS NORMALLY the same as the product that is being heated or cooled. For example, milk which has already been heated in the pasteurizer will be used as a medium to heat milk entering the heat exchanger so that on one side of the heat exchanger plates you will have hot pasteurized milk and on the other side of the plates is our cold milk, which begins to be heated as it commences its entry to the heat exchanger. The ‘exiting milk’ – the milk that has been pasteurized to about 165 F degrees – passes its heat through the plates and into the milk (on the other side of the plates) that is entering the heat exchanger, so that the entering milk becomes hot (about 140 F, as above), while the already-heated milk cools as its heat is transferred away. This technology is referred to as regeneration, as heat from pasteurized milk is regenerated and transferred to new cold milk.
(2) In next phase of pasteurization, the milk enters the heating section, where it travels through the heat exchanger along the same type of metal plates, only that now, there is extremely hot water on the back side of the plates, and the heat from the water steam passes through the plates into the milk to rapidly achieve a temperature of about 165 F. (3) The heated milk is subsequently retained at 165 F or so in a holding tube, where it remains for about 10 seconds at that temperature. Heating and maintaining the milk at this high temperature (steps 2 and 3) constitute the actual pasteurization, as the 165 F heat destroys the milk’s harmful bacteria at this temperature. The pre-heating phase (step 1) merely prepares the milk for quick pasteurization.
Internal temperature probes measure the heat of the milk as it exits the holding tube; if for some reason its temperature is below the requisite level, there is a divert system which automatically sends the milk back to the balance tank to be pasteurized again.
(4) Milk which is successfully pasteurized exits the heat exchanger via its cooler, where it travels on the other side of the metal plates upon which it flowed when first entering the heat exchanger. Again, these plates have incoming, cold milk on their opposite side and the already-pasteurized milk passes its heat through the plates to the incoming milk to pre-heat it to approximately 140 F. (5) Finally, the pasteurized milk is cooled all the way down to 40 F or so as it travels along plates with chilled water on their back sides, which absorb the milk’s heat. (Milk also flows through a homogenizer as part of this system, where the milk’s fat globules are disintegrated into the milk in order to attain a smooth texture; however, pareve beverages are rarely homogenized. After pasteurization, yogurt and dairy products other than milk flow to a storage tank where they held at chilled temperatures in order for their molecular structures to settle.)

Following pasteurization, milk travels to a filler, where it is packaged into bottles or cartons.

The above depicts regular pasteurization systems, referred to as the “HTST” or “high temperature-short time” method of pasteurization. Products which undergo HTST pasteurization need to be refrigerated at all times, as they still have some bacteria, and a harmful scenario can ensue if the product is left warm and the bacteria develop and grow.

Some dairy and pareve beverages, however, are pasteurized under an aseptic “UHT”, or “ultra-high temperature” system, where the pasteurization temperature is so high – 212-275 degrees F – such that all bacteria which can later grow are totally destroyed. UHT products are sealed in air-tight vacuum packaging and thus have long shelf-lives and do not require refrigeration when stored before opening. Examples of UHT products are juice boxes and non-refrigerated beverage pouches. UHT plate pasteurization equipment is similar to HTST equipment, although some UHT products are processed in a tube-and-shell pasteurizer, in which a tube that contains the beverage is surrounded by intense steam, heating the enclosed beverage.

Now think about it; all of this equipment, used to process milk, is also frequently used to process juice and all types of pareve-certified beverages. How do kashrus agencies deal with it?

The easiest solution would be not to pasteurize pareve-certified beverages. This is also the most dangerous solution, as unpasteurized juice can be fatal. There are stories of organic juices that were not pasteurized, in the belief that pasteurization ruins the juices’ natural qualities, and the results were lethal. Bacteria grows in juices and must be taken very seriously.

The other solution is to kasher the dairy equipment with hag’alah – hot water purging. Equipment used for hot liquids which undergoes hag’alah is rendered pareve.
All dairies have built into their pasteurization systems a standard cleaning protocol called a CIP (‘cleaning in place’ ), whereby the equipment is programmed or activated to automatically be washed with hot caustic solution, acid and fresh water. Typically, after set intervals throughout the day, or at least once per day, the whole system will undergo a CIP, where it will be flushed with acid and caustic solution at temperatures slightly above production temperatures, followed by a cool fresh water rinse.

There are those who have erred and assumed that dairy equipment which undergoes a CIP is automatically considered to be pareve, as they thought that CIP is the equivalent of hag’alah. This is inaccurate, as hag’alah must be done at roschin (boiling) temperatures, and the average CIP is often well below this level. Furthermore, many poskim require hag’alah to be performed with fresh water rather than with other fluids (such as caustic solution); in normative CIP, the fresh water phase is often done with ambient water, surely not qualifying for hag’alah.

