Rapid Quality Evaluation Research Articles

Rapid chain tracing of polypeptide backbones in electron-density maps

A method for the rapid tracing of polypeptide backbones has been developed. The method creates an approximate chain tracing that is useful for visual evaluation of whether a structure has been solved and for use in scoring the quality of electron-density maps. The essence of the method is to (i) sample candidate C(alpha) positions at spacings of approximately 0.6 A along ridgelines of high electron density, (ii) list all possible nonapeptides that satisfy simple geometric and density criteria using these candidate C(alpha) positions, (iii) score the nonapeptides and choose the highest scoring ones, and (iv) find the longest chains that can be made by connecting nonamers. An indexing and storage scheme that allows a single calculation of most distances and density values is used to speed up the process. The method was applied to 42 density-modified electron-density maps at resolutions from 1.5 to 3.8 A. A total of 21 428 residues in these maps were traced in 24 CPU min with an overall r.m.s.d. of 1.61 A for C(alpha) atoms compared with the known refined structures. The method appears to be suitable for rapid evaluation of electron-density map quality.

Use of hyperspectral imaging for evaluation of the shelf-life of fresh white button mushrooms (Agaricus bisporus) stored in different packaging films

Abstract The shelf life of mushrooms packaged using different polymer top-films (PVC, PET with different levels of perforations) was investigated using hyperspectral imaging (HSI). Packaged mushrooms were stored at 4 ± 0.2 °C for 14 days and weight loss, Hunter L, a, b values, maturity index and in-pack gas composition (% CO2 and O2) were also measured. The results obtained showed that the PET film perforated with small holes (1 mm in diameter) was generally superior in terms of maintaining overall mushroom quality. Regression models were built to correlate HSI data with measured quality parameters. Prediction maps were generated from hyperspectral data to show the model performance at pixel level. Results presented in this work show hyperspectral imaging can be used to evaluate the effect of different packaging systems on mushroom quality and that perforated PET packaging film is a viable alternative to the conventional PVC packaging, facilitating an increase in shelf life from 10 to 14 days. Industrial relevance The present study demonstrates HSI can be used for rapid evaluation of mushroom quality facilitating non-destructive evaluation of the effect of packaging systems on mushroom shelf-life. In addition, this work suggests an effective packaging solution to extend shelf life of mushrooms during storage. The proposed solution potentially improves the packaging recyclability as the same polymer material (PET) is used for the tray and top film, compared to conventional mushroom packaging where PVC is used for the top film and polypropylene (PP) for the tray.

Estimation of olive oil acidity using FT-IR and partial least squares regression

Olive oil characteristics are directly related to olive quality. Information about olive quality is of paramount importance to olive and olive oil producers, in order to establish its price. Real-time characterization of the olives avoids mixtures of high quality with low quality fruits, and allows improvement of olive oil quality. This work describes an indirect determination of olive acidity and that allows a rapid evaluation of olive oil quality. The applied method combines chemical analysis (30 min Soxhlet olive pomace extraction) in tandem with a spectroscopic technique (FT-IR) and multivariate regression (PLS1). The most suitable calibration model found used SNV pre-processing and was built with 4 Latent Variables giving a RMSECV of 8.7% and a Q2 of 0.97. This accurate calibration model allows the estimation of olive acidity using a FT-IR spectrum of the corresponding Soxhlet oil dry extract and therefore is a suitable method for indirect determination of FFA in olives.

Size‐Exclusion HPLC of Protein Using a Narrow‐Bore Column for Evaluation of Breadmaking Quality of Hard Spring Wheat Flours

ABSTRACTThe objective of this study was to investigate whether a narrow‐bore column (NBC) (300 × 4.5 mm, i.d.) improved analyses of unreduced proteins in flour by size‐exclusion HPLC (SE‐HPLC) and subsequent evaluation of breadmaking quality of hard spring wheat flours. Total protein extracts and SDS buffer extractable and unextractable proteins were analyzed by SE‐HPLC. NBC separated proteins in 10 min at a flow rate of 0.5 mL/min with similar resolution to a regular column (300 × 7.8 mm, i.d.) which took 30 min. SE‐HPLC absorbance area (AA) data obtained from an NBC showed comparable or superior repeatability and correlations with flour breadmaking characteristics when compared with those of a regular column. AA values of total protein that were calculated by adding AA values of SDS extractable and unextractable proteins showed greater repeatability and correlations with quality characteristics than those of actual total protein extracts. The improvements including employment of an NBC in SE‐HPLC provide enhancement of rapid quality evaluation and decreased consumption of hazardous organic solvents.

