Monitoring of Feed-Nutritional Components, Toxic Heavy Metals and Pesticide Residues in Mushroom Substrates According to Bottle Type and Vinyl Bag Type Cultivation

ABSTRACT This study was carried out to monitor feed-nutritional components, toxic heavy metals (Cd, Pb and As) and pesticide residues through three cultivation stages (1 st initial culture stage, 2 nd mycelial growth stage, and 3 rd fruit body-harvested stage) of king oyster mushroom ( Pleurotus eryngii ) produced by bottle type cultivation and oyster mushroom ( Pleurotus osteratus ) produced by vinyl bag type cultivation. For both cultivation types, compared with the initial culture, the weight reduction rate in spent mushroom substrates (SMS) after fruit body harvest was 29% for total wet mass, 2125% for dry and organic matters and 19 22% for neutral detergent fiber. Two thirds to 3/4 of organic matter degraded and utilized by mycelia and fruit bodies was originated from fiber, of which the primary source (5070%) was hemicellulose. The effect of mycelial growth stage on chemical compositional change in culture was little (P>0.05) for bottle type cultivation of king oyster mushroom but considerable (P<0.05) for vinyl type cultivation of oyster mushroom. Culture nutrients uptake by fruit bodies was very active for the bottle type cultivation. Compared with SMS, harvested fruit bodies (mushrooms) contained higher (P<0.05) crude protein, non-fibrous carbohydrate, and crude ash and lower (P<0.05) neutral detergent fiber. Regardless of stages, no culture samples were contaminated with toxic heavy metals and pesticide residues. In conclusion, the increase of fiber (neutral and acid detergent fibers) and indigestible protein contents and the decrease of true protein content in SMS indicated that the feed-nutritional value of SMS was significantly reduced compared with that of the initial culture and they were safe from toxic heavy metals and pesticide residues.(