A mathematical model for moisture movement during continous and intermittent drying of <Emphasis Type="Italic">Eucalyptus saligna</Emphasis>

A modified diffusion-based mathematical model is proposed to describe the moisture movement during continuous and intermittent drying of Eucalyptus saligna. This model includes the temperature change, the surface drying coefficient (β _n ) and 2 diffusion coefficients [from green to FSP (D _f ) and from FSP to dry condition (D _o )] as important parameters. The final model expression obtained was M?=?exp (??25 β _n ² D _t /l²) with the β _n used was 1.5807 kg m^?2 s^?1, the D _f was 2.26?×?10^?11 m² s^?1, and the D _o was 5.85?×?10^?12 m² s^?1. The range of temperature change between heating and non-heating phases in the intermittent drying regimes was from 24.9 to 31.8 °C. The R² values obtained when the model was fitted into the drying data of different intermittent regimes ranged from 71.5 to 85.9%. The R² value was 87.4% when the model was fitted into continuous trial data. The high values of R² indicate that the model can be used to understand the moisture reduction both in intermittent and continuous regimes.     

A Case Study on Optimization of Biomass Flow During Single-Screw Extrusion Cooking Using Genetic Algorithm (GA) and Response Surface Method (RSM)

In the present study, response surface method (RSM) and genetic algorithm (GA) were used to study the effects of process variables like screw speed, rpm (x ₁), L/D ratio (x ₂), barrel temperature (°C; x ₃), and feed mix moisture content (%; x ₄), on flow rate of biomass during single-screw extrusion cooking. A second-order regression equation was developed for flow rate in terms of the process variables. The significance of the process variables based on Pareto chart indicated that screw speed and feed mix moisture content had the most influence followed by L/D ratio and barrel temperature on the flow rate. RSM analysis indicated that a screw speed?>?80 rpm, L/D ratio?>?12, barrel temperature?>?80 °C, and feed mix moisture content?>?20% resulted in maximum flow rate. Increase in screw speed and L/D ratio increased the drag flow and also the path of traverse of the feed mix inside the extruder resulting in more shear. The presence of lipids of about 35% in the biomass feed mix might have induced a lubrication effect and has significantly influenced the flow rate. The second-order regression equations were further used as the objective function for optimization using genetic algorithm. A population of 100 and iterations of 100 have successfully led to convergence the optimum. The maximum and minimum flow rates obtained using GA were 13.19?×?10^?7 m³/s (x ₁?=?139.08 rpm, x ₂?=?15.90, x ₃?=?99.56 °C, and x ₄?=?59.72%) and 0.53?×?10^?7 m³/s (x ₁?=?59.65 rpm, x ₂?=?11.93, x ₃?=?68.98 °C, and x ₄?=?20.04%).     

Antioxidant Activity and Determination of Phenolic Compounds from <Emphasis Type="Italic">Eugenia involucrata</Emphasis> DC. Fruits by UHPLC-MS/MS

Fruits have been the focus of several studies aimed at finding new antioxidant sources for protection against the damage caused by reactive species. In this study, the antioxidant activity and the presence of phenolic compounds in all parts (peel, pulp, and seeds) of Eugenia involucrata DC. fruits were evaluated. DPPH^·, ABTS^·+, and ORAC methods were used to determine the antioxidant activity, and an UHPLC-MS/MS method was developed for determining the phenolic compounds (gallic, chlorogenic, ferulic, p-coumaric and ellagic acids, quercetin, and myricetin). In the determination of both antioxidant activity and phenolic composition, the efficiency of solvents with different polarities—methanol/H₂O (80:20, v/v), ethanol/H₂O (80:20, v/v), methanol/acidified water with phosphoric acid pH 3.00 (80:20, v/v), and ethyl acetate—for the extraction of the phenolic compounds, was also evaluated. All parts of E. involucrata fruits showed antioxidant activity, in the range of 36.68 ± 1.44 to 873.87 ± 18.24 μmol TE g^?1, being the highest values found in the seeds and peel when more polar extraction solvents were used. Six, five, and three phenolic compounds were identified and quantified in the pulp, peel, and seeds, respectively, with the highest abundance as p-coumaric acid (14 ± 2 mg kg^?1) in the pulp, quercetin (47 ± 5 mg kg^?1) in the peel, and gallic acid (74 ± 4 mg kg^?1) in the seeds, also when more polar solvents were used. Although antioxidant activity methods suggested that the peel and seeds have more antioxidant potential, a wider variety of compounds were determined in the pulp.     

