Headspace Gas Composition Research Articles

A comprehensive model for estimating the shelf life of young radish (Raphanus sativus L.) kimchi packaged in partially breathable film pouches

Continuous fermentation by lactic acid bacteria (LAB) causes packaging bursting, presenting a challenge in the commercialization of kimchi by reducing its shelf life. This study explored the use of partially breathable film pouches (PBFP) as a packaging solution for young radish kimchi (YRK). Furthermore, the shelf life of YRK was estimated through multivariate accelerated shelf life testing (MASLT). Packaged YRK samples were stored for 60 d at different temperatures (0, 5, 10, and 15 °C). The gas permeability of the PBFP and LAB metabolism controlled the volume and headspace gas composition of the packaged YRK samples during storage. The PBFP did not negatively impact YRK quality. Principal component (PC) analysis successfully reduced the physicochemical and microbial characteristics of YRK to a single variable. The exponential plateau model better described the variation in the time-related PC score than the zero- and first-order models. The P value within 15% of the comprehensive model, incorporating exponential and Arrhenius models, indicated its adequacy for predicting the shelf life of YRK. This study offers both insights into packaging technology and a predictive model, contributing to the improvement of the distribution management system for fermented vegetables.

Varied Attributes of Jalapeño Pepper Cultivars Influence Fresh-cut Product Quality

During the past 40 years, the US fresh-cut product market has experienced a consistent increase in demand because consumers prioritize health and convenience. Increased interest in fresh-cut products and ready-to-eat vegetables has led to innovations in breeding, product selection, and packaging. However, despite the increased popularity of bell pepper and chile pepper (Capsicum annuum L.), research of fresh-cut jalapeño pepper is limited. This study was conducted to identify jalapeño cultivars that could be suitable as a raw fresh-cut product and explore measures beyond tissue membrane electrolyte leakage (EL) of processed products that may be useful for the identification of cultivars suitable for fresh-cut applications. A total of 22 fresh-cut parameters were examined across five cultivars of jalapeño peppers and 10 intercrosses of these cultivars, including visual quality based on an image analysis via a computer vision system, package headspace gas composition, tissue membrane EL, and texture. Based on our results, the genotypes were grouped into five clusters using a cluster analysis. Variables including tissue softening (r2 = 0.95), EL (r2 = 0.95), total energy of the mesocarp (r2 = 0.95), and package headspace carbon dioxide (CO2) partial pressure (r2 = 0.94) had strong associations with the cluster. A principal component analysis with biplots further confirmed the results. Cultivars Goliath and Emerald Fire and their hybrids in the first and second clusters showed good quality for fresh-cut applications. The fifth cluster, represented by a single cultivar, Jalapeño M, had the smallest physical size, rapid shelf-life decline, accumulated CO2 partial pressures, increased EL, and rapid tissue softening in comparison with the other genotypes. All jalapeño cultivars except Jalapeño M maintained good quality until day 14 postprocessing, and some maintained good quality until 21 days postprocessing. Hybrid crosses suggested that two of the cultivars evaluated, Goliath and Emerald Fire, were useful as parents when transferring superior fresh-cut quality traits to progeny. Traditionally, the EL level has been used as an index of freshness (or tissue deterioration). Our results showed that other quality analyses, including measurements of tissue softening via an imaging analysis, and physical analyses of tissue firmness can also be used as indices for the freshness of fresh-cut jalapeños. The results suggest that fruit size, wall thickness, and skin toughness might be useful as predictive measures in the field for the selection of jalapeño genotypes with superior fresh-cut quality.

The acute effects of rumen pulse-dosing of hydrogen acceptors during methane inhibition with nitrate or 3-nitrooxypropanol in dairy cows

