Mild Processing Research Articles

Byssochlamys nivea inactivation in pineapple juice and nectar using high pressure cycles

The aim of this work was to assess the inactivation of Byssochlamys nivea ascospores in pineapple juice and nectar by combining pressure sequences involving high pressure cycles with relatively mild thermal processing. The effect of 550 and 600 MPa sustained pressures (holding time of 15 min), combinations of sustained pressures and pressure pulses (holding time of 10 s), and pressure cycles (two, three and five cycles of 550 and 600 MPa for 7.5, 5 and 3 min, respectively), at 20, 40, 60, 70, 80 and 90 °C were compared. B. nivea ascospores were inactivated by applying sustained a pressure of 600 MPa at 90 °C for 5 min (juice) and 15 min (nectar), and three and five cycles of pressure at 600 MPa and 80 °C for nectar with holding time of 5 and 3 min, respectively, and in all pressure cycles for juice. In general, pressure cycles were more effective for inactivating B. nivea ascospores than the application of sustained high pressures.

Bacterial stressors in minimally processed food.

Stress responses are of particular importance to microorganisms, because their habitats are subjected to continual changes in temperature, osmotic pressure, and nutrients availability. Stressors (and stress factors), may be of chemical, physical, or biological nature. While stress to microorganisms is frequently caused by the surrounding environment, the growth of microbial cells on its own may also result in induction of some kinds of stress such as starvation and acidity. During production of fresh-cut produce, cumulative mild processing steps are employed, to control the growth of microorganisms. Pathogens on plant surfaces are already stressed and stress may be increased during the multiple mild processing steps, potentially leading to very hardy bacteria geared towards enhanced survival. Cross-protection can occur because the overlapping stress responses enable bacteria exposed to one stress to become resistant to another stress. A number of stresses have been shown to induce cross protection, including heat, cold, acid and osmotic stress. Among other factors, adaptation to heat stress appears to provide bacterial cells with more pronounced cross protection against several other stresses. Understanding how pathogens sense and respond to mild stresses is essential in order to design safe and effective minimal processing regimes.

Silk fibroin/hyaluronan scaffolds for human mesenchymal stem cell culture in tissue engineering

The design of new bioactive scaffolds mimicking the physiologic environment present during tissue formation is an important frontier in biomaterials research. Herein, we evaluated scaffolds prepared from blends of two biopolymers: silk fibroin and hyaluronan. Our rationale was that such blends would allow the combination of silk fibroin's superior mechanical properties with the biological characteristics of hyaluronan. We prepared scaffolds with porous microstructures by freeze-drying aqueous solutions of silk fibroin and hyaluronan and subsequent incubation in methanol to induce water insolubility of silk fibroin. Hyaluronan acted as an efficient porogenic excipient for the silk fibroin scaffolding process, allowing the formation of microporous structures within the scaffolds under mild processing conditions. Mesenchymal stem cells were seeded on silk fibroin/hyaluronan scaffolds and cultured for three weeks. Histology of the constructs after cell culture showed enhanced cellular ingrowth into silk fibroin/hyaluronan scaffolds as compared to plain silk fibroin scaffolds. In the presence of tissue-inductive stimuli, in vitro stem cell culture on silk fibroin/hyaluronan scaffolds resulted in more efficient tissue formation when measured by glycosaminoglycan and type-I and type-III collagen gene expression, as compared to plain silk fibroin scaffolds. In conclusion, our data encourages further exploration of silk fibroin/hyaluronan scaffolds as biomimetic platform for mesenchymal stem cells in tissue engineering.

