New York Codes, Rules and Regulations › Title 1 - DEPARTMENT OF AGRICULTURE AND MARKETS › Appendices › Appendix 3

Current through Register Vol. 46, No. 28, July 10, 2024
PASTEURIZATION EQUIPMENT AND PROCEDURES
(cf. Part 2)
I. HTST
			 Pasteurization
OPERATION OF HTST SYSTEMS
HTST pasteurization has become important to the dairy industry
				because of the operating efficiencies which it affords. Properly operated,
				these units allow high volume of production in a minimum of processing
				space.
The ability of HTST pasteurizers to assure a safe, finished
				product hinges on the reliability of the time-temperature-pressure
				relationships which must prevail whenever the system is in operation. It is
				important that the plant operator understand the HTST process in order to
				maintain proper surveillance over the equipment. The basic flow pattern is
				described below:
1. Cold raw milk, in
			 a constant level supply tank, is drawn into the regenerator section of the HTST
			 pasteurizer.
Note: --Some operators prefer to bypass the regenerator when
				starting. Under this system, cold milk is drawn directly through the timing
				pump (step 3) and into the heater section. The remaining steps are performed
				without exception. This bypass arrangement facilitates and speeds up the
				starting operation. After forward flow is established at the flow-diversion
				device, the bypass, which may be manually or automatically controlled, is not
				used and the raw milk flows through the regenerator. A second start-up
				technique involves the use of sanitizer solution at 170° F (77° C).
				This is passed through the complete unit and followed immediately by milk.
				Dilution of the first milk does occur, however, and care must be taken to
				prevent this from being packaged.
2. In the regenerator section, the cold raw
			 milk is warmed by hot pasteurized milk flowing in a counter current direction
			 on the opposite sides of thin stainless steel surfaces.
3. The raw milk, still under suction, passes
			 through a positive displacement timing pump which delivers it under pressure
			 through the rest of the HTST pasteurization system.
4. The raw milk is pumped through the heater
			 section where hot water or steam on opposite sides of thin stainless steel
			 surfaces heats the milk to a temperature of at least 161° F (72°
			 C).
5. The milk, at pasteurization
			 temperature, and under pressure, flows through the holding tube where it is
			 held for at least 15 seconds. (The maximum velocity of the milk through the
			 holding tube is governed by the speed of the timing pump, the diameter and
			 length of the holding tube and surface friction.).
6. After passing the sensing bulbs of an
			 indicating thermometer and a recorder/controller, the milk passes into the
			 flow-diversion device which automatically assumes a forward-flow position if
			 the milk passes the recorder/controller bulb at the preset cut-in temperature
			 (i.e. 161° F (72° C) or higher). The valve automatically assumes the
			 diverted-flow position if the milk passes the recorder/controller bulb below
			 the preset cut-out temperature (i.e. 161° F (72° C)).
7. Improperly heated milk flows through the
			 diverted-flow line back to the raw milk constant level supply tank
8. Properly heated milk flows through the
			 forward-flow line to the pasteurized milk regenerator section where it serves
			 to warm the cold raw milk and, in turn, is cooled.
9. The warm milk passes through the cooling
			 section, where coolant, on the sides of thin stainless steel surfaces opposite
			 the pasteurized milk, reduces its temperature to 40° F (4° C) and
			 below.
10. The cold pasteurized
			 milk then passes to a storage tank or vat to await
			 packaging.