A CIRCULAR-DICHROISM STUDY OF THE ENTEROTOXIN FROM CLOSTRIDIUM PERFRINGENS TYPE A

Far-UV circular-dichroism spectra of the enterotoxin from Clostridium perfringens type A were recorded under different conditions, and conformational analysis was performed. The native enterotoxin (pH 6.8) was shown to contain about 80% pleated sheet, 20% random coil and no helix structure. By adding small amounts of the detergent sodium dodecyl sulfate (0–261 mol SDS/mol enterotoxin), the β-sheet structure could gradually be changed to a more α-helical structure. Treatment with 8 M urea resulted in limited alterations of the secondary structure of the enterotoxin, while heat treatment (60°C, 30 min), treatment with 6.5 M guanidine hydrochloride or 0.01 M NaOH led to a dramatic increase in the amount of random coil.     

Instant infusion pasteurisation of bovine milk. II. Effects on indigenous milk enzymes activity and whey protein denaturation

Direct heat treatment of two milk types, skimmed and nonstandardised full‐fat, was performed by instant steam infusion and compared with indirect heating. Infusion conditions were temperatures of 72–120°C combined with holding times of 100–700 ms, and indirect heat conditions were 72°C/15 s and 85°C/30 s. The activity of indigenous enzymes such as alkaline phosphatase, lactoperoxidase, xanthine oxidase and γ‐glutamyl transpeptidase was evaluated. Infusion temperature was the main determinant of inactivation. Whey protein denaturation represented by β‐lactoglobulin increased significantly with infusion temperature. The nonstandardised milk had a higher denaturation rate than skimmed milk. The effect of instant infusion on pH and milk fat globule size in relation to whey protein denaturation and association is discussed.     

Analysing the hypoglycaemic counter-regulation: a clinically relevant phenomenon?

This paper describes and analysis of the temporal relation between episodes of low blood glucose (hypoglycaemia) and counter-regulations, i.e., episodes of elevated blood glucose (hyperglycaemia), in patients with insulin dependent diabetes. The relation was assessed by statistical methods based on a metabolic computer model of the human glucose metabolism. The study material was standard collected clinical data on meals, insulin injections, and measured blood glucose from hospitalised patients. We have found that a typical hypoglycaemic counter-regulation begins 6–8 h after the hypoglycaemia, that it lasts 16–18 h, giving a total duration of 24 h, and that it elevates the blood glucose by 4–10 mmol/l. The phenomenon was demonstrated in the data from more than half of the patients with hypoglycaemic episodes.     

BIOCHEMICAL DIFFERENCES IN SOCKEYE SALMON THAT ARE OCEAN FEEDING AND ON THE SPAWNING GROUNDS

Various biochemical parameters measured in sockeye salmon, Oncorhynchus nerka, feeding in the Gulf of Alaska in July during the maturation process were contrasted with those obtained from mature sockeye salmon in Steep Creek, a small salmon stream near Juneau, Alaska. Degenerative changes in muscles, such as decrease in total lipid and protein contents in mature salmon were attributed both to the progressed activation of lipid hydrolytic enzymes and to autolytic activity, in addition to the inactivation of lipid and protein syntheses in muscle and liver. The depletion of lipid is associated with the energy utilization for migration and gonadal maturation as a result of the cessation of feeding.     

Hybrid vortex simulations of wind turbines using a three‐dimensional viscous–inviscid panel method

A hybrid filament‐mesh vortex method is proposed and validated to predict the aerodynamic performance of wind turbine rotors and to simulate the resulting wake. Its novelty consists of using a hybrid method to accurately simulate the wake downstream of the wind turbine while reducing the computational time used by the method. The proposed method uses a hybrid approach, where the near wake is resolved by using vortex filaments, which carry the vorticity shed by the trailing edge of the blades. The interaction of the vortex filaments in the near vicinity of the wind turbine is evaluated using a direct calculation, whereas the contribution from the large downstream wake is calculated using a mesh‐based method. The hybrid method is first validated in detail against the well‐known MEXICO experiment, using the direct filament method as a comparison. The second part of the validation includes a study of the influence of the time‐integration scheme used for evolving the wake in time, aeroelastic simulations of the National Renewable Energy Laboratory 5 MW wind turbine and an analysis of the central processing unit time showing the gains of using the hybrid filament‐mesh method. Copyright © 2017 John Wiley & Sons, Ltd.     

Instant infusion pasteurisation of bovine milk. I. Effects on bacterial inactivation and physical–chemical properties

Two types of milk, skim milk and non-standardised raw milk, were heat treated using direct heating by instant infusion pasteurisation with treatment temperatures in the range from 72°C to 120°C and with holding times of less than 1 second. Indirect heating by HTST pasteurisation (72°C for 15 seconds) was used for comparison. The inactivation of microorganisms reached at least the same level when using instant infusion pasteurisation compared to HTST pasteurisation. Changes in the physical-chemical properties were observed in the skim milk fractions of instant infusion pasteurised non-standardised milk, whereas for instant infusion pasteurised skim milk less influence from the treatments was observed.     

Texture and Microstructure of Steam Cooked, Vacuum Packed Potatoes

Uniaxial compression tests combined with light microscopy and scanning electron microscopy were used to study textural properties of vacuum packed, steam cooked (VPS-cooked) potato tubers. Comparisons were made with conventionally water cooked tubers for cooking intervals of 0–60 min. In the VPS-cooked potatoes the gelatinized starch formed dense clusters. In contrast, water cooked cells were filled with gelatinized starch. The textural attributes declined with increased cooking time, faster for water cooked potatoes than for VPS-cooked. After >30 min cooking, firmness of VPS-cooked potatoes increased, while cell separation and disintegration of tissue made the water cooked tubers less firm. Textural properties and cell structure were directly affected by processing conditions.     

FATTY ACID COMPOSITION AND TOCOPHEROL CONTENT OF AMAZONIAN PALM OILS

The characteristics of oils recovered from seeds of Astrocaryum chambira and A. urostachys have been evaluated. The gas chromatographic analyses showed that lauric and myristic acids are predominant fatty acids accounting for 50.8–52.3 and 26.2–28.1% of the total, respectively; thus, resembling closely to palm kernel stearines. Tocotrienols were the major antioxidants present in both Astrocaryum chambira and A. urostachys Kernel oils. Application of these oils in the confectionery industry without use of any fractionation techniques is recommended.     

DIAS-NIDDM--a model-based decision support system for insulin dose adjustment in insulin-treated subjects with NIDDM

The effects of using two methods (item mean and person mean) for replacing missing data in Likert scales were studied. The results showed that both methods were good representations of the original data when both the number of respondents with missing data and the number of items missing were 20% or less. As the numbers of missing items and of respondents with missing data increased for the person mean substitution method, a spurious increase in the inter-item correlations (and, therefore, reliability) for the sale was produced. The item mean substitution reduced the reliability estimates of the scale. These results suggest caution in the use of the person mean substitution method as the numbers of missing items and respondents increase.