EFFECT OF PARTICLE SIZE ON THE QUALITY OF PEANUT PASTES

A spread made from light colored, bland peanut paste flavored with cheese, meat, fruit or chocolate would enhance the probability of increased utilization of peanuts. The effect of particle size on quality of pastes prepared from whole peanut kernels subjected to water extraction (WE) and chopping was determined. Results indicated that the paste prepared from coarsely or moderately chopped peanuts was found to be light in color and have the lowest flavor intensity scores. Paste prepared from finely chopped peanuts had the darkest color among all treatments.     

HEAT TRANSFER TO PARTICLES IN CANS WITH END-OVER-END ROTATION: INFLUENCE OF PARTICLE SIZE AND CONCENTRATION (%V/V)

The heat transfer coefficients (U and h_fp) associated with particulate fluids in cans were evaluated with suspended Nylon particles, during end-over-end rotation. Can rotation speed (10 to 20 rpm), particle diameter (19 to 25 mm) and particle concentration (single particle to 40% v/v) were studied as variables using fluids of two different viscosities (1.0 × 10^?6 and 1 × 10^?4m²/s). Particle transient temperatures were measured by placing a flexible thermocouple attached to the particle, allowing particle motion inside the can. Transient heat conduction equations for a spherical particle with convective boundary condition at fluid-particle interface were numerically solved to obtain h_fp. An overall heat balance equation was solved to obtain U. The h_fp values varied from 170 to 1165 W/m².K with oil and 175 to 1550 W/m².K with water depending upon process conditions. The U values varied from 110 to 220 W/m².K with oil and 480 to 800 W/m².K with water. The h_fp increased 10 to 60% with decreasing particle diameter from 25 to 19 mm while it increased about 3 folds as the particle concentration changed from a single particle to 30%. Further increase in panicle concentration to 40% decreased the h_fp between 5 and 20% depending upon processing conditions. The effects of particle size and particle concentration on the U were similar to those obtained with h_fp with lower magnitudes.     

THE INFLUENCE OF PANTOTHENATE CONCENTRATION AND INOCULUM SIZE ON THE FERMENTATION OF A DEFINED MEDIUM BY SACCHAROMYCES CEREVISIAE

Laboratory fermentations were carried out using defined media containing from 0.02 to 0.40 mg pantothenate 1^?1 and a brewing strain of Saccharomyces cerevisiae at inocula of 1 × 10⁶ to 1 × 10⁷ cells ml^?1, Cell size, increase in cell number, increase in yeast weight, production of ethanol. n-propanol, isobutanol, isoamyl alcohols, acetaldehyde and ethyl acetate were measured. All the properties were influenced to some extent by pantothenate concentration and/or inoculum size but no general correlations were found. At high inoculum levels variation in the pantothenate concentration above 0.1 mg 1^?1 did not have a major effect on the total quantity of volatile compounds produced but did alter the relative proportions of the individual compounds.     

EXTRUDED CORN MEAL AND WHEY PROTEIN CONCENTRATE: EFFECT OF PARTICLE SIZE

Blends of whey protein concentrate (WPC) and corn meal, which were separated into four particle fractions (residual on a #30 screen, #40 screen, #60 screen and through a #60 screen), were extruded at two moisture conditions (23 and 28%) to determine the effects of particle size on the extrudate properties. Smaller particle size fractions exhibited increased solubility and significantly higher viscosity both with and without added protein. When WPC was added to the corn meal, a large reduction in paste viscosity was observed regardless of the particle size. The blend with similar particle size distributions of corn meal and WPC had a significantly higher viscosity than the other blends. The expansion ratio, porosity and breaking strength of this blend, when extruded at the lower moisture content, were improved to the extent that they behaved similarly to extrudate made from corn meal alone.     

