Recent developments in applications of physical fields for microbial decontamination and enhancing nutritional properties of germinated edible seeds and sprouts: a review.

Germinated edible seeds and sprouts have attracted consumers because of their nutritional values and health benefits. To ensure the microbial safety of the seed and sprout, emerging processing methods involving physical fields (PFs), having the characteristics of high efficiency and environmental safety, are increasingly proposed as effective decontamination processing technologies. This review summarizes recent progress on the application of PFs to germinating edible seeds, including their impact on microbial decontamination and nutritional quality and the associated influencing mechanisms in germination. The effectiveness, application scope, and limitation of the various physical techniques, including ultrasound, microwave, radio frequency, infrared heating, irradiation, pulsed light, plasma, and high-pressure processing, are symmetrically reviewed. Good application potential for improving seed germination and sprout growth is also described for promoting the accumulation of bioactive compounds in sprouts, and subsequently enhancing the antioxidant capacity under favorable PFs processing conditions. Moreover, the challenges and future directions of PFs in the application to germinated edible seeds are finally proposed. This review also attempts to provide an in-depth understanding of the effects of PFs on microbial safety and changes in nutritional properties of germinating edible seeds and a theoretical reference for the future development of PFs in processing safe sprouted seeds.

Spoilage indicator bacteria in farmed Atlantic salmon (Salmo salar) stored on ice for 10 days.

This study investigated the growth of indicator and spoilage bacteria on whole Atlantic salmon (Salmo salar) stored aerobically at 2 °C. On days 0, 2, 3, 6, 8 and 10 microbiological analysis was carried out on inner flesh and outer skin samples as well as outer skin swabs (25 cm2 surface areas). Mesophilic total viable counts (TVCm) on skin, flesh and swab samples increased from 1.9, 1.1 and 2.7 log10 CFUcm2 to 6.0, 5.1 and 5.7 log10 CFU/cm2 after 10 days, respectively. Psychrotrophic counts (TVCp), increased from 2.2, 1.8 and 3.1 log10 CFU/cm2 to 6.2, 5.3 and 5.9 log10 CFU/cm2, for skin, flesh and swab samples respectively. Hydrogen sulphide producing bacteria (HSPB), lactic acid bacteria (LAB), Pseudomonas spp., Brochothrix thermosphacta and Photobacterium spp. grew well with similar growth rates (mean generation times of 17.2-26 h). It was concluded that the shelf-life of salmon at 2 °C was approximately 10 days and that HSPB, LAB, Pseudomonas spp., Br. thermosphacta and Photobacterium spp. may be a better indicator of fish spoilage rather than TVC growth, with a count of 5-6 log10 CFU/cm2 indicating the end of shelf-life.

High intensity light pulses to reduce microbial load in fresh cheese.

The present study focused on the utilisation of High Intensity Light Pulses (HILP) treatment to preserve mozzarella cheese. First, the susceptibility of Pseudomonas fluorescens and Enterobacteriaceae to HILP (fluences from 0·39 to 28·0 J/cm2) in a transparent liquid was evaluated (in-vitro tests). Afterwards, the effects on inoculated mozzarella cheese were also assessed. Then untreated (Control) and HILP treated samples were packaged and stored at 10 °C for 2 weeks. Enterobacteriaceae, Pseudomonas spp. and pH were monitored during storage. In a transparent liquid (in-vitro tests) there was a significant microbial inactivation just with 2 s of treatment. On the inoculated cheese a relevant microbial reduction of about 1 log cycle was observed, according to the exposure to the treatments. For Pseudomonas spp. in particular, in the treated samples, the microbiological acceptability limit (106 cfu/g) was never reached after 2 weeks of refrigerated storage. To sum up, the efficacy of this treatment is very interesting because a microbial reduction was observed in treated samples. HILP treatment is able to control the microbial growth and may be considered a promising way to decontaminate the surface of mozzarella cheese.

Light based technologies for microbial inactivation of liquids, bead surfaces and powdered infant formula.

