Apple Pomace

Pressing separates an apple into a liquid fraction and a solid one. The liquid is the juice; the solid is pomace, and it retains the fruit's skins and the fibrous structure of the flesh along with the cores and seeds that went through the mill. It is not depleted material — it holds fibre, pectin, residual sugars, and polyphenols concentrated by the removal of the water and dissolved solids that left in the juice.

Fresh pomace is wet, and wet is expensive. It is heavy relative to its dry matter, which makes it costly to move any distance; it ferments quickly, so it cannot be stockpiled; and it moulds, which rules it out of feed and food uses once it has. The three routes out of this are all time-critical: feed it fresh to livestock nearby, ensile it so that controlled fermentation preserves it, or dry it into a stable material that can be stored and shipped.

Drying is what unlocks the higher-value outlets, because pectin extraction and food-ingredient use need a stable, transportable input. It is also energy-intensive, and the economics of drying a wet residue are marginal enough that the choice between drying and disposal often comes down to how close the plant sits to a livestock operation.

Livestock feed is the largest outlet and the simplest: fresh or ensiled pomace is fed to ruminants as a palatable, fibrous, energy-bearing feed material, and its use is governed by the feed regulations of the jurisdiction concerned. Dried pomace supports the higher-value routes — it is a major raw material for commercial pectin, the gelling agent extracted from apple and citrus residues, and it is milled into apple fibre for food use. Smaller volumes are composted or used as a fuel and digester feedstock.

• Feed — fresh or ensiled pomace fed to ruminants, the dominant outlet
• Industrial — pectin extraction from dried pomace
• Food — apple fibre and polyphenol ingredients from dried, milled pomace
• Energy — anaerobic digestion feedstock and composting where no better outlet exists

Because pomace concentrates the skins and cores, it also concentrates whatever was on or near them, which makes the soundness and cleanliness of the incoming fruit directly relevant to the by-product's suitability for feed and food use.