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Ultrasonic cutting of foods: Effects of excitation magnitude and cutting velocity on the reduction of cutting work 总被引:1,自引:0,他引:1
Susann Zahn Yvonne Schneider Harald Rohm 《Innovative Food Science and Emerging Technologies》2006,7(4):288-293
The effects of vertical cutting velocity and the magnitude of ultrasonic excitation on the reduction of the work necessary to separate various food materials were investigated. Generally, cutting work increased with increasing cutting velocity but, at each particular cutting velocity, decreased with increasing magnitude of the ultrasonic excitation of the cutting tool. Interactions between cutting velocity and the maximum vibration speed at the cutting edge, which is determined by both excitation amplitude and excitation frequency, are significant. Depending on the food under action, the relative amount of cutting work reduction is either affected by the maximum vibration speed or, additionally, by vertical cutting velocity. No distinct effects of the excitation frequency (20 or 40 kHz) were observed.
Industrial relevance
Ultrasonic cutting is used in the food industry, especially for the separation of products consisting of layers with different rheological properties to achieve minimally damaged cut surfaces. The results of the study may be useful for selecting operational variables (cutting velocity, excitation amplitude) during cutting to achieve a controlled reduction of the cutting work. 相似文献2.
Cutting with devices excited by ultrasound is a promising alternative to conventional cutting when the materials contain particles which differ in stiffness and elasticity from the surrounding bulk or when they consist of layers which exhibit largely differing mechanical properties. Aim of the present study was to evaluate the impact of ultrasonic excitation and blade inclination (slice-to-push ratio) on cutting forces and cutting work of different foods with a fast-moving device which was excited in a way that the direction of vibration was parallel to the edge of the blade. The results show that ultrasonic excitation significantly reduces cutting force, that the magnitude of cutting force reduction largely depends on the product, and that cutting force and cutting work increase with increasing cutting velocity. Whereas these interactions are because of the micro-saw movement of the cutting tool, it was not possible to explain the product-dependent response to blade inclination. 相似文献
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The cutting resistance, of thin rectangular strips of a restructured dehydrated fruit bar was measured over a range of water activity, 0.30-0.97. There was a 100-fold increase in cutting force as the product was dried from an initial cutting resistance of 4.4 N at aw , = 0.86 to a maximum of 452 N at aw = 0.33. Below a water activity of 0.33, samples became brittle and showed lower cutting resistances; for example, 68 N at aw = 0.30. The major ingredients in the fruit product affecting cutting resistance were the level of apple puree and maltodextrin. 相似文献
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A puncture test was used to describe the mechanical and textural behavior of crispy-puffed food extrudates. Four criteria were identified from the force-time curves: (1) the average puncturing force, Fm , (2) the spatial frequency of structural ruptures, Nwr , (3) the average specific force of structural ruptures, fwr , and (4) the crispness work, Wc . The discriminating power of these criteria was shown through the effects of moisture content and recipe composition in the extrusion-cooking process. Relationships between puncture criteria were also studied. The effect of water activity showed that the force related criteria described well the mechanical behavior of expanded extrudates. 相似文献
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ABSTRACT: Total elimination of oxygen (O2 ) in modified atmosphere packaging of bakery products is difficult to achieve. Because of the typical porous texture of the packaging, air can be retained inside. The effect of O2 absorbers alone or in combination with modified atmosphere on Eurotium amstelodami, E. herbariorum, E. repens , and E. rubrum growth was investigated. Cakes of 0.80 to 0.90 water activity ( aw ) were packaged with different atmospheres (air, 100% N2; 70% N2:30% CO2 ) and O2 absorbers of 2 different absorption capacities. The use of absorbers with a suitable absorption capacity led to a significant increase of cakes with mold-free shelf life, regardless of aw and pH level, at 25 °C. 相似文献
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Ultrasonic cutting of cheese: Composition affects cutting work reduction and energy demand 总被引:1,自引:0,他引:1
Eight cheese varieties with different moisture (357–488 g kg?1), fat (183–335 g kg?1) and protein content (202–292 g kg?1) were subjected to ultrasonic cutting using a 40 kHz guillotine sonotrode. Cutting force curves were evaluated with respect to ultrasound-induced cutting work reduction and energy demand of the sonotrode. With cutting velocity and ultrasonic amplitude set to 2500 mm min?1 and 12 μm, respectively, composition had a significant effect on the response of the cheeses. Whereas cutting work reduction was mainly determined by fat-in-dry matter, the energy demanded by the sonotrode to maintain vibration was inversely interrelated to the ratio of moisture to solids-non-fat. Three selected cheeses were subjected to cutting experiments with systematically varied cutting velocity and amplitude. The results indicate that the cheeses respond differently to the cutting parameters, and that their careful adjustment is helpful for a target-orientated design of the process. 相似文献