This study evaluates the potential of continuous wave Ultraviolet C light (UV-C) and broad-spectrum intense pulsed light (in this study referred to as High Intensity Light Pulses, HILP) for the inactivation of pathogens of public concern in powdered infant formula (PIF) producers. To achieve this goal a sequential set of experiments were performed, firstly in clear liquid media, secondly on the surface of spherical beads under agitation and, finally in PIF. L. innocua was the most sensitive microorganism to both technologies under all conditions studied with reductions exceeding 4 log10 cycles in PIF. In the clear liquid medium, the maximum tolerance to light was observed for C. sakazakii against UV-C light and for B. subtilis spores against HILP, with a fluence of approximately 17 mJ/cm2 required for a 1 log10 cycle inactivation (D value) of each species. In PIF it was possible to inactivate >99% of the vegetative cell populations by HILP with a fluence of 199 mJ/cm2 and of B. subtilis spores by doubling the fluence. By contrast, for UV-C treatments a fluence of 2853 mJ/cm2 was needed for 99.9% reduction of C. sakazakii, which was the most light-resistant microorganism to UV-C. Results here obtained clearly show the potential for light-based interventions to improve PIF microbiological safety.

Quality attributes and retention of vitamin E in reduced salt chicken sausages fortified with vitamin E.

The effect of salt reduction and vitamin E (α-tocopherol) fortification, at a level in excess of that required for a European Food Safety Authority (EFSA) health claim, on the quality of chicken sausages was investigated. Four formulations of chicken sausages were prepared: C (control, 1.3% NaCl, 0 mg/kg added α-tocopherol), L (low salt, 0.47% NaCl, 0 mg/kg added α-tocopherol), CE (1.3% NaCl, 200 mg/kg added α-tocopherol), LE (0.47% NaCl, 200 mg/kg added α-tocopherol). Salt or α-tocopherol level did not significantly affect the fat content, protein content, moisture content, lipid oxidation, microbial growth, cook loss or texture profile analysis values of raw or cooked sausages. There was a significant effect of salt level on the ash content of raw and cooked sausages. Colour of cooked sausages was affected by salt reduction, with fried low salt sausages being darker and yellower than control, while grilled low salt sausages were lighter and redder than control. Cooking and storage did not significantly affect α-tocopherol retention, and enough was retained to meet both the EFSA nutrient and health claims. The sensory properties of the sausages were unaffected by the reduction in salt, and by fortification with α-tocopherol.

An assessment of the impact of pulsed electric fields processing factors on oxidation, color, texture, and sensory attributes of turkey breast meat.

Pulsed electric fields (PEF) is a novel nonthermal technology that has the potential to cause physical disruption to muscle tissue which in turn could alter the sensorial aspects of meat in both a positive (e.g., enhanced tenderization) and a negative way (e.g., off-flavor development). If there is a risk of off-flavor development it should be identified prior to embarking on an extensive investigation on PEF in meat tenderization and turkey meat was chosen for this purpose as it is particularly prone to oxidation. The objective of this study was to investigate the effect of various PEF treatments on the quality attributes of turkey breast meat. Turkey breast meat obtained 1 d postslaughter was treated in a batch PEF chamber with increasing electric field strength up to 3 kV/cm and analyzed for lipid oxidation by thiobarbituric acid reactive substances assay (TBARS) with up to 5 d storage at 4°C in aerobic conditions. In a separate experiment, turkey breast meat samples were exposed to PEF under various combinations of pulse number, frequency, and voltage. Following PEF treatments weight loss, cook loss, lipid oxidation, texture, and color were assessed by instrumental methods. A sensory analysis was also performed to determine consumer acceptability for color, texture, and odor of the samples. Lipid oxidation in all PEF-treated samples progressed at the same rate with storage as the untreated samples and was not found to be significantly different to the control. Under the conditions examined PEF treatments did not induce differences in instrumentally measured weight loss, cook loss, lipid oxidation, texture, and color (raw and cooked) either on fresh or frozen samples. However, the sensory evaluation suggested that panelists could detect slight differences between the PEF-treated samples and the controls in terms of texture and odor.

