The Influence Of Process Parameters On Crystallization Behavior Of Margarine

In this study, the influence of process parameters on crystallization behaviour ofmargarine and the change of hardness, foaming degree, rheological behaviors andthermostability which were made by above crystallization behaviour had been discussedfirstly. Secondly, the process parameters were optimized and the samples with optimumpeocess parameters were applied in cakes. At last, the physical properties (solid fat content(SFC), hardness and rheological behaviors) and functionality (spreadablity and foamingdegree) of margarines were investigated and correlated with each other.Tempering temperature, flow rate, pin-worker speed and liquid ammonia temperaturewere investigated. The conclusions included:(1) The samples tempered at20°C had defectsof over-hardness, higher foaming degree and post-crystallization occurred; The samplestempered at30°C were too soft with higher foaming degree and poor thermostability.Sandness and β form crystal happened at30°C; When the tempering temperature was25°C,the samples had a proper instant solid fat content, hardness, and foaming degree, with also astable crystallization network, mean while the stability is better and the crystals mostlypresent as β’ form under temperature cycles during storage.(2) The samples at the flow rate of30L/h had bigger rheological behaviors and destroyed crystal network. Post-hardness,sandness and β form crystal happened during storage; Proper hardness, foaming degree andrheological behaviors like commercial margarine were observed in the samples at the flowrate of50and70L/h. The samples of50L/h were stable and had lots of β’ form crystalsunder temperature cycles. Sandness and β form crystal happened at the flow rate of70L/h.(3)At the pin-worker speed of100rpm and300rpm, the samples had poor thermostability,post-crystallization and sandness happened during storage. The samples of300r/min were toosoft and had lots of β form crystal. The samples of200rpm had proper hardness and foamingdegree, mean while the stability is better and the crystals mostly present as β’ form undertemperature cycles.(4) The samples at the three liquid ammonia temperature could retained β’form crystal at all the time of storage, but the samples of-20°C had smallest hardness, poorthermostability and sandness. The samples of-10and-15°C were stable under temperaturecycles and had similar hardness and rheological behaviors, mean while good thermostabilityand none sandness were observed. The samples of-10had best forming degree. In conclusion,the best process parameters was Tempering temperature25°C, flow rate50L/h, pin-worker speed200rpm and liquid ammonia temperature-10°C.Liquid ammonia temperature, flow rate and pin-worker speed were optimized byorthogonal test with response of foaming degree and the difference of hardness withcommercial margarine (130g/cm2). The optimum peocess parameters were: liquid ammoniatemperature-10°C, flow rate30L/h and pin-worker speed300rpm. The hardness andfoaming degree of samples optimum peocess parameters was146g/cm2and0.56. The cakesmade of above samples could accord with the standard of commercial cakes about appearance,volume and hardness and had smoother texture.The physical properties and functionality of nine margarines were investigated andcorrelated with each other. The conclusions included:(1) The hardness had significantcorrelation with spreadability (R2=0.695，p<0.01) and no linear correlation with foamingdegree, but it gave influence on the whipping process. The hardness had significantcorrelation with rheological parameters, specially with tan (R2=0.903，p<0.01). This resultindicated that rheological behaviours have important influence on texture.(2) Low correlationwas observed between SFC and other properties (hardness, spreadability and foaming degree).(3) Spreadability and static yield value had high correlation (R2=0.963，p<0.01), as well asfoaming degree and tan after thixotropy (R2=0.868，p<0.01). This result indicated thatspreadability and foaming degree of margarine could be predicted accordingly by rheometerreplace traditional methods.