Manuka Oil vs. Rosemary Oil: Antimicrobial Efficacies in Wagyu and Commercial Beef against Selected Pathogenic Microbes.

Essential oils possessing antimicrobial characteristics have acquired considerable interest as an alternative to chemical preservatives in food products. This research hypothesizes that manuka (MO) and kanuka (KO) oils may possess antimicrobial characteristics and have the potential to be used as natural preservatives for food applications. Initial experimentation was conducted to characterize MOs (with 5, 25, and 40% triketone contents), rosemary oil (RO) along with kanuka oil (KO) for their antibacterial efficacy against selected Gram-negative (Salmonella spp. and Escherichia coli), and Gram-positive (Listeria monocytogenes and Staphylococcus aureus) bacteria through disc diffusion and broth dilution assays. All MOs showed a higher antimicrobial effect against L. monocytogenes and S. aureus with a minimum inhibitory concentration below 0.04%, compared with KO (0.63%) and RO (2.5%). In chemical composition, α-pinene in KO, 1, 8 cineole in RO, calamenene, and leptospermone in MO were the major compounds, confirmed through Gas-chromatography-mass spectrometry analysis. Further, the antimicrobial effect of MO and RO in vacuum-packed beef pastes prepared from New Zealand commercial breed (3% fat) and wagyu (12% fat) beef tenderloins during 16 days of refrigerated storage was compared with sodium nitrate (SN) and control (without added oil). In both meat types, compared with the SN-treated and control samples, lower growth of L. monocytogenes and S. aureus in MO- and RO- treated samples was observed. However, for Salmonella and E. coli, RO treatment inhibited microbial growth most effectively. The results suggest the potential use of MO as a partial replacement for synthetic preservatives like sodium nitrate in meats, especially against L. monocytogenes and S. aureus.

Multitarget preservation technologies for chemical-free sustainable meat processing.

Due to the growing consumer demand for safe and naturally processed meats, the meat industry is seeking novel methods to produce safe-to-consume meat products without affecting their sensory appeal. The green technologies can maintain the sensory and nutritive characteristics and ensure the microbial safety of processed meats and, therefore, can help to reduce the use of chemical preservatives in meat products. The use of chemical additives, especially nitrites in processed meat products, has become controversial because they may form carcinogenic N-nitrosamines, a few of which are suspected as cancer precursors. Thus, the objective of reducing or eliminating nitrite is of great interest to meat researchers and industries. This review, for the first time, discusses the influence of processing technologies such as microwave, irradiation, high-pressure thermal processing (HPTP) and multitarget preservation technology on the quality characteristics of processed meats, with a focus on their sensory quality. These emerging technologies can help in the alleviation of ingoing nitrite or formed nitrosamine contents in meat products. The multitarget preservation technology is an innovative way to enhance the shelf life of meat products through the combined use of different technologies/natural additives. The challenges and opportunities associated with the use of these technologies for processing meat are also reviewed.

Contribution of the proximal and distal gastric phases to the breakdown of cooked starch-rich solid foods during static in vitro gastric digestion.

In vitro gastric digestion studies commonly focus on the acidic environment of the stomach (the distal phase), neglecting that the contact time between food and salivary amylase can be extended during bolus' temporary storage in the proximal stomach (the proximal phase). Consequently, the role of the proximal phase of gastric digestion on the breakdown of solid starch-based foods is not well understood. This study aimed to address this question using a static in vitro digestion approach. Cooked starch-rich foods of different physical structures (wheat couscous, wheat pasta, rice couscous, rice noodle, and rice grain) were subjected to 30 s oral phase digestion, followed by prolonged incubation of the oral phase mixture (pH 7) for up to 30 min representing different proximal phase digestion times. Each proximal phase sample was sequentially incubated in excess simulated gastric fluid (distal phase, pH 2) for up to an additional 180 min. The proximal phase aided solid food breakdown through starch hydrolysis that caused leaching of particles <2 mm. The distal phase led to softening of food particles, but the softening process was not enhanced with longer proximal phase. In foods with smaller initial size (couscous and rice couscous), a proximal phase of 15 min or longer followed by 180-min distal phase increased starch hydrolysis in the liquid and suspended solid fractions of the digesta, indicating the influence of food structure on acid hydrolysis during in vitro gastric digestion.

