Study On Fermentation Biscuit Texture Variation And Shelf-life Prediction In Different Storage Conditions

The storage period of fermentation biscuits is very long from production toconsumption. If they are packaged improperly, their quality will deteriorate in a shortterm because of damp, and it affects the use value and commercial value of thebiscuits. Nowadays the amount of types of packaging material in the market is in largequantity and its barriar is different from each other. It is a problem for the biscuitfactories to master the relationship between packaging materials and the shelf-life ofbiscuits. In addition, there is no relevant research about how the biscuit texturechanges. Therefore, the research of packaging materials on humidity resistance andthe study of biscuit textural changes in damp condition are of practical value.In this paper, fermentation biscuit was the research object. We tested its moistureisotherms and the variation of the biscuit texture in the hot and humid condition, andresearched thoroughly the shelf-life theory of packaged biscuit and the change of itstexture. The main research results are as follows:1. The research of moisture isotherms of fermentation biscuitSeven kinds of commonly used moisture model was selected to fit the moisture dataof fermentation biscuits at25°C and it was found that the best model was the GABmodel. The moisture isotherms model of fermentation biscuits wasWhere M–Fermentation biscuit moisture content (%); RH-Relative humidity ofenvironment(%).2. The research of textural property of fermentation biscuit in the hot and humidconditionThe fermentation biscuit was stored in50°C,80%RH environment to accelerate thedeterioration of biscuits. Texture was tested during the storage, and its correlationwith the sensory was studied.The result showed that the sensory hardness, chewiness,organizational structure and flavor were closely related with thetexture parameters. Under the experimental conditions, we also analyzed the data bystepwise multiple regression and found that the fermentation biscuit sensory hardnessand sensory flavor were positively correlated with texture hardness; sensory chewiness was positively correlated with texture cohesiveness; sensory organizationalstructure was positively correlated with texture resilience and negatively correlatedwith texture hardness.3. The research of shelf-life test of biscuit packaged in different materials in the hotand humid conditionWe tested the moisture content of fermentation biscuit packaged in BOPP/PP,VMPET/PE and OPP/PE/VMPET/CPP stored at30°C (80%RH),40°C (80%RH),50°C (80%RH) conditions. The results showed that the moisture content offermentation biscuit packaged in BOPP/PP and VMPET/PE played positive linearcorrelation with the storage time, and the higher the temperature, the better thelinear. Then map between the rate of moisture content and temperature was took andit showed that the rate of moisture content played a positive linear correlation withtemperature,and the equation was as follows:BOPP/PP: k=0.00004T-0.0119, R~2=1;VMPET/PE: k=0.00003T-0.0087, R~2=1;Where k-moisture change rate; T-storage temperature (K); R~2-coefficient of determination.It could be derived that the shelf-life of biscuit packaged in BOPP/PP was415daysand the shelf-life of biscuit packaged in VMPET/PE was34.6days according to theequation above at room temperature (25°C). The moisture content of fermentationbiscuit packaged in OPP/PE/VMPET/CPP growed lightly, and by the end of theexperiment it was still no more than the value of national standard (5%).4. The research of texture change of biscuit packaged in different materials in thehot and humid conditionWe tested the texture parameters of biscuit packaged in BOPP/PP, VMPET/PE andOPP/PE/VMPET/CPP, stored at30°C (80%RH),40°C (80%RH),50°C (80%RH)conditions. The results showed that texture springiness, cohesiveness, resilience,chewiness increased, and texture hardness decreased during the storage, and thehigher the temperature, the greater the texture parameters amplitude change. Inaddition, the results from BOPP/PP and VMPET/PE showed that the moisture contentof biscuit was lower than the limit of the national standard(5%), when the texturespringiness was lower than0.50, the texture cohesiveness lower than0.28, the textureresilience lower than0.14.5. The shelf-life prediction of packaged fermentation biscuit In order to forecast the shelf-life of fermentation biscuit quickly, the shelf-lifeequation of packaged fermentation biscuit under normal temperature conditions wasderived according to the moisture isotherms of fermentation biscuit, the permeabilityof packaging material and relative humidity of storage environment,and it wasshowed as follows:Where t-the shelf-life of fermentation biscuit (s); d-the thickness of packaging material (cm);N-permeability coefficient of packaging materials; A-the effective area of packaging materials(cm2); pθ-the saturated vapor pressure in the temperature θ℃(Pa); Q-moisture content (g); RH1-relative humidity (%); W–the dry weight of fermentation biscuits (g).Took example of three kinds of packaging materials: BOPP/PP, VMPET/PE andOPP/PE/VMPET/CPP. The parameters of packaging materials were brought into theshelf-life equation of packaged fermentation biscuit to forecast the shelf-life of biscuitpackaged in this three kinds of materials under normal temperature (80%RH)conditions: the shelf-life of biscuit packaged in BOPP/PP was420days; the shelf-lifeof biscuit packaged in VMPET/PE was38days; and the shelf-life of biscuit packagedin OPP/PE/VMPET/CPP was456days. The results that the predicted value close tothe acceleration test value in the hot and humidity condition proved that it wasfeasible to predict the shelf-life of packaged biscuit by ‘the shelf-life equation ofpackaged fermentation biscuit’.