Optimization of pulsed electric field pre-treatments to enhance health-promoting glucosinolates in broccoli flowers and stalk.

BACKGROUND: The effect of pulsed electric field (PEF) treatment variables (electric field strength and treatment time) on the glucosinolate content of broccoli flowers and stalks was evaluated. Samples were subjected to electric field strengths from 1 to 4 kV cm(-1) and treatment times from 50 to 1000 µs at 5 Hz. RESULTS: Data fitted significantly (P < 0.0014) the proposed second-order response functions. The results showed that PEF combined treatment conditions of 4 kV cm(-1) for 525 and 1000 µs were optimal to maximize glucosinolate levels in broccoli flowers (ranging from 187.1 to 212.5%) and stalks (ranging from 110.6 to 203.0%) respectively. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values, with low average mean deviations (E%) ranging from 0.59 to 8.80%. CONCLUSION: The use of PEF processing at moderate conditions could be a suitable method to stimulate production of broccoli with high health-promoting glucosinolate content.

Roles of physical fields in the extraction of pectin from plant food wastes and byproducts: A systematic review.

Pectin is a naturally occurring hydrocolloid found in the cell wall and middle lamella of many plants and has numerous functional applications in food and other related industries. The type of extraction methods used in production has a strong influence on the structural or physicochemical properties of the resultant pectin and the potential application or market value of the produced pectin. Many conventional extraction methods are well-established and commercially well adopted. However, the increased demand for pectin due to limitations of the existing methods in terms of efficiency and influence on end product quality has been renewed in developing novel techniques or procedures that help to alleviate these problems. In this review paper, a series of strategies involving the application of physical fields, such as acoustic, electromagnetic, electric and mechanical one, are reviewed for potential opportunities to improve the yield and quality attributes of pectin extracted from plant food wastes and byproducts. The extraction mechanism, processing equipment, key operating parameters as well as advantages and disadvantages of each method are systematically reviewed, and findings and conclusions on the potential applications of each method are described. Moreover, the challenges and future directions of physical field assisted extraction (PFAE) of pectin are also discussed to facilitate a better understanding of the complex mechanism in PFAE and optimizing operational parameters. This review may also provide specific theoretical information and practical applications to improve the design and scale up PFAE of pectin.

Examination of the interrelationships between nutrition, environmental sustainability and food-processing: A concept study using model diets.

Recent work has focused on understanding the link between diet quality and environmental impact, however it is also important to consider the role food processing plays in this relationship. Using model meal plans, this paper examines the link between nutrient content, environmental impact, and processing. Four distinct meal plans were considered - 'Healthy', 'Unhealthy', 'Healthy (plant-based)', 'Healthy (plant-based, processed)'. For each a variety of environmental impact, processing and nutritional composition metrics were compared. Alternative healthy eating index (AHEI) score for the Unhealthy diet was significantly lower than the other three diets. The 'Healthy (plant-based)' diet had the highest AHEI score but was not significantly different to the 'Healthy (plant-based, processed)' and 'Healthy' diet scores. The greenhouse gas emissions for the two plant based diets were not significantly different to each other or to the 'Healthy' diet but were significantly lower than the 'Unhealthy' diet. The 'Healthy', 'Unhealthy', and 'Healthy (plant-based)' diets had similar processing specific energy consumption values however, the 'Healthy (plant-based, processed)' diets had significantly greater specific energy consumption. There was no clear link between diet quality and food processing when considered using processing specific energy value. When the number of processes in each diet was estimated, the unhealthier diet had considerably more processes associated with it. Examining the interaction of nutritional quality, environmental impact and processing of diets in this way highlights the complexity of the inter-relationships. Understanding these interactions is necessary to support the transition to healthy diets from sustainable sources.

Effect of crust freezing applied alone and in combination with ultraviolet light on the survival of Campylobacter on raw chicken.