Dietary methane (CH4) mitigation is in some cases associated with an increased hydrogen (H2) emission. The objective of the present study was to investigate the acute and short-term effects of acceptors for H2 (fumaric acid, acrylic acid or phloroglucinol) supplemented via pulse-dosing to dairy cows fed CH4 mitigating diets (using nitrate or 3-nitrooxypropanol), on gas exchange, rumen gas and VFA composition. For this purpose, 2 individual 4 × 4 Latin square experiments were conducted with 4 periods of 3 d (nitrate supplementation) and 7 d (3-nitrooxypropanol supplementation), respectively. In each study, 4 rumen cannulated Danish Holstein cows were used. Each additive for CH4 mitigation was included in the ad libitum fed diet within the 2 experiments, to which the cows were adapted for at least 14 d. Acceptors for H2 were administered twice daily in equal portions through the rumen fistula immediately after feeding of the individual cow. In Exp. 1 (nitrate), the treatments were CON-1 (no H2-acceptor), FUM-1 (fumaric acid), ACR-1 (acrylic acid) and FUM+ACR-1 (50% FUM-1 + 50% ACR-1). In Exp. 2 (3-nitrooxypropanol), the 3 treatments, CON-2, FUM-2, and ACR-2, were similar to CON-1, FUM-1 and ACR-1 treatments, however the fourth treatment was PHL-2 (phloroglucinol). Gas exchanges were measured in respiration chambers, while samples of rumen liquid and headspace gas were taken in time series relative to feeding and dosing on specific days. Headspace gas was analyzed for gas composition and rumen liquid was analyzed for volatile fatty acid composition and dissolved gas concentrations. Headspace gas composition and dissolved gas concentration were only measured in Exp. 2. Dry matter intake was reduced upon acrylic acid supplementation. There were no significant effects of any treatments in any experiments on H2 emission, except for a decrease in hourly H2 emission rate (g/h) at 1 h after feeding in both experiments. In Exp. 2, H2 headspace proportions increased by ACR-2 supplementation, whereas dissolved concentrations were unaffected. In Exp. 1, cows on ACR-1 increased propionate proportion at 1 h after feeding. In Exp. 2, both FUM-2 and ACR-2 increased rumen propionate proportion in the hours after feeding and dosing. There was no effect on rumen acetate for cows on PHL-2. There was a strong positive correlation between rumen dissolved CH4 and headspace CH4 (r = 0.84), whereas the equivalent correlation was weaker for H2 (r = 0.41). For the relationship between dissolved concentrations and emissions of CH4 and of H2, there was a moderate positive correlation for CH4 (r = 0.54), whereas it was weak for H2 (r = 0.28) with zero slope. In conclusion, the results suggested that fumaric acid and acrylic acid to some extent was reduced to propionate without associative effects on measures for H2 redirection. Furthermore, phloroglucinol seemed not to be metabolized in the rumen in the present study, as no effects on rumen acetate or measures of H2 were observed. Changes in H2 headspace and emission may be a poor proxy for actual changes in the rumen fluid concentration of H2.

Excessive Ethanol Oxidation Versus Efficient Chain Elongation Processes

PurposeChain elongation is a metabolic feature that consists of the elongation of short-chain fatty acids to longer and more valuable acids when ethanol is available. To lower the operational costs, the process can also be performed using mixed microbial cultures. However, certain microorganisms in the mixed cultures can use the ethanol provided in competing reactions, which is usually termed excessive ethanol oxidation (EEO). Although minimizing ethanol use is essential, there is a lack of studies analyzing the extent, causes, and solutions to excessive ethanol oxidation processes.MethodsTo address this knowledge gap, ethanol, and acetic acid mixtures, at a molar ratio of 5 to 2, were fermented, and the following were analyzed: the fermentation profile at different (1) pH and (2) headspace gas compositions, (3) a 16S analysis of the headspace gas composition fermentations, and (4) a thermodynamic analysis of the reactions involved.Results and Conclusions: All fermentations, except the ones at the lowest pH (5.3), exhibited a significant EEO activity that reduced the yield of chain-elongated products. It was demonstrated that neither the inhibition of methanogenic activity nor the increased H2 partial pressure is an efficient method to inhibit EEO. It was also shown that CO2 can act as an electron acceptor for EEO, promoting the growth of acetogenic bacteria. In the absence of CO2, sulfate was used as an electron acceptor by sulfate-reducing bacteria to facilitate EEO. Methods such as low pH operation with in-line extraction, and the use of alternative sulfur salts, are proposed to increase the ethanol use efficiency in chain elongation processes.Graphical

Optimization of the Use of a Commercial Phage-Based Product as a Control Strategy of Listeria monocytogenes in the Fresh-Cut Industry.

