Food oral breaking and the determining role of tongue muscle strength

Some previous studies have revealed a great variation of tongue muscle strength among healthy individuals. However, the implication of different tongue muscle strengths to individuals' oral capability of food handling is yet to be determined. In this work, vege-gels (with a resilient consistency of jelly) and pastry food (mashed potato) were used to investigate tongue-only oral breaking (smashing) of these foods by individuals who have different tongue muscle strengths. The aim of the work is to determine whether a correlation exists between the tongue muscle strength and its capability of food breaking. A series of vege-gels and mashed potato samples ranging from soft to hard were constituted with increasing consistency. Mechanical/textural properties of test food samples were characterised by a texture analyser. Three experimental tasks were designed: characterisation of individual's tongue muscle strength by measuring the maximum isometric tongue pressure (MITP) (Task 1); assessment of individual's capability of tongue-only food breaking (Task 2); and measurement of tongue–palate pressure generation for food oral breaking (Task 3).Our results confirm the great variability of tongue muscle strength among healthy individuals, with the highest MITP reaching 75 kPa and the lowest at only 17 kPa. The correlation study of tongue strength and the threshold gel/mashed potato strength for tongue-only oral breaking reveals a positive relationship between the two factors, which suggests that strong tongue muscle strength is always advantageous for oral handling (break/smashing) of viscoelastic and pastry foods. Conclusions obtained from this work can be a useful guidance to food design for elderly consumption.     

Heat and Mass Transport during Microwave Heating of Mashed Potato in Domestic Oven—Model Development,Validation, and Sensitivity Analysis

A 3‐dimensional finite‐element model coupling electromagnetics and heat and mass transfer was developed to understand the interactions between the microwaves and fresh mashed potato in a 500 mL tray. The model was validated by performing heating of mashed potato from 25 °C on a rotating turntable in a microwave oven, rated at 1200 W, for 3 min. The simulated spatial temperature profiles on the top and bottom layer of the mashed potato showed similar hot and cold spots when compared to the thermal images acquired by an infrared camera. Transient temperature profiles at 6 locations collected by fiber‐optic sensors showed good agreement with predicted results, with the root mean square error ranging from 1.6 to 11.7 °C. The predicted total moisture loss matched well with the observed result. Several input parameters, such as the evaporation rate constant, the intrinsic permeability of water and gas, and the diffusion coefficient of water and gas, are not readily available for mashed potato, and they cannot be easily measured experimentally. Reported values for raw potato were used as baseline values. A sensitivity analysis of these input parameters on the temperature profiles and the total moisture loss was evaluated by changing the baseline values to their 10% and 1000%. The sensitivity analysis showed that the gas diffusion coefficient, intrinsic water permeability, and the evaporation rate constant greatly influenced the predicted temperature and total moisture loss, while the intrinsic gas permeability and the water diffusion coefficient had little influence.     

响应面法优化马铃薯泥面条工艺配方

为加快马铃薯主食化进程,降低马铃薯全粉面条的成本,有效利用马铃薯中的营养成分,以马铃薯泥为原料,对马铃薯泥面条的工艺配方进行研究。在单因素试验的基础上,利用响应面法优化马铃薯泥面条工艺配方,研究面条中马铃薯泥添加量、盐添加量、水添加量对感官得分和断条率的影响,得出回归方程预测模型。结果表明:马铃薯泥、盐和水的添加量分别为40.65%、0.40%、17.13%时,感官得分最高为98.13,面条的断条率最低为6.15%。该研究为马铃薯泥面条的进一步研究提供理论依据。     

A SIMPLIFIED ANALYTICAL MODEL FOR FREEZING TIME CALCULATION IN BRICK-SHAPED FOODS

A simplified analytical model for the freezing time prediction of brick-shaped foodstuffs was developed. It was assumed in the model that the solution to the unsteady, one-dimensional heat conduction equation with constant thermophysical properties was valid during cooling and freezing for each of the three directions of the brick-shaped food. Cooling and freezing times were calculated by superposition of the solutions of the unsteady, one-dimensional heat conduction equation with constant thermophysical properties for each direction. the latent heat effects were incorporated into an effective thermal diffusivity term. the predictions of the model were compared to the available experimental data on freezing of two- and three-dimensional bricks and to the experimental data obtained in this research for the freezing of ground beef and mashed potato bricks. Mean errors varying between -6.3% and 2.3%, and standard deviations from the mean being between 6.6% and 14.0% were obtained for the data sets considered.     

