Pomace Fibre, Slow Filters and Low Press Yield: Fibre-Splitting Enzyme Complexes for Juice, Fruit Wine and Plant Extraction

An enzyme system that carries hemicellulase alongside cellulase is used on fruit and vegetable pulp and pomace to break the plant cell wall and release what is inside the cells. The outcomes it is bought for are a higher juice yield, a thinner mash, and more sugar and soluble solids in the juice. The second saving is at the filter: breaking down soluble and insoluble pectin together with hemicellulose prevents floc from forming, lowers viscosity, speeds up filtration and lengthens the interval between cleanings of the ultrafiltration membrane. Membranes are a cost centre of their own in a juice plant, which also buys enzyme cleaners for its ultrafiltration and reverse-osmosis units. For plant extraction the argument is the process itself: an enzymatic extraction runs at a lower temperature and gives a higher efficiency than the traditional route.

Hemicellulase for food use is sold as a liquid at 50000 U/mL as well as a solid, so the first choice is between metering a liquid into the mash line and weighing a powder into a tank. A cellulase for plant extraction is specified at up to 20,000 U/g, and the strength can be customised. Extraction cellulase is also sold at a much lower 3500 U/g. A liquid cellulase at 10000 U/mL is aimed at herbal raw material. A xylanase for food processing from Trichoderma, an endo-xylanase with a beta-xylosidase beside it, is far more concentrated and is dosed at 0.01-0.5 kg per tonne across pH 3.0-7.5, with its best activity at pH 4.0-6.0. A juice pectinase reaches 300000 U/g. A beta-glucanase is sold for brewing and for fruit and vegetable juice. Units from different enzymes cannot be compared with each other, so a bigger number on one drum says nothing about a different enzyme in another.

Production packs are 25 kg drums with a 12 month shelf life in a cool, dry store, and berry and trial grades also come as 1 kg bottles. The neutral extraction compound is packed smaller, in 10 kg drums. Buyers who take hemicellulase for fruit wine commonly put a pectinase or a cellulase in the same order.

On crushed grapes, a pectin enzyme given several hours of contact raises juice yield, most of all in pectin-rich varieties, and even a short contact gives clearly more free-run juice. Colloidal pectin blocks filters and holds particles in suspension, so the enzyme added after pressing is what makes the juice settle and filter. Commercial preparations carry side activities, and a glucanase side activity matters most on mould-affected grapes that are full of viscous glucan. The effect of those side activities on aroma is hard to predict, and over-clarifying the juice is a real risk, so a winery trial should taste as well as measure.

Cold cellars change the dose. Within its working range a fruit enzyme works harder the warmer it is, and below 15 C both the dose and the contact time should go up. Contact should never be shorter than an hour, and longer contact helps. Bentonite must wait until the enzyme has finished its work, and the enzyme is first dissolved in a little pure water and then stirred well into the tank.

Extraction plants use the cellulase and hemicellulase complex to open the cell wall so the active substances come out, at pH 4.5-6.5 and 40-55 C. Where the extract must stay close to neutral, a separate neutral extraction compound is used at pH 4.5-6.0 and 40-55 C.

Name the fruit or plant material, the pH and temperature of the mash or extraction tank, and how long the material stays there. Say what you want to move: press yield, soluble solids, filter time, membrane cleaning interval or extract yield. Ask for the enzymes in the complex and the activity of each with its unit, the working pH and temperature window, the dose per tonne, the form and the pack size.