Another problem is that hag’alah should be performed when a vessel is aino ben yomo – unused for 24 hours. In many dairies, there is seldom more than a few hours of down-time, impeding the equipment from acquiring ben yomo status.

Furthermore, Halacha postulates that there is a concern that taste may pass through the wall of a utensil (Yoreh Deah 92:5). In the case of heat exchangers, one needs to consider that the milk’s taste may pass through the metal plates into the heating or cooling water on the plates’ other sides. CIP does not deal with this. How, then, do kashrus agencies?

The proper way to kasher HTST dairy plants for pareve production is as follows:
The fresh water phase of CIP must be raised to a boil, so that all equipment gets purged via hag’alah. Some kashrus agencies require a mashgiach to be present for this, whereas others verify the boil by having the plant’s engineer reprogram the CIP to assure a fresh water boil and by the mashgiach checking the plant’s Taylor charts, which are graphs that automatically record the temperature of the pasteurization equipment. In all cases, the pasteurization system must be turned on during CIP kashering, as hag’alah requires water of a keli rishon – water that is heated as it kashers. If the heating system is off during hag’alah, and hot water is merely hosed in, it will constitute iruy – pouring of pre-heated water – and will not suffice.

Most pareve-certified beverages made in dairies are manufactured as the first product of the week in plants which do have a full 24-hour break, so that the equipment is aino ben yomo. However, this is not always the case.

The Shulchan Aruch (Yoreh Deah 95:4) rules that a vessel which has become pagum (embittered) by absorbing a bitter non-kosher substance cannot become non-kosher through such absorption. Although this position is the subject of much dispute (see Shach ibid. sk 21 and Taz ibid. sk 15 who question it), many poskim concur with the Shulchan Aruch. (Aruch Ha-Shulchan 95:24, Chochmas Adam 48:15, Tzemach Tzedek s. 91, Chazon Ish YD s. 23)

The reason that a keli must be aino ben yomo before undergoing hag’alah is that its non-kosher or dairy absorped taste must be pagum in order for hag’alah to be effective (unless the volume of hag’alah water is 60 times the size of the vessel, which is often not the case). If one adopts the opinion of the Shulchan Aruch, one can obtain pegimah (embitterment) in a keli by exposing it to hot caustic liquid, obviating the need for 24 hours of down-time.

Therefore, when such down-time is not feasibile, some kashrus agencies will arrange and verify for the caustic phase of a dairy plant’s CIP to be set at temperatures required for pegimah, as a prerequisite for subsequent hag’alah with fresh water.

The heat exchanger’s regeneration and cooling sections need special attention. One can mistakenly assume that kashering these areas should consist of sanitizing them by running acid, caustic and fresh water through them in the same manner that milk runs through them.

The problem is that – if this is done – the CIP (kashering) water will never be hot enough to kasher in the regeneration and cooling sections, as the cool liquid on the other side of the plates keeps the hot CIP liquid too cool to kasher. What must be done – and this is critical – is to make sure that the system is set to CIP mode, shutting off all cooling units and recirculating the hot water throughout everything – from the balance tank through the cooler – for 30 minutes or so at boiling temperatures, so that there is a constant flow of hot water throughout the entire system, kashering all surfaces at boiling temperatures. This author was privy to an inadequate attempt to kasher a heat exchanger on the part of a “low-tier” kashrus agency; in that case, the agency did not insist that CIP mode be used, and the cooling system kept chilling the kashering water! The mashgaich was wondering why the water came out of the system so cool…

UHT systems in dairies are simpler to kasher, as they undergo hot water sterilization at temperatures approaching close to 300 degrees F; there is no need to work out a system to raise the ambient fresh water rinse temperature, so long as the system is sterilized before pareve production. (However, the caustic pegimah must be dealt with as in HTST plants, as caustic CIP is often not done at temperatures that all would consider to constitute kashering.)

The hot water and steam that heat the heating section or heating tube need to be carefully addressed, as they may have dairy taste absorbed from milk. This possibly-dairy heating water and steam needs to be disposed of prior to pareve production, or it can be chemically embittered, as per the kashrus agency’s input and monitoring.

Thankfully, fillers in dairy plants are used cold. So long as they are cleaned after use for milk (which is always the case), there are no kashrus concerns.

In some cases, holding silos retain dairy and pareve (cold) beverages for quite some time. In such plants, if the silos hold dairy material for 24 hours or more, the silos cannot be used for certified pareve products unless they are kashered, as equipment which holds cold liquid for 24 hours absorbs the taste of that liquid. (It becomes “kavush”; see Yoreh deah 105:1). Some plants accommodate kashrus requirements by shifting dairy liquids from silo to silo every 20 hours or so, so that the halacha of kavush not apply.

Pareve juice, iced tea and lemonade – what a complicated kashrus history that each of these beverages brings to the consumer.