Keeping cold-chain loads in range

A temperature excursion is rarely one dramatic failure. WHO defines it as a product exposed to temperatures outside the range prescribed for its storage or transport. That range comes from the product, not the vehicle. Four causes account for most of them on Indian roads.

The load was never cold enough. A reefer holds a load at temperature; it does not pull a warm one down. The FSSAI figures are set out further down. Load above them and the trip starts behind.

The dock let the heat in. Every door opening at a warm bay pushes humid air over the coil. WHO asks that loading and receiving bays be protected from direct sunlight and from extremes of heat and solar radiation, and expects vehicles to hold their set points across the full annual ambient range on their routes. A May afternoon in Nagpur is squarely what that is written for.

The unit stopped doing its job. A failing compressor, an iced evaporator, a long defrost, or a driver switching the unit off between stops. FSSAI's storage and transport handbook is blunt about the last one: the establishment must ensure the driver does not turn off the cooling unit while transporting food.

The set-point hid the drift. A controller reports what it is aiming at. It does not tell you what the pallet at the back of the second compartment is actually living through.

Watch the load, not just the vehicle. WHO's model guidance for temperature-sensitive medicines is specific about road vehicles: control sensors accurate to 0.5°C or better, in the return air stream and independent of the monitoring system; monitoring sensors of the same accuracy, placed to catch worst-case temperatures and recording at least six times an hour for each position. Food fleets are not bound by that clause, but the logic carries across.

Placement is most of the argument. An air sensor reads the air, which moves faster than the product does, so a badly placed probe can read warm while the load is fine. Put sensors where they represent the load, and check the product with a calibrated probe at handover.

• Temperature per compartment, not per vehicle. A multi-zone trailer running chilled and frozen together needs a reading for each.
• Set-point against actual, side by side. The gap between them is the early warning.
• Door events with timestamps, so an open door at a dock reads differently from an open door on the highway.
• Reefer run state and fuel. A unit that has stopped because it ran dry looks healthy until the temperature starts to move.
• Defrost cycles, so a routine rise is not treated as an excursion, and a stuck defrost is.

An alert that fires on every wobble gets muted within a week. Design for the response you want.

• Pair a threshold with a duration. Out of range for two minutes at a delivery stop is ordinary. Out of range for twenty minutes is not.
• Tell the driver first. WHO expects temperature-controlled vehicles to carry alarms that alert the driver to an excursion or a refrigeration unit failure. The driver is usually the only person who can close a door or restart a unit.
• Escalate on silence, not only on severity. If nobody acknowledges within ten minutes, send it to the next person on the list.
• Keep excursion alerts outside quiet hours. A chilled load does not respect a shift roster.
• Try the rule against last month's data before switching it on, so you know how often it would have fired and on which vehicles.

Most excursions are settled before the vehicle moves. Pre-cool the body to the carrying temperature, then load product that is already at temperature. FSSAI's handbook asks for a probe thermometer at delivery and says food delivered at the wrong temperature must be rejected. Run the same check in your own yard on the way out.

Keep the air moving. The same handbook asks for proper air circulation throughout the shipment, with food arranged so it stays chilled or frozen as required. WHO's vehicle qualification asks you to define zones in the payload area that should not be packed at all, such as those close to cooling coils or cold air streams.

Then learn your failure window. The same qualification asks you to demonstrate how long temperatures take to exceed the designated maximum if the cooling unit fails. That number tells a dispatcher whether a breakdown 180 kilometres out is a repair job or a rescue.

FSSAI's handbook is direct: complete temperature logs shall be kept for chilled or frozen vehicles and made available on request. Where food becomes unfit in transit, the vehicle or container number, the last consignment carried, the trip's temperature record and the maintenance and cleaning records are recorded and submitted to the food control authority on request.

Retention depends on what you carry. For food, clause 8.2 of Schedule 4 asks for records of storage, distribution and service to be kept for one year or the shelf life of the product, whichever is more. CDSCO's draft guidelines propose the shelf life plus one year for medicines. WHO asks for records generally to be retained for not less than three years, and for temperature records of stored product to be kept at least one year after the end of its shelf life. Where more than one applies, keep the longest.

Calibration is what makes a log mean something, and the two reference points differ. WHO asks for transport temperature control and monitoring devices to be calibrated against a certified, traceable reference standard at least once a year, unless otherwise justified. CDSCO's draft guidelines ask only that vehicle data loggers be maintained and calibrated at regular intervals, at least once a year or earlier depending on how critical the product is. FSSAI's handbook asks for recording devices to be checked at regular intervals and tested for accuracy, and for an annual calibration of the cooling units. File the certificates with the logs; a reading from an uncalibrated probe is an opinion.

Write down what happens after an excursion, too. CDSCO's draft guidelines expect a deviation in transport to be reported to the distributor and the recipient, and written procedures to be in place to investigate any failure to comply with storage requirements.

This is general guidance, not legal advice. Which rules bind you depends on what you carry and the licence you hold.

For food, the Food Safety and Standards (Licensing and Registration of Food Businesses) Regulations, 2011 apply through Schedule 4. Conveyances and containers must be able to maintain the requisite temperature, humidity and atmosphere. The receiving temperature of potentially high-risk food is at or below 5°C, and frozen food -18°C or below. FSSAI's FoSTaC handbook is training material rather than a notified standard, and audits are conducted against your licence conditions and Schedule 4 — the handbook is useful because it shows how FSSAI itself explains those requirements. It adds a delivery vehicle air temperature of 0°C to +5°C for chilled food and -18°C for frozen: the air in the body, not the product at handover. After a transport spill, it treats potentially hazardous food that has stayed between 5°C and 65°C for more than four hours as temperature-abused and discarded.

For medicines, the binding requirements come from the Drugs and Cosmetics Act, 1940 and the Drugs and Cosmetics Rules, 1945, whose rules 64 and 65 set the conditions attached to sale, stocking and distribution licences. CDSCO's draft guidelines on good distribution practices cover transport and monitoring in India. They were published for stakeholder comment and have not been finalised, so treat them as direction rather than a binding rule. WHO's TRS 961 Annex 9 is the model guidance for time- and temperature-sensitive pharmaceutical products.

Vehicle-side rules sit elsewhere again. Permits and operating conditions are state matters and do vary. Confirm your own position with your FSSAI licensing authority, with your RTO or state transport department, and, for medicines, with the marketing authorisation holder, before writing anything into a standard operating procedure.

Six checks. Only one waits on hardware.

• List every compartment and the range it must hold, and write down where that range comes from.
• Confirm which compartments and doors are actually instrumented today, and write down the gaps.
• Pull last month's logs. Count the excursions, then count how many produced a recorded action.
• Find the calibration certificate for every logger and every cooling unit. If you cannot find it, treat that data as unproven.
• Time one loading cycle. Note how long the doors stand open and what the return air temperature does.
• Write the failure plan: who the driver calls, where the nearest transfer point is, and how long the load has.