Effect of extrinsic factors on the production of guaiacol by Alicyclobacillus spp.

Alicyclobacillus spp. is of significance to the fruit juice industry due to the production of guaiacol. Studies on Alicyclobacillus regarding guaiacol focus mainly on novel ways to detect guaiacol or evaluate guaiacol-producing potential of isolated Alicyclobacillus. Basic studies on factors that induce or affect the production of guaiacol and the conversion pathway of vanillic acid to guaiacol are not available. The goal of this study was to evaluate how extrinsic factors can affect the production of guaiacol by Alicyclobacillu s isolates. Guaiacol-producing Alicyclobacillus isolates 1016 and 1101 were used in this study and the effects of temperature (25 to 55 °C), pH (3.0 to 5.5), and oxygen concentration on guaiacol production in laboratory media was investigated. Maximum production of guaiacol by isolate 1016 was detected within 9 h when incubated at 43 °C, pH 4.0, under microaerophilic conditions. Isolate 1101 produced detectable amounts of guaiacol within 8 h at pH 5.0. However, maximum guaiacol production was achieved within 14 h by isolate 1101 when incubated at 50 °C. Our results indicate that the production of guaiacol, contrary to common belief, is a rapid reaction under desirable conditions specific to each isolate. The results of this study can be useful for developing rapid guaiacol monitoring methods for Alicyclobacillus-related spoilage or be applied to more detailed enzyme-related studies.

Molecular level activation insights from a NR2A/NR2B agonist.

N-methyl D-aspartate receptors (NMDARs), a subclass of glutamate receptors have broad actions in neural transmission for major brain functions. Overactivation of NMDARs leading to "excitotoxicity" is the underlying mechanism of neuronal death in a number of neurological diseases, especially stroke. Much research effort has been directed toward developing pharmacological agents to modulate NMDAR actions for treating neurological diseases, in particular stroke. Here, we report that Alliin, a sulfoxide in fresh garlic, exhibits affinity toward NR2A as well as NR2B receptors based on virtual screening. Biological activities of Alliin on these two receptors were confirmed in electrophysiological studies. Ligand-binding site closure, a structural change precluding ion channel opening, was observed with Alliin during 100 ns molecular dynamics simulation. Alliin interactions with NR2A and NR2B suggest that residues E/A413, H485, T690, and Y730 may play important roles in the conformation shift. Activation of NR2A and NR2B by Alliin can be differentiated from that caused by glutamate, the endogenous neurotransmitter. These characteristic molecular features in NR2A and NR2B activation provide insight into structural requirements for future development of novel drugs with selective interaction with NR2A and NR2B for treating neurological diseases, particularly stroke.

Discovery of novel insomnia leads from screening traditional Chinese medicine database.

Insomnia is a prominent modern disease that affects an increasing population. Undesirable side effects of commercial drugs highlight the need to develop novel insomnia drugs. Virtual screening of traditional chinese medicine Database@Taiwan (TCM Database@Taiwan) identified 2-O-Caffeoyl tartaric acid (1), 2-O-Feruloyl tartaric acid (2), and Mumefural (3) as potential agonists for both gamma-amino butyric acid (GABA) or benzodiazepine (BZ) binding sites. The TCM candidates exhibited higher affinity than GABA and Zolpidem, a phenomenon that could be attributed to higher quantity of stabilizing H-bonds. Efficacy profiles using support vector machines and pharmacophore contour also suggest drug potential of the TCM candidates. Fragments added to the de novo derivatives 3a, 3b, 3c for GABA binding site, and 1a, 2a, and 3d for BZ binding site contributed to new binding sites and structural stability, further optimizing binding to GABA or BZ binding sites. Increased opening of the ion channel by candidate ligands provide strong support for their potential biological functions. The dual binding properties of the TCM candidates present a unique opportunity to develop twin-targeting drugs with less side effects. Derivative structures can be used as starting points for developing high affinity GABAA receptor agonists with specificity towards GABA binding site and BZ binding site.

Drug design for neuropathic pain regulation from traditional Chinese medicine.