FT-IR Methodology for Quality Control of Arabinogalactan Protein (AGP) Extracted from Green Tea (Camellia sinensis)

A rapid methodology of quality control was developed for arabinogalactan proteins (AGP) extracted and purified from green tea. Using the vectorial angle method and IR spectrum analysis, the 1200-800 cm(-1) region in second-derivative IR spectra was determined as the key fingerprinting region of green tea AGP, with the 1090-900 cm(-1) region reflecting their conservative and common characteristics. In fact, the key monosaccharides, galactose (Gal) and arabinose (Ara), were shown to have intense peaks at about 1075 and 1045 cm(-1), respectively, and uronic acids at about 1018 cm(-1) in second-derivative IR spectra. The variable region was identified to be at about 1134-1094 and 900-819 cm(-1) and was probably due to compositional and structural differences between AGPs. The constructed methodology was tested on green tea AGP extracted by three treatments and purified to apparent homogeneity as water-extracted Camellia sinensis AGP (CSW-AGP), pectinase-extracted C. sinensis AGP (CSP-AGP), and trypsin-extracted C. sinensis AGP (CST-AGP) with an Ara/Gal ratio of 1.37, 1.57, and 1.82, respectively. Regarding in vitro antioxidant activity, the AGPs (CSW-AGP and CST-AGP) with higher similarity (closer cos theta values calculated for second-derivative IR spectra) exhibited a similar ability of chelating ferrous ions and had a similar capability for scavenging hydroxyl radicals. In conclusion, the combination of second-derivative IR spectrum analysis and the vectorial angle method has allowed a successful characterization of green tea AGPs and was shown to be suitable for their compositional and activity discrimination and rapid quality evaluation.

Rapid Estimation of the Composition of Animal Manure Compost by near Infrared Reflectance Spectroscopy

Composting of animal manure is an effective method of managing organic waste in agriculture and reducing environmental and human health risks. Rapid determination of composition of animal manure compost could facilitate the composting process and improve the quality of compost products. This study aimed to explore the feasibility of analysing the composition of animal manure compost based on a dried and fresh weight basis using near infrared (NIR) reflectance spectroscopy. A total of 120 animal manure compost samples, collected from 22 provinces in China, were scanned (4000–10,000 cm−1) and NIR calibrations were developed by partial least-square regression. Results showed that for dried and milled animal manure compost samples, the NIR method could accurately predict the contents of volatile solid (VS), total organic carbon (TOC) and total nitrogen (TN). The validation coefficient of determination ( r 2) and the ratio of the standard deviation of the reference data in the validation set to the standard error of prediction ( RPD) were 0.85 (2.60), 0.85 (2.56) and 0.97 (6.95), respectively. For fresh animal manure compost samples, the NIR method could provide accurate predictions of moisture, electriconic conductivity, VS, TOC and TN content with r2 and RPD of 0.98 (7.48), 0.90 (3.10), 0.94 (4.05) 0.91 (3.17), and 0.97 (6.11), respectively. Poorer calibrations were obtained for pH, carbon to nitrogen ratio and total phosphorus using either dry or fresh samples. Overall, the results indicated that NIR analysis could be very useful for the rapid quality evaluation of animal manure compost.

Characterisation of the volatiles of yellowfin tuna (Thunnus albacares) during storage by solid phase microextraction and GC–MS and their relationship to fish quality parameters

SummaryInvestigations were carried out to extract the volatile compounds of fish using solid phase microextraction (SPME) in order to develop a new rapid indicator for determining the quality of fish. Changes in the aroma composition of yellowfin tuna (Thunnus albacares) was studied at 30 °C and in ice, using SPME GC–MS, and their relationship with the fish quality parameters – total volatile basic nitrogen and sensory analysis – was determined using principal component analysis (PCA) and stepwise multiple regression analysis. Hexanal (30.9%) and 2‐nonanone (28.4%) were recorded in relatively high amounts in fresh fish, whereas 3‐methyl‐1‐butanol and 3‐hydroxy‐2‐butanone increased with storage time. PCA clearly differentiated the volatile profile of each sampling stage (P < 0.05) throughout storage treatments. Regression analysis showed a significant relationship between the fish quality and the levels of 3‐methyl‐1‐butanol and pentadecane. The findings highlight the possibility of developing a rapid quality evaluation method for fish using SPME GC–MS.

