基于预测微生物学理论的南美白对虾仁货架期预测模型

Shelf-life prediction model of South Americawhite shrimp meat based on predictive microbiology theory

目的建立并评估南美白对虾仁贮藏期的货架期数学预测模型。方法将南美白对虾仁分别贮藏在-18℃、4℃条件下,定期对特定腐败菌进行检测,利用修正的Compertz方程构建不同温度下微生物生长的动力学模型,结合Belehradek方程,讨论特定腐败菌生长的最大比生长率μ_(max)和延滞时间λ与温度的关系。结果修正的Compertz方程能较好地拟合不同温度下南美白对虾仁特定腐败菌生长的S型曲线,r^2均大于0.95。温度对特定腐败菌的最大菌数N_(max)的影响不大,平均值为7.57 log(CFU/g);延滞时间λ随温度的上升而降低;最大比生长率μ_(max)随温度的上升而增大,结合Belehradek方程发现在-20~10℃温度范围内最大比生长率μ_(max)与μ_(max)^(0.5)、(λ-1)^(0.5)之间均有良好的线性关系。确定了最小腐败水平(Ns)并建立了南美白对虾仁的货架期预测模型SL,模型各参数为N_(max)=7.57log(CFU/g),b_μ=0.0302,T_(minμ)=-25.8179,b_λ=0.0010,T_(minλ)=-523.2000。通过测定5℃贮藏温度下南美白对虾仁特定腐败菌的生长状态,验证货架期预测模型SL的准确性,预测值和实测值之间的相对误差为7.2%。结论该货架期预测模型能有效预测南美对白对虾仁在-20~10℃范围内任意温度下的货架期。

Objective To establish and evaluatea mathematical prediction model for the shelf-life of white shrimp in South America. Methods South America white shrimp were storaged under the condition of-18 ℃ and 4 ℃, respectively, and the specific spoilage bacteria were detected on a regular basis. The modified Compertz equation was used to construct the dynamic model of microbial growth at different temperatures. Combining with Belehradekequation, the relationship between the maximum growth rate（μ_（max）） of specific spoilage bacteria and temperature, lag time and temperature were discussed. Results The modified Compertz equation could better fited the S-shaped curve of the growth of specific corrupt bacteria in South America at different temperatures, and r^2 was greater than 0.95. Temperature had little influence on the maximum number of bacteria of certain spoilage bacteria, and the average value was 7.57 log（CFU/g）.The lag time was decreased with the rise of temperature. The maximum ratio of the growth rate was increased with the increase of temperature. Combining Belehradek equations we could find that there was a good linear relationship between μ_（max） and μ_（max）^（0.5）,（λ-1）^（0.5） under 20~10 ℃ condition. The minimum level of corruption（Ns） was confirmed and the shelf-life prediction model SL for white South American shrimp was established.The parameters of the model were as follows： N_（max） =7.57 log（CFU/g）, b_μ=0.0302, T_（minμ）=-25.8179, b_λ=0.0010, T_（minλ）=-523.2000. The specific growth status of South America white shrimpstoraged at 5 ℃ wasdeterminated, and the exactness of the shelf life prediction model of SL was verified, the relative error between the predicted and measured values was 7.2%. Conclusion The shelf life prediction model can effectively predict the South Americawhite shrimp under-20~10 ℃ at any temperature in the range of shelf life.