FAAH-like anandamide transporter (FLAT) regulates anandamide transport for hydrolysis and may be an attractive drug target for pain regulation. We aimed to discover potential FLAT antagonists from traditional Chinese medicine (TCM) using virtual screening, ligand-based drug design and molecular dynamics simulation (MD). Guineensine and Retrofractamide A exhibited high Dock Scores in FLAT. Consensus from multiple linear regression (MLR; R(2) = 08973) and support vector machine (SVM; R(2) = 0.7988) showed similar bioactivities for Guineensine and the FAAH-1 inhibitor (9Z)-1-(5-pyridin-2-yl-1,3,4-oxadiazol-2-yl)octadec-9-en-1-one. Contour of Guineensine to CoMFA and CoMSIA features also imply bioactivity. MD revealed shake or vibration in the secondary structure of FLAT complexed with Guineensine and (9Z)-1-(5-pyridin-2-yl-1,3,4-oxadiazol-2-yl)octadec-9-en-1-one. Ligand movement might contribute to protein changes leading to vibration patterns. Violent vibrations leading to an overall decrease in FLAT function could be the underlying mechanism for Guineensine. Here we suggest Guineensine as a drug-like compound with potential application in relieving neuropathic pain by inhibiting FLAT.

Han ethnicity-specific type 2 diabetic treatment from traditional Chinese medicine?

Insulin-degrading enzyme (IDE) gene is one of the type 2 diabetes mellitus susceptibility genes specific to the Han Chinese population. IDE, a zinc-metalloendopeptidase, is a potential target for controlling insulin degradation. Potential lead compounds for IDE inhibition were identified from traditional Chinese medicine (TCM) through virtual screening and evaluation of their pharmacokinetic properties of absorption, distribution, metabolism, excretion, and toxicity. Molecular dynamics (MD) simulation was performed to validate the stability of complexes from docking simulation. The top three TCM compounds, dihydrocaffeic acid, isopraeroside IV, and scopolin, formed stable H-bond interactions with key residue Asn139, and were linked to active pocket residues His108, His112, and Glu189 through zinc. Torsion angle trajectories also indicated some stable interactions for each ligand with IDE. Molecular level analysis revealed that the TCM candidates might affect IDE through competitive binding to the active site and steric hindrance. Structural feature analysis reveals that high amounts of hydroxyl groups and carboxylic moieties contribute to anchor the ligand within the complex. Hence, we suggest the top three TCM compounds as potential inhibitor leads against IDE protein to control insulin degradation for type 2 diabetes mellitus. An animated interactive 3D complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:29.

A possible strategy against head and neck cancer: in silico investigation of three-in-one inhibitors.

Overexpression of epidermal growth factor receptor (EGFR), Her2, and uroporphyrinogen decarboxylase (UROD) occurs in a variety of malignant tumor tissues. UROD has potential to modulate tumor response of radiotherapy for head and neck cancer, and EGFR and Her2 are common drug targets for the treatment of head and neck cancer. This study attempts to find a possible lead compound backbone from TCM Database@Taiwan ( http://tcm.cmu.edu.tw/ ) for EGFR, Her2, and UROD proteins against head and neck cancer using computational techniques. Possible traditional Chinese medicine (TCM) lead compounds had potential binding affinities with EGFR, Her2, and UROD proteins. The candidates formed stable interactions with residues Arg803, Thr854 in EGFR, residues Thr862, Asp863 in Her2 protein, and residues Arg37, Arg41 in UROD protein, which are key residues in the binding or catalytic domain of EGFR, Her2, and UROD proteins. Thus, the TCM candidates indicated a possible molecule backbone for evolving potential inhibitors for three drug target proteins against head and neck cancer.

Memory enhancement by traditional Chinese medicine?