Study from microcosms and mesocosms reveals Escherichia coli removal in high rate algae ponds during domestic wastewater treatment is primarily caused by dark decay.

While high rate algal ponds (HRAPs) can provide efficient pathogen removal from wastewater, the mechanisms involved remain unclear. To address this knowledge gap, the mechanisms potentially causing Escherichia coli (E. coli) removal during microalgae-based wastewater treatment were successively assessed using laboratory microcosms designed to isolate known mechanisms, and bench scale assays performed in real HRAP broth. During laboratory assays, E. coli decay was only significantly increased by alkaline pH (above temperature-dependent thresholds) due to pH induced toxicity, and direct sunlight exposure via UV-B damage and/or endogenous photo-oxidation. Bench assays confirmed alkaline pH toxicity caused significant decay but sunlight-mediated decay was not significant, likely due to light attenuation in the HRAP broth. Bench assays also evidenced the existence of uncharacterized 'dark' decay mechanism(s) not observed in laboratory microcosms. To numerically evaluate the contribution of each mechanism and the uncertainty associated, E. coli decay was modelled assuming dark decay, alkaline pH induced toxicity, and direct sunlight-mediated decay were independent mechanisms. The simulations confirmed E. coli decay was mainly caused by dark decay during bench assays (48.2-89.5% estimated contribution to overall decay at the 95% confidence level), followed by alkaline-pH induced toxicity (8.3-46.5%), and sunlight-mediated decay (0.0-21.9%).

Structural breakdown of starch-based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations.

The digestion of starch-based foods in the small intestine as well as factors affecting their digestibility have been previously investigated and reviewed in detail. Starch digestibility has been studied both in vivo and in vitro, with increasing interest in the use of in vitro models. Although previous in vivo studies have indicated the effect of mastication and gastric digestion on the digestibility of solid starch-based foods, the physical breakdown of starch-based foods prior to small intestinal digestion is often less considered. Moreover, gastric digestion has received little attention in the attempt to understand the digestion of solid starch-based foods in the digestive tract. In this review, the physical breakdown of starch-based foods in the mouth and stomach, the quantification of these breakdown processes, and their links to physiological outcomes, such as gastric emptying and glycemic response, are discussed. In addition, the physical breakdown aspects related to gastric digestion that need to be considered when developing in vitro-in vivo correlation in starch digestion studies are discussed. The discussion demonstrates that physical breakdown prior to small intestinal digestion, especially during gastric digestion, should not be neglected in understanding the digestion of solid starch-based foods.

Escherichia coli removal during domestic wastewater treatment in outdoor high rate algae ponds: long-term performance and mechanistic implications.

Escherichia coli (E. coli) first-order decay rates ranging from 3.34 to 11.9 d-1 (25-75% data range, N = 128) were recorded in two outdoor pilot-scale (0.88 m3) high rate algal ponds (HRAPs) continuously fed primary domestic wastewater over two years (influent E. coli cell count of 4.74·106 ± 3.37·106 MPN·100 mL-1, N = 142). The resulting removal performance was relatively constant throughout the year (log10-removal averaging 1.77 ± 0.54, N = 128), apart from a significant performance drop during a cold rainy period. E. coli removal performance was not strongly correlated to any of the meteorological or operational parameters recorded (e.g. sunlight intensity, pH, temperature). Hourly monitoring of E. coli cell count evidenced that E. coli removal, pH, dissolved oxygen (DO) and pond temperature peaked in the late afternoon of sunny summer days. Such improved daytime removal was, however, not evidenced in spring, even under sunny conditions causing milder increases in pH, DO and temperature. Overall, the data confirm the potential of HRAPs to support efficient E. coli removal during secondary domestic wastewater treatment and suggests E. coli decay was mainly caused by dark mechanisms episodically enhanced by indirect sunlight-mediated mechanisms and/or high pH toxicity.