An approach for extraction,purification, characterization and quantitation of acylated-anthocyanins from <Emphasis Type="Italic">Nitraria tangutorun</Emphasis> Bobr. fruit

In the present study, a systematic approach for extraction, purification and analysis of acylated-anthocyanins from Nitraria tangutorun Bobr. fruit was explored. Six acylated-anthocyanins in N. tangutorun fruit were identified by HPLC-MS/MS, and a rapid and efficient HPLC-DAD method was developed to analyze the acylated-anthocyanins. Ultrasonic-assisted extraction conditions of acylated-anthocyanins were optimized using response surface methodology, extraction at 70 °C for 32 min using 70% methanol solution (0.1% HCl, v/v) rendered an extract with 80.37?±?2.66 mg/100 g of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and 97.88?±?4.06 mg/100 g of total acylated-anthocyanins. Nine macroporous resins were investigated for preliminary purification of acylated-anthocyanins. According to the static/dynamic adsorption and desorption tests, XDA-6 macroporous resin exhibited the maximum potential for preparing acylated-anthocyanins. The purity of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside (43.30 mg/g) in purified acylated-anthocyanins was 201.89 times of that of the extract (0.21 mg/g), and the purity of total acylated-anthocyanins increased from 0.36 to 56.44 mg/g. Besides, the stability (t _1/2) of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total acylated-anthocyanins increased by more than five-fold after purification using XDA-6. The established methods of analysis, extraction and purification of acylated-anthocyanins were hopefully utilized in food industry.     

Smart NMR Method of Measurement of Moisture Content of Vegetables During Microwave Vacuum Drying

Microwave drying is usually combined with vacuum environment in conjunction with hot air flow to draw the moisture rapidly. The moisture content of the vegetables undergoing drying is hard to measure online. This research designed a microwave vacuum drying (MVD)-low-field nuclear magnetic resonance (NMR) smart device and investigated the feasibility of NMR method for online measurement of state of moisture during MVD. The relation between the signal amplitude (A ₂) and the true moisture content (M ₁) of six kinds of vegetables (mushroom, carrot, potato, lotus, edamame, vegetable corn) was fitted to estimate if NMR can measure the M ₁ of vegetables directly. Results showed that A ₂ and M ₁ of different fresh vegetables had no single empirical mathematical model to fit. However, for each kind of these vegetables, the A ₂ and corresponding M ₁ in different MVD stages showed a significant linear relationship. The predicted moisture content (M ₂) of mushroom: M ₂ = 5.25351 × 10^?4 A ₂ ? 0.34042, R = 0.996; carrot: M ₂ = 5.78756 × 10^?4 A ₂ ? 0.14108, R = 0.998; potato: M ₂ = 3.10019 × 10^?4 A ₂ ? 0.10612, R = 0.991; lotus: M ₂ = 2.32415 × 10^?4 A ₂ ? 0.01573, R = 0.998; edamame: M ₂ = 3.13310 × 10^?4 A ₂ ? 0.4198, R = 0.996; vegetable corn: M ₂ = 1.69461 × 10^?4 A ₂ ? 0.09063, R = 0.995. The linear models between M ₂ and A ₂ were able to estimate the end point (M ₁ < 8%) of MVD with a high accuracy (P > 0.950).     