Rapid evaluation of olive oil quality by NIR reflectance spectroscopy

AbstractNIR spectroscopy calibrations have been developed for a range of quality parameters in olive oil, including FFA, PV, polyphenol content, induction time, chlorophyll, and the major FA. A set of 216 olive oil samples from throughout the Australian olive‐growing areas were used to provide a representative range of quality. The variation in the oils tested virtually covered the range of the chemical standard limits described by the International Olive Oil Council. A FOSS NIRSystems® 6500 spectrophotometer with a liquid cell holder was used. Multiple correlation coefficients squared (R2) for minor components stearic acid (0.86), and linolenic acid (0.85) were relatively low because the concentration range is very narrow compared with the reproducibility of the reference method. However, the major FA, oleic (0.99) and linoleic (1.00), FFA (0.97), and chlorophyll (0.98) provided high levels of accuracy. All of the parameters measured were sufficiently accurate for routine screening of olive oil.

Accuracy of sperm velocity assessment using the Sperm Quality Analyzer V.

Aim: The correct diagnosis of the functional capacity of human sperm is limited. The Sperm Quality Analyzer (SQA) with the visualization system (SQA V, Medical Electronic System, Hatavorzo, Israel), an upgraded version of SQA, was recently developed to provide a rapid and low-cost quantitative evaluation of sperm quality as well as sperm velocity assessment. The aim of the present study was to evaluate whether the SQA V's new parameters correlate with computer-aided sperm analysis (CASA) estimates. Methods: Semen quality analysis of 66 fresh samples was determined using SQA V and CASA. Results: There were significant correlations of total sperm concentration (P<0.001), sperm motility (P=0.145), and percentage of progressive motile sperm (P=0.001), between the SQA V variables and the CASA estimates. The sperm velocity assessed by SQA V was significantly correlated with some of the CASA estimates, including sperm motility (P=0.001), the percentage of progressively motile sperm (P<0.001), straight-line velocity (P<0.001), curvilinear velocity (P<0.001) and average path velocity (P<0.001). However, it did not correlate with amplitude of lateral head displacement, beat cross frequency, straightness, or linearity, assessed by CASA. Conclusion: Assessment of sperm motility has been shown as one of the important factors to predict the functional capacity of human sperm. On the basis of the present study, SQA V is considered useful for screening sperm quality in the management of male infertility. (Reprod Med Biol 2003; 2: 151-157).

Rapid evaluation of imprint quality using optical scatterometry

Optical scatterometry was used for the rapid and nondestructive testing of submicron and micron scale periodic patterns imprinted into the Shipley Microposit S1805 photoresist with the thickness of nearly 0.2 μm. Imprints were made using asymmetrical heating of imprint system and separation of the stamp without cooling cycle. Tests have showed that optimal conditions of imprint lithography with acceptable uniformity and repeatability are achieved when temperature is set to 120–130 °C, holding time is 60–90 s, and pressure is equal to 4 MPa. In the region of 100–110 °C imprint quality is poor because of the dominating elastic response of polymer layer. Rising of the temperature up to 140 °C leads to the noticeable liquefaction of the polymer. Thus, rapid separation of the mold and substrate cause certain damage of the imprinted grating.

Rapid evaluation of pasture quality for a critically endangered mammal, the northern hairy-nosed wombat (Lasiorhinus krefftii)

Near-infrared spectroscopy (NIRS) was used to predict the nutritive value of forage species available to the critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii). Nutritive attributes of the forage successfully estimated included total nitrogen concentration, fibre (including neutral detergent fibre, acid detergent fibre and acid lignin), organic matter, water soluble carbohydrates and in vitro dry matter digestibility. The reported results demonstrate the seasonal variability of the forage resource available to L. krefftii in its tropical savanna habitat. Multivariate modelling of the spectra enabled the nutritive value of forage samples to be estimated with coefficients of determination (r2) of 0.770–0.995 and standard errors of the cross-validation of 0.070–2.850 using a modified partial least-squares analysis technique. The standard error of the laboratory was 0.02–1.42. This study demonstrates that broad-based NIRS predictive equations can be used to predict the nutritive value of a number of plant types available to a herbivore over time. By using NIRS the analyst can rapidly analyse large numbers of samples with limited reduction of precision, thereby enabling large-scale ecological applications that may have previously been impeded by time and costs.