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Decontamination Efficacy of Combined Chlorine Dioxide with Ultrasonication on Apples and Lettuce 总被引:2,自引:0,他引:2
Tung-Shi Huang Chuanling Xu Ken Walker Patricia West Shuqing Zhang Jean Weese 《Journal of food science》2006,71(4):M134-M139
ABSTRACT: The bacterial reduction of Salmonella and Escherichia coli O157:H7-inoculated apples and lettuce by ClO2 at 0, 5, 10, 20, and 40 ppm with and without 170-kHz ultrasonic treatments for 3, 6, and 10 min, respectively, have been studied. The treatments of ClO2 at 20 and 40 ppm for 3, 6, and 10 min or at 5 and 10 ppm for 6 and 10 min with 170-kHz ultrasonication caused 3.115 to 4.253 log reductions in Salmonella and 2.235 to 3.865 log reduction in E. coli O157:H7 on inoculated apples. Using combined ClO2 and ultrasonication to treat 4.48 × 104 CFU/g Salmonella and 1.07 × 105 CFU/g E. coli O157:H7-inoculated lettuce, the bacterial reductions were 2.257 to 2.972 and 1.357 to 2.264 log, respectively. The residual ClO2 decreased with increasing treatment times, over 80% of ClO2 was detected after the 3-min treatment, and more than 70% remained after the 10-min treatment time. No bacteria were recovered from the posttreatment solutions of ClO2 or ClO2 combined with ultrasonication. The temperature of the ClO2 treatment was 20.1 °C, and it increased to 40.1, 44.9, and 50.3 °C, with 170-kHz ultrasonic treatments for 3, 6, and 10 min, respectively, on apples. 相似文献
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Influence of Oxygen, Carbon Dioxide, and Degree of Cutting on the Respiration Rate of Rutabaga 总被引:1,自引:0,他引:1
ABSTRACT: Both the O2 -consumption and CO2 -production rates of uncut and cut rutabaga were measured in a closed system. Compared to enzymatic and 1st-order linear models, a 2nd-order expression was found to best predict respiration rates under the conditions typically found in modified atmosphere packages. The concept of degree of cutting was introduced to quantitatively analyze the effect of wounding on respiration rates. A linear relationship was observed between the respiration rates at a fixed pO2 and pCO2 and the quantified degree of cutting injury. Mathematical expressions were developed that accurately describe the relationship between respiration rates, O2 and CO2 partial pressures, and the degree of cutting. 相似文献
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Mechanical properties of dried bread (a cellular baked product) equilibrated at different water activities (Aw ) were measured using three-point bending and uniaxial compression to compare their responses to moisture sorption. The glass-to-rubber transition was clearly demarcated in all the mechanical property-Aw curves, although there were differences in critical Aw (0.32–0.56) at which the dramatic changes in mechanical properties occurred. The role of water appeared to be strictly that of a plasticizer where flexural mechanical parameters were concerned, leading to reduced modulus and fracture stress but increased fracture strain with increasing Aw . Uniaxial compression tests revealed moisture-induced mechanical antiplasticization effects on the material in the glassy state which resulted in maximum compressive fracture stress but minimum fracture strain over the Aw range from 0–0.56. Compressive modulus apparently was not affected much by moisture sorption up to an Aw of 0.43, above which it decreased sharply. 相似文献
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ABSTRACT: :
To evaluate the relationship between the factors affecting coagulation, the hot wire method was used for direct measurements of the renneting milk process as well as a central composite design with 3 factors: rennet concentration (x1 ), renneting pH (x2 ), and temperature (x3 ). Second-order models for maximum voltage (Y1 ), time at maximum voltage (Y2 ), and coagulation time (Y3 ) were employed to generate response surface contours. Optimum conditions for cutting time were found with x1 = 0.0278 R.U./mL milk, x2 = 6.60, and x3 = 35 °C, for which the responses were Y1 = 2854 ± 171 μV, Y2 , = 14.08 ± 3.04 min, and Y3 = 7.16 ± 1.12 min. No significant differences (p > 0.01) were found between the 3 responses obtained in the experiment and the ones predicted by the models. The use of the objective and non-destructive monitoring of curd formation and the response surface methodology can be recommended to optimize milk coagulation. 相似文献
To evaluate the relationship between the factors affecting coagulation, the hot wire method was used for direct measurements of the renneting milk process as well as a central composite design with 3 factors: rennet concentration (x
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A laboratory evaluation of a novel hot water cabinet for the decontamination of sides of beef 总被引:2,自引:0,他引:2
A hot water cabinet based on an idealized distributor design for the decontamination of sides of beef is described and a laboratory evaluation of this novel cabinet is reported.
Beef sides were inoculated with E. coli and exposed to mean water temperatures at the surface tissue ( Tf ) of 83.5, 74.2, 66.0 and 44.5°C for 10 or 20 s. Mean log10 reductions of bacteria for 10-s exposures were 2.23, 1.40, 0.91 and 0.2. For 20 s, reductions were 2.98, 2.14, 1.17 and 0.1. There was a significant ( P < 0.05) linear relationship between log reductions and T f which varied with exposure time. At a T f of 83.5°C with exposure times greater than 20 s, carcass bloom was judged to be permanently and adversely affected. At shorter times or with lower temperatures this did not occur.
Evaporative heat losses were well correlated with the pressure driving force ( r = 0.89) and gravity driving force ( r = 0.92) for air interchange between the cabinet and its surrounds.