Partition Behaviors of Different Polar Anthocyanins in Aqueous Two-Phase Systems and Extraction of Anthocyanins from <Emphasis Type="Italic">Nitraria tangutorun</Emphasis> Bobr. and <Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr.

This study aimed to investigate the partition behaviors of various polar anthocyanins in NaH₂PO₄/(NH₄)₂SO₄-ethanol aqueous two-phase systems (ATPS) and to extract anthocyanins from Nitraria tangutorun Bobr. and Lycium ruthenicum Murr. Anthocyanins in Hibiscus sabdariffa L., Morus atropurpurea Roxb., N. tangutorun, and L. ruthenicum were profiled using HPLC-ESI-MS/MS and HPLC-DAD, and the partition behaviors of total anthocyanins and main anthocyanins were studied. The partition coefficient of anthocyanins increased with increased hydrophobicity, and low-polarity anthocyanins exhibited a higher preference for the top phase in NaH₂PO₄/(NH₄)₂SO₄-ethanol ATPS. Additionally, the NaH₂PO₄-ethanol ATPS gave higher selectivity and total anthocyanin yield than the (NH₄)₂SO₄-ethanol system. Extraction at 65 °C for 45 min and at 45.5 °C for 45 min using 28% NaH₂PO₄ and 26% ethanol (w/w) led to the recovery of 98.91 ± 0.03% of N. tangutorun anthocyanins (3.62 ± 0.05 mg/g) and 99.84 ± 0.01% of L. ruthenicum anthocyanins (13.16 ± 0.29 mg/g) from raw material; more than 70% of total sugars were removed in a single step. NaH₂PO₄-ethanol aqueous two-phase extraction is a promising method for extracting anthocyanins from N. tangutorun and L. ruthenicum.     

Comparative inactivation studies of <Emphasis Type="Italic">Aegle marmelos</Emphasis> (<Emphasis Type="Italic">bael</Emphasis>) peroxidase in crude extract of fruit by heat processing and ultrasonication treatment

Bael (Aegle marmelos) is considered as a holy fruit comprised of vast number of phytonutrients. Whole bael tree including all its parts has medicinal significance. Lack of awareness and seasonal nature makes its processing rather challenging. Conventional heat processing may lead to inactivation of quality hampering enzymes such as peroxidase, but at the cost of loss in essential phytonutrients. In the present work it was observed that thermal inactivation of bael peroxidase obeyed first order kinetics with enzyme activation energy of 7.7 kJ mol^?1. Complete inactivation of bael peroxidase was achieved within 11 min at 85?°C while ultrasound treatment attained in lesser time of 4 min at 64.07 W cm^?2 ultrasonic intensity. Loss of marmelosin a well-known phytonutrient in bael fruit was found to be 83.29?% by heat (11 min, 85?°C) and only 50.20?% by ultrasonication (4 min, 64.07 W cm^?2 ultrasonic intensity). Ultrasonication has potential to overcome harmful effects of heat processing with retention of phyto-constituents and hence has promising future in various food processing applications.     

Steady- and Unsteady-State Determination of the Water Vapor Permeance (<Emphasis Type="Italic">WVP</Emphasis>) of Polyethylene Film to Estimate the Moisture Gain of Packed Dry Mango

The water vapor permeance (WVP; g m^?2 d^?1 Pa^?1) of packaging films quantifying the water vapor transfer rate between foods and its surroundings is usually determined in units operating under steady-state conditions that do not necessarily reflect food handling scenarios. This study evaluated the determination of the WVP of a polyethylene (PE) film by steady-state method ASTM F1249-06 using a permeability cell and unsteady-state method ASTM E96/E96M in which 102 vacuum-sealed PE bags containing silica gel were stored (37.8 °C, 75% relative humidity) and weighed over 25 days. Average steady-state WVP (2.935 ± 0.365 × 10^?3, n = 4) fell within the 95% quantiles of unsteady-state WVP values (1.818–3.183 × 10^?3, n = 2142). Moisture uptake of dehydrated mango stored at 37.8 °C and 75% relative humidity was predicted with WVP values obtained by both methods. Predictions were validated by monitoring over 25 days the weight gain of 100 PE bags with dry mango. Experimental moisture averages during storage fell within one standard deviation of predictions using the unsteady-state WVP (R ² = 0.974). The same was observed only until day 15 for predictions obtained with the steady-state WVP. Calculations for days 20–25 overestimated the moisture uptake by 6.0–7.2%, resulting in registered R ² = 0.924. The unsteady-state WVP determination is low-cost, uses large numbers of film samples, and allowed more accurate predictions of dry mango moisture uptake. Knowledge of the moisture uptake controlled by the film WVP is essential when predicting the safety and quality changes limiting the shelf-life of foods.     