Delaying microbial proliferation in freshly peeled shallots by active packaging incorporating ethanol vapour-controlled release sachets and low storage temperature.

This research was conducted to investigate effects of ethanol vapour released in active packaging and storage temperatures on the quality of freshly peeled shallots. The package tested was a solid polypropylene tray incorporating an ethanol vapour-controlled release sachet. The sachet was made of an aluminium foil film on one side and either low-density polyethylene or nylon/polyethylene on the other. Individual sachets contained silica gel adsorbent as the carrier pre-loaded with ethanol. One sachet was placed in each tray containing the peeled shallots and the tray was heat sealed with the low-density polyethylene film lid. Packages were stored at either 10 or 25 ℃ for 10 d. Trays containing only peeled shallots were designated as controls. High storage temperature stimulated quality changes in the shallots. Although ethanol vapour accumulated in the active package headspace, the extent to which ethanol concentrations increased within the shallots was not significantly different from that in the control packages. Microbial proliferation in terms of yeast and mould counts could be delayed through a combination of 10 ℃ and ethanol vapour released from the low-density polyethylene sachet. The ethanol vapour accumulated in the packages did not have a significant effect on mass loss, firmness, and colour changes in the peeled shallots, or on the concentrations of oxygen and carbon dioxide in the packages.

Defining the end-point of mastication: A conceptual model.

The great risks of swallowing are choking and aspiration of food into the lungs. Both are rare in normal functioning humans, which is remarkable given the diversity of foods and the estimated 10 million swallows performed in a lifetime. Nevertheless, it remains a major challenge to define the food properties that are necessary to ensure a safe swallow. Here, the mouth is viewed as a well-controlled processor where mechanical sensory assessment occurs throughout the occlusion-circulation cycle of mastication. Swallowing is a subsequent action. It is proposed here that, during mastication, temporal maps of interfacial property data are generated, which the central nervous system compares against a series of criteria in order to be sure that the bolus is safe to swallow. To determine these criteria, an engineering hazard analysis tool, alongside an understanding of fluid and particle mechanics, is used to deduce the mechanisms by which food may deposit or become stranded during swallowing. These mechanisms define the food properties that must be avoided. By inverting the thinking, from hazards to ensuring safety, six criteria arise which are necessary for a safe-to-swallow bolus. A new conceptual model is proposed to define when food is safe to swallow during mastication. This significantly advances earlier mouth models. PRACTICAL APPLICATIONS: The conceptual model proposed in this work provides a framework of decision-making to define when food is safe to swallow. This will be of interest to designers of dietary foods, foods for dysphagia sufferers and will aid the further development of mastication robots for preparation of artificial boluses for digestion research. It enables food designers to influence the swallow-point properties of their products. For example, a product may be designed to satisfy five of the criteria for a safe-to-swallow bolus, which means the sixth criterion and its attendant food properties define the swallow-point. Alongside other organoleptic factors, these properties define the end-point texture and enduring sensory perception of the food.

Oxygen consumption by bovine granulosa cells with prediction of oxygen transport in preantral follicles.

The rate of oxygen consumption by granulosa cells is a key parameter in mathematical models that describe oxygen transport across ovarian follicles. This work measured the oxygen consumption rate of bovine granulosa cells in vitro to be in the range 2.1-3.3×10⁻¹6 mol cell⁻¹ s⁻¹ (0.16-0.25 mol m⁻³ s⁻¹). The implications of the rates for oxygen transport in large bovine preantral follicles were examined using a mathematical model. The results indicate that oocyte oxygenation becomes increasingly constrained as preantral follicles grow, reaching hypoxic levels near the point of antrum formation. Beyond a preantral follicle radius of 134 µm, oxygen cannot reach the oocyte surface at typical values of model parameters. Since reported sizes of large bovine preantral follicles range from 58 to 145 µm in radius, this suggests that oocyte oxygenation is possible in all but the largest preantral follicles, which are on the verge of antrum formation. In preantral bovine follicles, the oxygen consumption rate of granulosa cells and fluid voidage will be the key determinants of oxygen levels across the follicle.