Use of PCR analysis for detecting low levels of bacteria and mold contamination in pharmaceutical samples

PCR assays were developed and compared to standard methods for quality evaluation of pharmaceutical raw materials and finished products with low levels of microbial contamination. Samples were artificially contaminated with less than 10 CFU of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Aspergillus niger. Bacterial DNA was extracted from each enrichment broth by mild lysis in Tris–EDTA–Tween 20 buffer containing proteinase K while mold DNA was extracted by boiling samples in Tris–EDTA–SDS buffer for 1 h. A 10-μl aliquot of extracted DNA was added to Ready-To-Go PCR beads and specific primers for E. coli, S. aureus, and P. aeruginosa. However, 50-μl aliquots of extracted mold DNA were used for amplification of specific A. niger DNA sequences. Standard methods required 6–8 days while PCR detection of all microorganisms was completed within 27 h. Low levels of microbial contamination were detected in all raw materials and products using PCR assays. Rapid quality evaluation of pharmaceutical samples resulted in optimization of product manufacturing, quality control, and release of finished products.

Molecular Detection of Burkholderia cepacia in Toiletry, Cosmetic, and Pharmaceutical Raw Materials and Finished Products

A polymerase chain reaction (PCR) assay was developed and compared with standard methods for rapid detection of Burkholderia cepacia, a major industrial contaminant, in cosmetic and pharmaceutical raw materials and finished products. Artificially contaminated samples were incubated for 24 h in trypticase soy broth containing 4% Tween 20 and 0.5% soy lecithin. DNA was extracted from each sample using a proteinase K-tris-EDTA-Tween 20 treatment at 35 degrees C. The extracted DNA was added to Ready-To-Go PCR beads and specific DNA primers for B. cepacia. The B. cepacia DNA primers coded for a 209-base pair (bp) fragment of the 16S rRNA ribosomal gene. No DNA amplification was observed in samples that were not spiked with B. cepacia. However, all contaminated samples showed the specific 209-bp fragment for B. cepacia. There was a 100% correlation between standard methods and the PCR assay. Standard microbiological methods required 5-6 days for isolation and identification of spiked microorganisms, whereas PCR detection and identification was completed in 27 h. PCR detection of B. cepacia allows for rapid quality evaluation of cosmetic and pharmaceutical raw materials and finished products.

A preliminary report on the application of Macrobrachium amazonicum Heller, 1862 (Decapoda:Palaemonidae) as a biomarker

A method is described for the rapid evaluation of water quality through monitoring the respiratory response of Macrobrachium amazonicum a dominant benthic macroinvertebrate of Northeast Brazil constituting a source of nutrients for fish and humans. By maintaining the organism in a respiratory chamber supplied with test water (gravity-feed) at a rate of 10 ml min-1, it is possible to identify when the organism is in stress. Respiration rates were determined before (control) and after test concentrations were introduced. The herbicide paraquat was used because of its popularity with sugar cane cultivators and reported low toxicity. There was a discrete increase in respiration associated with acute toxicity at all concentrations tested above 0.035 μg l-1. At 0.01 μg l-1 no increase in respiration was observed and prawn survival continued until the experiment was terminated (25 days).

A new interference-free lysine biosensor using a non-conducting polymer film

An electrochemical biosensor for the determination of lysine to be used for rapid evaluation of food quality has been developed. Platinum electrodes have been coated by electropolymerisation with 1,2-diaminobenzene (1.2-DAB) using cyclic voltammetry. The reduction in the oxidation of interferents compared with the bare platinum electrode was 100% for ascorbic acid, 99% for acetaminophen and 99% for cysteine. The enzyme L-lysine-α-oxidase was then immobilised onto the polymer layer by passive adsorption and a calibration curve for lysine constructed. This gave a linear range of 1×10 −5 mol/l to 1×10 −3 mol/l and a limit of detection of 2×10 −7 mol/l.