Development and characterization of reconstituted hydrogel from <Emphasis Type="Italic">Aloe vera</Emphasis> (<Emphasis Type="Italic">Aloe barbadensis</Emphasis> Miller) powder

Structural and rheological characterization of reconstituted hydrogels developed from A. vera non-fibrous alcohol insoluble residue (NFAIR) powder using different methods [viz., shaking (S), heating-shaking (HS), and heating (H)] and concentrations (viz., 0.2–1.6 %, w/v) was carried out. Functional group distribution by FTIR spectroscopy and Congo red (CR) method revealed the presence of acetylated acemannan in A. vera powder. Dynamic oscillation studies of A. vera (NFAIR) fluids at all concentrations of 0.2–1.6 %, w/v, showed gel strength in the order of H > HS > S method. However, in H method, increase in concentration from 0.2 to 1.6 %, w/v showed the conformational transition from semi-diluted solution to weak gel nature. Rheological models described the effect of heating temperatures (HT); 30–90 °C, and times (Ht); 15–60 min on viscoelastic behavior in reconstituted A. vera fluids. The reconstituted A. vera hydrogel prepared with a concentration of 1.6 %, w/v using 50 °C (HT) and 30 min (Ht) condition showed a good agreement with the Power law (storage modulus, G′) and Weak gel model (complex modulus, G*) fitted data (R² > 0.94) resulting higher viscoelastic moduli intercepts; G′₀ (71.5 Pa s ^n′), G″₀ (33.5 Pa s ^n″), lower slopes; n′ (0.22), n″ (0.06), higher network strength (A _F , 121.3 Pa s^1/z ) and number of network (z, 5.3) values. The obtained results suggested that heating at 50 °C/30 min can develop aqueous weak gel networks of A. vera with enhanced gel strength which may be utilized as a novel gelling agent for wide variety of targeted applications in food and pharmaceutical sectors.     

Synergistic Processing of Skim Milk with High Pressure Nitrous Oxide,Heat, Nisin,and Lysozyme to Inactivate Vegetative and Spore-Forming Bacteria

Individual and combined effects of high pressure nitrous oxide (HPN₂O), heat, and antimicrobials on the inactivation of Escherichia coli, Listeria innocua, and Bacillus atrophaeus endospores in milk were all evaluated after 20-min treatments. Stand-alone milk treatments with HPN₂O (15.2 MPa), heat (45 and 65 °C), or nisin (50 and 150 IU mL^?1) resulted in log₁₀ reductions ranging only from 0.1 to 2.1 for E. coli and L. innocua. Combining HPN₂O (15.2 MPa) with heat (65 °C) inactivated 6.0 and 5.1 log₁₀ in the vegetative bacteria, respectively. Similarly, reductions of 5.9 and ≥ 6.0 log₁₀ of respective E. coli and L. innocua cells in milk were achieved through a combination of HPN₂O (15.2 MPa), heat (65 °C), and nisin (150 IU mL^?1). A 2.5 log₁₀ cycle inactivation of spores was obtained by HPN₂O, nisin (at both 50 and 150 IU mL^?1), and lysozyme (50 μg mL^?1) at 85 °C. Combining these processing techniques resulted in significantly greater microbial inactivation (p < 0.05) than the sum of individual reductions from each treatment alone, indicating synergistic effects. HPN₂O irrespective of processing temperatures did not cause any occurrence of sub-lethally injured cells or disruption in colloidal stability of milk at 65 and 85 °C (p ≥ 0.05). Color and pH changes in milk following the most demanding treatment conditions were minimal.     

