Scaling up the marae kitchen
A marae trust wants to supply 180 frozen meals per week to kaumātua in the surrounding area, up from about 40 now. The kitchen is 3.2 m by 2.4 m with a 6-burner range, one domestic oven, a 220 L fridge, a chest freezer and a single sink. Two paid staff work 18 hours a week; six volunteers help on Wednesdays. The trust has $12,000, a 32 A single-phase supply, and a Food Act food control plan that requires cooked food to be cooled from 60°C to 21°C within 2 hours and from 21°C to 5°C within a further 4 hours, with records kept. A supplier has quoted $9,000 for a blast chiller that would occupy 0.8 m² of the 7.7 m² floor and draw 10 A. A second option is to cook smaller batches and cool in a chilled water bath with an ice supply at $45 per week. Some kaumātua have dietary requirements: no pork for two households, low salt for six, and one texture-modified meal.
1. Evaluate the two cooling options against the trust's constraints and the cooling requirement, and justify a recommendation.
Read the worked answer
The blast chiller and the ice-bath option fail and pass on different constraints, so the comparison has to be explicit.
Blast chiller
- Meets the cooling requirement reliably: it is designed to move a batch from 60°C to 5°C inside the time window, and produces automatic records.
- Uses $9,000 of the $12,000, leaving $3,000 for trays, labels, an additional freezer and packaging for 180 meals - likely insufficient at 180 meals a week.
- Consumes 0.8 m² of 7.7 m² floor in a kitchen where two people already work around each other; that constrains the work triangle and the volunteer shift.
- Draws 10 A of the 32 A supply, which is workable but must be checked against simultaneous oven and range use.
Ice-bath cooling
- Costs $45 a week, about $2,340 a year - affordable in year one but a recurring cost with no asset.
- Depends on ice arriving, volunteers being trained, and batches staying small enough to cool in two hours. At 180 meals a week the batch sizes get larger, and larger batch volume cools more slowly - the exact point where the method is most likely to fail.
- Produces records only if someone writes them.
Recommendation: the ice bath cannot be justified at this volume against a hard 2-hour limit, but the chiller cannot be justified alone at $9,000 of $12,000. A defensible path is a smaller capacity chiller or a staged purchase funded with a grant, with ice-bath cooling retained for small batches and a written cooling log. The reasoning must show the trade-off, not just the choice.
2. Describe the trials and evidence the trust should gather before committing to 180 meals a week, including how success would be judged.
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The trust is scaling 4.5 times with the same staff hours, so the trial has to test volume, safety and the people doing the work - not just whether the food tastes right.
Trials
- Cooling validation: cook the largest planned batch, insert a probe in the thickest portion of three sample trays, and record temperature every 15 minutes until 5°C. Repeat three times. This produces evidence for the food control plan as well as the decision.
- Throughput trial: run a Wednesday volunteer shift at 90 meals and time each step - prep, cook, portion, cool, seal, freeze. Identify the bottleneck before doubling again.
- Cold-chain check: data-log the chest freezer and fridge over two weeks to see whether 180 meals fit and stay below 5°C, and how often the lid is opened.
- Dietary variant trial: produce and label the no-pork, low-salt and texture-modified meals within the same shift, and have the recipients or their whānau assess them.
- Volunteer and staff load: ask the team to record actual hours for two weeks.
Success criteria set in advance
- Every batch reaches 5°C inside the required window, with records completed.
- All 180 meals produced within existing paid hours plus one volunteer shift, without unpaid hours creeping in.
- No more than a stated reject rate on seals and labels.
- Dietary variants correctly identified by recipients in a blind check.
- Cost per meal within budget.
If any criterion fails, the trust adjusts the target volume or the process rather than absorbing the failure.
3. Identify the main risks in this scale-up and explain how the project plan should manage each one.
Read the worked answer
The risks cluster around food safety, capacity and the reliance on goodwill.
1. Cooling failure (highest severity). Larger batches cool more slowly, and a single missed batch can make dozens of people ill. Manage with validated procedures, calibrated probes, a written cooling log checked by a named person each shift, and a documented rule for what happens if a batch misses the window. Do not rely on the blast chiller alone - the food control plan must be robust to it breaking down.
2. Equipment and power. A 10 A chiller plus range plus oven on a 32 A supply needs a load check by an electrician, and the chiller needs a service arrangement. Budget for maintenance, not just purchase.
3. Space and workflow. At 7.7 m², adding 0.8 m² of equipment removes storage or bench space. Plan the layout with the people who work in it and check for cross-contamination paths between raw and cooked, and between normal and no-pork meals.
4. Volunteer dependency. Six volunteers on one day is a single point of failure; illness or seasonal work will break the schedule. Build a trained second shift or reduce the target.
5. Dietary and cultural requirements. Mislabeling a no-pork meal is a serious failure of trust, not a minor error. Control with a separate, labelled prep stage and a second-person check.
6. Cost creep. Track cost per meal monthly against the $12,000 and the ongoing ice or maintenance costs; set a review point at three months.