Fungi, Food and Health 1. Edible fungi- Chap. 18 2. Fungi in food processing - 19 3. Fungi and food spoilage - 20/21 4. Poisonous /Hallucinogenic fungi - 22. 5. Fungi of Medical importance - 23. Obviously with so much material to cover, only an overview is expected !

Edible Fungi - Mushrooms Many edible species popular in various parts of the world BUT some poisonous ones too. So CARE needed in identification. Can be good source of protein

Edible Fungi - Mushrooms some important American and European species Agaricus sp. - supermarket mushroom Pleurotus - Oyster mushroom Tuber - truffles Morchella - morels Cantharus - chanterelle Calvatia - puffballs Armillaria - honey mushroom.

Edible Fungi - Morels 500,000 people may take part in the annual Morel hunts in Michigan

Edible Fungi - Truffles Trufles can fetch $1000 /kg in N. America

Edible Fungi - Mycelial cultures Several attempts to produce cheap and nutritious food from fungi grown in big vats or fermentors eg Fusarium graminearum -45% protein, 20-25% fibre Nucleic acid content intially too high at 10% - causes gout. -reduced to 1% by heating - sold as ‘Quorn’ - animal and human food Yeasts (Saccharomyces and Torula sp.) Can be grown on cheap substrates e.g effluent from food processing. High protein (40-50%) and high Vit. B. BUT - too high nucleic acid and low in certain amino acids. May become a useful food supplement in future.

Fungi and Food Processing. Cheeses - milk products ripened by action of bacteria (mostly) but also some fungi e.g. Camembert, Brie etc - Penicillium camembertii Fungi on surface of cheese produce extracellular proteases - digest milk proteins - creamy cheese. Blue cheeses (Roquefort, Stilton, Gorgonzola etc.) -P. roquefortii tolerates high CO2 and low O2 so can grow right through cheeses - blue veins due to conidia Asian markets - many products utilize fungi in processing e.g. Soy sauce - digested with Aspergillus oryzae, yeast and Lactobacillus

Mycotoxins - Chap 21 Even in absence of visible ‘mould’, Fungi can also spoil food - especially by production of dangerous mycotoxins, produced as secondary metabolites, many of which are toxic to man or animals The yellowish colonies are of Aspergillus flavus, a producer of aflatoxin. The green colonies are of Penicillium, another mycotoxin-producing genus (ochratoxin, patulin, penitrem, PR toxin).

Mycotoxins - Chap 21 Ergots and St. Anthony’s Fire Over 65 recorded ancient cases of ergot poisoning (grains contaminated with ergots - fruit bodies of Ascomycete, Claviceps purpurea. Produced:- Gangrenous ergotism - ‘burning’ in limbs, later numbness, extremities turn black, shrivel and drop off! Convulsive ergotism - fomication (ants under skin), itching, numbness, convulsions, brain damage, death

Mycotoxins - Chap 21 Ergot chemicals effects on muscles - ergotamine tartrate - now drug for headaches. Ergometrine - now drug to induce labour. effects on CNS - lysergic acid diethylamide (LSD) - hallucinogen - used for mental illnessess.

Mycotoxins - Chap 21 Aflatoxins - Aspergillus flavus on peanuts contaminated peanut animal feed has caused many huge losses of turkeys, pigs, ducks, trout. aflatoxins are potent toxins , also potent carcinogens. fortunately (because A. flavus is very common and even used in food preparation in Asia), it does not produce aflatoxins under many conditions. also can be a problem with other nuts and seeds and even in other foods too (milk, pasta) Active chemicals aflatoxin B1 and B2 - blue fluorescence aflatoxin G1 and G2 - green fluorescence

Mycotoxins - Chap 21 Mouldy bread and Oesophageal Cancer Lin Xian,China - 25% used to die from oesophageal cancer - due to v. high nitrosamines in their bodies. Why such high levels ? Low Mo in soil - crops accumulate nitrites Boiled corn for hours - concentrating nitrites - then made soup Made bread suply every 3 weeks - bread got mouldy Not much Vit. C in diet. leads to high body nitrite levels Result a) mould had carcinogenic mycotoxins eg fumonisin b) nitrites converted to nitrosamines

Mycotoxins - Chap 21 Many other examples of mycotoxins affecting humans and animals 1. Alimentary Toxic aleukia - Siberia - eating of grain after storage for too long - became mouldy - Fusarium sp producing tricothecenes 2. Trichothecenes also responsible for ‘Hole in the Head’ in Horses; ‘Yellow rain’ problems ???; Vomiting in pigs 3. Remember endophytes ? Fungi growing within forage grasses may produce toxins. Also saprophytic fungi on dead forage grasses.

Fungi and Food Spoilage Fungi spoil food in obvious ways such as rots, moulds etc but also in more subtle ways e.g by producing hidden mycotoxins. Spoilage occurs in field, transport storage shelf Over 25% typically lost due to spoilage

Prevention of Spoilage Try to prevent fungal access to food - difficult Try to prevent growth e.g. by killing fungus with heat or irradiation or chemicals (fungicides) . inhibiting its growth with low water store in dry, cold conditions or dessicate (raisins) add sugars or salt to reduce available water (high osmotic pressure) inhibiting growth with low O2 chemical inhibitors (preservatives) eg calcium propionate, sodium benzoate

Strategies of Spoilers Extension of plant pathogenic activities after harvesting Necrotrophs - toxins kill cells ahead of fungus growth Other fungi can resist adverse conditions eg survive under:- dry or low water availability conditions - xerotelerance hot or cold extremes - thermotolerance and psychrotolerance acid conditions low O2 or high CO2 conditions