Cognitive repair by insulin-like growth factor-I (IGF-I) through activation of insulin-like growth factor-I receptor (IGF-IR) is well established, but not used for clinical therapy due to its link to cancer. We hypothesize that IGF-IR activation rather than IGF-I per se may be essential for cognitive repair and attempted to identify ligands from traditional Chinese medicine (TCM) with drug-like potential towards IGF-IR. TCM ligands, 3-(2-carboxyphenyl)-4(3H)-quinazolinone from Isatisin digotica, (+)-N-methyllaurotetanine from Lindera aggregate, and (+)-1(R)-Coclaurine from Nelumbonucifera Gaertn, exhibited high binding affinities and good blood brain barrier (BBB) penetration crucial for accessing IGF-IR. Stable complex formation of the candidates was observed during molecular dynamics (MD) simulation. Interactions with Leu975 and Gly1055 or Asp1056 were important for ligand binding. Amino acid distance analysis revealed residues 974/975, 984-986, 996-1006, 1040-1056, and 1122-1135 as "hotspots" for ligand binding in IGF-IR. Versatile entry pathways for the TCM candidates suggest high accessibility to the binding site. Blockage of the binding site opening by the TCM candidates limits binding site access by other compounds. Multiple linear regression (R² = 0.9715), support vector machine (R² = 0.9084), Bayesian network (R² =0.8233) comparative molecular field analysis (CoMFA, R² = 0.9941), and comparative molecular similarity indices analysis (CoMSIA, R² = 0.9877) models consistently suggest that the TCM candidates might exert bioactivity on IGF-IR. Contour of representative MD conformations to CoMFA and CoMSIA maps exhibits similar results. Properties including BBB passage, evidence of ability to form stable complexes with IGF-IR by MD simulation, and predicted bioactivity suggest that the TCM candidates have drug-like properties and might have potential as cognitive-enhancing drugs.

Uroporphyrinogen decarboxylase as a potential target for specific components of traditional Chinese medicine: a virtual screening and molecular dynamics study.

Uroporphyrinogen decarboxylase (UROD) has been suggested as a protectant against radiation for head and neck cancer (HNC). In this study, we employed traditional Chinese medicine (TCM) compounds from TCM Database@Taiwan (http://tcm.cmu.edu.tw/) to screen for drug-like candidates with potential UROD inhibition characteristics using virtual screening techniques. Isopraeroside IV, scopolin, and nodakenin exhibited the highest Dock Scores, and were predicted to have good Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) properties. Two common moieties, 2H-chromen-2-one and glucoside, were observed among the top TCM candidates. Cross comparison of the docking poses indicated that candidates formed stable interactions with key binding and catalytic residues of UROD through these two moieties. The 2H-chromen-2-one moiety enabled pi-cation interactions with Arg37 and H-bonds with Tyr164. The glucoside moiety was involved in forming H-bonds with Arg37 and Asp86. From our computational results, we propose isopraeroside IV, scopolin, and nodakenin as ligands that might exhibit drug-like inhibitory effects on UROD. The glucoside and 2H-chromen-2-one moieties may potentially be used for designing inhibitors of UROD.

In silico identification of potent pancreatic triacylglycerol lipase inhibitors from traditional Chinese medicine.

Pancreatic triacylglycerol lipase (PNLIP) are primary lipases that are critical for triacylglyceride digestion in human. Since reduced metabolism of triacylglyceride might be a plausible concept for weight loss, we screened for potential PNLIP inhibitors from traditional Chinese medicine (TCM) with the aim to identify weight loss candidate compounds. TCM candidates Aurantiamide, Cnidiadin, and 2-hexadecenoic acid exhibited higher Dock Scores than the commercial drug Orlistat, and were also predicted to have inhibitory characteristics against PNLIP using constructed MLR (R(2) = 0.8664) and SVM (R(2) = 0.9030) models. Molecular dynamics indicated that the TCM-PNLIP complexes formed were stable. We identified that the PNLIP binding site has several residues that can serve as anchors, and a hydrophobic corridor that provides additional stability to the complex. Aurantiamide, Cnidiadin, and 2-hexadecenoic acid all have features that correspond to these binding site features, indicating their potential as candidates for PNLIP inhibitors. The information presented in this study may provide helpful insights to designing novel weight-control drugs.

