Hunting and harvesting
The truffle is the fruiting body of the fungus. It is located up to 30cm below ground and weighs between 30 and 300g, but can be as heavy as 1.2kg. The shape of truffles varies wildly with some being a uniform round shape while others may have numerous crevices and lobes.
The shape appears to be partially influenced by the soil. Truffles formed in soft soils with fewer stones tend to be rounder while truffles formed in hard stony soils may be knobblier in appearance. While the shape does not seem to confer any particular aromatic characteristics and ugly knobbly truffles are just as likely to have the same aromatic characteristics as round truffles, restaurateurs and retail outlets may favour the more evenly-shaped truffle.
Harvesting commences in the Manjimup/Pemberton area in late May and continues until early September. Dogs and their handlers usually begin hunting in the early morning. High winds can impair the dogs ability to locate the ripe truffles. Dogs of any breed can be used provided they have a good sense of smell and are capable of being trained. They will also need to have some endurance as detection requires lots of walking. Common breeds include spaniels and Labradors.
It is important to train dogs to detect ripe healthy truffles to prevent disturbance of immature truffles. In the early part of the season, dogs may detect slightly immature truffles. If the truffle is not disturbed it may continue to mature in the following days. Handlers and harvesters will carry a small sharp knife to nick a small piece of skin from the truffle to determine whether it is fully mature. As the season progresses this problem diminishes.
Dogs are generally trained to 'mark' the site where they smell the truffle by lightly scratching the ground. The handler will smell the soil, usually by taking a handful or trowel-full of earth. The aromas of a ripe truffle permeate the local soil creating a rich sweet earthy smell. If this is present, the dog is rewarded and the truffle is dug up either by hand or with a small trowel. It is often more practical to have a second person to dig up the truffles after the dog handler has marked the sites where ripe truffles have been detected.
Female pigs can be used, as one of the principal truffle aromas is very similar to a pheromone produced in the saliva of male pigs. However, pigs will eat the truffles if they can and it can be very difficult to prevent a 100kg pig from eating truffles.
Grading
Harvested truffles are thoroughly washed and may require scrubbing with a small brush to remove all dirt. Large producers may utilise a modified vegetable washing assembly to speed up the process. Once truffles are washed and dried they are then individually graded.
The aromas of healthy ripe truffles vary markedly, even in truffles harvested from the same orchard. Nonetheless, damaged truffles will emit very unattractive odours, while unripe truffles will lack appreciable aromas. Grading involves assessment of the aroma and then the shape and health of the truffle. Each truffle is smelled by an experienced grader to detect any off-notes that may indicate a sub-standard truffle or internal damage. The truffle is then visually assessed and weighed.
Grading in WA is based on a modified version of the European UNEC Grading Standard (2010).
Marketing
Production of truffles in Australia is counter-seasonal to that of Europe and most production is exported. Current exports go to Europe, North America and Asia. The acceptance of Australian grown black truffle has taken considerable effort.
Using truffles
Fresh truffles are best stored wrapped in paper towel in a glass jar (with lid on) in the fridge. The paper towel should be changed every couple of days. The glass jar is necessary to prevent the entire contents of the refrigerator becoming infused with truffle aromas. A healthy truffle may keep for up to two weeks if stored in this way. Truffles are traditionally sliced very thinly using truffle planes, but a very fine grater can also be used. Truffles can be snap-frozen, though the aroma profile will change. Frozen truffle is best planed or grated while still frozen as it will become mushy when thawed.
Truffles added to recipes, generally at the end of cooking, will add earthy, blue-cheese, mushroom, garlic and chocolate notes, depending on the quantity used and the other ingredients. Truffles may also be added to recipes to act as a general flavour enhancer, without adding a strong truffle character to the dish. This latter method works well in meaty casseroles or pies. Truffle lovers can of course boost flavours by adding grated or planed truffle at the table.
A delicious way to try truffle is to grate or plane very thin slices of fresh truffle over foods such as scrambled/poached eggs just as the cooking is finished. This also works very well with steaks. Grated or planed truffles can be added to mashed potato and left to infuse for a couple of minutes prior to serving. Creamy pasta dishes also benefit from the addition of truffle at the end of cooking. Usually, 5-10g per person is used in a dish. Eggs stored with truffles will be infused with the truffle aroma which is retained when lightly cooked.
Further reading
Bonet et al 2009, Cultivation methods of the black truffle, the most profitable Mediterranean non-wood forest product; a state of the art review. EFI Proceedings no.57. Modelling, Valuing and Managing Mediterranean Forest Ecosystems for Non-Timber Goods and Services. Marc Palahi, Yves Birot, Felipe Bravo and Elena Gorriz (eds).
Gareth Renowden, The Truffle Book. Limestone Hills Publishing 2005.
Ian Hall, Gordon Brown and Alessandra Zambonelli, Taming the truffle: the history lore and science of the ultimate mushroom'. Timber press, 2008, Portland OR/US.
Acknowledgments
Christine Fischer, Forest Sciences Centre of Catalonia Spain; Mel Booth, Truffle Dogs WA; Al Blakers, Manjimup Truffles; Anne Mitchell, Manjimup Underground and Celeste Linde, Australian National University.