马铃薯熟泥添加量对挂面品质的影响

为简化马铃薯挂面生产工艺,研究利用马铃薯熟泥代替水制作马铃薯小麦挂面,添加马铃薯熟泥(水分含量81.11%)从65 g到85 g至200 g小麦粉中,探讨马铃薯熟泥添加量对挂面品质的影响。结果表明:随着混合面团中熟泥的增加,马铃薯面条的煮熟增重率和烹调损失率均呈上升趋势;L*值降低,a*值、b*值升高;马铃薯小麦挂面的断裂距离先升高后降低,断裂强度、坚实度和剪切功均呈下降趋势。     

Mathematical modeling of ohmic heating of two-component foods with non-uniform electric properties at high frequencies

The ohmic heating (OH) of two-component foods (consisting of mashed potato and mashed potato with 1% NaCl) configured using four different filling patterns (parallel, series, and two concentric patterns) was investigated experimentally and by modeling. The electrical conductivities of the samples at 50 Hz and 20 kHz were obtained in the range of 20–85 °C. The differences between the thermal behaviors of the two-component foods were analyzed using internal thermal images and temperature profiles from four positions. A three-dimensional OH model for high frequencies was developed based on electric field analysis using Maxwell's equations. The model agreed sufficiently with the measured results and was able to confirm that the current applied to the sample follows the path that presents minimum electrical resistance, which is independent of the filling pattern configuration. Analysis of the heat flux density provided a better understanding of the heating behavior of two-component foods during OH.Industrial relevanceAlthough several mathematical approaches used to simulate the OH process of solid foods have been published in recent years, the simulation of temperature and electric field distributions using simplified methods, such as by the solution of Laplace's equation, is still a problem for two-component solid foods with special configurations of the internal components treated using an OH process at high frequencies. This problem can be solved using a more fundamental solution based on Maxwell's equations and electric field analysis via computer simulation. A comprehensive mathematical simulation of the thermal behavior and the effect of the orientation of the current within the two-component foods can be used to accurately predict the heat during OH. Therefore, the modeling of heating patterns of complex foods can assist in the design of food sterilization and pasteurization processes. Moreover, it will contribute in industrial applications for a better design of OH systems and electrode configurations for rapid and uniform heating.     

Influence of heating conditions and starch on the storage modulus of Russet Burbank and Yukon Gold potatoes

The storage modulus of Russet Burbank (RB) and Yukon Gold (YG) potato discs (13.3 mm × 4.5 mm) was measured continuously during heating in water at temperatures ranging from 40 to 80 °C for 120 min using a dynamic mechanical analyser with a heating stage. The starch content of YG potatoes was higher than that of RB potatoes, but the raw starch granule size distribution of both varieties was similar. RB samples had the highest storage modulus values (25% higher than raw tissue) when heated in 60 °C water for 35 min. Image analysis revealed that the perimeters of starch granules in the potato samples increased by about 50% during heating for 30 min at 60 °C. Heating temperature and time and starch content influenced the storage modulus. © 2001 Society of Chemical Industry     

马铃薯泥面条制作工艺优化及品质分析

为保留马铃薯的风味和营养成分,提高面条品质,加快马铃薯主食化进程,采用马铃薯泥和小麦面粉复配制作马铃薯泥面条。以感官评分为评价指标,结合单因素实验和正交试验,进而得到较优的马铃薯泥面条加工工艺。结果表明,在马铃薯泥占比50%的条件下,面条的较佳加工工艺参数为:面团醒发温度20 ℃、醒发时间30 min。复配改良剂最佳配方为:谷朊粉添加量3%、魔芋粉添加量1%、单甘酯添加量1%。该条件下制作的马铃薯泥面条品质较好,感官评分达90.1分。研究表明,在小麦面粉中加入马铃薯泥,所制备面条品质降低,但适当的添加改良剂可在一定程度上提升马铃薯泥面条品质。     

A simplified approach to assist process development for microwave assisted pasteurization of packaged food products

The purpose of this study was to develop a convenient method to assist the food industry in developing process schedules for production of ready-to-eat meals using microwave assisted pasteurization system (MAPS). An analytical model was applied to estimate the temperature increase in the cold zone in packaged foods during heating in a 915 MHz single-mode microwave system. This model was validated in a pilot-scale four-cavity MAPS using mashed potato-gellan gum model food with different thicknesses (22 to 36 mm) and salt contents (0.0 to 1.0%). Mobile sensors were placed in the packages to measure temperature at the pre-determined cold spots. For 2.48 min of microwave heating with 5, 5, and 8.7 kW 915 MHz microwave powers, the highest temperature increase at the cold spot during microwave heating was 33.2 °C in the 22 mm thick model food with 0.6% salt content, whereas the lowest temperature increase was 10.3 °C in the 36 mm thick model food with 1.0% salt content. There was a deviation of 1.9 ± 1.2 °C between experimental and predicted data with an R² of 0.89. A simplified chart was developed based on the validated analytical results to allow rapid prediction of temperature increases in MAPS as influenced by food dielectric properties and package thickness. Examples were used to illustrate how the chart could assist in process scheduling. The chart can help assess the heating rates of various pre-packaged food products in a specific industrial MAPS or guide product development for desired heating uniformity.     

