Studies On The Moulds Population During Ripening And Their Effects On The Safety And Quality Of Jinhua Ham

As a famous traditional product, Jinhua ham has produced bytraditional way that maturing under natural environmental condition for along time. Consequently, the problems of potential microorganism safetyand the instability of quality may exist. To investigate moulds populationand safety during ripening and their effects on the quality of Jinhua ham,a control product (naturally maturing hams) and different treatments withinoculated Penicillium nalgiovense, sprayed antiseptic and inoculatedPeniciilium nalgiovense and Staphylococcus aureus were assayed. Theresults showed as follows:During maturing, moulds population of Jinhua ham was analyzed.Totally 72 strains were isolated belonging to the genera Penicillium(43.06 %), Aspergillus (34.72 %), Alternaria (5.56 %), Mucor (9.72%)and Rhizopus (6.94%). Among them, the mould microflora wasdominated by P. chrysogenum, P. citrinum and P. crustosum ofPenicillium spp. and A. parasiticus, A. tamarii of Aspergillus spp.. There were less toxigenic strains of Aspergillus spp. in hams with P.nalgiovense,only found one strain of A. parasiticus and one of A. tamari. But 23strains of Aspergillus spp. were isolated from control product and 78% ofthem were potentially toxigenic strains through the test of inhibiton ofStaphylococcus aureus. Therefore, hams with P. nalgiovense surpassedcontrol product of their safety by the number of potentially toxigenicstrains and the toxicity of metabolites.The appearance of Jinhua ham varied obviously during ripening andthe moulds population changed rapidly. It was bellow 10~4cfu/g on thepre-ripening phase, then increased quickly until reaching its peak, andlower at the end of the ripening process. P. nalgiovense grew well on theham surfaces. Because of low Aw of hams, S. aureus could not bedetected after one month ripening. The moulds population maintained10~3cfu/g of hams with antiseptic.Generally, Aw and water content of superficial muscle on Jinhuaham decreased during ripening that varied 42.27% to 14.13% and 0.842to 0.726 of traditional ones respectively. NaCl concentration increasedgradually (5.51% to 7.90%) and pH decreased from 6.65 to 6.08. Aw,water content, NaCl concentration and pH were different among severaltreatments.By the comparison of superficial muscle, the instrumentalmeasurement of colour gave rise to some significant differences among four treatments. L* value was 41.22, 36.10, 45.09 and 36.18 respectively.The highest and lowest a* value were found in batches with P.nalgiovense and antiseptic comparing with different treatments. And theresults were similar to b* value. Judged by bamboo spike, smell of theproduct with antiseptic performed poorly that the proportion of bad smellspikes was 22.2% which was 6.7%, 4.4% in control and inoculatingbatches. And seventeen kind of free amino acid (FAA) with differentcontent were detected that the concentration of GLU and ASP were highwhich represent umami taste. By the comparison of several treatments,concentration of umami taste amino in inoculating batch was larger thanothers. The total content of FAA in two inoculation treatments were503.811and 459.416 mg/100g dry matter, a little larger than controlgroup(430.640 mg/100g dry matter) and antiseptic treatment (399.101mg/100g). Furthermore, the batch inoculated with P. nalgiovense showedan increase for hardness and chewiness in relation to uninoculated controland antiseptic treatment. Antiseptic batch had the highest value ofcohesiveness and lowest of adhesiveness among four treatments.Springess showed less significant difference between several treatments.From the result of fuzzy appraisal to samples it can be concluded that thequality of batch inoculated with P. nalgiovense superior to uninoculatedcontrol and antiseptic treatment.