Assessment of the Influence of the Decanter Set-up During Continuous Processing of Olives at Different Pigmentation Index

New generation decanters allow operators to make real-time adjustments during the virgin olive oil extraction process in order to gain the best performance possible. However, the opportunity to act in line requires a deep understanding of the consequences of changing machine parameters. To this purpose, an experiment was carried out at industrial scale. The decanter feed rate (Fr), ranging from 4075 to 5820 kg h^?1, the bowl/screw conveyor differential speed (?n), set at 18 and 22, and two ripening degrees of the olives were considered as process variables. Two combinations Fr-?n, namely 4620 kg h^?1 at ?n-18 and 5210 kg h^?1 at ?n-22, were found to similarly maximize the process efficiency, regardless the raw material features. After pointing out the best working settings, the corresponding virgin olive oils were compared. The analysis of variance showed that peroxide value, K ₂₃₂, K ₂₇₀, phenols, chlorophylls, β-tocopherol, fruity and bitter notes, and C6 volatile compounds were significantly affected by the machine parameters. An inverse proportionality was observed between the combination Fr-?n and the phenolic compounds. On the whole, the sampling factor exerted a larger influence on the product quality than the decanter set-up.     

Antioxidant activity and acetylcholinesterase inhibition of field and in vitro grown <Emphasis Type="Italic">Musa</Emphasis> L. species

Bananas and plantains (Musa L. species) have medicinal applications against diseases such as hypoglycemia, hypertension, and neurological disorders, especially Alzheimer’s disease. The demand for these plants is growing very fast, resulting in a relatively heavy load on Musaceae genetic resources. The study evaluated and compared the acetylcholinesterase (AChE) inhibition and antioxidant activity of field and in vitro plant materials of nine accessions of Musa spp. consisting of Tropical Musa banana (TMb: TMb 106, TMb 145, TMb 8, TMb 82, TMb 55) and Tropical Musa plantain (TMp: TMp 116, TMp 24, TMp 36) from the International Institute of Tropical Agriculture and Musa sapientum (MS) from the University of Ibadan Botanical garden, Nigeria. Musa accessions were estimated onto Murashige and Skoog (MS) medium supplemented with 0.18 mg/L indole acetic acid (IAA) and 4.5 mg/L benzyl amino purine (BAP). The in vitro grown accessions behaved differently with TMb 8 having the highest average shoot length of 5.03?±?0.66 cm, and average number of leaves of 5.65?±?0.38 cm at the end of 6 weeks. Leaf extracts provide more quantity of phenolics, flavonoids and higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity than the fruit extracts. The AChEI activity of the field plants ranged from 60.54?±?0.54 to 98.46?±?0.09?% and in vitro plants from 61.88?±?0.11 to 76.60?±?0.34?% at 200 µg/mL. Crude methanol extract (CME) of the in vitro plants showed higher DPPH antioxidant activity than the field plants with IC₅₀ (extract concentration providing 50?% inhibition) values ranging from 9.57?±?0.24 to 48.37?±?0.62 µg/mL compared with CME of the field samples, which had IC₅₀ ranging from 75.86?±?1.76 to 162.20?±?3.77 µg/mL. Plant tissue culture can be a reliable alternative cultivation method for mass propagation and conservation of Musa species for the production of antioxidant and acetylcholinesterase metabolites.     

