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A continuously working pilot plant-scale prototype was used to evaluate the effects of continuous-flow ultrasound-temperature treatment for bacterial decontamination of model suspensions and various liquid food systems such as milk, fruit, and vegetable juices. Escherichia coli K12 DH 5 alpha and Lactobacillus acidophilus were used as test microorganisms. In addition, treated juices were investigated for damage caused by heat or ultrasound-induced degradation of sensory and nutritional properties after treatment and storage. Changes in color and destruction of heat-labile and slightly oxidizable L-ascorbic acid content were monitored as an index to measure processing effects. Results were assessed with respect to the total energy requirement and compared with those using a conventional, indirect heating method having similar processing conditions. For the bacteriological process evaluation, the temperature- and time-dependent process lethality was used as the basis; for the quality- and energy-related investigations, the degree of bacterial inactivation was used. At identical degrees of bacterial inactivation, the ultrasound-assisted thermal treatments required a lower processing temperature than treatment with conventional thermal processing. However, according to energy balances, the total energy consumption was not reduced compared to conventional heating. Indications for a positive influence on shelf life, with improvements in surface color stability (lightness) and L-ascorbic acid retention, were found among quality parameters of treated orange juice.

Aims: To examine cellular injuries occurring in cells of Escherichia coli (Gram-negative bacteria) and Lactobacillus rhamnosus (Gram-positive bacteria) in response to a high-intensity ultrasound treatment using classical plate count technique and flow cytometry. Method and Results: According to plate count results, E. coli (D-value 8AE3 min) was far more sensitive than L. rhamnosus (D-value 18AE1 min) in their response to the ultrasound intensity applied (20 kHz, 17AE6 W). The dye precursor carboxyfluorescein diacetate (cFDA) could freely diffuse across the cytoplasmic membrane of intact cells of Gram-positive bacteria L. rhamnosus, resulting in its intracellular enzymatic conversion and emission of green fluorescence. In contrast, the presence of an outer membrane on E. coli, which represents the class of Gram-negative bacteria, apparently disabled the penetration of viability marker cFDA. Ultrasound application on E. coli yielded in an increasing population with disintegrated outer membrane, which allowed penetration of cFDA and its intracellular enzymatic conversion as well as accumulation. In both organisms evaluated only a small population was labelled by propidium iodide upon exposure to ultrasound for up to 20 min. Within the experimental conditions investigated ultrasound did not considerably affect the cytoplasmic membrane, although according to plate count results viability loss occurred. Conclusions:The results compiled suggest, that ultrasound induced cell death, which may not be related to membrane damage. Significance and Impact of the Study: Limitation on the use of bacteriocins, which are aimed on destabilization of cytoplasmic membrane but inhibited by the outer membrane, could be overcome by ultrasound-assisted physical disruption of the outer membrane.

throughout the solution of the dynamic heat transfer model. In this work, the model is solved applying the Orthogonal Collocation Method on Finite Elements, in the axial position and it is integrated with numerical Solver (DASSL). In this procedure, it is possible to choice the right number of finite elements and also the best number of placement root for each finite element. This way, the better configuration for the system can be defined, which is based on the actual operating condition of the equipment. It also permits to identify the best heat load for the freezer. 30 832 7663From a current literature survey regarding the application of ultrasound in combination with heat it is concluded that further research is needed to determine the feasibility and usefulness of ultrasound applications for fluid systems in continuous flow. This study evaluates the effects of an ultrasound treatment in continuous flow for the preservation of liquid food. Microbial inactivation, energy consumption, and product quality have been assessed. A comparison between conventional heating and combined ultrasound in continuous flow has been carried out. At identical degrees of microbial inactivation the combined ultrasound and heat treatment requires a lower maximum processing temperature. From energy balances it is derived that the total energy consumption is not reduced compared to the conventional heating. Detrimental effect of the combined process on quality parameters like colour and L-ascorbic acid are not detectable.2 42 Engineering, von-Behring-Str. 9, D-34260 KaufungenRetaining food grade quality is essential for a bottle to bottle PET recycling process. A PET recycling process comprising reactive extrusion of bottle flakes under vacuum followed by solid-state polycondensation to again increase the viscosity to the required value of bottle blowing has been investigated in detail applying a comprehensive reaction model. Quality parameters like viscosity and content of carboxyl end groups and vinyl end groups (potential acetaldehyde) have been calculated for different process conditions. The recycling process is assessed under consideration of the requirements of the food packaging industry. 353* Clarification of Wines by Micro/UltrafiltrationF e r n a n d o G o n c Ë a l v e s M a r i a N o r b e r t a d e P i n h o *The present work addresses the optimisation of wine clarification by microfiltration (MF) and ultrafiltration (UF) in terms of productivity and macromolecular removal minimisation. Two DSS PVDF membranes were tested: one of MF with 0.45 lm pore size, and another of UF with 100 MWCO. The wine permeation flux was practically the same for micro and ultrafiltration. The use of pressures higher than 1 bar revealed no improvement in permeation flux. Clarification was achieved with both membranes with a particle removal of ca. 70 %. Low polysaccharide removal was obtained: 12 % for MF and 21 % for UF. The clarification of wine by membrane (MF and UF) had no significant effect on polyphenolic content.The engineering design...

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