A commercial phage biocontrol for reducing Listeria monocytogenes has been described as an effective tool for improving fresh produce safety. Critical challenges in the phage application must be overcome for the industrial application. The validation studies were performed in two processing lines of two industry collaborators in Spain and Denmark, using shredded iceberg lettuce as the ready-to-eat (RTE), high process volume product. The biocontrol treatment optimized in lab-scale trials for the application of PhageGuard ListexTM was confirmed in industrial settings by four tests, two in Spain and two in Denmark. Results showed that the method of application that included the device and the processing operation step was appropriate for the proper application. The proper dose of Phage Guard ListexTM was reached in shredded iceberg lettuce and the surface was adequately covered for the successful application of phages. There was no impact on the headspace gas composition (CO2 and O2 levels), nor on the color when untreated and treated samples were compared. The post-process treatment with PhageGuard ListexTM did not cause any detrimental impact on the sensory quality, including flavor, texture, browning, spoilage, and visual appearance over the shelf-life as the phage solution was applied as a fine, mist solution.

Illuminated septic tank – A microalgae assisted onsite wastewater treatment system

To reduce the anthropogenic nutrient loading into natural waterways, onsite wastewater treatment is essential for households without access to municipal sewer systems. However, many conventional septic tanks significantly underperform the centralized wastewater treatment. In the present study, a novel illuminated septic tank inoculated with the consortium of microalga Chlorella vulgaris and aerobic bacteria was developed by modifying the conventional configuration. The inclusion of microalgae facilitated aeration inside the septic tank through photosynthetic oxygen evolution, and the microalgae-bacteria consortium enhanced the wastewater treatment performance. With the operation at 15 ℃ and a hydraulic retention time of 2.5 days, the lab-scale algae-assisted septic tank significantly decreased the concentrations of ammonium-nitrogen (NH4+-N), soluble phosphorus (P), total P, and total chemical oxygen demand by 54%, 65.2%, 78.5%, and 90.7% in the discharged effluent, respectively (p < 0.05), whereas the conventional septic tank without microalgae did not exhibit any treatment of NH4+-N or soluble P and the total P removal efficiency was lower by 50%. Meanwhile, the photosynthetic activity of microalgae altered the gas composition in the tank headspace by consuming carbon dioxide, emitting oxygen, and inhibiting the evolution of methane, which further benefited the aeration requirement and contributed to the mitigation of greenhouse gas emissions from septic systems.

Effect of headspace gas composition in kimchi packaging on the quality characteristics of kimchi.

The online version contains supplementary material available at 10.1007/s13197-023-05795-z.

The Potential of Soluble Gas Stabilization (SGS) Technology in a Simulated Post-Frying Cooling Step of Commercial Fish Cakes.

Soluble gas stabilization (SGS) technology is a novel way to increase the effectiveness of modified atmosphere (MA) packaging. However, SGS can be time-consuming and difficult to include in an existing process. This can be overcome by including CO2 in an existing processing step, such as the product's cooling step. A full factorial design was set up with SGS times (0.5, 1.0, and 2.0 h) and temperatures of fish cakes (chilled (0 °C) or during chilling (starting at 85 °C)) as factors. MA-packaged fish cakes were included as a control. The response was headspace gas composition at equilibrium. Headspace gas composition at equilibrium showed significantly (p < 0.05) less dissolved CO2 in hot fish cakes after 0.5 h than in cold cakes. Still, no significant differences were found between hot and cold at 1.0 and 2.0 h. Also, all SGS samples, regardless of time and temperature, had a higher content of CO2 compared to modified atmosphere packaging (MAP).

Ready-to-Eat Egg Products Formulated with Nisin and Organic Acids to Control Listeria monocytogenes

