Measuring food production waste in brassicas

The coordinator visited fields in Cornwall in early November, just after the end of harvest for those fields.

Instead of sampling one row at a time, it was sensible to sample two adjacent rows each time, which widened the sample size. As many cauliflowers rolled into the furrows, cauliflowers were also counted in the furrows either to the right or left of each row (2 furrows for 2 rows).

It was often appropriate to state multiple reasons for rejection for some cauliflowers (e.g. diseased and overmature, yellow and oversized).

Results can be found under the results and reports tab on the field lab page.

At the workshop and in subsequent discussions, the group agreed on a plan for measuring on-farm waste/surplus.

Cauliflowers:

• The researcher/coordinator will visit selected fields after the final harvest run.
• For each farm, 2 locations will be visited, with a minimum of 2 fields at each location, and 5 x 20 metre-long samples per field. Sample points will be chosen randomly, to include some field edge as growers report higher losses due to pest and tractor damage.

• Any cauliflowers in the sample area will be counted and categorised by the reason for rejection (e.g. too yellow, diseased, undersized, oversized, overmature, leaf disease, no obvious reason, etc.)
• The researcher will compare these figures to the number planted, using info on planting density and taking into consideration the proportion of field edge, adjusting the figure to discount cauliflowers that failed to develop a curd
• Additional data on any unharvested fields or customer rejections to be sent to researcher

Kale:

• Farm agronomist to visit sample plots and do a base count of kale plants that managed to grow. Mark out these sample points.
• Revisit sample plots after harvest. For each sample point, collect anything left on the ground or plant and categorise the waste/surplus into reason for rejection. Weigh each category separately and record this
• Factory staff to carry out a waste audit, sorting and weighing waste/losses by reason, e.g. kale dust, yellow leaves, stalks, frost-damage
• Agronomist to send all data to researcher for analysis
• Additional data to be sent to researchers includes data of any fields where kale remained unharvested or was rotavated in, and any customer rejections

The growers met virtually in September with the coordinator and researcher, to discuss the major hotspots where brassica waste/surplus occurs, and the main reasons driving this waste.

Both cauliflowers and kale are hand-harvested, and each field undergoes several harvest runs.

Cauliflowers:
Pre-harvest losses include damage from tractors running over crops, pests such as pigeons and rabbits eating the cauliflower curd, hoeing damage, disease, rot, sun damage, etc. These are rejected at the point of harvest, in the field. Cauliflowers are trimmed and packed into packaging at the point of harvest in the field.

Some cauliflowers may be rejected at harvest due to over-maturity and others may be left in the field when they could have been picked. Some cauliflowers fail to develop a curd (the white centre).

Kale:
Kale may be rejected at the point of harvest if leaves are too yellow, old, diseased, damaged by pests or from harvesting technique.

At the packhouse, woody kale stems are separated as these are not marketable/typically consumed, and some product may be rejected due to frost-damage or the reasons above.

The group is comprised of three large-scale brassica producers; two with farms in Devon & Cornwall, and the third based in Lincolnshire. All supply major supermarkets, with total production spanning nearly 6000ha. UK brassica production is high-investment with low returns and razor sharp profit margins, meaning that any potential gains in efficiency would help the industry remain viable in a competitive market and retail price deflation in the UK.

Two of the growers will focus data collection on cauliflower waste/surplus. The third grower do not grow cauliflowers so will focus on kale.