The application of crust freezing (CF) applied as a stand-alone treatment or in combination with ultraviolet (UV) light for reducing the level of artificially inoculated Campylobacter jejuni on raw chicken was investigated. CF air temperatures of -5, -15 and -27 °C (±3 °C) with freezing times of 70, 15 and 6 min, respectively, were used. The level of C. jejuni on chicken was also examined following subsequent refrigerated (0-4 °C) storage at 3 and 7 days. All CF treatments resulted in significant reductions compared to untreated controls (P < 0.05). Although combining CF with UV also resulted in significant reductions for C. jejuni, the combined treatments were generally no more effective than treatment by CF alone. Overall, the color of chicken drumsticks was not affected by CF treatments (P ≥ 0.05). In general, CF resulted in increased drip loss (P < 0.05), which increased over storage time and was greater at higher CF temperatures. The current study indicates that CF has potential for reducing the levels of C. jejuni by between 0.5 and 1.5 log(10) CFU/g and impacts minimally on the color of treated skin.

Effects of dielectric properties and microstructures on microwave-vacuum drying of mushroom (Agaricus bisporus) caps and stipes evaluated by non-destructive techniques.

This research work aimed to investigate the effects of microstructures, dielectric property and temperature distributions on drying feature difference between the mushroom cap and stipe during the microwave-vacuum drying (MVD) process. Near-infrared hyperspectral imaging (NIR HSI) was employed to visualize distribution maps for moisture content (MC), dielectric constant ε' and dielectric loss factor ε'' of mushroom slices during the MVD process. Infrared (IR) thermal imaging was used to evaluate the temperature distribution of the mushroom slices. Results demonstrated higher MC, ε' and ε'' values in MVD mushroom stipes. Nevertheless, the centre area of the mushroom slice showed the highest temperature, while the MVD mushroom cap displayed a more porous structure. The effect of microstructure could encounter effects of dielectric properties and temperature to cause higher water evaporation in the MVD cap. This work highlights the novelty to combine different detection techniques to investigate the effects of microstructures, dielectric property and temperature distributions on drying patterns of mushroom slices.

Efficacy of high-intensity pulsed light for the microbiological decontamination of chicken, associated packaging, and contact surfaces.

The efficacy of high-intensity light pulse (HILP) technology (3 Hz, maximum of 505 J/pulse, and a pulse duration of 360 µs) for the decontamination of raw chicken and associated packaging and surface materials was investigated. Its ability to reduce microbial counts on raw chicken through plastic films was also examined. Complete inactivation of Campylobacter spp., Escherichia coli, and Salmonella Enteritidis in liquid was achieved after 30 sec HILP treatment. Reductions of 3.56, 4.69, and 4.60 log10 cfu/cm²) were observed after 5 sec HILP treatment of Campylobacter jejuni, E. coli, and Salmonella Enteritidis inoculated onto packaging materials and contact surfaces, respectively. The greatest reductions on inoculated chicken skin were 1.22, 1.69, and 1.27 log10 cfu/g for C. jejuni, E. coli, and Salmonella Enteritidis, respectively. Corresponding reductions on inoculated skinless breast meat were 0.96, 1.13, and 1.35 log10 cfu/g. The effectiveness of HILP treatment for reducing microbial levels on chicken increased as the film thickness decreased. HILP treatments of 2 sec did not significantly affect the color of raw chicken although treatments of 30 sec impacted color. This study has shown HILP to be an effective method for the decontamination of packaging and surface materials. Additionally, it has demonstrated the potential of HILP to be used as a decontamination method for packaged chicken.

The impact of emerging domestic and commercial electro-heating technologies on energy consumption and quality parameters of cooked beef.