Formulating ready-to-eat (RTE) products with growth inhibitors minimizes the risk of listeriosis. In part I, RTE egg products formulated with 6.25 ppm nisin were evaluated to control Listeria monocytogenes. Individual experimental units were surface inoculated with 2.5-log CFU/g of L. monocytogenes, packaged in pouches with a headspace gas of 20:80 CO2:NO2, and stored at 4.4°C for 8 weeks. Formulations with finished product pH of 6.29 ± 0.07 limited growth to <2-log for 4 weeks. Products at pH values of 7.42 ± 0.12 and 7.84 ± 0.11 were not different (p > 0.05) from the control without nisin at pH 7.34 ± 0.13, all supported 4-log growth by 4 weeks. In part II, a nisin bioassay test was performed to evaluate the stability of nisin in eggs as affected by the product pH (6.00 ± 0.03, 7.00 ± 0.00, 7.50 ± 0.03, and 8.00 ± 0.02) and cooking to an internal temperature of 73.9 or 85°C for 90 s. The nisin activity loss increased as the product pH or the cooking temperature increased (p < 0.05). Part III evaluated the effectiveness of 6.25 ppm nisin in combination with either an acetate-based antimicrobial used at 1.0% (w/w) in egg formulation (A1.0), propionate at 0.3% (P0.3), acetate-diacetate at 1.0% (AD1.0), acetate-diacetate at 0.6% (AD0.6), and lactate at 2.0% (L2.0) as a positive control. These formulations had a finished product pH, moisture, and salt contents of 5.97 ± 0.21, 72.4 ± 0.9%, and 0.67 ± 0.05%, respectively. L. monocytogenes did not grow in formulations A1.0 and AD1.0, whereas L2.0 and P0.3 supported 2-log growth by weeks 6 and 15, respectively and AD0.6 supported <1-log growth over 20 weeks at 4.4°C. Evaluation of uninoculated control units in parts I and III showed no changes (p > 0.05) in the CO2 and O2 headspace gas composition, generally no detection or growth of background microbes, and no changes (p > 0.05) in the pH of the formulations during storage, all assuring absence of uncontrolled interferences for the growth of L. monocytogenes.

Composition-based statistical model for predicting CO2 solubility in modified atmosphere packaging application

Carbon dioxide (CO 2 ) is an important gas used in modified atmosphere packaging of non-respiring foods where it solubilizes into the aqueous and lipid phases of food and exerts an antimicrobial effect. Prediction of CO2 solubility within food is thus of paramount importance to anticipate its benefit on food preservation. In the present study, machine learning algorithms were applied on a set of 362 values of CO 2 solubilities collected from the scientific literature to tentatively predict the solubility as a function of food composition (water, protein, fat and salt content) and temperature. The best option kept was a random forest algorithm that was used to predict CO 2 solubility in four food case studies (ham, salmon, cheese and pâté) that were further used as input parameters in the MAP’ OPT tool, predicting the evolution of headspace gas composition. Predicted CO 2 solubilities used as input parameters succeeded in representing the CO 2 headspace dynamic as a function of time in the four case studies.

Shelf Life of Aquaponically-grown Finstar Lettuce in Different Oxygen Transmission Rate Films

The effects of oxygen transmission rate of packaging material on the shelf life of aquaponically-grown Finstar lettuce was studied. Parameters of packaging headspace gas composition (oxygen and carbon dioxide concentrations), lettuce pH, percentage weight loss, total aerobic microorganisms, and color were analyzed every ten days for sixty days. Finstar lettuce was stored at 4○C in four different types of packages (treatments), including a clamshell package and three film bags with oxygen transmission rates (OTR) of 3.0-6.0 cc/(m2/24 hr/1 atm), 80-90 cc/(m2/24 hr/1 atm), and &amp;gt;225 cc/(m2/24 hr/1 atm). The percentage weight loss of the 3.0-6.0 OTR package (-0.76-1.05%) was lowest while the percentage weight loss of the clamshell package was highest (0.81-7.72%) among packaging treatments. Nearly &amp;frac12; of the panelists rated lettuce as fresh enough to eat as is after 50 days of storage in 80-90 cc/(m2/24 hr/1 atm) films while lettuce packaged in the other treatments had less that 1/3 of the panelists judging the lettuce fresh enogh to eat as is. The long shelf-life may be attributed to Finstar having resilient genetic properties along with being greenhouse-grown which lessens the possibility of contamination compared to field-grown lettuces.

Application of Near Infrared Spectroscopy to Monitor the Quality Change of Sour Cherry Stored under Modified Atmosphere Conditions.