EFFECT OF PARTICLE SIZE ON VISCOAMYLOGRAPHIC BEHAVIOUR OF RICE FLOUR AND VERMICELLI QUALITY

The effect of particle size on the cooking behaviour of rice (Oryzae sativa, sub sp. Indica kato) flour was studied with the Brabender Viscoamylograph. Among the flours of different average particle sizes (307, 214, 165, 138, 114, 90 and 71 μ) studied, flours of 138 and 165 μ showed high breakdown ratios of 0.984 and 0.866 and set back ratios of 2.333 and 2.143, respectively. Comparatively, for vermicelli making, the flours of 138 and 165 μ yielded a product with better scores for textural profile, highlighting the importance of particle size of flours in the preparation of rice based vermicelli.     

THE RELATIONSHIP BETWEEN HAZE AND THE SIZE OF PARTICLES IN BEER

Haze measurements have been obtained for suspensions of polystyrenelatex particles of known diameter using two light scattering instruments which measure at angles of 90° and 13° respectively. The results agree well with the theory of light scattering and demonstrate the significant effects of particle size and angle of detection upon the instrumental values for haze. This information has been used to correlate the particle size distributions of a number of beers, as measured by Coulter Counter, with the corresponding, measured haze values.     

CREEP AND DYNAMIC RHEOLOGICAL BEHAVIOR OF TOMATO CONCENTRATES: EFFECT OF CONCENTRATION AND FINISHER SCREEN SIZE

Based on laser diffraction, pulp particles > 900 μm were detected in tomato concentrates; particles greater than 100–200 μm were found in serum from a concentrate. Creep-compliance and dynamic rheological data showed that viscoelastic properties of 21 °Brix tomato concentrates using a 0.84 mm finisher screen were higher than those from a 0.69 mm screen. Both types of viscoelastic properties were sensitive to increase in concentration in that they increased with increase in Brix of the concentrates. Magnitudes of instantaneous modulus (G₀= 1/J₀) of the tomato concentrates were of the same order of magnitude as the storage modulus (G') at 1 rad s^-1.     

EFFECT OF PARTICLE SIZE AND HEAT ON ABSORPTIVE PROPERTIES OF SOY HULLS1,2

Given the potential contribution of soy hulls to the human diet, a methodology was developed to determine their moisture and lipid absorptive properties under conditions simulating those within a restructured pork product during thermal processing. Laboratory procedures were developed to determine the interactive effects of particle size, heat (25, 50, 75, and 95°C), and varying levels of available water, pork lipids, and water/pork lipids emulsion upon absorption abilities. Absorption of all media was influenced by particle size; as particle size increased, media absorption generally increased. Higher temperatures tended to increase water and water/pork lipid emulsion absorption, but had no effect on pork lipid absorption. Water was found to be preferentially absorbed over lipids. These results can be used by food processors in developing a restructured pork/soy hull product for human consumption.     

染料微胶囊粒径大小和分布的影响因素

探讨了原位聚合法制备分散染料微胶囊时，造壁剂滴加速度、系统调节剂MS用量及分散剂种类对染料微胶囊粒径和分布情况的影响。结果表明：造壁剂滴加速度为0.5ml/min时，平均粒径最小（d^-=3.2635μm），分布最窄；系统调节剂MS用量80％－100％（owf)时平均粒径变小（d^-=3.7413-3.5643μm），用量过大会导致胶囊缔合；分散剂NNO对染料微胶囊分散效果最为明显，粒径变得更小且分布更集中。     

EFFECT OF UNIMODAL PARTICLE SIZE AND PULP CONTENT ON RHEOLOGICAL PROPERTIES OF TOMATO PUREE

The vane method in controlled shear stress mode was used to determine the yield stress and the shear rate—shear stress data of tomato purees containing 10–35% pulp of two different average particle sizes: 0.34 and 0.71 mm. Consistency index and apparent viscosity increased significantly with pulp content and decreased with average particle size. The effect of pulp weight fraction (P) on relative viscosity (η_r) could be described by the single parameter equation: η_r= [1 – (P/A)]⁻², while the effect of particle diameter on η_r could be described using Peclet number. Magnitudes of yield stress determined directly by the vane method were higher than those obtained by using the Casson model, and were proportional to the square of pulp content. Reduced Casson yield stress—P data on purees of both particle sizes followd a single curve. Effects of pulp content and particle size on vane yield stress and apparent viscosity were evident from the correlation forms with high values of R².     

