Effect of Heating and Homogenization on the Stability of Coconut Milk Emulsions

: The effects of homogenization and heat treatment on the colloidal stability of coconut milk were studied. Fresh coconut milk (15% to 17% fat, 1.5% to 2% protein) was extracted and stored at 30 °C before homogenization at 40/4 MPa (stage I/stage II). Both homogenized and non‐homogenized samples were heated at 50 °C, 60 °C, 70 °C, 80 °C, and 90 °C for 1 h. Homogenization reduced the size of the primary emulsion droplets from 10.9 to 3.0 μm, but increased the degree of flocculation, presumably via a bridging mechanism. This flocculation was also responsible for increased viscosity of the homogenized samples. Heating increased the degree of flocculation in both non‐homogenized and homogenized samples. A slight amount of coalescence was also observed after heating above 80 °C. All samples creamed after 24 h of storage, but the heated samples formed a larger cream layer, presumably because the flocculated droplets packed together less efficiently. Optical microscopy was used to confirm the combination of flocculation and creaming responsible for changes in coconut milk quality. The information obtained from this study provides a better understanding of the emulsion science important in controlling coconut milk functionality.     

The late elongated hypocotyl mutation of Arabidopsis disrupts circadian rhythms and the photoperiodic control of flowering

The dominant late elongated hypocotyl (lhy) mutation of Arabidopsis disrupted circadian clock regulation of gene expression and leaf movements and caused flowering to occur independently of photoperiod. LHY was shown to encode a MYB DNA-binding protein. In wild-type plants, the LHY mRNA showed a circadian pattern of expression with a peak around dawn but in the mutant was expressed constantly at high levels. Increased LHY expression from a transgene caused the endogenous gene to be expressed at a constant level, suggesting that LHY was part of a feedback circuit that regulated its own expression. Thus, constant expression of LHY disrupts several distinct circadian rhythms in Arabidopsis, and LHY may be closely associated with the central oscillator of the circadian clock.     

Past the ‘perfect kind of age’? Styling selves and relationships in over‐50s dating advertisements

Dating ads are a revealing site for analyzing age-identity negotiations. Through a distributional survey and qualitative analyses of older people's ads, this paper shows how advertisers respond to, and negotiate, normative constraints on their communicative task in this genre. Older people's dating ads tend to express restrained, modest, and nonsexual relational goals. Their references to age often are mitigated. Appearance is given less emphasis and is represented less evaluatively than in text written by younger advertisers. However, several instances stretch the boundaries of the dating ad genre. They find ways to comment on, and sometimes undermine, the ageist assumptions that restrict older people's relational and lifestyle ambitions.     

Physical properties of liquid edible oils

Literature values of density, viscosity, adiabatic expansion coefficient, thermal conductivity, specific heat (constant pressure), ultrasonic velocity, and ultrasonic attenuation coefficient are compiled for a range of food oils and water at 20°C, and a series of empirical equations are suggested to calculate the temperature dependency of these parameters. The importance of these data to the application of ultrasonic particle-sizing instruments to food emulsions is discussed.     

Ultrasonic Monitoring of Powder Dissolution

Sucrose (20 wt%) and lactose (10 wt%) powders were mixed with water (at 2, 20, and 40 °C) and allowed to dissolve. The proportion of an ultrasonic pulse reflecting at the interface between a polymer delay line and the dissolving sugars decreased during the dissolution process, and the magnitude of this signal, normalized to the echo from pure water, was proportional to only the dissolved portion. Ultrasonic reflectance is thus an appropriate sensor to monitor powder dissolution since it can distinguish dissolved and undissolved fractions without prior separation. The kinetics of sucrose dissolution were modeled using a cube‐root equation and the rate constant of the process increased with temperature.     

Chemical and sensory analysis of strawberry flavoured yogurt supplemented with an algae oil emulsion

A yogurt mix (2 g fat and 17g solids/100 g) was supplemented with an algae oil emulsion to provide 500 mg omega-3 fatty acids per 272 g serving of yogurt white mass. The emulsion was added to the yogurt mix either before or after the homogenization step and prior to pasteurization. It was then flavoured with a strawberry fruit base and fermented and stored for up to three weeks. The oxidative deterioration of the products was determined by hydroperoxide measurements and by trained and consumer sensory evaluations. The hydroperoxide content of the supplemented yogurts increased over the storage treatment and was unaffected by the stage of addition. The trained panel could distinguish a stronger fishy flavour in both of the supplemented yogurts after 22 days storage, but the consumer panel rated both control and supplemented samples similarly, as 'moderately liked'.     

Ultrasonic determination of the effect of shear on lipid crystallization

The design and calibration of a novel rheometer incorporating ultrasonic sensors are described. The instrument is capable of the simultaneous measurements of torque, rate of temperature change, and ultrasonic properties of a liquid as a function of time, temperature, and shear rate. The effect of shear rate on the crystallization onset temperature of a sample of confectionery coating fat is studied using this device. The instrument detected the phase transition in the sheared sample as abrupt changes in all of the measured parameters. The onset temperature increased significantly with shear rate, implying lipid crystallization can be accelerated by mixing. There were also significant differences between sensing modalities.