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.     

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.     

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.     

A FLAT TRIANGULAR SHELL ELEMENT WITH LOOF NODES

In the formulation of flat shell elements it is difficult to achieve inter-element compatibility between membrane and transverse displacements for non-coplanar elements. Many elements lack proper nodal degrees of freedom to model intersections making the assembly of elements troublesome. A flat triangular shell element is established by a combination of a new plate bending element DKTL and the well-known linear membrane strain element LST, and for this element the above-mentioned deficiencies are avoided. The plate bending element DKTL is based on Discrete Kirchhoff Theory and Loof nodes. The nodal configuration of the element is similar to the SemiLoof element, and the formulation is an improvement of a previous formulation. The element is used for both linear statics, linear buckling and geometrical non-linear analysis, and numerical examples are presented to show the robustness, accuracy and quick convergence of the element.     

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.     

物流运输调度问题的混沌烟花算法——基于多车型供应链

为了满足供应链物流的不同需求，考虑多种车型、车辆容量、车辆油耗、车辆最大配送距离等约束条件，以最小油耗、最短配送距离为目标，建立多车型供应链物流运输调度模型（Multi-Type Vehicle Routing Problem in Supply Chain，MTVRPSC），并提出一种混沌烟花算法求解该模型。该算法以烟花算法为核心，提出一种编解码策略实现连续空间到MTVRPSC离散空间的映射，重新定义算法的适应度函数、适应度值和适应度的比较方法，并采用混沌初始化策略和混沌搜索策略来增强算法收敛效果。实验结果表明，所提出的算法在求解MTVRPSC时具有较强的寻优能力和稳定性。     

Organoleptic and physical properties of yogurt made from lactose hydrolysed milk

Low-lactose yogurt has been manufactured by using two commercial lactase enzymes: Lactozym and Maxilact. For each lactase enzyme two different enzyme treatments were examined: hydrolysing before fermentation and hydrolysing during fermentation.
When evaluated by the triangle test it was not possible to detect any significant difference in organoleptic properties, including sweetness, between the control yogurt and the yogurt samples made from hydrolysed milk. The addition of fruit and sugar made it possible to detect a difference in sweetness when triangle tested.
When lactase was added to evaporated milk (approx. 10% S N F) together with the starter culture, the results showed that addition of an amount equal to 500 - 700 LAU/litre resulted in a yogurt with about 2% lactose. A technology based on these results seems applicable to industrial manufacture.