Studies evaluating the applicability of utilising the same concentration techniques for the detection of protozoan parasites and viruses in water

In this study concentration techniques regularly used for viral detection, i.e. flat-bed ultrafiltration and Filterite cartridge filtration, were evaluated for their efficacies in the recovery of protozoan parasites from water. Recovery of cysts was studied using tap water seeded with Giardia muris cysts and compared to methods designed for the detection of protozoan parasites. Recovery of cysts utilizing 1.2µm membrane filters was 11.1% (4.5-23%) compared to 11.6% (2.7-25.5%) with ultrafiltration (pore size 46-50 Å, with a molecular cut off of 50 000 daltons). Comparison of these methods for the isolation of Giardia cysts and Cryptosporidium oocysts from environmental water samples also indicated a similar efficacy. The recovery of cysts from 1001 of seeded samples using a Cuno wynd cartridge filter was 12.2% (1.6-46%) compared to 13.4% (5-24.2%) using a Filterite cartridge filter. Although the results indicated similar recovery efficacies for these two methods, use of Filterite resulted in a more consistent recovery rate. This study also indicated that the use of cartridge filters for the processing of large volume water samples (1001) showed a slightly better recovery efficacy than the flat-bed filtration technique which limits sample volume to about 101. This study shows that concentration techniques utilised for the isolation of enteric viruses can also be applied for the detection of protozoan parasites from water. This procedure allows for co-analysis of both viruses and protozoan parasites and provides a more rapid and cost-effective evaluation of water quality.

Studies evaluating the applicability of utilising the same concentration techniques for the detection of protozoan parasites and viruses in water

In this study concentration techniques regularly used for viral detection, i.e. flat-bed ultrafiltration and Filterite cartridge filtration, were evaluated for their efficacies in the recovery of protozoan parasites from water. Recovery of cysts was studied using tap water seeded with Giardia muris cysts and compared to methods designed for the detection of protozoan parasites. Recovery of cysts utilizing 1.2µm membrane filters was 11.1% (4.5–23%) compared to 11.6% (2.7–25.5%) with ultrafiltration (pore size 46–50 A, with a molecular cut off of 50 000 daltons). Comparison of these methods for the isolation of Giardia cysts and Cryptosporidium oocysts from environmental water samples also indicated a similar efficacy. The recovery of cysts from 1001 of seeded samples using a Cuno wynd cartridge filter was 12.2% (1.6–46%) compared to 13.4% (5–24.2%) using a Filterite cartridge filter. Although the results indicated similar recovery efficacies for these two methods, use of Filterite resulted in a more consistent recovery rate. This study also indicated that the use of cartridge filters for the processing of large volume water samples (1001) showed a slightly better recovery efficacy than the flat-bed filtration technique which limits sample volume to about 101.This study shows that concentration techniques utilised for the isolation of enteric viruses can also be applied for the detection of protozoan parasites from water. This procedure allows for co-analysis of both viruses and protozoan parasites and provides a more rapid and cost-effective evaluation of water quality.

Aspects of lead/acid battery technology 5. Dry charging of formed negative plates

The objective in the dry charging of formed negative plates in lead/acid batteries is to preserve the highly active sponge lead material from attack by atmospheric oxygen until the dry and unfilled charged battery is put into service. This review discusses the following methods that are commonly used for dry charging: (i) drying in a vacuum; (ii) drying by direct application of superheated steam; (iii) drying in an inert-gas atmosphere; (iv) removal of water by hot kerosene and subsequent drying in a closed kerosene vapour chamber and (v) drying in the presence of anti-oxidants. The protection of dry-charge characteristics, rapid evaluation of dry-charge quality and testing for excess wax or oil inhibitors are also described.

MKTA-2500 microanalyzer for engineering monitoring

Figure 2 shows diagrams providing rapid quality evaluation on a standard alloy. The resolving power is governed by the scale of the recording and is a few degrees, which enables one to judge whether the percent composition is correct and to maintain technological conditions. With a multicomponent alloy, this rapid method can be used to provide tolerance control, while with a two-component one, it can be used to judge the exact composition [3].

A Diagnostic Test Strip for the Semiquantitative Determination of Trimethylamine in Fish

ABSTRACTA diagnostic test strip assay for trimethylamine (TMA) was developed for the rapid evaluation of microbiological quality of seafood. The method is based on trimethylamine dehydrogcnase and is specific for TMA. Compounds such as trimethylamine oxide, dimethylamine, monomethylamine, and ammonia did not interfere with the measurement of TMA. The entire procedure required less than 5 min at room temperature. Visual comparison of unknown samples to a set of trimethylamine standards enabled the semiquantitative analysis in the range of 0.2 to 5 μg trimethylamine nitrogen. The method enabled the rapid evaluation of seafood quality and correlated well with the traditional spectrophotometric procedure for the determination of TMA.