Three-in-one agonists for PPAR-α, PPAR-γ, and PPAR-δ from traditional Chinese medicine.

Nowadays, the occurrence of metabolic syndrome, which is characterized by obesity and clinical disorders, has been increasing rapidly over the world. It induces several serious chronic diseases such as cardiovascular disease, dyslipidemia, gall bladder disease, hypertension, osteoarthritis, sleep apnea, stroke, and type 2 diabetes mellitus. Peroxisome proliferator-activated receptors (PPARs), which have three isoforms: PPAR-α, PPAR-γ, and PPAR-δ, are key regulators of adipogenesis, lipid and carbohydrate metabolism, and are potential drug targets for treating metabolic syndrome. The traditional Chinese medicine (TCM) compounds from TCM Database@Taiwan ( http://tcm.cmu.edu.tw/ ) were employed to virtually screen for potential PPAR agonists, and structure-based pharmacophore models were generated to identify the key interactions for each PPAR protein. In addition, molecular dynamics (MD) simulation was performed to evaluate the stability of the PPAR-ligand complexes in a dynamic state. (S)-Tryptophan-betaxanthin and berberrubine, which have higher Dock Score than controls, form stable interactions during MD, and are further supported by the structure-based pharmacophore models in each PPAR protein. Key features include stable H-bonds with Thr279 and Ala333 of PPAR-α, with Thr252, Thr253 and Lys331 of PPAR-δ, and with Arg316 and Glu371 of PPAR-γ. Hence, we propose the top two TCM candidates as potential lead compounds in developing agonists targeting PPARs protein for treating metabolic syndrome.

Identifying HER2 inhibitors from natural products database.

The relationship between abnormal HER2 expression and cancer is important in cancer therapeutics. Formation and spread of cancer cells may be restricted by inhibiting HER2. We conducted ligand-based and structure-based studies to assess the potency of natural compounds as potential HER2 inhibitors. Multiple linear regression (MLR) and support vector machine (SVM) models were constructed to predict biological activities of natural compounds, and molecular dynamics (MD) was used to assess their stability with HER2 under a dynamic environment. Predicted bioactivities of the natural compounds ranged from 6.014-9.077 using MLR (r(2) = 0.7954) and 5.122-6.950 using SVM (r(2) = 0.8620). Both models were in agreement and suggest bioactivity based on candidate structure. Conformation changes caused by MD favored the formation of stabilizing H-bonds. All candidates had higher stability than Lapinatib, which may be due to the number and spatial distribution of additional H-bonds and hydrophobic interactions. Amino acids Lys724 and Lys736 are critical for binding in HER2, and Thr798, Cys805, and Asp808 are also important for increased stability. Candidates may block the entrance to the ATP binding site located within the inner regions and prevent downstream activation of HER2. Our multidirectional approach indicates that the natural compounds have good ligand efficacy in addition to stable binding affinities to HER2, and should be potent candidates of HER2 inhibitors. With regard to drug design, designing HER2 inhibitors with carboxyl or carbonyl groups available for H-bond formation with Lys724 and Lys736, and benzene groups for hydrophobic contact with Cys805 may improve protein-ligand stability.

Lose weight with traditional chinese medicine? Potential suppression of fat mass and obesity-associated protein.

Overweight and obesity are common health problems in modern society, particularly in developed countries. Excessive body mass has been linked to numerous diseases, such as cardiovascular diseases, diabetes, and cancer. Fat mass and obesity-associated protein (FTO) activity have direct impact on food intake and results in obesity. Inhibition of FTO activity may cause weight loss and reduce obese-linked health risks. We investigated the potential weight loss effects of traditional Chinese medicine (TCM), particularly by inhibiting FTO functions. Molecular docking was performed to screen TCM compounds from TCM Database@Taiwan (http://tcm.cmu.edu.tw). Three candidates were identified that contained either a tetrahydropyridine group or potent electronegative phenol group in the structure scaffold. Molecular dynamics simulation analysis of the docking poses of each complex indicated stabilizing trends in the protein-ligand complex movements. In addition, the number of hydrogen bonds increased throughout the 20 ns simulation. These results suggest that these TCM candidates could be potential FTO inhibitors through competitive inhibition.