The role of oral processing in dynamic sensory perception.

Food oral processing is not only important for the ingestion and digestion of food, but also plays an important role in the perception of texture and flavor. This overall sensory perception is dynamic and occurs during all stages of oral processing. However, the relationships between oral operations and sensory perception are not yet fully understood. This article reviews recent progress and research findings on oral food processing, with a focus on the dynamic character of sensory perception of solid foods. The reviewed studies are discussed in terms of both physiology and food properties, and cover first bite, mastication, and swallowing. Little is known about the dynamics of texture and flavor perception during mastication and the importance on overall perception. Novel approaches use time intensity and temporal dominance techniques, and these will be valuable tools for future research on the dynamics of texture and flavor perception.

Theoretical investigation into the dissolved oxygen levels in follicular fluid of the developing human follicle using mathematical modelling.

Oxygen levels in the follicle are likely to be critical to follicle development. However, a quantitative description of oxygen levels in the follicle is lacking. Mathematical modelling was used to predict the dissolved oxygen levels in the follicular fluid of the developing human follicle. The model predictions showed that follicular fluid dissolved oxygen levels are highly variable among follicles, due to the unique geometry of individual follicles. More generally, predictions showed that oxygen levels in follicular fluid increase rapidly during the initial early antral stages of follicle growth before peaking in the later early antral phase. Follicular fluid dissolved oxygen levels then decline through to the beginning of the pre-ovulatory phase, from which they increase through to ovulation. Based on the best available parameter estimates, the model predictions suggest that the mean dissolved oxygen levels in human follicular fluid during the late antral and pre-ovulatory phases range between 11 and 51 mmHg (approximately 1.5-6.7 vol%). These predictions suggest that the human ovarian follicle is a low-oxygen environment that is often challenged by hypoxia, and are in agreement with only some published data on follicular fluid oxygen levels. Predictions are discussed in relation to follicle health and oocyte culture.

Bond rupture of biomolecular interactions by resonant quartz crystal.

Significant progress has been achieved in understanding affinity-based diagnostics, which use the highly specific "lock and key" recognition and binding between biomolecules, for example, an antibody and its antigen. These are the most specific of analytical tests. One of the most challenging issues is to distinguish between true binding and ever-present nonspecific binding in which more loosely bound proteinaceous material gives false results in conventional affinity methods. We have used bond-rupture scanning to eliminate nonspecific binding by introducing energy mechanically through displacement of a resonant quartz crystal. The removal of the analyte was recorded with a simple all-electronic detection system quickly providing confirmation of the presence of the target molecule. The system can measure the resonant frequency difference and detect noise signals, respectively, due to mass changes and bond breaks between biotinylated self-assembled monolayer (SAM) and streptavidin-coated polystyrene microspheres (SCPM). Both static and dynamic scanning modes can reveal previously unrecognized desorption of streptavidin-coated polystyrene microspheres. An established framework of bond-rupture scanning is a promising diagnostic tool for investigating the specific and nonspecific interactions by measuring the characteristic level of mechanical energy required to break the bond.

The effects of IVF aspiration on the temperature, dissolved oxygen levels, and pH of follicular fluid.

PURPOSE: To investigate the effects of IVF aspiration on the temperature, pH, and dissolved oxygen of bovine follicular fluid. METHODS: The temperature was monitored at various positions in an aspiration kit. Dissolved oxygen and pH were measured before and after aspiration. RESULTS: The temperature of follicular fluid dropped by 7.7 +/- 1.3 degrees C upon aspiration. Dissolved oxygen levels rose by 5 +/- 2 vol.%. The pH increased by 0.04 +/- 0.01. CONCLUSIONS: The temperature change was attributed mainly to evaporation of fluid in the collection tube. Changes in dissolved oxygen levels and pH were due to contact with air. Standard vacuum-based aspiration may induce changes in follicular fluid, which could be detrimental to oocyte health and affect attempts to correlate chemical characteristics with oocyte quality.