Macahnisim Of The Reduction Of Patulin In Batch Cultivation Of Penicillium Expansium

Patulin is a fungal toxin cousing cancer, deform, and mutation. Patulin is very common in apple and apple products. Penicillium expansum is the most significant patulin-producer in apples. Searching safe and efficient way to reduce patulin has very important meaning in controlling patulin. In order to explore the intrinsic reason for the degradation of patulin during the cultivation of Penicillium expansum, the thesis investigated and analyzed the change of substances and pH in the liquid culture of during the batch cultivation. Substances that can be tested by HPLC were investgated alonge the cultivation. The possible reasons were concluded according to the relationship between patulin degradation and the change of these substances. The main contents and results of the thesis were listed as followings:(1) In both batchs of static and shaking cultivations, patulin content increased firstly and then decreased. A clear second increase of cell growth appeared in the static cultivation, but not in the shaking cultivation. In total, residue sugar and pH kept decreasing and total titrable acids kept increasing through the whole cultivation in both static and shaking cultivations. During the cultivation, sugar was consumed for the cell growth and sythesis of patulin. Some kinds of acidic substance were produced in the cell growth and patulin sythesis.(2) In the batch of static cultivation, the period for the highest patulin production was consistent with the first high stable period for cell growth, in which spores of the P. expansum started to form. Patulin reduced quickly from when the second quick cell growth happened in the static cultivation and in the middle period of the stable cell growth in the shaking cultivation. Patulin reduction also happened at the later cultivation stage when cells appeared decrease. Compared with the static cultivation, the dried cell weight was about 2 times more than, but the patulin production was 1/2 lower than, that in the static cultivation. This indicated conditions for patulin production might be consistent with that for spore formation. Abundant oxygen would be good for the cell growth of P. expansum, but not for the patulin production.(3)Residue sugar, pH and total acid content, and dried cell weight did not show significant correlationship between the reduction of patulin. The reduction of patulin could not be caused by the inherent compositions in cells.(4) Oxygen had potential in accelerating the reduction of patulin. Some kinds of substances that could be tested by HPLC might be closely correlated with the reduction of patulin. These substances might be synthesized and excreted out of cell at the initial period of cell growt. They might be stored in cells and excreted when cell broken. These substances might be titrable acidic substances. Another possible way for reduction of patulin might be the patulin was used by the cell in the second period for cell growth.