SHEAR RATES DURING ORAL AND NONORAL PERCEPTION OF VISCOSITY OF FLUID FOODS

Relationships were established for five sensory methods of oral and nonoral viscosity evaluation between viscosity scores and instrumentally measured dynamic viscosity for model and real Newtonian fluid foods. These relationships were then used to predict the effective shear rates under which the sensory tests were performed. The highest shear rates were predicted for viscosity perception by compression of samples between tongue and palate, and the lowest for pouring the fluid foods from a teaspoon. Mixing with a teaspoon, slurping and swallowing exhibited nearly the same dependencies of apparent shear rates on equivalent instrumental viscosity. All relations were of the hyperbolic type. The resulting relationships between the apprent shear rates and equivalent instrumental viscosity are in good agreement with a similar relationship predicted by Shama and Sherman (1973a) (see Cutler et al. 1983) for oral perception.     

EFFECTS OF SOY PARTICLE SIZE AND COLOR ON THE SENSORY PROPERTIES OF GROUND BEEF PATTIES

A study was conducted to assess the effect of both size and color of textured soy protein particles on the visual and textural properties of extended (20% replacement) ground beef patties. A trained texture profile panel judged the hardness, cohesiveness, chewiness, moistness, and oiliness of nine different samples. In addition, judgments of the visual attributes of darkness, size of particles, and density of particles were made. Significant effects of soy ingredient were found for all judged attributes. It was concluded that soy ingredients having particle sizes smaller than the diameter of the openings of the grind plate used to process the meat/soy mixture produced the greatest change in the texture of the ground beef patties, because these particles passed through the grind plate unscathed, producing an easily discernable matrix of large meat particles and small soy particles. It was also concluded that carmel-colored soy ingredients produced less lightening of the cooked samples than uncolored soy ingredients.     

EFFECT OF CONCENTRATION ON THE RHEOLOGY AND SERUM SEPARATION OF TOMATO SUSPENSIONS

The °Brix value of the tomato concentrate, from which tomato suspensions were prepared, was shown to have a large effect on the resulting apparent viscosity and storage modulus. The apparent viscosity of a tomato suspension prepared from a 30 °Brix tomato concentrate was only 35% of that of a suspension prepared from a 4.9 °Brix juice, both standardized on the same water unextractable solids (WUS) (0.65%) and total tomato solids (TS) level. After homogenizing the difference in apparent viscosity was only about 10–15%. A similar trend was found for the dynamic moduli. The decrease in rheological parameters of the nonhomogenized suspensions is probably partly related to the decrease in diameter of the tomato particles due to the concentration process. Moreover, microscopic fracture of the cellulosic, microfibrillar network of the cell wall plays a part. Serum separation of diluted nonhomogenized tomato suspensions was higher if made from a concentrate that was concentrated to a higher °Brix value. This phenomenon is discussed in terms of variations in uniaxial compression of the network in the diluted tomato suspensions caused by gravitational force.     

聚丙烯酸酯浆料的酯基对混合浆相分离的影响

以初显分离时间和沉降率为量化指标，研究了酯基类型和含量、PVA类型、淀粉含量对混合浆相分离的影响。实验结果表明：酯基类型及数量对淀粉／PVA混合浆液的相分离行为有明显影响，BA链节有利于混合浆液的稳定性，而MA和MMA则能获取相对较低的相分离程度。随着BA含量的增加，混合浆的相分离速度减小，但相分离程度却有所增大。所介绍的几种聚丙烯酸酯浆料有助于降低淀粉与部分醇解型PVA混合浆液的相分离速度，不能改善淀粉与完全醇解型PVA混合浆的相分离速度。