The running cost using the distributor cabinet was one-third of that of an existing spray cabinet when compared at the maximum reduction of log 1.3 (95%) achieved by the spray cabinet. An additional advantage of the distributor cabinet is its constructional simplicity. 相似文献
Beef sides were inoculated with E. coli and exposed to mean water temperatures at the surface tissue ( T
Evaporative heat losses were well correlated with the pressure driving force ( r = 0.89) and gravity driving force ( r = 0.92) for air interchange between the cabinet and its surrounds.
The running cost using the distributor cabinet was one-third of that of an existing spray cabinet when compared at the maximum reduction of log 1.3 (95%) achieved by the spray cabinet. An additional advantage of the distributor cabinet is its constructional simplicity. 相似文献
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A NOTE ON THE SENSITIVITY OF FINGERS, TONGUE AND JAWS AS MECHANICAL TESTING INSTRUMENTS 总被引:1,自引:0,他引:1
M. PELEG 《Journal of texture studies》1980,10(3):245-251
Deformation of a specimen between the fingers or in the mouth usually results in a significant deformation of the contacting tissues. This implies that the mechanical response is related to both deformations or, in other words, to the mechanical resistance of the combined systems. Since the latter form an in-series configuration, the combined mechanical resistance (Mc ) is given by:
where M1 and Mx are the resistance of the sensory testing system and the test specimen, respectively. Thus, Mc can be a function of the geometry and the rate of force application. The equation provides a simple explanation as to why there are differences in the sensing range between the fingers and the jaws and why the human senses are practically insensitive to hardness beyond certain levels. The model indicates that the sensitivity decreases rather rapidly after the ratio Mx /M1 becomes greater than about 0.05, but leaves unanswered the question whether, or to what extent, we can compensate for the loss of sensitivity by additional information or modification of the testing procedure. 相似文献
where M
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MODELING FREQUENCY DISTRIBUTION of STEADY-STATE O2 PARTIAL PRESSURES IN MODIFIED-ATMOSPHERE PACKAGES
A mathematical model was developed to predict the frequency distribution of steady-state O2 partial pressures in modified-atmosphere packages of fresh and minimally processed fruits and vegetables. Variation in O2 uptake was predicted to have relatively larger influence on the package O2 distribution than variation in film permeability to O2 . the model also predicted that the range of O2 partial pressures in the packages would be larger for the products with lower K1/2 (a constant in product O2 uptake equation) values. the percent deviation of package O2 partial pressures from [O2 ]med increased with [O2 ]med up to about 3 kPa and gradually decreased thereafter. Package O2 distribution was symmetrical at higher [O2 ]med but became gradually asymmetrical with decreasing [O2 ]med from 6 kPa. the model was used to predict target [O2 ]med for the design of modified-atmosphere packages for different probability levels of having package O2 being equal to or less than a minimum tolerable level of the product. 相似文献
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INFLUENCE OF UNIAXIAL COMPRESSION RATE ON RHEOLOGICAL PARAMETERS AND SENSORY TEXTURE PREDICTION OF COOKED POTATOES 总被引:1,自引:0,他引:1
The effect of uniaxial compression rate (20–1000 mm/min) on the parameters: Stress (σftrue ), strain (εfHencky ) and work to fracture (Wf ), modulus of deformability (Ed ), maximum slope before fracture (Emax ) and work during 75% compression (Wtotal ) was investigated for ten potato varieties. Multivariate data analysis was used to study the correlation between and within the sensory and nonsensory measurements by Principal Component Analysis (PCA) which showed σftrue , Emax , Wf , and Wtotal to explain the same type of information in the data, and εfHencky versus Ed another type of information in the data. The deformation rate had a large effect on εfHencky . Nine sensory texture attributes covering the mechanical, geometrical and moistness attributes were evaluated. Relationships between uniaxial compression data at various deformation rates and the sensory texture attributes were studied by Partial Least Squares Regression (PLSR). A minor effect of deformation rate on the correlation with the sensory texture properties was obtained. Mechanical properties were predicted to a higher extent than the geometrical attributes and moistness. The prediction of the mechanical, geometrical and moistness attributes increased largely by using uniaxial compression supplemented by chemical measures such as dry matter and pectin methylesterase, but here no relevant effect of deformation rate was obtained. 相似文献
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干切混凝土时,金刚石锯片在实际工作过程中产生的振动和噪声是非常严重的。文章从理论上分析了混凝土锯切过程中的强振动、高噪音的原因。通过改变锯切速度、进给速度、切深以及通过采用两种不同的基体结构的锯片,研究了不同的切削参数以及锯片的结构对锯片振动和噪声的影响。在不同的锯切工艺参数和锯片结构下,测量了噪声值、噪声功率、噪声电压、振动功率和振动幅值,并对其进行频谱分析。可以从锯片的基体结构、金刚石节块的结构、锯切工艺以及锯机的整体性能等方面来进行改进,从而达到降低噪声与振动的目的。本文在理论分析和实验的基础上提出了一些降低噪声和振动的方法。 相似文献