Resistance of Listeria monocytogenes, Escherichia coli O157:H7 and Campylobacter jejuni after exposure to repetitive cycles of mild bactericidal treatments

While maintaining nutritional and sensorial attributes of fresh foods mild processing technologies generally deliver microbiologically perishable food products. Currently little information exists on possible increase in the resistance of pathogens after repetitive exposure to mild (sub-lethal) treatments. Multiple strain-cocktails of Listeria monocytogenes, Escherichia coli O157:H7 and Campylobacter jejuni were exposed to 20 consecutive cycles of sub-lethal inactivation by three different techniques. Used techniques comprised inactivation with lactic acid (LA), chlorine dioxide (ClO 2) and intense light pulses (ILP). Results showed that the selection of resistant cells was both species and technique dependent. While repetitive cycles of ClO 2 treatment did not result in increased resistance, repetitive inactivation with LA yielded L. monocytogenes culture of higher resistance in comparison to the parental culture. The increased resistance, expressed as decreased level of reduction in bacterial counts in subsequent inactivation cycles, was also observed with ILP for both L. monocytogenes and E. coli O157:H7 strains. Visual trend observations were confirmed through statistical linear regression analysis. No such effects were noted for C. jejuni which became undetectable after first 2–5 cycles. Current findings indicate the ability of foodborne pathogens to adapt to mild bactericidal treatments creating new challenges in risk assessment and more specifically in hazard analysis.

Carrot pectin methylesterase and its inhibitor from kiwi fruit: Study of activity, stability and inhibition

Abstract Carrot pectin methylesterase (PME) and its inhibitor (PMEI) from kiwi fruit were successfully purified by affinity chromatography. Enzyme and inhibitor activity and stability and PME–PMEI complex formation, as influenced by intrinsic product factors (pH and NaCl) and extrinsic process factors (temperature and pressure), were studied. The effect of temperature- or pressure-induced denaturation of PME and PMEI on their respective activities was assessed by estimating inactivation kinetic parameters. PME inactivation obeyed first-order kinetics. The enzyme was rather heat-labile but pressure-stable. PMEI inactivation was best described by a model taking into account a processing-stable PMEI intermediate. The behavior of PME and the PME–PMEI complex at elevated temperature or pressure in the presence of pectin was explored by following methanol formation as a function of treatment time. PME catalytic activity was stimulated up to a certain temperature or pressure level before declining. No conclusive evidence was obtained for a temperature-induced dissociation of the PME–PMEI complex, whereas high pressure exposure caused the complex to separate. Industrial relevance PME activity control is a major point of interest in the quest of obtaining high quality plant-derived food products. The current study demonstrates that both traditional thermal processing and novel high hydrostatic pressure processing allow stimulation as well as inactivation of PME and, hence, directing the PME-catalyzed pectin hydrolysis. An alternative or additional approach to control endogenous PME activity (e.g. to obtain cloud-stable juices) is through enzyme inhibition using kiwi PMEI. In this context, pH and NaCl boundaries for application were established, the existence of a temperature- and pressure-stable PMEI intermediate was shown and the PME–PMEI complex was proven not to be dissociated at mild temperature and pressure levels. These observations endorse the possibility of inhibiting undesirable PME activity remaining after mild processing.

Remembering to carry out intentions following traumatic brain injury in older adults

Research with young adults has found that many cognitive domains can be affected by mild traumatic brain injury (TBI), including attention, processing speed, learning and memory. Nevertheless, recovery of cognitive performance is generally expected by 3 months following an uncomplicated mild TBI. Whether similar good levels of recovery can be expected in an older population remains to be demonstrated. Furthermore, it has been argued that remembering delayed intentions (prospective memory) may be a more insightful outcome measure as it requires the integration and co-ordination of a number of cognitive processes, thus making it a sensitive and ecologically valid measure of cognitive functioning post-TBI.

Selective short-term memory deficits arise from impaired domain-general semantic control mechanisms.

