Agriculture & Future Food Systems · Article
Separate food from associated inedible parts
Waste totals depend on which fractions are counted. Consistent classifications reveal changes that a combined total can conceal.
Preparation and related reading
Shared Foundations
Related articles
This article helps you
- Distinguish food, associated inedible parts and packaging.
- Keep classification separate from current safety or avoidability.
- Compare fraction-specific and combined totals.
One container can hold different kinds of material
A kitchen's food-waste container holds unserved food and fruit stones, while its liner and container add mass of their own. The gross reading does not tell us how much of each fraction is present. A useful inventory needs both a clear material definition and a way to exclude packaging and the container.
Food intended for human consumption and associated parts not intended to be eaten can be recorded separately. The purpose is to understand the material account. It is not to decide, from a waste record, whether something is currently safe or suitable to eat.
Define fractions for the food system being studied
The FLW Protocol and UNEP's food-waste guidance identify food and associated inedible parts as distinct material types. Inedibility is defined in the particular supply-chain context. A part used as food in one practice may not be intended as food in another.
Document the classification rule and apply it consistently. Do not label every peel inedible merely because it was removed in one kitchen, or assume that a discarded ingredient ceased to be food. When classification is uncertain, retain that uncertainty rather than force a convenient total.
Keep classification, safety and preventability apart
A material can belong to the food fraction because it was intended for consumption, while having become unsuitable by the time it is discarded. Calling it food in an inventory does not authorize recovering it for a meal. Product safety depends on its history and the relevant controls.
Likewise, the food fraction is not automatically all avoidable loss, and associated inedible parts are not a complete account of unavoidable material. A prevention question needs causes and feasible alternatives. Different ingredients and preparation practices can change the fractions, even when a combined mass stays constant.
Reconcile an invented container reading
Suppose a container and its liner have an empty mass of 0.50 kg. The gross filled reading is 6.50 kg, so the net food-related material is 6.00 kg. An appropriate study records 3.60 kg as food and 2.40 kg as associated inedible parts under documented rules. No other material is present in this hypothetical account.
Food is 60% of the net material, while associated inedible parts are 40%. Dividing 3.60 kg by the gross 6.50 kg would answer a different question because it includes the container. The diagram follows the corrected reading and its stipulated split.
| Component | Mass | Share of net material |
|---|---|---|
| Food | 3.60 kg | 60% |
| Associated inedible parts | 2.40 kg | 40% |
| Container and liner | 0.50 kg | Excluded |
An invented reading and material split
Read the diagram as text
A 6.50 kg gross reading includes 0.50 kg of container and liner. The 6.00 kg net material comprises 3.60 kg food and 2.40 kg associated inedible parts under the stipulated classification.
Parts
- Gross: 6.50 kg
- Filled container, liner and food-related material.
- Tare: 0.50 kg
- Container and liner; excluded from material mass.
- Net: 6.00 kg
- Gross minus tare; no other material assumed.
- Food: 3.60 kg
- 60% of net mass under the documented rule.
- Associated parts: 2.40 kg
- 40% of net mass, classified inedible in this context.
Connections
- Gross: 6.50 kg → Net: 6.00 kg: gross
- Tare: 0.50 kg → Net: 6.00 kg: subtract
- Net: 6.00 kg → Food: 3.60 kg: classified
- Net: 6.00 kg → Associated parts: 2.40 kg: classified
A constant total can conceal a changing split
In a second invented period, net material is again 6.00 kg but comprises 2.80 kg food and 3.20 kg associated inedible parts. With consistent rules and measurement, recorded food mass is 0.80 kg lower, while the combined mass has not changed.
This observation is not, by itself, proof of successful prevention. Inputs, service volume, food state and the reasons for disposal may differ. Keep the fraction-specific record alongside the combined total, then investigate the circumstances rather than inferring a cause from the numbers alone.
Keep the definition with the result
Report whether a total includes food alone, associated inedible parts alone or both. Identify packaging exclusions, destinations, period and method. If classification changes, disclose it and avoid presenting the resulting difference as a change in performance.
The fraction record can help locate questions for purchasing, preparation and material recovery. Other articles explain those processes and their controls. Measurement is useful when the definitions remain visible, allowing another reader to understand what was actually counted.
Worked examples
Use the net denominator
With gross 6.50 kg and empty container plus liner 0.50 kg, what is the net material? What share is the stipulated 3.60 kg food fraction?
- Net material: 6.50 − 0.50 = 6.00 kg.
- Check the split: 3.60 + 2.40 = 6.00 kg.
- Food share: 3.60/6.00 × 100 = 60%.
The net material is 6.00 kg and food is 60% of it. Packaging and container mass are excluded.
Compare fractions without inventing a cause
Food mass changes from 3.60 to 2.80 kg while total net material stays 6.00 kg. What descriptive change can be calculated?
- Absolute food-mass difference: 3.60 − 2.80 = 0.80 kg.
- Relative decrease against the first food fraction: 0.80/3.60 × 100 ≈ 22.2%.
- Combined material change: 6.00 − 6.00 = 0.00 kg.
Recorded food mass is 0.80 kg, or about 22.2%, lower; the combined total is unchanged. Prevention and its cause remain unestablished.
Check your understanding
Should a plastic liner be counted as an associated inedible part of the food?
Show answer and reasoning
No.
It is packaging, not a component of the food.
Does classifying spoiled food in the food fraction imply that it is safe to eat?
Show answer and reasoning
No.
The classification concerns intended food use, not present safety.
Can two periods be compared directly if every peel is excluded in one and counted as food in the other, without adjustment?
Show answer and reasoning
No.
Changing the classification changes the scope of the measurement.
Key ideas
- Define food and associated inedible parts in context.
- Exclude packaging and tare from food-material mass.
- Keep classification separate from safety, preventability and causal claims.
References
Sources supporting the explanations and examples in this article.
FLW Protocol; World Resources Institute secretariat2 sources
- 2.a.5 Food waste indexUnited Nations Environment ProgrammeReference guide