Irradiação gama e quitosana como substitutos do nitrito em mortadelas: efeitos da qualidade e crescimento de Clostridium botulinum

Abstract

Nitrite is an additive that acts as an antioxidant, preservative (Clostridium botulinum) and added to products color, flavor and aroma of cured products. Although, nitrite under specific conditions can form N-nitrosamines (carcinogenic). This research suggests the replacement of total or partial nitrite by irradiation and chitosan, with the goal of reducing nitrosamine. In the 1°article, the aim was to assess the potential growth of inoculated C. botulinum (104 spores/g) in mortadella and its technological properties. Doses of irradiation (0,2,4,6KGy) were applied to the samples, which were added Chitosan (0 and 1.5%) and sodium nitrite (0, 50, and 150mg/kg), and kept refrigerated at 4°C for 30days. In the 1° day, the samples with chitosan (1,5%) and irradiation (2,4,6KGy) contributed to the non- growth of C. botulinum regardless of the presence of nitrite. The effect of irradiation was dose dependent (P<0.05). The samples were analyzed after 30 days and there was no growth potential of C. botulinum (δ < 0.5 log CFU/g), the combination of irradiation and chitosan remained efficient. Regarding color, the using of chitosan decreased L*, increased C*, and the curing color index (R650/570nm). There was an interaction between chitosan x nitrite level (P<0.05), it changed the cured color C* and h. The curing color index increased from 1.51 to 2.12 with nitrite level from 0 to 50mg/kg. Regarding texture, the using of chitosan decreased chewiness and springiness (P<0.05). And higher level of nitrite (50 and 150mg/Kg) increased hardness (P<0.05). Irradiation alone did not change color index or texture attributes (P<0.05). In the 2° article, the aim was to assess the physicochemical and quality properties of the samples when replaced nitrite by chitosan and irradiation during the storage at 4°C. Doses of irradiation were applied to the samples (0,2,4,6KGy), which were added chitosan (0 or 1.5%) and with nitrite levels (0, 50 and 150mg/Kg), they were kept refrigerated at 4°C for 60 days. The chitosan kept the TBARS values lower independent of irradiation application, chitosan worked as an antioxidant, without the use of nitrite and without its influence (P>0,05). The interaction among chitosan, nitrite level and storage were observed (P<0.05), resulting to the possibility of formation of a chitosan-nitrite complex that affected RNO2. The samples with chitosan and nitrite had higher values of RNO2 than nitrite (without chitosan), this data was contrary to the expected to be. Irradiation at 6kgy alone affected the RNO2 reducing its value, regardless of chitosan and storage time. Chitosan, nitrite level, irradiation and storage (P<0.05) had affected the color index (L*, C*, h°), in isolation or not by the interaction of chitosan x nitrite level x storage. The non-cured sample with chitosan were darker than cured (without chitosan). Irradiation (P<0,05), alone, interfered with the curing color. In conclusion, the application of chitosan (1.5%) and irradiation (2,4,6kGy) in partial or total could replace nitrite since the combination there is not disadvantageous changes that compromise the quality of mortadella. The use of chitosan with irradiation is recommended. However, it is necessary to study deeply the Chitosan-Nitrite complex.