The microstructure of ice cream and frozen desserts is known to influence their meltdown behavior. In this study, we hypothesized that the interaction of milk protein and galactomannans, specifically ...the phase separation often observed between hydrocolloids and protein, along with the interaction of hydrocolloids in the serum phase, affected meltdown behavior in non-fat aerated frozen foam. Ice creams were made with protein contents from 4 to 8%, with the addition of guar gum or locust bean gum. The effect of κ-carrageenan in protein and galactomannans was also studied. Melting characteristics were compared to the rheological and structural characteristics of the ice cream as well as to the phase separation in the mix and drip-through solution. The freezing-melting process inhibited microscopic and macroscopic phase separation in most locust bean gum samples, primarily due to the cryo-gel maintaining structural integrity and altering hydrocolloid-proteins interactions. The cryo-gel structure also led to slow melting rates and stable melted foams in the 4% milk protein system even in the absence of milk fat globules and clusters. Increasing milk protein from 4% to 8% in locust bean gum samples resulted in faster melting and a transition to complete dripping, indicating the disruption of the cryo-gel structure by increased proteins. In contrast, all guar gum samples fully dripped through the mesh with a fast melting rate. A negative trend was found between phase separation and melting rate in the guar gum samples containing κ-carrageenan, indicating that the diminishing interaction between the two immiscible phases accelerated liquid drainage.
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•Cryo-gel formed by locust bean gum provided good stability to the melted foam in the absence of the fat network.•The cryo-gel structure of locust bean gum inhibited phase separation between protein and polysaccharide.•The phase separation in the serum phase hindered the liquid drainage during the melting process.
A method is presented in this study to determine the junction temperature ( T j ) of LED in terms of the relationship between the diode reverse current ( I R ) and T j . A theoretical model for the ...dependence of I R on T j is derived on the basis of the Shockley equation and is validated by our experimental results. The method is compared with the conventional forward voltage method, and its advantages have been identified.
Presents a parameter estimator that is designed to estimate the frequencies, magnitudes, and phases of the components of a periodic signal. The structure of the algorithm is reminiscent of a ...phase-locked loop, although significant differences can be observed. The performance of the estimator is analyzed, and useful design guidelines are provided. A version of the algorithm is presented that combines different components of the signal and/or signals from multiple sensors in order to estimate the fundamental frequency. In this manner, the algorithm is able to maintain tracking of the fundamental frequency despite changes in signal characteristics. The results are verified in simulations and the algorithms are found to be simple and effective for estimation and tracking of time-varying parameters. Experimental results are reported where periodic signals are collected from an active noise control testbed.
We propose an experimental method that determines junction temperatures in light-emitting diodes by measuring currents while holding the low forward voltages constant. In this procedure, we first ...calibrate current-temperature-rela- tionship parameters under the condition of negligible thermal generation. With one of the two parametric values, we discover the existence of a forward voltage peak that yields most sensitive measurements of the junction temperature. Results show a nearly linear relationship between the algorithmic currents and temperature reciprocals with high testing precision.
This paper presents a multi-channel active noise control algorithm that is designed to reject periodic signals of unknown frequency. It is based on a so-called indirect approach, where the frequency ...of the disturbance is estimated in real time, and the estimate is used in a disturbance rejection scheme designed for a known frequency. Improvements over an earlier algorithm include an extension to multi-channel systems, a better frequency estimation algorithm, and a thorough experimental evaluation. For disturbance rejection, a so-called inverse
G algorithm is proposed and its properties are compared through analysis and experiments to those of a gradient algorithm. A new frequency estimator is also considered that is simple and flexible in design, and is able to use multiple harmonics or multiple signals in order to estimate the fundamental frequency of the noise source. In this manner, the algorithm maintains tracking of the fundamental frequency despite significant changes in signal characteristics. The ability of the indirect approach to reject periodic noise with fixed or time-varying frequency and amplitudes is demonstrated in active noise control experiments. The algorithm may also be useful in other control applications where periodic disturbances of unknown frequency must be rejected.
This study aims at exploring ice cream meltdown behavior by changing the levels of stabilizer (ST), polysorbate 80 (PS80), and overrun (OR). By adjusting the formulation of ice cream, the degree of ...fat destabilization (FD), mix viscosity (MV), and overrun can be controlled within a certain range, which in turn presents different meltdown behaviors for study. In addition to the drip‐through test, the shape of ice cream as it melts was recorded as height change to further investigate ice cream meltdown. Mix viscosity (at 50 s−1) and fat destabilization were found to have a significant effect not only on drip‐through rate, but also the induction time, final weight of the drip‐through part, height‐change rate, and final height of melted ice cream. On the other side, overrun was found only to have an effect on meltdown when no stabilizers were added. These results indicate serum phase viscosity (mix viscosity) and fat destabilization are important parameters to describe ice cream meltdown. Besides, the entire ice cream meltdown curve and height collapse curve provide important information on ice cream meltdown behavior.