Biodegradable Polymeric Films Incorporated with Nisin: Characterization and Efficiency against <Emphasis Type="Italic">Listeria monocytogenes</Emphasis>

Nisin (0.2 IU per cm² films) containing biodegradable films were produced from pea protein isolate (PPI), whey protein isolate (WPI), and polylactic acid (PLA). Nisin was released over 4 h at 22 °C and 8 h at 4 °C. PPI released more nisin compared to other films suppressing the growth of Listeria monocytogenes (P?<?0.05) based upon diffusion into agar and liquid culture media. The population of bacteria after 48 h in liquid media was 6 CFU/mL (1 log₁₀ increase) in PPI, 8.47 CFU/mL (3.47 log₁₀ increase) in WPI and 9 CFU/mL (4 log₁₀ increase) in PLA, which was significantly lower in protein based films compared to PLA (P?<?0.05). The inhibition zone in agar test was significantly higher (P?<?0.05) in PPI and WPI, compared to PLA film, which might be due to the higher hydration in protein based films. Fourier transform infrared spectroscopy (FTIR) showed that nisin altered the intensity of amide I peaks in protein based films suggesting that nisin can bind to the protein functional groups in PPI and WPI. Thermogram showed that nisin did not influence the glass transition and melting temperatures of the films. Nisin containing films exhibited significantly lower enthalpy compared to control films (P?<?0.05). PeakForce Quantitative Nano Mechanical Property Mapping (PeakForce QNM) was applied to extract material and mechanical properties in PPI, WPI and PLA films with and without nisin. Results showed significant reductions in material and mechanical properties of protein based films containing nisin compared to PLA films.     

Study of Ca<Superscript>2+</Superscript>-ATPase Activity and Solubility in the Whole Kuruma Prawn (<Emphasis Type="Italic">Marsupenaeus japonicus</Emphasis>) Meat During Heating: Based on the Kinetics Analysis of Myofibril Protein Thermal Denaturation

Protein denaturation is considered to be the main cause of physicochemical changes in prawns during heating. However, no studies have been analyzed the kinetics of protein denaturation and the relationship between the degree of denaturation and chemical changes. Therefore, we investigated the changes in Ca²⁺-ATPase activity, protein solubility, and total sulfhydryl content of whole prawn meat during heating by determining the thermal denaturation kinetics of the proteins. Activation energies (E _a ) for the denaturation of myosin (183.2 kJ/mol) and actin (178.8 kJ/mol) were obtained by non-isothermal differential scanning calorimetry analysis. Using the kinetic parameters, the distribution of protein denaturation was predicted in whole prawns under arbitrary heating conditions. The results revealed an uneven distribution of the protein denaturation in prawns that was dependent on the heating conditions. Ca²⁺-ATPase activity decreased with increasing heating times at 51 or 85 °C and was strongly related to the average degree of protein denaturation. The results of protein solubility analysis suggested that hydrogen bonds, hydrophobic interactions, and ionic bonds changed with protein denaturation. The number of ionic bonds was reduced, while hydrogen content was enhanced at both temperatures. Hydrophobic interactions increased gradually at 51 °C (p?<?0.05). At 85 °C, hydrophobic interactions increased notably at first (p?<?0.05); however, as heating continued, no significant changes were observed (p?>?0.05). Our results indicate that the extent of protein solubility is significantly correlated with the average degree of protein denaturation during the heating process.     

Intermittent and Continuous Microwave-Convective Air-Drying Characteristics of Sage (<Emphasis Type="Italic">Salvia officinalis</Emphasis>) Leaves

The effect of microwave-convective air-drying (continuous and intermittent) and convective air-drying of sage (Salvia officinalis) on color and essential oil content were studied. For microwave-convective air-drying, four pulse ratio levels (PR1, PR2, PR3, and PR4) at 25 °C drying air temperature were used and the average drying rates were 0.404, 0.158, 0.114, and 0.085 kg H₂O kg^?1 DM min^?1 for PR1, PR2, PR3, and PR4, respectively. For convective air-drying, two drying temperatures of 40 and 50 °C were examined and the average drying rates were 0.005 and 0.006 kg H₂O kg^?1 DM min^?1 for 40 and 50 °C, respectively. The experimental data were fitted to 11 different moisture ratio models to describe the drying kinetics under various drying conditions. Page model was found satisfactory to describe the drying curves of sage leaves. Comparing with the fresh sage, lightness (L*), greenness, and yellowness decreased for all drying applications. Lightness, greenness, and yellowness of the convective air-dried sage leaves were higher than those of microwave-convective air-dried sage leaves. The deviation from fresh product color (ΔE*) increased as the pulse ratio or the drying air temperature increased. The total quantity of essential oils of sage decreased considerably during microwave-convective air-drying whereas the loss of essential oils was limited during air-drying.     

