Material ParametersOver the years, numerous studies have investigated extrusion expansion, particularly of cereal foods. Chinnaswamy (1993) reviewed most of the work on extrusion expansion of starches and cereal flours up to that date. In the last decade, many other researchers continued to study expansion and the factors that affect it, aiming to create the basis for new or improved extruded foods. ABSTRACT: Expansion of biopolymer matrices is the basis for the production of a wide variety of cereal foods. A limited number of manufacturing processes provide practical solutions for the development of an impressive variety of expanded products, just by changing process variables. It is therefore essential that the mechanisms involved in expansion are well known and controlled. This paper summarizes the knowledge of nucleation and expansion in extruded andmicrowaved products available to date. The effect of processing conditions and properties of the biopolymeric matrix on nucleation and expansion are discussed. Moisture content enables the glassy polymeric matrix to turn into rubbery state at process temperatures, which allows superheated steam bubbles to form at nuclei and then expand, expansion being governed by the biaxial extensional viscosity of the matrix. Nucleation and expansion theories are presented along with quantitative data that support them.

Bacterial attachment to material surfaces can lead to the development of biofilms that cause severe economic and health problems. The outcome of bacterial attachment is determined by a combination of bacterial sensing of material surfaces by the cell and the physicochemical factors in the near-surface environment. This paper offers a systematic review of the effects of surface topography on a range of antifouling mechanisms, with a focus on how topographical scale, from micro- to nanoscale, may influence bacterial sensing of and attachment to material surfaces. A good understanding of these mechanisms can facilitate the development of antifouling surfaces based on surface topography, with applications in various sectors of human life and activity including healthcare, food, and water treatment.

c Attachment and biofilm formation by bacterial pathogens on surfaces in natural, industrial, and hospital settings lead to infections and illnesses and even death. Minimizing bacterial attachment to surfaces using controlled topography could reduce the spreading of pathogens and, thus, the incidence of illnesses and subsequent human and financial losses. In this context, the attachment of key microorganisms, including Escherichia coli, Listeria innocua, and Pseudomonas fluorescens, to silica and alumina surfaces with micron and nanoscale topography was investigated. The results suggest that orientation of the attached cells occurs preferentially such as to maximize their contact area with the surface. Moreover, the bacterial cells exhibited different morphologies, including different number and size of cellular appendages, depending on the topographical details of the surface to which they attached. This suggests that bacteria may utilize different mechanisms of attachment in response to surface topography. These results are important for the design of novel microbe-repellant materials.

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Background/Objectives:Prevention of biofilm formation by bacteria is of critical importance to areas that directly affect human health and life including medicine, dentistry, food processing and water treatment. This work showcases an effective and affordable solution for reducing attachment and biofilm formation by several pathogenic bacteria commonly associated with foodborne illnesses and medical infections.Methods:Our approach exploits anodisation to create alumina surfaces with cylindrical nanopores with diameters ranging from 15 to 100 nm, perpendicular to the surface. The anodic surfaces were evaluated for attachment by Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Staphylococcus epidermidis. Cell–surface interaction forces were calculated and related to attachment.Results:We found that anodic alumina surfaces with pore diameters of 15 and 25 nm were able to effectively minimise bacterial attachment or biofilm formation by all the microorganisms tested. Using a predictive physicochemical approach on the basis of the extended Derjaguin and Landau, Verwey and Overbeek (XDLVO) theory, we attributed the observed effects largely to the repulsive forces, primarily electrostatic and acid–base forces, which were greatly enhanced by the large surface area originating from the high density, small-diameter pores. We also demonstrate how this predictive approach could be used to optimise different elements of surface topography, particularly pore diameter and density, for further enhancing the observed bacteria-repelling effects.Conclusions:We demonstrate that anodic nanoporous surfaces can effectively reduce bacterial attachment. These findings are expected to have immediate, far-reaching implications and commercial applications, primarily in health care and the food industry.

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This work reports on a simple, robust and scientifically sound method to develop surfaces able to reduce microbial attachment and biofilm development, with possible applications in medicine, dentistry, food processing, or water treatment. Anodic surfaces with cylindrical nanopores 15 to 100 nm in diameter were manufactured and incubated with Escherichia coli ATCC 25922 and Listeria innocua. Surfaces with 15 and 25 nm pore diameters significantly repressed attachment and biofilm formation. Surface-bacteria interaction forces calculated using the extended Derjaguin Landau Verwey-Overbeek (XDLVO) theory indicate that reduction in attachment and biofilm formation is due to a synergy between electrostatic repulsion and surface effective free energy. An attachment study using E. coli K12 strains unable to express appendages also suggests that the small-pore surfaces may inhibit flagella-dependent attachment. These results can have immediate, far-reaching implications and commercial applications, with substantial benefits for human health and life.

The main objective of this work was to evaluate the effectiveness of pulsed light (PL) treatment for the inactivation of Escherichia coli in liquids with different levels of clarity. Nonpathogenic E. coli ATCC 25922 and pathogenic E. coli O157: H7 were used as challenge organisms. Butterfield's phosphate buffer (BPB), tryptic soy broth (TSB), apple juice, and apple cider were used as substrates. The inoculated liquids were placed in a thin layer (1.3 mm) into glass chambers (23 by 53 by 11 mm) and exposed to PL doses of up to 13.1 J/cm2. PL treatments were performed in a Xenon RS-3000C PL unit, both in static mode and under turbulence. Survivors were determined by standard plate counting or the most-probable-number technique. For static treatments, reduction levels exceeding 8.5 log were obtained in BPB for all strains and reduction levels of about 3.5 log were obtained in TSB. For apple juice, inactivation levels of 2.66 +/- 0.10 log were obtained for E. coli ATCC 25922 and 2.52 +/- 0.19 log for E. coli O157:H7. In cider, inactivation levels of 2.32 +/- 0.16 log and 3.22 +/- 0.29 log were obtained for the nonpathogenic and pathogenic strains, respectively. Inactivation kinetics was characterized using the Weibull model. Turbulent treatments resulted in 5.76 +/- 0.06 log reduction in cider and 7.15 +/- 0.22 log reduction in juice, which satisfies the U.S. Food and Drug Administration requirement of 5-log reduction of E. coli. These results show promise for the use of PL for the effective reduction of E. coli in apple juice and cider.