Semantic short-term memory (STM) patients have a reduced ability to retain semantic information over brief delays but perform well on other semantic tasks; this pattern suggests damage to a dedicated buffer for semantic information. Alternatively, these difficulties may arise from mild disruption to domain-general semantic processes that have their greatest impact on demanding STM tasks. In this study, mild semantic processing impairments were demonstrated in 2 semantic STM patients. They performed well on untimed semantic tasks but were deficient in accuracy and reaction times on speeded tasks. Demanding semantic production tasks were also affected. These patients were compared with a case series of individuals with semantic aphasia whose multimodal semantic difficulties stemmed from poor cognitive control. STM and semantic performance were more impaired in this group, but there were qualitative similarities to the semantic STM patients. The difference between the 2 patient types may be a matter of degree. In semantic aphasia, severe disruption to semantic control leads to global semantic impairments, whereas in semantic STM milder disruption might impact mainly on STM tests because of the high control demands of these tasks.

A Preliminary Study on Antimicrobial Edible Films from Pectin and Other Food Hydrocolloids by Extrusion Method

ABSTRACT Antimicrobial edible films were prepared from natural fiber of pectin and other food hydrocolloids for food packaging or wrapping by extrusion followed by compression or blown film method. Microscopic analysis revealed a well-mixed integrated structure of extruded pellets and an even distribution of the synthetic hydrocolloid in the biopolymers. The resultant composite films possess mechanical properties that are comparable to films cast from most natural hydrocolloids that are consumed as foods or components in processed foods. The inclusion of poly(ethylene oxide) alters the textures of the resultant composite films and therefore demonstrates a new technique for the modification of film properties. The composite films were produced in mild processing conditions, thus the films are able to protect the bioactivity of the incorporated nisin, as shown by the inhibition of Listeria monocytogenes bacterial growth by a liquid incubation method.

Simplifying the reaction system for the preparation of polyaniline nanofibers: Re-examination of template-free oxidative chemical polymerization of aniline in conventional low-pH acidic aqueous media

In this study, several polyaniline samples were prepared by oxidative chemical polymerization using only aniline, (NH 4) 2S 2O 8 and HCl in aqueous media at room temperature for morphological studies by SEM (scanning electron microscopy). The results show that polyaniline nanofibers can be obtained by template-free oxidative chemical polymerization in a conventional low-pH acidic aqueous medium (pH ∼ 0) at room temperature. The study indicates that it is crucial to employ a mild post-polymerization processing procedure, such as dialysis, to preserve the as-formed morphology of polyaniline nanofibers. Our study also suggests that polyaniline could adopt the nanofiber structure as its intrinsic morphology when it is synthesized in a simple oxidative chemical polymerization system consisting of only aniline, (NH 4) 2S 2O 8 and HCl in an aqueous medium at room temperature.

Characterization of High-Hydrostatic-Pressure Effects on Fresh Produce Using Chlorophyll Fluorescence Image Analysis

High hydrostatic pressure has the potential to affect food-related enzymes and microorganisms while retaining the produce’s characteristic properties. Although many studies on effects of high pressure on quality attributes of fruit and vegetables have been published, experimental results on the impact of high-pressure treatment on the physiological activity of products are rare. To characterize changes of the samples fast and noninvasive methods as well as a sensitive biological model system are required for this purpose. In this study, fresh lamb’s lettuce (Valerianella olitoria Poll.) was used as a model produce. For each treatment, two leaves were carefully inserted to small plastic pouches, sealed and then subjected to pressure (up to 7.5 min at 200 MPa) or thermal treatment (up to 1 min at 50°C). Chlorophyll fluorescence imaging was applied to measure the local and temporal dynamics of the physiological postprocessing effects. Measurements of the maximum photochemical efficiency F v/F m allows the immediate evaluation of photosynthetic activity as an indicator for cell and tissue vitality. Thermal treatment at pressure below 125 MPa and temperatures lower than 45°C showed minor fully reversible effects but a pronounced decline in the maximum photochemical efficiency was obtained after pressure treatment of 150 MPa and temperatures of 45°C or higher values. These changes were irreversible within 24 h of recovery time. Above these thresholds, high pressure and heat treatment may not be applicable for mild processing of highly perishable fresh produce. Chlorophyll fluorescence analysis has been proven to be a valuable tool for the rapid and comprehensive evaluation of postharvest processing of green perishables.

