Hello Mr RMAV,
Normally the cooling tunnels are designed with part of water reservoirs on the side of cooling tunnel containing mesh in slanting portion in between so that Dirt accumulation remains floating on one side of mesh and the other side contains clear water for Input to transfer pump ,to transfer water to spray nozzles. Cooling tunnels can be opened from sides and top for thorough cleaning of conveyor and nozzles ,it also has opening on sides near reservoirs for thorough cleaning below conveyors which contains other part of reservoir
Cooling tunnel is divided in three or more sections.
First section contains hot water through heat exchanger in reservoir for cleaning of spilled product on outside of bottles and second reservoir contains normal water and third reservoir is supplied with cold water through heat exchanger for final cooling of bottles.
You can contact your cooling tunnel machine designer for modification for better cleaning and sanitizing.
Regarding coliforms Please test you raw water before it enters in cooling tunnel and the Source of raw water for coliforms and other pathogens.
Most coliform bacteria do not cause disease. However, strains of E. coli, particularly the strain 0157:H7, can cause serious illness. Cooling tunnel water should be free of E.coli and other pathogens
Since the PET /GLASS bottles are hot filled products and with plastic caps /crown /roll on screw caps with high tamper evident and Seal Integrity, there is less chance of product contamination with cooling water. There fore Ingress of cooling tunnel water will be due to loss of seal integrity of caps. This problem of seal integrity is more in lug capped bottles rather than screw cap bottles.
Maintaining a clean and properly sanitized cooling tunnel is a key part of establishing the commercially stablility hot filled process.
Your cooling water cannot spill over to filling machine as filling machines are enclosed on all sides with plexi-glass.and cooling water tunnel is some distance away from filling machine..
On line quality checks are carried out for hot filling temperature of product, cap seal integrity,Torque test of caps etc.
Also check for vacuum in bottles of finished products, ph and commercial sterility, fermentation test and other physical,chemical and microbiological test are carried out.
Also have your cooling tunnel water and raw water from source periodically tested from accredited outside labs
Traditional methods for testing Coliforms
Traditionally the agar plate count method using VRBA (Violet Red Bile Agar) and the MPN methods are being used. The plate count method takes 24 hours to perform
and can use 1.0 ml of 1:10 dilution and as a result has a sensitivity of <10 cfu/gram.
When higher sensitivity is required the MPN (Most Probable Number) method can be used. Multiple tubes (typically 3) are inoculated for each dilution. The method involves the inoculation of at least 3 decimal dilutions (a total of 9 tubes) of LST (Lauryl Tyrptose Broth). Any LST tube that shows growth and gas production is transferred to BGLB (Brilliant green lactose bile), the MPN is calculated based upon the positive BGLB tubes. It takes 3-5 days to complete.
These coliforms can be further tested for presence of E.coli which should be absent.
Presently there is no data or specifications for cooling tunnel water .since spoilage of cooling Water depends on spillage of product outside bottles and production activity (no of shifts run/no of bottles packed in filling machine per minute).cooling tunnel is good environment for microbes to grow fast hence the only solution is proper maintainence and cleaning and sanitizing and to control product spillage in filling machine and bacteria in source of water and replacing of cooling tunnel water
as required and keeping the cooling tunnel dry after production and cleaning is over and during weekly off. RAW WATER TO COOLING TUNNEL TO BE ADDED AT THE START OF SHIFT.
Hence you have to establish your own data/specifications for cooling water and it should not contain any pathogens.
Raw Milk contains lots of bacteria per ml and some coliforms ,but it is pasteurised.