Linearity and iterator types for Gödel’s System

System Open image in new window is a linear λ-calculus with numbers and an iterator, which, although imposing linearity restrictions on terms, has all the computational power of Gödel’s System  Open image in new window . System Open image in new window owes its power to two features: the use of a closed reduction strategy (which permits the construction of an iterator on an open function, but only iterates the function after it becomes closed), and the use of a liberal typing rule for iterators based on iterative types. In this paper, we study these new types, and show how they relate to intersection types. We also give a sound and complete type reconstruction algorithm for System  Open image in new window .     

From Functional Programs to Interaction Nets via the Rewriting Calculus

We use the ρ-calculus as an intermediate language to compile functional languages with pattern-matching features, and give an interaction net encoding of the ρ-terms arising from the compilation. This encoding gives rise to new strategies of evaluation, where pattern-matching and 'traditional' β-reduction can proceed in parallel without overheads.     

Proteins isolated from Ganxet common bean (Phaseolus vulgaris L.) landrace: techno-functional and antioxidant properties

Ganxet protein isolates (GPI) were assessed for antioxidant and functional properties including emulsifying and foaming capacity. The protein content and water activity (a_w) value of GPI were 91.08 ± 4.15% and 0.248 ± 0.008%, respectively. The oil- and water-holding capacities of GPI were calculated as 2.76 ± 0.33 and 1.25 ± 0.11 g g⁻¹ of GPI, respectively (P < 0.05). Foaming and emulsifying properties were found to be pH-dependent (P < 0.05). The highest foaming capacity values were observed at pH 8.0 and 10.0 and were calculated as 86.25 ± 5.30% and 78.75 ± 1.77%, respectively. In addition, the generated emulsions were found to be stable, especially at pH 8.0 and 10.0 with emulsion stability values of 94.1 ± 0.0 and 93.9 ± 0.1, respectively (P < 0.05). Results obtained in the current study demonstrate the potential applications of Ganxet-derived proteins as techno-functional ingredients for the development of novel foods.     

Roadmap of cocoa quality and authenticity control in the industry: A review of conventional and alternative methods

Cocoa (Theobroma cacao L.) and its derivatives are appreciated for their aroma, color, and healthy properties, and are commodities of high economic value worldwide. Wide ranges of conventional methods have been used for years to guarantee cocoa quality. Recently, however, demand for global cocoa and the requirements of sensory, functional, and safety cocoa attributes have changed. On the one hand, society and health authorities are increasingly demanding new more accurate quality control tests, including not only the analysis of physicochemical and sensory parameters, but also determinations of functional compounds and contaminants (some of which come in trace quantities). On the other hand, increased production forces industries to seek quality control techniques based on fast, nondestructive online methods. Finally, an increase in global cocoa demand and a consequent rise in prices can lead to future cases of fraud. For this reason, new analytes, technologies, and ways to analyze data are being researched, developed, and implemented into research or quality laboratories to control cocoa quality and authenticity. The main advances made in destructive techniques focus on developing new and more sensitive methods such as chromatographic analysis to detect metabolites and contaminants in trace quantities. These methods are used to assess cocoa quality; study new functional properties; control cocoa authenticity; or detect frequent emerging frauds. Regarding nondestructive methods, spectroscopy is the most explored technique, which is conducted within the near infrared range, and also within the medium infrared range to a lesser extent. It is applied mainly in the postharvest stage of cocoa beans to analyze different biochemical parameters or to assess the authenticity of cocoa and its derivatives.     

Determination of free chlorine concentrations needed to prevent Escherichia coli O157:H7 cross-contamination during fresh-cut produce wash

This study was conducted to investigate the effect of free chlorine concentrations in wash water on Escherichia coli O157:H7 reduction, survival, and transference during washing of fresh-cut lettuce. The effectiveness of rewashing for inactivation of E. coli O157:H7 on newly cross-contaminated produce previously washed with solutions containing an insufficient amount of chlorine also was assessed. Results indicate that solutions containing a minimum of 0.5 mg/liter free chlorine were effective for inactivating E. coli O157:H7 in suspension to below the detection level. However, the presence of 1 mg/liter free chlorine in the wash solution before washing was insufficient to prevent E. coli O157:H7 survival and transfer during washing because the introduction of cut lettuce to the wash system quickly depleted the free chlorine. Although no E. coli O157:H7 was detected in the wash solution containing 5 mg/liter free chlorine before washing a mix of inoculated and uninoculated lettuce, low numbers of E. coli O157:H7 cells were detected on uninoculated lettuce in four of the seven experimental trials. When the prewash free chlorine concentration was increased to 10 mg/liter or greater, no E. coli O157:H7 transfer was detected. Furthermore, although rewashing newly cross-contaminated lettuce in 50 mg/liter free chlorine for 30 s significantly reduced (P = 0.002) the E. coli O157:H7 populations, it failed to eliminate E. coli O157:H7 on lettuce. This finding suggests that rewashing is not an effective way to correct for process failure, and maintaining a sufficient free chlorine concentration in the wash solution is critical for preventing pathogen cross-contamination.     