Modeling the Inactivation of <Emphasis Type="Italic">Listeria innocua</Emphasis> and <Emphasis Type="Italic">Escherichia coli</Emphasis> in Fresh-Cut Tomato Treated with Pulsed Light

The effectiveness of pulsed light (PL) treatments to inhibit microorganisms on fresh-cut tomatoes (Lycopersicon esculentum Mill., cv. Daniela) was investigated. Tomato slices inoculated with Escherichia coli or Listeria innocua were exposed to PL treatments (4, 6, or 8 J cm^?2 fluence) and kept cold at 4 °C for 20 days. L. innocua and E. coli counts, gases in the headspace of the containers (O₂ and CO₂), pH, titratable acidity, and soluble solid content were monitored throughout the cold storage. The PL treatments reduced significantly (p < 0.05) initial loads of both microbes. The effect of the PL fluence on the survival number of microoganisms was described by a log-linear model (R ² = 0.849–0.999). At any fixed time within the cold storing, the microbial counts for untreated samples were always higher than those cut tomatoes that had been previously PL-treated. The behavior of L. innocua and E. coli during the storage were well adjusted (R ² > 0.930) by Gompertzian models; the studied microorganisms exhibited different patterns during the storage period. On the other hand, O₂ and CO₂ partial pressures in containers with fresh-cut tomatoes were also significantly affected by PL treatments (p < 0.05). The highest PL fluence caused the greatest changes of O₂ and CO₂ contents. In addition, the application of PL triggered an acceleration of the O₂ consumption during the cold stage. PL treatments might be used to effectively extend the safety of fresh-cut tomatoes over 12 days of storage against E. coli and L. innocua growth.     

Pressure-Thermal Kinetics of Furan Formation in Selected Fruit and Vegetable Juices

Furan, a potential carcinogenic compound, can be formed in array of processed foods. The objective of this study was to conduct kinetic studies in pineapple juice and assess the interactive effects of pressure (0.1 to 600 MPa) and temperature (30 to 120 °C) on furan formation. Additional experiments were carried out in tomato, watermelon, cantaloupe, kale, and carrot juice to understand the influence of matrix and juice pH. Furan was monitored in raw (control) and processed samples by automated headspace gas chromatography mass spectrometry, and quantified by calibration curve method with d₄-furan as internal standard. The data were modeled using zero-, first-, and second-order equations. The zero-order rate constants (k _T,P ), activation energy (E _a ), and Gibbs free energy of activation (ΔG ^?) of furan formation in thermally processed (TP; 90–120 °C) pineapple juice were found to be 0.036–0.55 μg/kg/min, 98–114 kJ/mol, and 173.9–180.5 kJ/mol, respectively. Furan concentration was negligible and close to the detection limit (0.37 μg/kg) after pressure treatment (600 MPa at 30 °C) of juice samples. For similar process temperatures, the rate constants of pressure-assisted thermally processed (PATP; 600 MPa at 105 °C) pineapple juice were lower than that of TP samples. Furan formation was influenced by juice matrix and pH. On the other hand, PATP markedly suppressed furan (0.7 to 1.6 μg/kg) in these selected juices. In conclusion, furan formation increased with process temperature and treatment time, while pressure treatment at ambient temperature did not promote its production. Furan formation in TP fruit juices was also influenced by juice matrix and pH, but these were not the significant factors for PATP-treated juices.     