The purpose of this study was to investigate the effects of e-Cooker® and moderate electric field (MEF) cooking on physical and chemical changes occurring during the cooking of meat. Beef muscle samples (38.86 ± 0.08 g) were cooked in saline solution (0.5% w/w NaCl) to a target temperature of 72 °C, followed by a 2 min holding time. The experimental results revealed that e-Cooker® and MEF significantly reduced the come-up time required to achieve a target temperature of 72 °C to 1.16 ± 0.02 min and 0.86 ± 0.02 min, respectively compared to 14.12 ± 0.55 min in conventional cooking. The colour and instrumental texture of cooked meat by e-Cooker® and MEF systems were not significantly different (P > 0.05) from conventionally cooked ones. Overall, the results obtained demonstrated that e-Cooker® and MEF can be used to cook meat in a shorter time and reasonably low energy input while producing a product which is comparable in quality to conventionally cooked meat.

Fruit, vegetables, and mushrooms for the preparation of extracts with α-amylase and α-glucosidase inhibition properties: A review.

The inhibition of the α-amylase and α-glucosidase activity facilitates the maintenance of circulating glucose levels by decreasing the rate of blood sugar absorption. Existing enzyme inhibitors such as acarbose, miglitol, and voglibose are used for inhibiting the activity of these enzymes, however, alternative solutions are required to avoid the side-effects of using these drugs. The current study aims to review recent evidence regarding the in vitro α-amylase and α-glucosidase inhibition activities of extracts derived from selected fruit, vegetables, and mushrooms. The mechanisms of action of the extracts involved in the inhibition of both enzymes are also presented and discussed. Compounds including flavonoids, phenolic acids, anthocyanins, saponins, carotenoids, terpenes, sugars, proteins, capsaicinoids, fatty acids, alkaloids have been shown to have α-amylase and α-glucosidase inhibition activities. Harvesting period, maturity stage, sample preparation, extraction technique, and solvent type are parameters that affect the α-amylase and α-glucosidase inhibition activities of the extracts.

High-Pressure Processing for the Production of Added-Value Claw Meat from Edible Crab (Cancer pagurus).

High-pressure processing (HPP) in a large-scale industrial unit was explored as a means for producing added-value claw meat products from edible crab (Cancer pagurus). Quality attributes were comparatively evaluated on the meat extracted from pressurized (300 MPa/2 min, 300 MPa/4 min, 500 MPa/2 min) or cooked (92 °C/15 min) chelipeds (i.e., the limb bearing the claw), before and after a thermal in-pack pasteurization (F9010 = 10). Satisfactory meat detachment from the shell was achieved due to HPP-induced cold protein denaturation. Compared to cooked or cooked-pasteurized counterparts, pressurized claws showed significantly higher yield (p < 0.05), which was possibly related to higher intra-myofibrillar water as evidenced by relaxometry data, together with lower volatile nitrogen levels. The polyunsaturated fatty acids content was unaffected, whereas the inactivation of total viable psychrotrophic and mesophilic bacteria increased with treatment pressure and time (1.1-1.9 log10 CFU g-1). Notably, pressurization at 300 MPa for 4 min resulted in meat with no discolorations and, after pasteurization, with high color similarity (ΔE* = 1.2-1.9) to conventionally thermally processed samples. Following further investigations into eating quality and microbiological stability, these HPP conditions could be exploited for producing uncooked ready-to-heat or pasteurized ready-to-eat claw meat products from edible crab.

Improving vitamin D3 stability to environmental and processing stresses using mixed micelles.

Deficiency of vitamin-D is prevalent globally and can lead to negative health consequences. The fat-soluble nature of vitamin-D, coupled with its sensitivity to heat, light and oxygen limits its incorporation into foods. Mixed micelles (MM) have potential to enhance bioavailability of vitamin-D. This study explores the stability of MM to food processing regimes and their ability to protect vitamin-D. Subjecting MM to a range of shearing speeds (8,000-20,500 rpm) and to high pressure processing (600 MPa, 120sec) resulted in no change in MM size (4.1-4.5 nm). MM improved the retention of vitamin-D following exposure to UV-C light, near UV/visible light, and heat treatment. MM suspensions protected vitamin-D over a four week storage period at refrigeration or freezer conditions. Overall MM show potential to protect vitamin-D from degradation encountered in food processing and storage and may be beneficial as a mechanism to fortify foods with vitamin-D.