Determining and applying ‘good’ postharvest and quality control practices for otherwise highly sensitive fruits, such as sour cherry, is critical, as they serve as excellent media for a wide variety of microbial contaminants. The objective of this research was to report two series of experiments on the modified atmosphere storage (MAP) of sour cherries (Prunus cerasus L. var. Kántorjánosi, Újfehértói fürtös). Firstly, the significant effect of different washing pre-treatments on various quality indices was examined (i.e., headspace gas composition, weight loss, decay rate, color, firmness, soluble solid content, total plate count) in MAP-packed fruits. Subsequently, the applicability of near infrared (NIR) spectroscopy combined with chemometrics was investigated to detect the effect of various storage conditions (packed as control or MAP, stored at 3 or 5 °C) on sour cherries of different perceived ripeness. Significant differences were found for oxygen concentration when two perforations were applied on the packages of ‘Kántorjánosi’ (p < 0.01); weight loss when ‘Kánorjánosi’ (p < 0.001) and ‘Újfehértói fürtös’ (p < 0.01) were packed in MAP; SSC when ‘Újfehértói fürtös’ samples were ozone-treated (p < 0.05); and total plate count when ‘Kántorjánosi’ samples were ozone-treated (p < 0.01). The difference spectra reflected the high variability in the samples, and the detectable effects of different packaging. Based on the investigations with the soft independent modelling of class analogies (SIMCA), different packaging and storage resulted in significant differences in most of the cases even on the first storage day, which in many cases increased by the end of storage. The soft independent modelling of class analogies proved to be suitable for classification with apparent error rates between 0 and 0.5 during prediction regardless of ripeness. The research findings suggest the further correlation of NIR spectroscopic and reference parameters to support postharvest handling and fast quality control.

Microbiological characteristics and applied preservation method of novel ready-to-eat vegetarian spreads and dips

A range of spreads and dips as novel vegetarian ready-to-eat foods are being introduced on the (European) retail market to response to an increasing number of vegetarian’/flexitarian’ consumers and the shift towards plant-based foods consumption. This innovative food group was explored by a product survey (n = 369) in Belgium. The spreads and dips were classified on the presence of main ingredients, the applied preservation mode, the remaining shelf-life period, and the presence of additives. The majority of the products have soybeans or other seeds as the main ingredient, are containing preservatives (e.g. potassium sorbate; E202) and organic acids/acid regulators (e.g. lactic acid; E270 and citric acid; E330) as additives. 45% of the products were marketed under the organic label and 36% of them were indicated as so-called ‘clean label’. From a selection (78 refrigerated and 23 ambient stored products), the physicochemical characteristics (i.e. pH, water activity, and headspace gas composition) were determined as well as the microbiological quality, hygiene, and safety at the moment of purchase and the end of the indicated shelf-life. The analyzed microbiological quality indicators for refrigerated samples demonstrated a psychrotrophic total plate count range of 1.0–9.4 log CFU/g, psychrotrophic lactic acid bacteria range of 1.0–8.8 log CFU/g, yeast and fungi range of 2.0–9.5 log CFU/g and sulfite reducing Clostridia range of 1.0–3.7 log CFU/g. E. coli and coliforms were analyzed as hygiene indicators and solely coliforms were detected on three samples with a maximum count of 3.6 log CFU/g. Listeria monocytogenes was not detected in 10g. Bacillus cereus never exceeded 3.5 log CFU/g. For the ambient stored samples, mesophilic total plate count, mesophilic lactic acid bacteria, yeast and fungi, sulfite reducing Clostridia, B. cereus, B. cereus spores, aerobic spores, and anaerobic spores were determined. Most of the products showed cell counts below the limit of detection (= 1.0 log CFU/g). Only products based on chickpeas, sesame seeds, and other seeds showed cell counts for mesophilic total plate count and aerobic plate count ranging respectively from 1.0 to 4.3 log CFU/g and 1.0 to 5.1 log CFU/g. The research gives insight into the variable microbiological composition and multiple applied preservation modes of this innovative food group of ready-to-eat vegetarian dips and spreads.

Effects of different headspace gas compositions and partial pressures on productivity of H2 and liquid fermentation products during the fermentation of food wastewater

The homoacetogenesis reaction changes the degradation pathways of organic matter, thus changing the productivity of H2 and liquid fermentation products during anaerobic fermentation. The partial pressure of headspace gas, especially H2 and CO2 (PH2,PCO2,) has significant effect on the homoacetogenesis reaction, but different headspace gas compositions also affect homoacetogenesis. In this study, components, proportion, and vacuum degree of headspace gas were adjusted to explore their effects on homoacetogenesis with food wastewater as the raw material. Theoretical calculation showed that when PH2,andPCO2 were 40 kPa and 60 kPa, respectively, the homoacetogenesis reaction was the strongest. Maintaining headspace vacuum of 40 kPa did significantly increase the yield of acetic acid (HAc) because H2 and CO2 co-existence promotes the homoacetogenesis reaction. At 40 kPa headspace vacuum, H2 productivity was 136 % higher (84.7 ml/gSCODaddedd-1) than that in control group (100 %N2). Controlling the headspace vacuum was far superior to adjusting the headspace gas composition and gas proportion for H2 productivity. When the headspace gas was 50 %H2 + 50 %CO2 (PH2=50kPa,PCO2=50kPa), the homoacetogenesis reaction was the strongest with H2 consumption rate of 9.94 mmol/L· d-1, volatile fatty acids (VFA) productivity of 293.26 mg/gSCODaddedd-1, and acetic acid (HAc) productivity of 31.77 mg/gSCODaddedd-1, which was 50 %, 16 %, and 47 % higher than that in the control group, respectively. Our results indicate that the influence of PH2 on the fermentation process is greater than PCO2.