Quality and safety driven optimal operation of deep-fat frying of potato chips

Increasing oil temperature and heating duration in deep-fat frying of potato chips can improve textural quality but worsen the chemical safety of acrylamide formation. Optimal design of this complex process is formulated as a non-linear constrained optimization problem where the objective is to compute the oil temperature profile that guarantees the desired final moisture content while minimizing final acrylamide content subject to operating constraints and the process dynamics. The process dynamics uses a multicomponent and multiphase transport model in the potato as a porous medium taken from literature. Results show that five different heating zones offer a good compromise between process duration (shorter the better) and safety in terms of lower acrylamide formation. A short, high temperature zone at the beginning with a progressive decrease in zone temperatures was found to be the optimal design. The multi-zone optimal operating conditions show significant advantages over nominal constant temperature processes, opening new avenues for optimization.     

Determination of convective heat transfer coefficient and specific energy consumption of potato using an ingenious self tracking solar dryer

In the present work, an attempt has been made to experimentally determine the heat transfer properties of potato in terms of convective heat transfer coefficient, specific energy consumption and specific heating rate. Drying experiments with potato cylinders have been performed in an in-house fabricated laboratory scale natural convection indirect solar dryer with self tracking mechanism. The convective heat transfer coefficient of cylindrical potato samples was evaluated by considering the combined effects of heat capacities of food product as well as radiative heat transfer from drying chamber to the food product. This study revealed that the convective heat transfer coefficient for potato cylinders was varying from 11.73 to 16.23 W/m² °C with an experimental error of 7.86 %. The specific energy consumption was decreasing exponentially with drying time, and the average value was estimated to be 3,491 kJ/kg. It was also observed that the specific heating rate for potato cylinders decrease with dimensionless moisture content.     

Observation of anisotropic water movement in Pinus radiata D. Don sapwood above fiber saturation using magnetic resonance micro-imaging

Magnetic resonance micro-imaging has been used to visualise the movement of water during the drying of Pinus radiata D. Don (radiata pine) wood samples of varying annual ring orientation and dimension. The drying process has shown a strong influence of annual ring orientation for thin boards with drying deviating from the classical core-shell model. Diffusion tensor micro-imaging shows the direction of greatest restriction to diffusion being in the transverse radial direction. Similarly, anisotropic values for T ₂ relaxation are observed, with values obtained when the transverse face is normal to the static magnetic field being higher than in the case when the radial or tangential faces are normal to the field.     

Effective use of nisin to control Bacillus and Clostridium spoilage of a pasteurized mashed potato product

Heat-resistant spore-forming bacteria such as Bacillus and Clostridium can survive and grow in cooked potato products. This situation represents both a public health problem and an economic problem. The natural food preservative nisin is used in heat-treated foods to prevent the growth of such bacteria. A cocktail of Clostridium sporogenes and Clostridium tyrobutyricum spores was inoculated into cooked mashed potatoes, which were vacuum packed, pasteurized, and incubated at 8 and 25 degrees C. The shelf life of the mashed potatoes at 25 degrees C was extended by at least 58 days with the addition 6.25 microg of nisin per g. At 8 degrees C, in control samples not containing nisin, the natural contaminant Bacillus grew, but the inoculated Clostridium strains did not until the temperature was raised to 20 degrees C after 39 days. No bacterial growth occurred in nisin-containing samples. The shelf life of the mashed potatoes was extended by at least 30 days with 6.25 microg of nisin per g. In trials involving a cocktail of Bacillus cereus and Bacillus subtilis strains, 6.25 microg of nisin per g extended the shelf life of mashed potato samples that were not vacuum packed by at least 27 days at 8 degrees C. At 25 degrees C, 25 microg of nisin per g extended shelf life by a similar period. Shelf life extension was also observed at lower nisin levels. Microbiological analysis of the mashed potato ingredients showed that a high spore level was associated with the onion powder. It is emphasized that the preservative and the ingredients must be well mixed to ensure good nisin efficacy. Nisin remained at effective levels after pasteurization, and good retention was observed throughout the shelf life of the mashed potatoes.     

Interactions of heat and mass transfer in steam reheating of starchy foods

Steaming is a common practice in both household and industrial food processing; however, the process of heat transfer during steaming has not been fully explored. In this study, mathematical models that consider coupled energy, water and vapor transport were developed, and were solved using finite element software (COMSOL Multiphysics) for their application to the steam reheating of non-porous starch gel radish cake and steamed buns with porous matrices. Our simulation results indicated that the reheating of non-porous starch gel is a heat conduction process. During the reheating of the porous starch matrix, the infusion of condensate and evaporation–condensation mechanism contribute to steep sigmoid-shaped temperature profiles that are different from those of normal heat conduction. The validity of our mathematical model is corroborated by our experimental work of the steam reheating of samples with and without PE film wraps in a rice cooker. It shows a good agreement between the simulation and experimental results in terms of temperature and increased moisture. The implications of these models can provide a basis for future elucidation of more complicated food steaming processes.     