A Rapid and Visual Single Primer Isothermal Amplification-Based Method for the Detection of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> in Raw Pork Products

Staphylococcus aureus (S. aureus) is an important food-borne pathogen which poses a severe threat to public health worldwide. Rapid detection of S. aureus with high sensitivity is of particular importance for food safety. In this study, a novel single primer isothermal amplification (SPIA) method was established to detect S. aureus in food, targeting the accessory gene regulator (agr) gene with a DNA/RNA primer. The developed SPIA method has the advantages of visualization and avoiding tedious electrophoresis. In order to confirm the specificity of this method, 7 S. aureus strains and 26 non-S. aureus strains were detected with their pure cultures. The sensitivity and detection limit of S. aureus with artificially inoculated raw pork products by SPIA were evaluated through fluorescence and turbidity by naked eye and the amplification curve, which were 4.3?×?10⁰ CFU/mL and 5.6?×?10⁰ CFU/g, respectively. Compared with the conventional PCR method, the SPIA has 100-fold higher sensitivity and 100-fold lower detection limit. Therefore, the developed SPIA method is a potentially reliable tool for rapid and visual detection of S. aureus in food.     

Conventional and Microwave-Assisted Extraction of Mucilage from <Emphasis Type="Italic">Opuntia ficus-indica</Emphasis> Cladodes: Physico-Chemical and Rheological Properties

Cactus pear cladodes processing has potential value for mainstream industries and is equally important for marginal rural communities in arid regions. This work is focused on physico-chemical and rheological properties of Opuntia ficus-indica (OFI) peeled cladodes extracted by conventional method “CE” and using microwave-assisted extraction “MAE.” MAE gave the highest yield extraction (8.13 %, w/w) within the lowest extraction time (500 W/7 min) and provided more protein (×1.03) and carbohydrates (×1.51) than CE. The monosaccharides detected by gas chromatography were arabinose, galactose, rhamnose, xylose, and galacturonic acid. The dialyzed mucilage solution characterized by SEC/MALS/VD/DRI (size-exclusion chromatography coupled with online multi-angle light scattering, viscometer detectors, and differential refractive index) revealed fractions with molecular weight (M _w ) ranging from 15.3–15.7?×?10⁶ g mol^?1 for the CE extracts and about 16.7–17.5?×?10⁶ g mol^?1 for the MAE extracts. Dynamic oscillatory testing has been used to study the rheological properties of mucilage solution within the concentration of 0.50–3.00 % (w/v) at 25 °C. The rheological profiles of CE and MAE showed similar behavior. At low frequency and low mucilage concentration (<2.00 %), the viscous component (G") predominated over the elastic component (G'), while for higher frequencies, the behavior is reversed (G'?>?G"). If safely controlled, alternative energies like microwaves could extract soluble polymers with comparable properties to commercial ones, conventionally extracted.     

Optimization of Ultrasound-Assisted Extraction of Lycopene from Papaya Processing Waste by Response Surface Methodology

Lycopene possesses strong antioxidant ability, which may provide protection against cancer and other degenerative diseases. An ultrasound-assisted extraction method has been developed for the extraction of lycopene from papaya (Carica papaya L.) processing waste. Optimization conditions were firstly determined using single factor experiment, and then response surface methodology was used. Analysis showed that second-order polynomial models produced a satisfactory fitting of the experimental data with regard to lycopene (R ²?=?0.9147, P?<?0.001). The optimal conditions were 42.28 % ethanol in ethyl acetate as a solvent and extraction for 26.09 min at 50.12 °C. Under these conditions, the maximum yield of lycopene was 189.8?±?4.5 μg/g fresh weight (FW), which was higher than that obtained using the traditional extracting method (153.9?±?7.8 μg/g FW) and the Soxhlet extraction method (68.3?±?4.1 μg/g FW). The crude extract obtained could be used as either food additive or for further isolation and purification of lycopene. The results obtained are helpful for full utilization of papaya.