Giant squid skin gelatin: Chemical composition and biophysical characterization

Gelatin was extracted from the skin of giant squid (Dosidicus gigas) with a yield of 7.5% on a wet weight basis through a novel cold maturation process and it was chemical, physicochemical and structurally characterized. Squid skin gelatin (SSG) had high protein content (89%) with an amino acid profile similar to that of interstitial collagen. Infrared spectroscopy and circular dichroism confirmed the existence of specific bands of collagen and gelatin which are modified during their thermal transition. Amino acids present in SSG were revealed by NMR signals. Fluorescence spectroscopy revealed emission due to pyridinoline cross-links. Differential scanning calorimetry confirmed that SSG is a weak thermo-reversible gel. Scanning electron microscopy showed porous components within the SSG structure which agree with the viscosity and water holding capacity values obtained. These results led to a better understanding on the molecular structure of SSG which accounts for its well known rheological and physicochemical properties.     

Comparison of MALDI-TOF-MS and HPLC-ESI-MS/MS for Endopeptidase Activity-Based Quantification of Anthrax Lethal Factor in Serum

Diagnosing and treating anthrax at the earliest stage of disease is critical. We developed a method to diagnose anthrax at early stages of infection by detecting anthrax lethal factor (LF) at the attomol/mL level in plasma or serum. This method uses antibody capture and quantification of LF endoproteinase activity by isotope dilution matrix-assisted laser-desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). Many public health laboratories do not use MALDI-TOF-MS; thus, we have adapted the LF method for detection by electrospray ionization (ESI) tandem MS (MS/MS), which allowed comparison of both MS platforms for LF quantification. Calibration curves were linear from 0.05-2.5 ng/mL when measured after 2 h and from 0.005-1.0 ng/mL after 18 h incubation time. The limit of detection was 0.005 ng/mL using a 200 μL sample. The coefficient of variation for quality control samples was 6-12% for both MS platforms. Samples used to perform cross-validation included 158 serum samples from a study in rabbits exposed to anthrax spores by inhalation. Some were treated with anthrax immune globulin before exposure. Concentrations measured by ESI-MS/MS matched those by MALDI-TOF-MS with p = 0.99 (r(2) = 0.997) and -0.25% mean relative difference (±9% standard deviation). This study shows that isotope dilution MALDI-TOF-MS is a robust and precise quantitative MS platform.     

Microbiological and physicochemical quality of fresh-cut apple enriched with the probiotic strain Lactobacillus rhamnosus GG

The effectiveness as protective culture of the probiotic Lactobacillus rhamonosus GG (L. rham. GG) against Salmonella and Listeria monocytogenes on minimally-processed apples throughout storage as well as its effect on apple quality and natural microflora was evaluated. Survival to subsequent exposure to gastric stress was also reported. Apples were cut into wedges and dipped in a solution containing Salmonella and L. monocytogenes (10⁵ cfu mL⁻¹) and/or L. rham. GG (10⁸ cfu mL⁻¹). Apple wedges were packed and stored at 5 and 10 °C. Periodically, microbial population, bacterial survival to gastric stress and quality of apple wedges were evaluated. Although Salmonella was not affected by co-inoculation with L. rham. GG, L. monocytogenes population was 1-log units lower in the presence of L. rham. GG. L. rham. GG population maintained over recommended levels for probiotic action (10⁶ cfu g⁻¹) along storage, however, viable cells after gastric stress were only above this level during the first 14 days. Pathogen survival after gastric stress was <1% after 7 days at 5 °C. Moreover, apple wedges quality was not affected by L. rham. GG addition. Thus, L. rham. GG could be a suitable probiotic for minimally-processed apples capable to reduce L. monocytogenes growth; nevertheless shelf life should not be higher to 14 days to guarantee the probiotic effect.