Practical application
A new direction of analysis of ice cream meltdown behavior is provided in this study. The induction time, the final drip‐through weight, and the height change during the meltdown process were found to be the indicators on the influence of microstructure on ice cream meltdown behavior for the future study.
The ice cream meltdown test has been utilized to comprehend the structural changes in ice cream. While there is broad knowledge regarding the impact of ingredients and processing conditions on ...meltdown, an understanding of the fundamental mechanisms by which the structure influences the meltdown process remains limited. This study aims to investigate how the structural components of ice cream (fat destabilization, overrun, and mix viscosity) influence the entire meltdown process. Additionally, a sucrose model system was designed to aid in understanding the role of rheological properties, overrun, and phase separation between milk protein-polysaccharides in the meltdown process in both aerated and non-aerated systems.The induction time, melting rate, final drip-through weight extracted from the meltdown curve as well as the height change rate and final height calculated from the height-change curve offer as parameter to describe the meltdown process. Among all the structural components examined, ice cream mix viscosity was the most important parameter on the meltdown process. Only without the stabilizer, which meant the mix viscosity was the lowest, did the extent of fat destabilization and overrun influence the meltdown process.In the non-aerated system, it was observed that the type of polysaccharides, rather than rheological properties like mix viscosity or shear-thinning behavior, influenced the melting behavior. Specifically, the anionic polysaccharide exhibited a faster melting rate compared to the neutral ones. In the aerated system, when polysorbate 80 was included, there was a positive correlation between mix viscosity and both the induction time and melting rate. However, this correlation was not observed between shear- thinning behavior and rheological properties. Considering the strong correlation between shear-thinning behavior and apparent viscosity, as well as the relatively insignificant impact of shear-thinning behavior on the meltdown process compared to the apparent viscosity, the apparent viscosity appeared to be a more suitable parameter for describing the meltdown process.When the milk protein was introduced into the system, both the phase separation behavior and its correlation with the meltdown were investigated. It was observed that the locust bean gum system prevented of phase separation after freezing-melting, attributed to the formation of cryo-gel by locust bean gum. This cryo-gel structure further contributed to the maintenance of the foam structure during the meltdown test.Overall, this study provides a deeper insight into each main component's impact on the meltdown process. This knowledge contributes to the design of healthier frozen desserts with enhanced heat resistance.
Although the ice phase greatly influences the properties of ice cream, other structural components also affect its rheological behavior, particularly after melting. In this study, mix viscosity ...(serum phase viscosity), extent of fat destabilization (FD), and overrun were manipulated to produce different microstructures. The effects of these structural components were evaluated on the rheological properties of the ice creams and melted ice creams. In oscillatory thermorheometry, mix viscosity and then overrun, influenced G’ and tanδ below −10 °C. When ice phase decreased (between −10 and −2.7 °C), mix viscosity had reduced effects, but continued to strongly affect G’ and tanδ, followed by FD, and with lower effects from overrun. When the ice phase was completely melted at 0 °C, FD had most influence on G’ and tanδ, followed by overrun, and with lower effects from mix viscosity. In creep/recovery test, six‐element model described well creep behavior of melted ice cream at 0 °C. Viscous behavior at lower shear rate (η0 0 °C) was most influenced by mix viscosity, followed by FD, and lower overrun effects. In stress growth measurement, transient behavior, represented by σY 0 °C, of melted matrix at 0 °C was most influenced by FD, followed by mix viscosity, with lower overrun effects. In flow ramp measurement, Hysteresis Area was most affected by mix viscosity, followed by overrun, and with lower FD effects. Moreover, correlation between Hyst 0 °C and tanδ Peak suggested that structure formation affected the magnitude of tanδ Peak. These results document the importance of microstructure on properties of melted ice cream.
Practical Application
The understanding of how structural components, such as mix viscosity, fat destabilization, and overrun, affect the ice cream matrix can help manufacturers to control its rheological behavior. The influence of these structural components on the G’, tanδ, η0 0 °C, σY 0 °C, and Hyst 0 °C can be also used to understand the structural rearrangements that occur in meltdown tests and sensory analyses for future studies. Therefore, elucidation of these mechanisms on the rheological properties can directly assist in quality control and new product development in the ice cream industry.
Planetary gear trains are complex flight critical components of helicopters and other aircraft. Failure modes on such components may lead to loss of life and/or aircraft. It is essential, therefore, ...that incipient failures or faults be detected and isolated as early as possible and corrective action be taken in order to avoid catastrophic events. Research thus far has focused on gear teeth faults and available methods could not detect a crack in the planetary gear plate under all operating conditions. A wavelet domain methodology is suggested for the analysis and feature extraction of the vibration data from the planetary gear system of military helicopters. Complex Morlet wavelets are employed and the time domain knowledge, preserved by the wavelet decomposition, is used to extract useful features that distinguish between faulted and healthy gear plates from experimental data made available from both on-aircraft and test cell experiments. A statistical method based on the z-test is also suggested to evaluate the relative performance of these features.
