BRAZILIAN HULL-LESS AND MALTING BARLEY GENOTYPES: II. THERMAL AND RHEOLOGICAL PROPERTIES OF STARCH

Thermal and rheological properties of starch isolated from two Brazilian barley experimental lines, malting and hull‐less, are reported. Gelatinization's thermal properties were T_o 53.3 and 58C, T_p 59.4 and 62.7C, and ΔH 6 and 6.8 J/g for the malting and hull‐less starch, respectively. A trend to slightly higher retrogradation rates were obtained for the malting (73.3%) compared with the hull‐less (72.1%) starch, while lower hot‐paste peak and final viscosity were observed in the former (125 and 114 RVU versus 169 and 179 RVU, respectively). Changes in storage (G′) and loss (G″) moduli during heating and cooling showed higher values for the starch from the hull‐less line. During heating, G′was higher than G″and developed at higher temperatures. A trimodal distribution pattern of G″was observed in the starch from the hull‐less barley line. Two G′peaks at 75 and 87.5C were 6.2 and 2.4 times higher, respectively, in the starch from the hull‐less line than that from the malting line.     

Piezoelectric Biosensor for Detection of Salmonella typhimurium

A flow injection analysis (FIA) system was developed based on a piezoelectric biosensor for detection of Salmonella typhimurium. The anti-Salmonella spp antibody was immobilized onto the gold electrode coated quartz crystal surface through a polyethylenimine-glutaraldehyde (PEG) technique and dithiobis-succinimidyl propionate (DSP) coupling. The PEG technique proved more successful for FIA applications than the DSP coupling. The biosensor had responses of 23–7 Hz in 25 min when the PEG immobilization technique was employed, with R²0.94 for Salmonella typhimurium concentrations of 5.3.10⁵ to 1.2.10⁹ CFU/mL.     

THERMOPHYSICAL PROPERTIES OF COCONUT WATER AFFECTED BY TEMPERATURE

The effect of temperature on the thermophysical properties of coconut water was investigated from 5 to 80C, taking density, Newtonian viscosity, thermal diffusivity and thermal conductivity into consideration, besides specific heat. The validation of existent models of other foodstuffs, as well as the proposal of new models, was also investigated. It was verified that temperature significantly affected these properties, presenting in general a linear behavior, except for Newtonian viscosity, which presented an exponential behavior. Among the existent equations, results from the multiple linear model were appropriated to predict the density, thermal diffusivity and thermal conductivity values, while the model, which depended on solids fraction, was the best one for specific heat value, and the exponential model was the best in relation to Newtonian viscosity values. The proposed models fitted well, and were simple and easy to use.

PRACTICAL APPLICATIONS

Most of the known values of thermophysical properties of fluid foods typically concern products from subtropical and cold areas. Until today, there was little information concerning tropical products such as coconut water. Food composition and temperature are important factors that affect thermal properties. In order to create and adapt specific equipment, optimize processes that involve pumping and heat transfer, contributing to an effective design of food-processing equipment for tropical fluid foods, it is important to know the factors. Besides, the evaluation of existent models and equations, and the introduction of new equations is important to allow an adequate prediction of studied properties, thus saving time, material and money.     

Floating Wind Turbine Motion Suppression Using an Active Wave Energy Converter

This paper proposes a new concept of an actively-controlled wave energy converter for suppressing the pitch and roll motions of floating offshore wind turbines. The wave energy converter consists of several floating bodies that receive the wave energy, actuators that convert the wave energy into electrical energy and generate the mechanical forces, and rigid bars that connect the floating bodies and the wind turbine platform and deliver the actuator forces to the platform. The rotational torques that are required to minimize the platform pitch and roll motions are determined using a linear quadratic regulator. The torques determined in this manner are realized through the actuator forces that maximize the wave power capture as well. The performance of the proposed wave energy converter in simultaneously suppressing the platform pitch and roll motions and extracting the wave energy is validated through simulations.     

THERMODYNAMIC PROPERTIES OF BINARY LIQUID MIXTURES OF ETHANE AND ETHYLENE WITH METHANE AND THE RARE GASES

Two series of binary liquid mixtures containing either ethylene or ethane have been investigated, at one or more temperatures (usually at the triple-point temperature of the component with the higher melting-point). In the ethylene series liquid-vapour equilibrium and liquid density studies were carried out for mixtures with methane, krypton and xenon; the heats of mixing were also measured for the ethylene + krypton mixtures. In the ethane series, which comprised mixtures with methane, argon, krypton and xenon, all three properties were measured except for the ethane + methane and ethane + argon systems where the enthalpies of mixing were already known. The ethylene + ethane system was also investigated at 161.39 K.

The results have been used to estimate the thermodynamic excess functions G^E , V^E and H^E . The G^E values decrease, within each series, as one moves from the lighter to the heavier rare gas, the values being lower in the ethane series. For the ethane + xenon mixtures both G^E and H^E are negative, showing a weak attraction between the two molecules. The V^E values for the mixtures of hydrocarbons suggest the probable formation of interlocking structures between the two components.

The values of the thermodynamic excess functions have been interpreted in the light of the model of Frisch-Longuet Higgins-Widom for the liquid state.     

PHYSICAL AND SENSORY PROPERTIES OF MEATSTICK PRODUCTS AS AFFECTED BY FORMULATION AND DRYING: SENSORY-INSTRUMENTAL RELATIONSHIPS

Shelf‐stable meats are of interest to industry and are important in military ration development. Stability is commonly achieved through control of pH and water activity. However, reduction in moisture as a means to lower a_w can significantly affect texture. Other ingredients, such as fat, can also potentially affect texture and possibly mitigate hardening due to lowered moisture. Meatsticks dried to three water activities, 0.88, 0.90, and 0.92, each from batters at three fat levels, 14, 17, and 21%, were produced, yielding products varying in both moisture and fat content. Products were subjected to mechanical and sensory testing and image and color analysis. Meatstick modulus, shear force, L* value, and percent of area of cut surfaces covered by separated fat were correlated with sensory assessments of interior hardness, hardness with skin, color, and visual fat, respectively. These parameters were significantly influenced by composition, particularly fat and protein contents and fat‐protein interaction.