Time-Sensitive Aspects of Mars Sample Return (MSR) Science.

Time-Sensitive Aspects of Mars Sample Return (MSR) Science.

The nature of gas production patterns associated with methanol degradation in natural aquifer sediments: A microcosm study

With growing global use of methanol as a fuel additive and extensive use in other industrial processes, there is the potential for unintended release and spills into soils and aquifers. In these subsurface systems it is likely that methanol will be readily biodegraded; however, degradation may lead to the production of by-products, most importantly methane possibly resulting in explosion hazards and volatile fatty acids (VFAs) causing aesthetic issues for groundwater. In this study, the formation of these potentially harmful by-products due to methanol biodegradation was investigated in natural sand and silt sediments using microcosms inoculated with neat methanol (100%) ranging in concentration from 100 to 100,000 ppm. To assess the rate of degradation and by-product formation, water and headspace samples were collected and analyzed for methanol, volatile fatty acids (VFAs, including acetic, butyric, and propionic acid), cation (metal) concentrations (Al, Ca, Fe, K, Mg, Mn and Na), microbial community structure and activity, headspace pressure, gas composition (CH4, CO2, O2 and N2), and compound specific isotopes. Methanol was completely biodegraded in sand and silt up to concentrations of 1000 ppm and 10,000 ppm, respectively. Degradation was initially aerobic, consuming oxygen (O2) and producing carbon dioxide (CO2). When O2 was depleted, the microcosms became anaerobic and a lag in methanol degradation occurred (ranging from 41 to 87 days). Following this lag, methanol was preferentially degraded to acetate, coupled with CO2 reduction. Microcosms with high methanol concentrations (10,000 ppm) were driven further down the redox ladder and exhibited fermentation, leading to concurrent acetate and methane (CH4) generation. In all cases acetate was an intermediate product, further degraded to the final products of CH4 and CO2. Carbonates present in the microcosm sediments helped buffer VFA acidification and replenished CO2. Methane generation in the anaerobic microcosms was short-lived, but temporarily reached high rates up to 13 mg kg−1 day−1. Under the conditions of these experiments, methanol degradation occurred rapidly, after initial lag periods, which were a function of methanol concentration and sediment type. Our experiment also showed that methanol degradation and associated methane production can occur in a stepwise fashion.

Non-Destructive Measuring Systems for the Evaluation of High Oxygen Stored Poultry: Development of Headspace Gas Composition, Sensory and Microbiological Spoilage.

As poultry is known to be a perishable food, the use-by date is set in such a way that food safety is guaranteed even with a higher initial bacterial count. This means, however, that some products are wasted, even if they are still safe to eat. Therefore, non-destructive measurement devices might be a good opportunity for individual shelf-life prediction, e.g., in retail. The aim of this study was therefore to use non-destructive measurement devices based on fluorescence quenching (oxygen detection) and mid-infrared laser spectroscopy (carbon dioxide detection) for the monitoring of high-oxygen-packed poultry in different storage conditions. During 15 days of storage, the gas composition of the headspace was assessed (non-destructively and destructively), while total plate count was monitored and a comprehensive sensory evaluation was performed by a trained panel. We were able to demonstrate that in most cases, non-destructive devices have comparable precision to destructive devices. For both storage conditions, the sensory attribute slime was correlated with reaching the critical microbiological value of 107 CFU/g; the attribute buttery was also useful for the prediction of regularly stored poultry. The change in the gas atmosphere as a sign of premature spoilage, however, was only possible for samples stored in irregular conditions.

