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Background
Cold chain logistics is a crucial element in the supply chain design of any temperature-sensitive food product. We designed an experiment to measure the temperature variation within a variety of food packaging constructs over a 30-hour period. We used the data thus obtained to identify the most appropriate packaging solution to ensure that the contents remain frozen for at least 30 hours. My Local Indian is an environmentally friendly business. We decided to use biodegradable/compostable or recyclable materials for the entire packaging.
Our experiment
The temperatures within four identical corrugated cardboard boxes with different insulating and refrigerant agents, packed with identical food products were compared. The efficacy of similar volumes of refrigerants – Dry Ice (Carbon-di-oxide solid), Ice Packs & Gel Packs, were compared with an added layer of aluminium foil used as liner within the cardboard box. Temperature fluctuations within a corrugated cardboard box without the aluminium foil lining with similar volume of dry ice as the refrigerant was also studied.
The air temperature within the sealed boxes as well as the surface temperature of the primary food packaging were recorded.
Results
Our study indicates that under typical test conditions, the surface temperature of the primary food pack was measured to be -8.7 ± 0.5°C at the end of 24 hours since packaging and the temperature continues to rise linearly with time even beyond 30 hours since packaging without plateauing out. This indicates that the contents of the food pack continue to remain completely frozen since the temperature measurements would have remained constant if the contents within the pack had started thawing, until the thawing process is complete.
The frozen state was best preserved in the box with dry ice lined with foil lining. Gel pack with foil and dry ice without foil were comparable and the food remained frozen after 24 hours. Ice packs with foil lining of the box was also effective, but after 24 hours, the periphery of the containers showed partial thawing.
Summary
Although we found that the use of gel packs would be more economical and produce satisfactory results at the end of 24 hours within similar packaging, we endeavour to provide the best possible quality to our customers and hence opt to use dry ice as the passive coolant. The addition of a layer of aluminium foil within the corrugated cardboard box is optional and can provide optimum freezing temperature within the box well beyond 30 hours. Thus our packaging gives assurance that the contents of each food container would remain frozen when it reaches you the next day.