A Printed and Flexible Field‐Effect Transistor Device with Nanoscale Zinc Oxide as Active Semiconductor Material

A family of single-source precursors for low temperature processing of uniform, transparent, and adherent ZnO thin films on various substrates is studied. They decompose cleanly under very mild processing conditions of 150 °C. The resulting ZnO thin films exhibit promising semiconducting properties when printed in a field-effect transistor (FET) device structure. This class of precursor compounds is compatible with existing printing technologies and allows printing of semiconductors on flexible polymer substrates under mild conditions.

Silk fibroin spheres as a platform for controlled drug delivery

The goal of this proof-of-concept study was the fabrication of drug-loaded silk fibroin (SF) spheres under very mild processing conditions. The spheres were fabricated using the laminar jet break-up of an aqueous SF solution, which was induced by a nozzle vibrating at controlled frequency and amplitude. SF particles were spherical in shape as determined by SEM with diameters in the range of 101 µm to 440 µm, depending on the diameter of the nozzle and the treatment to induce water insolubility of SF. Both treatments, either methanol or exposure to water vapor, resulted in an increase in β-sheet content as analyzed by FTIR. High encapsulation efficiencies, close to 100%, were obtained when salicylic acid and propranolol hydrochloride-loaded SF spheres were left untreated or exposed to water vapor. Methanol treatment resulted in drug leaching and lowered the overall encapsulation efficiency. When 9% SF solutions were used for SF sphere preparation, release rates were more sustained than from spheres made with 3% SF solutions, and propranolol hydrochloride release was more sustained than salicylic acid release. However, no difference in the release profiles was observed between methanol and water vapor treated SF spheres. Because of its very mild conditions, which are potentially advantageous for the encapsulation of sensitive drugs, we also tested this method for the encapsulation of insulin-like growth factor I (IGF-I). Again encapsulation efficiencies were close to 100%, even after treatment with methanol. IGF-I was continuously released over 7 weeks in bioactive form, as analyzed by the proliferation of MG-63 cells. These results favor further investigation of SF spheres as a platform for the controlled release of sensitive biologicals.

Release of a model protein from biodegradable self assembled films for surface delivery applications

Layer-by-layer (LbL) films have multiple features that make them attractive for drug delivery, including the potential to sequentially deliver growth factors from implantable medical devices or tissue engineering scaffolds. To date, however, characterization has been lacking for protein delivery from such films. Here, LbL polyelectrolyte films constructed with the model protein lysozyme and a hydrolytically degradable and biocompatible synthetic polycation are characterized. Milligram/cm 2 scale linear or power law release profiles can be achieved over 2 to 34 days, and control over loading and release are demonstrated through parameters such as tuning the degradability of the synthetic polycation, changing the number of layers used, or changing the polysaccharide polyanion. Functionality is maintained at nearly 100%, underscoring mild processing conditions apt to preserve fragile protein function. LbL films thus have promise as a tool for exploring protein modulation of the interaction between implanted surfaces and the cells they contact.

Virgin hemp seed oil: An interesting niche product

AbstractVirgin hemp seed oil is not widespread on the market, although it is characterised by an interesting fatty acid composition with a high content of polyunsaturated fatty acids. Linoleic acid is the predominant fatty acid, which comes, together with α‐linolenic acid (18:3n‐3), to approximately 80% of the total fatty acids. From a nutritional point of view, up to 7% γ‐linolenic acid (18:3n‐6) and 2.5% stearidonic acid (18:4n‐3) are very interesting. The total amount of tocopherols is high between 80 and 110 mg/100 g, with γ‐tocopherol as the main tocopherol (85%). Due to the high amount of unsaturated fatty acids, hemp seed oil is very susceptible to oxidative deterioration, which results in a fast impairment of the oil during storage. In addition, the high amounts of chlorophyll in the oil due to harvesting of high amounts of immature seeds require light protection, which is often neglected because of merchandising purposes. The virgin oil is characterised by a nutty taste with a slightly bitter aftertaste. The use of virgin hemp seed oil is recommended during mild processing of food without heat.