Novel Technologies for Preserving Ricotta Cheese: Effects of Ultraviolet and Near-Ultraviolet-Visible Light.

Ricotta cheese is a potential growth medium for a wide range of microorganisms. The aim of the current study was to investigate the efficacy of ultraviolet (UV-C) and near-ultraviolet-visible light (NUV-vis) in microbial decontamination of ricotta artificially inoculated with Pseudomonas fluorescens. Cheese samples were stored at 4 °C, and microbiological and sensory analyses were performed for 9 days. From the microbiological point of view, control samples became unacceptable after less than 5 days, whereas ricotta treated by both UV-C and NUV-vis light remained acceptable for more than 6 days. Similar effects of UV-C and NUV-vis light were also recorded in terms of sensory quality. The shelf life of the samples subjected to the treatments was thus extended by 50%, suggesting the potential application of UV-C and NUV-vis light for cheese decontamination.

Monitoring the effect of different microwave extraction parameters on the recovery of polyphenols from shiitake mushrooms: Comparison with hot-water and organic-solvent extractions.

The current study aimed to investigate the effect of different microwave-assisted extraction (MAE) parameters (i.e., particle size of the sample, solid-to-liquid ratio, microwave power, and extraction time) on the total phenolic content (TPC), antioxidant capacity (DPPH and CUPRAC), chlorogenic acid and caffeic acid contents of shiitake mushrooms. All the independent variables affected TPC and antioxidant capacity values. Only the sample particle size had no significant effect on phenolic acid contents. The highest TPC, DPPH, and CUPRAC values were obtained when a particle size of 1.75 mm, solid-to-liquid ratio of 1/40, microwave power of 600 W, and extraction time of 15 min were used. The extracts obtained by MAE were compared with those obtained after hot-water extraction (HWE) and organic-solvent extraction (OSE). Scanning electron microscopy (SEM) confirmed that MAE resulted in cell wall disruption which might be due to an increase in the pressure of the inner part of the cells.

Ohmic heating of meats: Electrical conductivities of whole meats and processed meat ingredients.

The ohmic heating rate of a food is highly influenced by its electrical conductivity (σ). A survey of σ values of commonly used meat ingredients when dispersed as 5% (w/w) aqueous solutions/suspensions was undertaken. A subset was further investigated at typical usage levels in solution/suspension, and/or when incorporated into beef blends, while σ of selected cuts from five meat species (beef, pork, lamb, chicken and turkey) was also measured. Measurements were made from 5 to 85°C and showed a linear increase in σ values with increasing temperature. In processed beef, addition of sodium chloride and phosphate (P22) caused a significant increase in σ which in turn would lead to an increase in ohmic heating rates. Furthermore, whole meats with lower endogenous fat or processed meats with the least added fat displayed higher σ and reduced ohmic heating times. In beef maximum σ was observed when fibres were aligned with the current flow.

Combined effect of temperature and pulsed electric fields on apple juice peroxidase and polyphenoloxidase inactivation.

Pulsed electric fields (PEF) were applied to freshly prepared apple juice using a laboratory scale continuous PEF system to study the feasibility of inactivating peroxidase (POD) and polyphenoloxidase (PPO). Square wave PEF using different combinations of electric field strength, pre-treatment temperature and treatment time were evaluated in this study and compared to conventional pasteurisation (72°C; 26s). Inactivation curves for the enzyme were plotted for each parameter and inactivation kinetics were calculated. Results showed the highest level of decrease in the enzymatic activity of 71% and 68%, for PPO and POD, respectively, were obtained by using a combination of preheating to 50°C, and a PEF treatment time of 100µs at 40kV/cm. This level of inactivation was significantly higher (P<0.05) than that recorded in juice processed by conventional mild pasteurisation where the activity of PPO and POD decreased by 46% and 48%, respectively. The kinetic data for the inactivation of both enzymes could be described using a 1st-order model (P<0.001).