Hydraulic Permeability of Food Tissues

Pressure driven flow can arise in a food process due to various reasons such as rapid internal evaporation in microwave heating of a food. Whether intended or unintended, pressure driven flow can be a very significant mode of transport of water, vapor, and other components. The physics of pressure driven flow cannot be lumped into effective diffusivity type formulation in general. Permeability, a material property that is needed to properly describe this physics of pressure driven flow using mechanistic models and is generally unavailable. For the first time, intrinsic permeability of potato and muscle tissues to water were measured by making water flow through the samples under pressure and measuring the flow rate in a dedicated commercial setup for measuring permeability. Intrinsic permeability values were found to be in the range of 10^?17 – 10^?19 m². Permeability of soft food materials change significantly with pressure, however, electron microscope pictures showed no change in structure in potato tissue.     

MOISTURE LOSS AS RELATED TO HEATING UNIFORMITY IN MICROWAVE PROCESSING OF SOLID FOODS

Moisture loss due to internal evaporation and its relationship to nonuniformity of heating in microwave reheating of high moisture solid foods was studied. A simple heat and mass transfer model was developed that excluded diffusional limitations of moisture movement. Microwave absorption and some dielectric and thermal properties were measured as input parameters to the model. Effect of varying microwave penetration with moisture level and temperature was included. For smaller total moisture loss, typical for a reheating application, predictions of total moisture loss and temperatures matched well with experimental data. Most of the moisture loss occurred from the edges due to higher temperature at these locations. Uniformity of heating to achieve a given average temperature is the key variable controlling total moisture loss. When starting from a frozen material, heating is much more nonuniform, leading to a greater moisture loss. As surface area increases for a given volume, uniformity of heating increases and the total moisture loss reduces. This simple model can be an effective tool in computer-aided optimization of food products and processes.     

Temperature Profiles in a Cylindrical Model Food During Pulsed Microwave Heating

ABSTRACT: Cylindrical 2%-agar gel samples were heated by pulsed and continuous microwave applications. The total microwave application time of 3 min was maintained for all experiments. Sample temperature was measured at various depths along the radial dimension to experimentally determine the internal temperature profile as a function of heating time. A local hot spot was observed at the center portion of the sample during the continuous microwave application. This hot spot was less significant during pulsed microwave applications, especially when longer intermittent power-off times were employed. An implicit finite-difference model was used to estimate temperature profiles within the sample during microwave heating. The estimated temperature profiles matched the experimental values well.     

Characterization of Thermal Properties of Potato Dry Matter–Water and Starch–Water Systems

ABSTRACT: Potato dry matter samples of varying moisture contents were analyzed by differential scanning calorimetry (DSC). One endothermic and one exothermic transition were observed when the moisture content was < 50% (w/w) in the dry matter–water system. Both endothermic and exothermic transitions of potato dry matter were influenced by moisture content. One endothermic transition at about 66 °C was observed when the samples were reheated after 2 wk of storage at 5 °C. Gelatinization and retrogradation of starch are chiefly responsible for the endothermic transitions in the potato dry matter. The exothermic transition may originate from chemical reactions such as Maillard and caramelization during heating of a potato dry matter–water system when water is limited (< 50%, w/w) and at temperatures > 120 °C     

MATHEMATICAL MODELLING of RADIAL CONTINUOUS CROSSFLOW AGRICULTURAL DRYERS

Circular grain dryers in which grainflow is continuous and airflow is in radial direction are widely used as on-farm grain dryers. A concurrentflow drying model is adapted to the crossflow drying of the moving bed of grain. the simulated air and grain temperatures and moisture contents of wheat and corn samples were compared to the experimental drying of these grains in laboratory dryers. the results show that the model can be used to describe temperature of grain within 1°C and moisture content within 0.3% w.b.     

甘薯泥粘度数学模型预测

考察了不同干物浓度和不同温度下甘薯浆的流变学特性。结果表明,甘薯浆属于典型的假塑型流体,且干物浓度和温度对其黏稠系数影响显著,幂律模型可以较好地拟合甘薯浆流动行为。甘薯浆表观黏度随着温度和剪切速率的增加而逐渐下降,呈现剪切变稀的趋势。建立了影响因子为温度和干物浓度的数学模型来预测甘薯浆的表观黏度,采用平均百分误差、卡方检验、建模效率等统计学参数对该模型评估发现其拟合精度较高。