Research On Combination Of TTIs And Dimensional Analysis In Predicting The Shelf Life Of Ham

Ham is a type of low-temperature meat products.Compared with high-temperature meat products,it is more nutritious.The delicate and special meat make your mouth feel fragrant.However,due to temperature abuse and other circumstances,the remaining microorganisms after pasteurization are provided with a good growth environment,which shortens the shelf life of the ham,causes food waste and even causes safety problems.The purpose of this research is to effectively predict the shelf life of ham,and explore the quality changes of ham under temperature abuse.And taking glucoamylase as the research object,using the embedding-diffusion method,developed a time-temperature indicator(TTI)that can monitor food quality for a long time.The developed combination of TTIs and dimensional analysis method predicts the shelf life of ham under variable temperature conditions,laying a foundation for the design of a complete ham and other food packaging system,and also provides a new idea for food shelf life prediction.The main research contents and conclusions are as follows:1.Through 4-25?constant temperature storage experiment to simulate the quality change of ham under temperature abuse.Regular sampling,sensory scores of the samples,and determination of aerobic bacterial count,texture,total volatile basic nitrogen and other physical and chemical indicators,explored the relationship between the bacterial diversity and volatile flavor compounds of ham at different storage temperatures.It was found that quality indicators such as hardness were extremely significantly correlated with aerobic bacterial count(P<0.01).The volatile flavor compound n-hexanal is significantly positively correlated with Aeromonas and Streptococcus before and during the 4?period(r=0.868,P<0.05).However,?-caryophyllene,which is the key volatile flavor compound in the late storage period at 4,10,15,20 and 25?,was significantly negatively correlated with Burkholderia(r=-0.816,P<0.05).2.Compare the methods for predicting the shelf life of ham.The results showed that the shelf life prediction model of ham stored at a constant temperature of 4-25?established by the dimensional analysis method,R²?R²_adj>0.85,MARE is the smallest,12.03%.A_f and B_f are 1.1300 and 0.9923 respectively,and their difference from 1 is the smallest.The results show that the shelf life prediction model established by the dimensional analysis method can effectively predict the shelf life of ham at constant temperature of 4-25?.3.Preparation of solid-state enzyme type time and temperature indicator.Firstly,microcapsules were prepared by immobilization of glucoamylase by the embedding method,and single factor and response surface tests were carried out to determine the optimal ratio for preparing immobilized enzyme with porous structure,namely 0.89%chitosan,1.80%sodium alginate,0.3 mol/L Ca Cl₂,2.50%polyethylene glycol fixed0.2 g glucoamylase.Then to improve the color of the liquid TTI,4.44%maltodextrin,0.40%iodine solution and immobilized enzyme containing 0.25 g of free enzyme were fixed on the polyvinyl alcohol film respectively to develop a diffusion-type solid enzyme TTI.Finally,based on the accelerated test and kinetic analysis,the prepared solid enzyme TTI was predicted to react for 134.76 d at 4?.The activation energy of the reaction was 45.62 k J/mol,and the difference between the reaction activation energy and ham was less than 40 k J/mol,indicating that the TTI prepared could indicate the time and temperature history of ham.4.The time-temperature history of the three temperature variations in the range of 4-25?is monitored by the prepared time-temperature indicator,and the equivalent temperature of the variation is obtained.It was combined with dimensional analysis method to predict the shelf life of ham.The three models R² and R²_adj>0.80at variable temperatures,MARE are 10.27%,16.04%,14.45%,A_f and B_f are close to1,indicating that this method can effectively predict the shelf life of ham with the assistance of TTI under variable temperature conditions.