Prep waste is the single biggest category of food waste in most kitchens. WRAP's research puts it at around 45% of total waste—more than plate waste and spoilage combined.
That's both bad news and good news. Bad because it means nearly half of what you're throwing away happens before food even reaches a customer. Good because prep waste is almost entirely within your control. You can't force customers to finish their plates, but you can absolutely change how your team handles prep.
Here are seven things that actually work.
1. Standardise Your Knife Work
Watch your team prep for an hour. Count how many different ways carrots get peeled. Count how much flesh comes off with the skin on a butternut squash. There's usually a 20-30% difference in yield between your most skilled and least skilled prep cooks.
This isn't about blaming people—it's about training and standards. Document your prep methods. Show new staff exactly where to cut. Post photos of correct trim at prep stations. A chef I know reduced carrot waste by 15% just by demonstrating proper peeling technique in a team meeting.
2. Actually Use Your Trim
"We make stock" is something I hear constantly. When I ask to see the stock pot, it's often empty or hasn't been touched in weeks.
If you're going to use trim, systematise it. Specific containers for each type of trim. A scheduled stock day. Someone responsible for making it happen. Otherwise it's just good intentions that become compost.
Better yet, find uses beyond stock. Carrot and parsnip peels make decent crisps. Cauliflower leaves roast beautifully. Citrus peels can be candied or dried for garnish. Herb stems go into marinades. Get creative, or at minimum, get consistent.
3. Right-Size Your Prep
Over-prepping is endemic in kitchens because nobody wants to run out mid-service. The problem is that most prepped veg has a 24-48 hour window before quality drops noticeably. Prep too much on Tuesday and you're binning it Thursday.
Look at your actual usage data. If you're consistently prepping 20% more than you use, that's 20% going in the bin. Some buffer is fine—running out is genuinely bad—but most kitchens buffer way more than they need to.
Smaller, more frequent prep batches often work better than big prep days. Yes, it's less efficient in terms of labour. But if the alternative is throwing away a quarter of what you prepped, the maths changes.
4. Fix Your Storage
Prep waste often happens because of spoilage that shouldn't have occurred. Prepped veg stored uncovered. Containers without dates. Items shoved in the back of the walk-in and forgotten.
Proper storage isn't glamorous but it matters. Everything covered. Everything dated. First-in-first-out actually enforced, not just theoretically. Clear containers so you can see what's in them without opening.
One chef told me they cut spoilage-related prep waste by 40% just by reorganising their walk-in and buying see-through containers. It's not rocket science; it's just discipline.
5. Review Your Yield Expectations
Recipe cards often have yields that don't match reality. The recipe says 1kg of potatoes yields 800g peeled. Your team is getting 650g. Either the recipe is wrong or your technique needs work.
Do the maths on your top 20 ingredients. Weigh before prep, weigh after. Compare to what your recipes assume. You might find that some of your costing is based on fantasy yields, which means you're either under-pricing dishes or wasting more than you realised.
6. Audit Your Ordering
Sometimes prep waste is actually an ordering problem in disguise. You ordered too much of something, it's about to turn, so someone preps all of it to extend its life. Then half the prep gets binned because you couldn't use it fast enough.
If you see the same items showing up in prep waste repeatedly, look upstream. Are you ordering too much? Could you order smaller quantities more frequently? Is there a menu item that uses this ingredient that's not selling well?
The best prep team in the world can't save you from over-ordering.
7. Make Waste Visible
Put a clear bin or container in the prep area specifically for avoidable waste. Make it obvious—a different colour, clearly labelled. When prep cooks can see what's accumulating throughout service, behaviour changes.
Some kitchens weigh this bin at the end of each shift and post the number. Competition between shifts can be surprisingly effective. Nobody wants to be the team that threw away 8kg when yesterday's shift only threw away 3kg.
The Compound Effect
None of these things is revolutionary on its own. But stack a few of them together and you're looking at 30-50% reduction in prep waste within a few months. On a kitchen with €100k monthly food spend and 10% waste, half of which is prep, that's saving €1,500-2,500 per month.
Worth a team meeting.
See what waste reduction could save you, or get a free savings report with recommendations specific to your operation.