Identification of potent EGFR inhibitors from TCM Database@Taiwan.

Overexpression of epidermal growth factor receptor (EGFR) has been associated with cancer. Targeted inhibition of the EGFR pathway has been shown to limit proliferation of cancerous cells. Hence, we employed Traditional Chinese Medicine Database (TCM Database@Taiwan) (http://tcm.cmu.edu.tw) to identify potential EGFR inhibitor. Multiple Linear Regression (MLR), Support Vector Machine (SVM), Comparative Molecular Field Analysis (CoMFA), and Comparative Molecular Similarities Indices Analysis (CoMSIA) models were generated using a training set of EGFR ligands of known inhibitory activities. The top four TCM candidates based on DockScore were 2-O-caffeoyl tartaric acid, Emitine, Rosmaricine, and 2-O-feruloyl tartaric acid, and all had higher binding affinities than the control Iressa®. The TCM candidates had interactions with Asp855, Lys716, and Lys728, all which are residues of the protein kinase binding site. Validated MLR (r²â€Š= 0.7858) and SVM (r²â€Š= 0.8754) models predicted good bioactivity for the TCM candidates. In addition, the TCM candidates contoured well to the 3D-Quantitative Structure-Activity Relationship (3D-QSAR) map derived from the CoMFA (q²â€Š= 0.721, r²â€Š= 0.986) and CoMSIA (q²â€Š= 0.662, r²â€Š= 0.988) models. The steric field, hydrophobic field, and H-bond of the 3D-QSAR map were well matched by each TCM candidate. Molecular docking indicated that all TCM candidates formed H-bonds within the EGFR protein kinase domain. Based on the different structures, H-bonds were formed at either Asp855 or Lys716/Lys728. The compounds remained stable throughout molecular dynamics (MD) simulation. Based on the results of this study, 2-O-caffeoyl tartaric acid, Emitine, Rosmaricine, and 2-O-feruloyl tartaric acid are suggested to be potential EGFR inhibitors.

High performance screening, structural and molecular dynamics analysis to identify H1 inhibitors from TCM Database@Taiwan.

New-type oseltamivir-resistant H1N1 influenza viruses have been a major threat to human health since the 2009 flu pandemic. To resolve the drug resistance issue, we aimed to identify a new type of inhibitors against H1 from traditional Chinese medicine (TCM) by employing the world's largest TCM database () for virtual screening and molecular dynamics (MD). From the virtual screening results, sodium (+)-isolaricireinol-2 alpha-sulfate, sodium 3,4-dihydroxy-5-methoxybenzoic acid methyl ester-4-sulfate, sodium (E)-7-hydroxy-1,7-bis(4-hydroxyphenyl)hept-5-ene-3S-sulfonate, and 3-methoxytyramine-betaxanthin were identified as potential drug-like compounds. MD simulation of the binding poses with the key residues Asp103 and Glu83, as well as other binding site residues, identified higher numbers of hydrogen bonds than N-Acetyl-D-Glucosamine (NAG), the natural ligand of the esterase domain in H1. Ionic bonds, salt bridges, and electrostatic energy also contribute to binding stability. Key binding residues include Lys71, Glu83, Asp103, and Arg238. Structural moieties promoting H-bond or salt bridge formations at these locations greatly contribute to a stable ligand-protein complex. An available sodium atom for ionic interactions with Asp103 can further stabilize the ligands. Based on virtual screening, MD simulation, and interaction energy evaluation, TCM candidates demonstrate good potential as novel H1 inhibitors. In addition, the identified stabilizing features can provide insights for designing highly stable H1 inhibitors.

Investigation into potent inflammation inhibitors from traditional Chinese medicine.