Effects of organic matter degradation in cohesive sediment: linking sediment rheology to spatio-temporal patterns of organic matter degradability

PurposeSediment organic matter (SOM) influences settling and thus the rheological behavior of suspended particles by enhancing flocculation or reducing surface charges by forming organo-mineral complexes that facilitate particle–particle interactions in consolidating sediments. It was, therefore, assumed that the microbial degradation of SOM and its spatio-temporal variability would affect sediment rheological properties and enhance port maintenance dredging and navigability of ports and waterways.MethodsTo investigate this effect, samples were taken at six locations along a transect of 30 river kilometers through the Port of Hamburg, Germany, during nine sampling campaigns within two years. The collected samples were divided into different layers based on the differences in visual consistency and strength. For analysis of SOM degradability, the samples were incubated in the laboratory for 250 days in glass bottles under aerobic and anaerobic conditions following the evolution of gas composition (CH4, CO2) and pressure in the bottle headspace over time. Yield stress was analyzed before and after the dissolved organic matter (DOM) decay using a rheometer with Couette geometry. Standard properties of solids and pore water were also analyzed.ResultsShear strength decreased upon SOM decay under both anaerobic and aerobic conditions. Under anaerobic conditions, organic matter decay reduced static and fluidic yield stresses to an average of 74% and 79% of the fresh sample values. Consolidated layers at lower depths showed the highest absolute decrease in fluidic yield stress of up to –110 Pa due to a larger absolute amount of degradable organic matter in these layers in connection to higher bulk density. Pronounced spatial trends with higher changes in yield stress at upstream locations and lower yield stress changes at downstream locations coincided with a decreasing gradient of SOM degradability from upstream to downstream. Seasonal trends indicated that the investigation area is impacted by temporally changing factors.ConclusionThe availability of easily degradable organic matter significantly affects sediment strength, especially under the anaerobic conditions, even when the mass loss of organic matter mass loss is small. Seasonal variability in yield stress changes upon SOM decay indicate that the site-specific responses were modulated by overarching seasonal effects impacting the entire investigation area. It was assumed that during an anaerobic decay, the formation of gas bubbles added an additional physical component to the effect of biological SOM decay.

Effect of ozone and antimicrobial treatments on the shelf life of cauliflower under modified atmosphere packaging.

The study focuses on development of modified atmosphere packaging for fresh-cut minimally processed cauliflower to increase its shelf-life and enhancing the on-farm value addition by utilizing perforated packaging films along with pretreatments with ozonated water and antimicrobials. The samples were treated with ozonated water, oregano essential oil (antimicrobial), and cinnamon essential oil (antimicrobial). Based on preliminary treatments, the number of perforations made by specially prepared tool was kept as 6 and 12, which represented 5.1×10-5 and 1.02×10-4% of the total surface area of packages. These perforated packaged samples were stored in cold room at 4 °C temperature for 28days. The shelf life and quality of treated cauliflower samples were compared with untreated samples. The quality analysis of the samples was carried up to 28days at 7days intervals based on their weight loss, headspace gas composition, texture, pH, total soluble solids, ascorbic acid, total phenolics, total microbial count, and sensory characteristics. The quality analysis revealed that ozonated water-treated samples at 12 perforations and stored at 4 °C for 28days were most efficient in keeping it fresh without any significant reduction in quality as compared to the cauliflower stored for one week at normal conditions.

Effect of Bioaugmentation with Anaerobic Fungi Isolated from Ruminants on the Hydrolysis of Corn Silage and Phragmites australis

Anaerobic fungi produce extracellular hydrolytic enzymes that facilitate degradation of cellulose and hemicellulose in ruminants. The purpose of this work was to study the impact of three different anaerobic fungal species (Anaeromyces mucronatus YE505, Neocallimastix frontalis 27, and Piromyces rhizinflatus YM600) on hydrolysis of two different lignocellulosic substrates, corn (Zea mays L.) silage and reed (Phragmites australis (Cav.) Trin. ex Steud.). Biomass from each plant species was incubated anaerobically for 11 days either in the presence of live fungal inoculum or with heat-inactivated (control) inoculum. Headspace gas composition, dry matter loss, soluble chemical oxygen demand, concentration of volatile fatty acids, and chemical composition were measured before and after hydrolysis. While some microbial activity was observed, inoculation with anaerobic fungi did not result in any significant difference in the degradation of either type of plant biomass tested, likely due to low fungal activity or survival under the experimental conditions tested. While the premise of utilizing the unique biological activities of anaerobic fungi for biotechnology applications remains promising, further research on optimizing culturing and process conditions is necessary.