Effect of Different Packaging Methods on the Quality of Crispy Shrimp Balls

To study the effects of different packaging methods on the quality of crispy shrimp balls during storage, polyethylene/polyamide (PE/PA) was chosen as the packaging material and seven types of packaging methods including ordinary heat-sealed packaging, gas-sealed packaging (100% N₂, 70% N₂+30% CO₂, 50% N₂+50% CO₂, 30% N₂+70% CO₂, 100% CO₂) and vacuum packaging were used to evaluate the changes of sensory scores, lipids, proteins and microbiological indexes of crispy shrimp balls under different storage times, so as to determine the best packaging method for crispy shrimp balls. Meanwhile, the flavor quality changes of crispy shrimp balls under the optimal packaging condition during storage were investigated using electronic nose/tongue and gas chromatography-mass spectrometry (GC-MS). The results showed that 30% N₂+70% CO₂ gas packing group had the best packaging performance. During storage, the peroxide value, carbonyl valence, malondialdehyde content, protein carbonyl content and total number of colonies in the 30% N₂+70% CO₂ modified atmosphere packaging group and the 100% CO₂ modified atmosphere packaging group were lower than those in the other groups. The scores and protein thiol content were higher than other groups (P<0.05). And the increasing of CO₂ concentration resulted in a decline in quality deterioration rate of crispy shrimp balls, but the 100% CO₂ modified atmosphere packaging group had collapse phenomenon after 30 days of storage. Therefore, 30% N₂+70% CO₂ modified atmosphere packaging was considered as the optimum one in the study. Under the optimal packaging method (30% N₂+70% CO₂ modified atmosphere packaging), the results showed that the flavor of crispy shrimp balls changed significantly during storage. The volatile species and contents of alcohols, aldehydes, nitrogen-sulfur and oxygen-containing species in crispy shrimp balls increased significantly (P<0.05) after storage for 30 days. There were 39 and 57 volatile flavor compounds in fresh and crispy shrimp balls stored for 30 days, respectively. The contents of vinyl formate, cyclobutanol, 3,4-decadiene and 3,3-diphenyl-5-methylimidazole were relatively high, but vinyl formate, 2-isocyano-cyclohexanol (trans), 3-cyclohexyl propanol, (E,E)-2,4-dodecanal, lemon aldehyde, 2-isocyano-2,4,4-trimethylpentane and 2,3-epoxybutane were higher in content in crispy shrimp balls after storage for 30 days. This study showed that 30% N₂+70% CO₂ gas conditioning packaging could effectively slow down the quality deterioration of crispy shrimp balls.