Development of a colorimetric pH indicator using nanofibers containing Spirulina sp. LEB 18.

A colorimetric pH indicator was developed using nanofibers of poly(lactic acid) (PLA) and polyethylene oxide (PEO) combined with biomass of the microalga Spirulina sp. LEB 18. This study evaluates the potential use of microalgal biomass encapsulated in polymer nanofibers to develop a colorimetric pH indicator. Nanofibers containing the biomass were exposed to solutions with different pH values (pH 1-10), and color variations were measured using a colorimeter. The wettability analysis of the nanofibers showed hydrophilicity (zero angle with water), which allows ions to interact with the biomass, indicating a fast color response as a function of pH. When subjected to pH variations, indicators containing 1, 2 or 3% (w v-1) of biomass provided ΔΕ values >12, indicating an absolute difference in color. Therefore, this innovative material has the potential to be applied as a intelligent indicator to verify food quality through a visual signal of the product condition.

Development of Aa New Time Temperature Indicator for Enzymatic Validation of Pasteurization of Meat Products.

This paper presents the development of a new smart time-temperature indicator (TTI) of pasteurization whose operating principle is based on the complexation reaction between starch and iodine, and the subsequent action of an amylase on this complex causing its discoloration at a rate dependent on time and temperature of the medium. Laboratory simulations and tests in a manufacturing plant evaluated different enzyme concentrations in the TTI prototypes when exposed to pasteurization conditions. The results showed that the color response of the indicators was visually interpreted as adaptive to measurement using appropriate equipment, with satisfactory reliability in all conditions studied. The TTI containing 6.5% amylase was one whose best results were suited for use in validating the cooking of hams. When attached to the primary packaging of the product, this TTI indicated the pasteurization process inexpensively, easily, accurately, and nondestructively.

Use of smart photochromic indicator for dynamic monitoring of the shelf life of chilled chicken based products.

This study evaluated the applicability of a photochromic time temperature indicator (TTI) to monitor the time-temperature history and shelf life of chilled boneless chicken breast. The results showed that the smart indicator showed good reproducibility during the discoloring process in all the conditions investigated. The response was not only visibly interpretable but also well adaptable to measurement using appropriate equipment. For an activation configuration of 4 s of ultraviolet light (UV) per label, the TTI's rate of discoloration was similar to the quality loss of the meat samples analyzed. Thus, the photochromic label (4 s UV/label) attached to the samples set out to be a dynamic shelf-life label, assuring consumers the final point of quality of chilled boneless chicken breast in an easy and precise form, providing a reliable tool to monitor the supply chain of this product.

Survey of extended-spectrum beta-lactamases in Escherichia coli isolates from a Portuguese hospital and characterisation of a novel class 1 integron (In60A) carrying the blaCTX-M-9 gene.

Between November 2001 and November 2004, 231 Escherichia coli isolates resistant to beta-lactam antibiotics were identified. In 14 isolates, bla(TEM-24) (2 isolates), bla(TEM-52) (5 isolates) and bla(TEM-26) (7 isolates) were identified. In 145 E. coli isolates with the same M13 fingerprinting profile and the same resistance phenotype, the bla(CTX-M-15) gene was found in association with an insertion sequence ISEcp1. The bla(CTX-M-2) gene was identified in one E. coli isolate (290HSM), and in other E. coli isolate (246HSM) the bla(CTX-M-9) gene was contained in a new complex sul1-type class 1 integron (named In60A). This is the first report of three cefotaximases (CTX-M-15, CTX-M-2 and CTX-M-9) in E. coli isolates from a Portuguese hospital.

High-level expression of IMP-5 carbapenemase owing to point mutation in the -35 promoter region of class 1 integron among Pseudomonas aeruginosa clinical isolates.

Eight strains of Pseudomonas aeruginosa producing IMP-5 carbapenemases were collected from three Portuguese hospitals. All isolates were epidemiologically unrelated. The bla(IMP-5) gene was inserted into a class 1 integron previously reported in Acinetobacter baumannii 65FFC. Expression of the the bla(IMP-5) gene in P. aeruginosa has been shown to be driven by the P(1) promoter [TTGATA] in which the cytosine was replaced by thymine, which caused an increase in transcription of bla(IMP-5) that was confirmed by site-directed mutagenesis. The minimum inhibitory concentrations (MICs) of imipenem for Escherichia coli pGMLA-1 (the recombinant from A. baumannii 65FFC) and E. coli pATG-2 (the recombinant from P. aeruginosa isolates) were 0.5 mg/L and >32 mg/L, respectively. This study reports the spread of a class 1 integron In76 with a new point mutation in the P(1) promoter sequence leading to overproduction of IMP-5.