Enhanced survival of spray-dried microencapsulated Lactobacillus rhamnosus GG in the presence of glucose

The survival of spray dried Lactobacillus rhamnosus GG (LGG) preparations encapsulated in whey protein isolate (WPI)-maltodextrin, WPI-maltodextrin-glucose, WPI-inulin, and WPI-inulin-glucose mixtures during storage at 25 °C (11%, 57% and 70% relative humidity, RH) was examined. The glass transition temperature of each encapsulant formulation was also assessed. RH was most important for maintaining viability over time; the inclusion of glucose improved viability, irrespective of when all formulations were in a glassy or rubbery state. When LGG microcapsule powders were stored at the same RH, the addition of glucose in the encapsulant formulation had a greater influence on survival of LGG during storage than the maintenance of a glassy state. Both the maintenance of a glassy state during storage and the incorporation of glucose in the encapsulant formulation were required for optimal survival of probiotic microcapsule powders prepared from fresh cultures.

Practical significance

The incorporation of glucose into the encapsulant formulation prior to spray drying of protein-carbohydrate based LGG formulations improves the survival of LGG during long term storage.     

Carrot pectin methylesterase and its inhibitor from kiwi fruit: Study of activity, stability and inhibition

Carrot pectin methylesterase (PME) and its inhibitor (PMEI) from kiwi fruit were successfully purified by affinity chromatography. Enzyme and inhibitor activity and stability and PME–PMEI complex formation, as influenced by intrinsic product factors (pH and NaCl) and extrinsic process factors (temperature and pressure), were studied. The effect of temperature- or pressure-induced denaturation of PME and PMEI on their respective activities was assessed by estimating inactivation kinetic parameters. PME inactivation obeyed first-order kinetics. The enzyme was rather heat-labile but pressure-stable. PMEI inactivation was best described by a model taking into account a processing-stable PMEI intermediate. The behavior of PME and the PME–PMEI complex at elevated temperature or pressure in the presence of pectin was explored by following methanol formation as a function of treatment time. PME catalytic activity was stimulated up to a certain temperature or pressure level before declining. No conclusive evidence was obtained for a temperature-induced dissociation of the PME–PMEI complex, whereas high pressure exposure caused the complex to separate.

Industrial relevance

PME activity control is a major point of interest in the quest of obtaining high quality plant-derived food products. The current study demonstrates that both traditional thermal processing and novel high hydrostatic pressure processing allow stimulation as well as inactivation of PME and, hence, directing the PME-catalyzed pectin hydrolysis. An alternative or additional approach to control endogenous PME activity (e.g. to obtain cloud-stable juices) is through enzyme inhibition using kiwi PMEI. In this context, pH and NaCl boundaries for application were established, the existence of a temperature- and pressure-stable PMEI intermediate was shown and the PME–PMEI complex was proven not to be dissociated at mild temperature and pressure levels. These observations endorse the possibility of inhibiting undesirable PME activity remaining after mild processing.     

Transverse jets and their control

The jet in crossflow or transverse jet has been studied extensively because of its relevance to a wide variety of flows in technological systems, including fuel or dilution air injection in gas turbine engines, thrust vector control for high speed airbreathing and rocket vehicles, and exhaust plumes from power plants. These widespread applications have led over the past 50+ years to experimental, theoretical, and numerical examinations of this fundamental flowfield, with and without a combustion reaction, and with single or multi-phase flow. The complexities in this flowfield, whether the jet is introduced flush with respect to the injection wall or from an elevated pipe or nozzle, present challenges in accurately interrogating, analyzing, and simulating important jet features. This review article provides a background on these studies and applications as well as detailed features of the transverse jet, and mechanisms for its control via active means. Promising future directions for the understanding, interrogation, simulation, and control of transverse jet flows are also identified and discussed.     

Work characteristics associated with injury among light/short-haul transport drivers

Introduction

This study aims to describe the hazard environment facing drivers of light freight vehicles and short-haul transport drivers and to examine the relationships between hazard exposure and injury.

Methods

Drivers (n = 321) of rigid vehicles up to 12 tonnes Gross Vehicle Mass working within a 100 km radius of their base across the Australian state of New South Wales were surveyed regarding their experience of occupation-specific hazards and their experience of workplace injury in the past year.

Results

Principal components analysis identified four clusters of hazards corresponding to those associated with work organisation, vehicles, road and access, and interpersonal conflict. In logistic regression analysis, work organisation and vehicle-related hazards, explained unique variance in the experience of injury in the past year. However, frequent stress replaced work organisation when included as a predictor in the analysis.

Conclusions

Drivers’ most common safety concern (road and driving issues) reflected the frequency of their exposure to road and access hazards but did not parallel their injury experience. Examination of the hazards most strongly associated with injury suggest that industry risk management efforts should target work organisation and vehicle-related hazards, and particularly work practices that engender frequent stress among drivers.     

利用植物能量储存系统贮存太阳能的创新

以前,太阳能只能作为白天使用的能源。直到如今,贮存额外的太阳能,供以后使用,由于受制于昂贵和低效的能量贮存系统,实际是不易实现的。美国麻省理工大学的研究人员受植物光合作用的启发,发明了1种简单、廉价且高效的存储太阳能的方法。这种方法需要的只是无公害的,且丰富的自然界的物质。     

Adaptive log domain filters for system identification using floating gate transistors

We describe an adaptive log domain filter with integrated learning rules for model reference estimation. The system is a first-order low pass filter implemented using multiple input floating gate transistors operating in subthreshold to realize on-line learning of gain and cut-off frequency. We use adaptive dynamical system theory to derive robust control laws for gain and cut-off frequency adaptation in a system identification task. Simulation results show that convergence is slower using simplified control laws but still occurs within milliseconds. Experimental results confirm that the estimated gain and cut-off frequency track the parameters of the reference filter. The adaptive log domain filter has measured power consumption of 33 μW. During operation, deterministic errors are introduced by mismatch within the analog circuit implementation. An analysis is presented which attributes the errors to current mirror mismatch.