Microsomal prostaglandin E synthase-1 (mPGES-1) is the key enzyme for prostaglandin E2 (PGE2) generation during inflammation and is a potential target for designing anti-inflammatory drugs. Potential inhibitors of m-PGES-1 were selected from traditional Chinese medicine (TCM Database@Taiwan) based on the pharmacophore map generated by the top HypoGen hypothesis and validated using structure- and ligand-based analysis. Key features for potential m-PGES-1 inhibitors include pi-interactions and H-bond donors. TCM compounds, shanciol B, shanciol A, castilliferol, and aurantiamide acetate, contoured to the quantitative structure-activity relationship pharmacophore and exhibited high docking scores and binding stability with m-PGES-1. Bioactivity models multiple linear regression (MLR) and support vector machine also supported activity predictions for the candidate compounds. Our results indicate that the investigated TCM compounds could be of use for development into mPGES-1 inhibitors.

Two birds with one stone? Possible dual-targeting H1N1 inhibitors from traditional Chinese medicine.

The H1N1 influenza pandemic of 2009 has claimed over 18,000 lives. During this pandemic, development of drug resistance further complicated efforts to control and treat the widespread illness. This research utilizes traditional Chinese medicine Database@Taiwan (TCM Database@Taiwan) to screen for compounds that simultaneously target H1 and N1 to overcome current difficulties with virus mutations. The top three candidates were de novo derivatives of xylopine and rosmaricine. Bioactivity of the de novo derivatives against N1 were validated by multiple machine learning prediction models. Ability of the de novo compounds to maintain CoMFA/CoMSIA contour and form key interactions implied bioactivity within H1 as well. Addition of a pyridinium fragment was critical to form stable interactions in H1 and N1 as supported by molecular dynamics (MD) simulation. Results from MD, hydrophobic interactions, and torsion angles are consistent and support the findings of docking. Multiple anchors and lack of binding to residues prone to mutation suggest that the TCM de novo derivatives may be resistant to drug resistance and are advantageous over conventional H1N1 treatments such as oseltamivir. These results suggest that the TCM de novo derivatives may be suitable candidates of dual-targeting drugs for influenza.

Inactivation of Escherichia coli O157:H7 and Salmonella spp. on alfalfa seeds by caprylic acid and monocaprylin.

Alfalfa and other seed sprouts have been implicated in several Escherichia coli O157:H7 and Salmonella spp. human illness outbreaks in the U.S. Continuing food safety issues with alfalfa seeds necessitate the need for discovery and use of novel and effective antimicrobials. The potential use of caprylic acid (CA) and monocaprylin (MC) for reducing E. coli O157:H7 and Salmonella spp. populations on alfalfa seeds was evaluated. The effectiveness of three concentrations of CA and MC (25, 50, and 75 mM) to reduce E. coli O157:H7 and Salmonella spp. populations in 0.1% peptone water and on alfalfa seeds was evaluated. Surviving populations of E. coli O157:H7 and Salmonella spp. were enumerated by direct plating on tryptic soy agar (TSA). Non-inoculated alfalfa seeds were soaked for up to 120 min to evaluate the effect of CA and MC solutions on seed germination rate. For planktonic cells, the efficacy of the treatments was: 75 MC > 50 MC > 25 MC > 75 CA > 50 CA > 25 CA. Both E. coli O157:H7 and Salmonella spp. were reduced to below the detection limit (0.6 log CFU/ml) within 10 min of exposure to 75 MC from initial populations of 7.65 ± 0.10 log CFU/ml and 7.71 ± 0.11 log CFU/ml, respectively. Maximum reductions of 1.56 ± 0.25 and 2.56 ± 0.17 log CFU/g for E. coli O157:H7 and Salmonella spp., respectively, were achieved on inoculated alfalfa seeds (from initial populations of 4.74 ± 0.62 logCFU/g and 5.27±0.20logCFU/g, respectively) when treated with 75 MC for 90 min. Germination rates of CA or MC treated seeds ranged from 84% to 99%. The germination rates of CA or MC soaked seeds and water soaked seeds (control) were similar (P > 0.05) for soaking times of ≤ 90 min. Monocaprylin (75 mM) can be used to reduce E. coli O157:H7 and Salmonella spp. on alfalfa seeds without compromising seed viability.

