| Multiple Layer Oil Cake is a famous traditional snacks in Yangzhou.Owing to its sweet and soft taste as well as delicate shape,Multiple Layer Oil Cake is very popular with broad masses of eaters.As the storage time goes on,Multiple Layer Oil Cake is easily to be with starch retrogradation.In the meanwhile,the quality of product would also decline accordingly,which greatly restrict the industrialization development of Multiple Layer Oil Cake.At present,the Multiple Layer Oil Cake is mainly frozen packaging products.After frozen storage,the Multiple Layer Oil Cake is easy to lose water,resulting in a rough taste Besides,it has high requirement for the storage and transportation condition,which greatly influences its market expansion.Therefore,it's a general trend to study the edible quality improvement of Multiple Layer Oil Cake under normal temperature storage.This paper takes Multiple Layer Oil Cake as the research object to find the key factors of starch retrogradation,and selects the assay methods for the process of retrogradation Combined with the production cost of the enterprise,by studying the effect of compound improved formula to the retrogradation of Multiple Layer Oil Cake,the optimum process and formula of making Multiple Layer Oil Cake at room temperature(25 ±1?)is determined.Besides,the shelf life prediction model of Multiple Layer Oil Cake is established based on the retrogradation degree and the total number of bacterial colony Finally,this paper provides a preliminary theory for the standardization and industrialization of Multiple Layer Oil cake,by assessment to the nutritive index of Multiple Layer Oil cake,and studying the health and safety condition during storage at room temperature.It could solve the practical problems in production and processing,and fill the gap in the field of basic application research.The research results can be used by enterprises to expand the business,carry forward the traditional food culture and promote the research on the modernization of traditional Chinese flour products technology1 The analysis of retrogradation characteristics and the determination of retrogradation index for Multiple Layer Oil CakeBy analysis of various retrogradation indexes(sensory score,texture parameters,thermodynamic parameter,soluble starch content,and water content),it's found that the retrogradation process of Multiple Layer Oil Cake was the fastest within 7 days.Then it slows down as the storage time goes on.The main reason is the aging recrystallization of amylose in early stage,but the long-term regeneration is caused by the recrystallization of amylose.By the analysis of the correlation analysis,it's found that the aging parameters are well correlated.Through comprehensive analysis,the hardness of the quality and structure parameters and the enthalpy change value of thermodynamic parameters are selected as the main aging parameters of the Multiple Layer Oil Cake.The accuracy of the aging condition of the Multiple Layer Oil Cake is verified,by analyzing aging kinetic model with Avrami equation.Through analysis,it's found that hardness Avrami index n=0.6349 and enthalpy change value Avrami index n=0.4858 are all<1.It's indicated that the nuclei for the aging crystallization of Multiple Layer Oil Cake during 4? storage are mainly formed at the initial stage of storage,which is consistent with the experimental results.2 Study on the formulation of compound anti-aging improver for Multiple Layer Oil CakeBased on the single factor experiment,with the hardness difference value and sensory score before and after 7 days' storage at 4? as evaluation indexes,the formulation of anti-aging modifier is optimized in combination with box-behnken response surface experiment.The experimental result indicates that separately adding modified potato starch,trehalose,SSL and beta-amylase all could significantly improve the hardness and sensory scores of the Multiple Layer Oil Cake,and the compound use of four kinds of additives is better than the single use in the improvement of Multiple Layer Oil Cake.The most appropriate amount of the compound additives are 5%of modified potato starch,6.4%of trehalose,0.1%of SSL and 0.02%of beta-amylase.Under this condition,the hardness difference before and after the storage of Multiple Layer Oil Cake is as low as 190.33N,which is basically consistent with the predicted value of 182.677N,and the relative error is only 4.2%.The experimental results show that the quality index,sensory score and thermodynamic parameters are significantly better than the control group.3 The construction of shelf life prediction model for Multiple Layer Oil CakeIt's predicted to the shelf life of Multiple Layer Oil Cake by the kinetic equation.The results show that under 15?,25? and 35? storage condition,the aging degree and the total number of colonies would increase at different rates with the increase of storage time and storage temperature.The correlation coefficients R2 of the first-order reaction kinetics model and the Arrhenius formula are both>0.9,and the fitting degree is relatively high,so the shelf life prediction model of the Multiple Layer Oil Cake is established.By measuring the aging degree at 25?,the shelf life of the melalea cake is predicted to be 380 d,and the shelf life of the Multiple Layer Oil Cake is predicted to be 439 d by measuring the total number of bacterial colonies.Compared with the actual shelf life,the relative errors are less than 10%,which can meet the prediction accuracy requirements.Therefore,this model can be used to evaluate the shelf life of the Multiple Layer Oil Cake under normal temperature which sale in market.4 Analysis to the nutritional composition of Multiple Layer Oil CakeIn accordance with the relevant national standards,the nutrition components of the Multiple Layer Oil Cake are detected and analyzed,and the results show that every 100g Multiple Layer Oil Cake contain 1196kJ energy,33.7g water,8.2g protein,8.4g fat,0.9g total ash,48.8g carbohydrates,75.3mg calcium,7.4mg magnesium,63.3mg phosphorus,78.4mg potassium,194mg sodium and 0.7mg iron.The evaluation of Amino acid indicates that every 100g Multiple Layer Oil Cake contain the total amount of amino acid 11.17g.Which Glu is the most abundant,up to 4.24g.The highest content of EAA was Leu(0.79 g).The ratio of product EAA/NEAA is 43.38%(WHO/FAO recommended value<60%)Therefore,the Multiple Layer Oil Cake in this study is not a high quality protein source.The lowest AAS is Lys(4.36),so Lys is the first restricted amino acid.It is recommended to make a reasonable collocation when eating Multiple Layer Oil Cake to achieve a balanced diet.5 Evaluation to the health and safety of Multiple Layer Oil CakeIn accordance with the relevant national standards,the physicochemical index and microbiological index of Multiple Layer Oil Cake are detected.The results of physicochemical indexes show that with storage time increasing,the acid value and peroxide value of Multiple Layer Oil Cake present an increasing trend,but it's lower than the allowable range of national standards(acid value?5mg KOH/g;The peroxide value?0.25g/100g),and it would not lead to food safety problems.Through the determination of heavy metals in the Multiple Layer Oil Cake,it's found that the content of chromium is 0.375 mg/kg,arsenic is 0.124 mg/kg,cadmium is 0.00346 mg/kg,lead is 0.107 mg/kg,and the content of mercury has not been found,which do not exceed the national standard limit requirements.Thus,there is no food safety problem of excessive heavy metals.However,attention should be paid to the residual problem of heavy metal chromium in wheat flour.Microbiological test results show that in different storage time,the total number of colonies would increase,which meets the national food safety standards.There is without Coliforms and molds found in the experimental test. |
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