The Impact of Mild Central Auditory Processing Disorder on School Performance During Adolescence

The Impact of Mild Central Auditory Processing Disorder on School Performance During Adolescence

Mild processing defect of porcine ΔF508-CFTR suggests that ΔF508 pigs may not develop cystic fibrosis disease

Recent efforts have made significant progress in generating transgenic pigs with the ΔF508-CFTR mutation to model the lung and pancreatic disease of human cystic fibrosis. However, species differences in the processing and function of human, pig and mouse ΔF508-CFTR reported recently raise concerns about the phenotypic consequence of the gene-targeted pig model. The purpose of the present study was to characterize the ΔF508 mutant of porcine CFTR to evaluate the severity of its processing defect. Biochemical and immunofluorescence analysis in transfected COS7 and FRT cells indicated that pig ΔF508-CFTR efficiently targets to the plasma membrane and is present mainly as the mature glycosylated protein. Functional characterization in stably transfected FRT cells by fluorometric and electrophysiological assays supported efficient plasma membrane targeting of pig ΔF508-CFTR. The mild cellular processing defect of pig ΔF508-CFTR suggests that its gene-targeted pig model may not develop the lung and pancreatic phenotypes seen in CF patients.

Novel mechanism of modulating natural antioxidants in functional foods: involvement of plant growth promoting Rhizobacteria NRRL B-30488.

The significance of plant growth-promoting rhizobacteria (PGPR) mediated increase in antioxidant potential in vegetables is yet unknown. The plant growth-promoting bacterium Bacillus lentimorbus NRRL B-30488 (B-30488) mediated induction of dietary antioxidant in vegetables ( Trigonella foenum-graecum, Lactuca sativa, Spinacia oleracea, and Daucus carota) and fruit ( Citrus sinensis) after minimal processing (fresh, boiled, and frozen) was tested by estimating the total phenol content, level of antioxidant enzymes, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide scavenging activities along with integral radical scavenging capacity by photochemiluminescence assay and inhibition of lipid peroxidation. Minimal processing of vegetables showed that T. foenum-graecum had the highest phenol content in B-30488-treated plants followed by L. sativa, D. carota, and S. oleracea. Thermally treated vegetables T. foenum-graecum (26-114.5 GAE microg mg (-1)) had an exceptionally high total phenolic content, followed by D. carota (25.27-101.32 GAE microg mg (-1)), L. sativa (23.22-101.10 GAE microg mg (-1)), and S. oleracea (21.87-87.57 GAE microg mg (-1)). Among the vegetables and fruit used in this study for enzymatic estimation, induction of antioxidant enzymes, namely, polyphenol oxidase (PPO), ascorbate peroxidase (APX), catalase (CAT), and superoxidase dismutase (SOD), was observed in edible parts of T. foenum-graecum, L. sativa, S. oleracea, and D. carota, after inoculation with B-30488. The scavenging capacity of the vegetables treated with B-30488 against DPPH and superoxide anion radical activity was found to be significantly high as compared to nontreated control. Mild food processing had no adverse effect on radical scavenging capacity. Photochemiluminescence also ascertains the above findings. The ability of the plant extracts to protect against lipid peroxidation and its ability to prevent oxidation of reduced glutathione (GSH) was measured in rat liver homogenate, and the results suggested that the inoculated plant exhibited better activity in all of the screened plants. Significant increases in shoot length, root length, and dry weight, averaging 164, 132, and 135% in T. foenum-graecum, 174, 141, and 156% in L. sativa, 129, 141, and 59%, in S. oleracea, and 125, 146, and 42% in D. carota, respectively, over untreated controls, were attained in greenhouse trials. To the best of the authors' knowledge, this is the first report of PGPR-mediated induction of antioxidant enzyme activity (PPO, APX, CAT, and SOD) along with the antioxidant activity of the extracts in both in vitro (DPPH radical scavenging and superoxide scavenging) and ex vivo conditions using the rat liver tissue (percent inhibition of lipid peroxidation and prevention of oxidation of GSH) and phenolic content. The results demonstrate the PGPR-mediated induction of antioxidant level in vegetables and fruit controls oxidative damage even after minimal processing and thus is indicative of its potential as a viable substitute of synthetic antioxidants.