Control of foodborne pathogens on ready-to-eat roast beef slurry by epsilon-polylysine.

This study evaluates the antimicrobial effectiveness of epsilon-polylysine against Escherichia coli O157:H7, Salmonella typhimurium and Listeria monocytogenes in laboratory media and roast beef slurry. epsilon-Polylysine supplemented laboratory media and roast beef slurry were inoculated with three-strain cocktails of each pathogen and survival was periodically monitored using conventional spread plating. Inoculated laboratory media was stored at room temperature (22 degrees C) for 48 h, and inoculated roast beef slurry was stored at 4 degrees C for up to 7 days. Maximum log reductions in laboratory media/roast beef slurry were 6.01+/-1.43/3.81+/-0.37, >7.82+/-0.05/5.23+/-0.08, and 4.58+/-0.86/5.83+/-0.48 for E. coli O157:H7, S. typhimurium, and L. monocytogenes, respectively. Injured cells were produced as a result of exposure to polylysine. This study confirms the effectiveness of polylysine against pathogens in laboratory media, and demonstrates its potential as a novel antimicrobial agent in complex food matrix such as roast beef.

Efficacy of chlorine dioxide gas against Alicyclobacillus acidoterrestris spores on apple surfaces.

Alicyclobacillus acidoterrestris is a thermophilic spore-forming bacterium that spoils acidic juices. In the orchard, apples may be contaminated with spores which can potentially grow in the resulting juice and cause spoilage. This study was undertaken to evaluate the efficacy of gaseous chlorine dioxide against A. acidoterrestris spores on apple surfaces. A. acidoterrestris spores were inoculated onto apple surfaces and were placed at room temperature, in a tightly sealed chamber containing a chlorine dioxide generating sachet, low, medium, or high release, for 30 min, 1, 2, and 3 h. After exposure, surviving spores were enumerated on K agar. Chlorine dioxide treated apples were stored at 4 degrees C for 7 days to assess the effect on visual quality. Inoculated, untreated apples served as the visual quality control. After exposure to high and medium release sachets for 1 h, spores were reduced to an undetectable level, a 5 log10 reduction; however, visual quality was compromised. After 1, 2, and 3 h of exposure to low release sachets, spore reductions were 2.7, 3.7, and 4.5 log10, respectively. And, after 7 days of storage, there were no significant visual quality differences between the apples exposed to low release sachet for all treatment times when compared to the control. Gaseous chlorine dioxide can effectively reduce viable A. acidoterrestris spores on apple surfaces. Due to the efficacy and easy of use, chlorine dioxide gas sachets may be useful to maintain apple quality during storage and shipping.

Rapid discrimination of Alicyclobacillus strains in apple juice by Fourier transform infrared spectroscopy.

Alicyclobacillus spp. are thermoacidophilic, spore-forming bacteria. Some of which cause spoilage in pasteurized and heat-treated apple juice products through the production of guaiacol. Fourier transform infrared (FT-IR) spectroscopy was used to discriminate between eight Alicyclobacillus strains (WAC, 81-2, Oly#21, 51-1, KF, 1016, 1101, and A-Gala A4) in apple juice. FT-IR vibrational combination bands reflected compositional differences in the cell membranes of Alicyclobacillus strains in the "fingerprint region" at wavenumbers between 1500 and 800 cm(-1). Distinctive segregation among spectral sample clusters of different Alicyclobacillus strains was observed using principal component analysis (PCA). Two closely related strains (1016 and 1101) of Alicyclobacillus acidoterrestris could be distinguished, suggesting that this method can be highly selective. Results of soft independent modeling of class analogy (SIMCA) demonstrated that guaiacol-producing and non-guaiacol producing Alicyclobacillus strains could be differentiated up to 89% of the time. This technique may provide a tool for fruit juice producers to detect Alicyclobacillus rapidly and to monitor and control guaiacol formation.