Transferring pharmaceuticals into the gas phase

The dissolution of molecules of biological interest in supercritical carbon dioxide is investigated using pulsed molecular beam mass spectrometry. Due to the mild processing temperatures of most supercritical fluids, their adiabatic expansion into vacuum permits to transfer even thermally very sensitive substances into the gas phase, which is particularly attractive for pharmaceutical and biomedical applications. In addition, supercritical CO2constitutes a chemically inert solvent that is compatible with hydrocarbon-free ultrahigh vacuum conditions. Here, we report on the dissolution and pulsed supersonic jet expansion of caffeine (C8H10N4O2), the provitamin menadione (C11H8O2), and the amino acid derivative l-phenylalanine tert-butyl ester hydrochloride (C6H5CH2CH(NH2)COOC(CH3)3⋅HCl), into vacuum. An on-axis residual gas analyzer is used to monitor the relative amounts of solute and solvent in the molecular beam as a function of solvent density. The excellent selectivity and sensitivity provided by mass spectrometry permits to probe even trace amounts of solutes. The strong density variation of CO2 close to the critical point results in a pronounced pressure dependence of the relative ion currents of solute and solvent molecules, reflecting a substantial change in solubility.

A novel approach in preparing polymer/nano-CaCO3 composites

An novel compounding process using nano-CaCO3 aqueous suspension for preparing polymer/nano-CaCO3 composites with nanoparticles dispersed at the nanoscale is reported. The process is called the mild mixing method. In this method, the pre-dispersed nano-particle suspensions are blended with melting polymers in a weak shearing field using an extruder, followed by removing the water from the vent. The four typical polymeric nanocomposites were prepared by mild mixing method. The dispersion of nano-CaCO3 in the matrix of the polymer at the nanoscale was confirmed by scanning electron microscopy (SEM). The molecular weights of polycarbonate (PC) and its nanocomposite showed that the degradation had not occurred during the mild mixing processing. The mechanical properties of the composite with 1.5 wt-% nano-CaCO3 improve slightly. It proved that this approach is suitable for the preparation of nano-composites based on both polar and non-polar polymers.

The relationship between semantic short-term memory and immediate serial recall of known and unknown words and nonwords: Data from two Chinese individuals with aphasia.

The present study investigated verbal recall of semantically preserved and degraded words and nonwords by taking into consideration the status of one's semantic short-term memory (STM). Two experiments were conducted on 2 Chinese individuals with aphasia. The first experiment showed that they had largely preserved phonological processing abilities accompanied by mild but comparable semantic processing deficits; however, their performance on STM tasks revealed a double dissociation. The second experiment found that the participant with more preserved semantic STM had better recall of known words and nonwords than of their unknown counterparts, whereas such effects were absent in the patient with severe semantic STM deficit. The results are compatible with models that assume separate phonological and semantic STM components, such as that of R. C. Martin, M. Lesch, and M. Bartha (1999). In addition, the distribution of error types was different from previous studies. This is discussed in terms of the methodology of the authors' experiments and current views regarding the nature of semantic STM and representations in the Chinese mental lexicon.