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.     

Purification and characterization of <Emphasis Type="Italic">β</Emphasis>-glucosidase from <Emphasis Type="Italic">Oenococcus oeni</Emphasis> 31MBR

This study was designed to characterize a β-glucosidase from Oenococcus oeni 31MBR, a strain widely used in Chinese winemaking. An intracellular β-glucosidase (EC 3.2.1.21) was partially purified using a combination of ammonium sulfate precipitation and chromatographic methods. A single band was obtained in SDS-PAGE electrophoresis, indicating that the enzyme was highly purified and had an estimated molecular mass of 38.9 kDa. The enzyme exhibited highest activity at pH 4.5–5.0. The optimum temperature was 45 °C. Ethanol promoted the activity of this enzyme up to three times. Among the several metal ions assayed, only Mn²⁺ exhibited a partial promotion effect. The K _m and V _max values for p-nitrophenyl-β-d-glucopyranoside were 1.05 mmol/L and 0.957 nmol/min, respectively. Up to now, this study contains the first characterization of a native β-glucosidase purified from crude extracts of O. oeni 31MBR.     

Microbial Enzymes as Substitutes of Chemical Additives in Baking Wheat Flour—Part I: Individual Effects of Nine Enzymes on Flour Dough Rheology

In this work, we evaluated the effects of nine commercial enzymes—fungal (AMY-F), bacterial (AMY-B), and maltogenic (AMY-M) α-amylases, fungal (XYL-F) and bacterial (XYL-B) xylanases, glucose oxidase (GOX), laccase (LAC), lipase (LIP), and transglutaminase (TG) on the rheological properties of common wheat flour. Falling Number (FN), farinography, and alveography analysess were carried out varying the enzyme concentrations from 25 to 833 U kg^?1, aiming to reach baking quality. α-Amylases affected mainly the farinographic properties, reducing the water absorption (WA) and stability time (ST). AMY-B was the most effective enzyme to adjust the FN, needing 150 U kg^?1, while for AMY-F and AMY-M, it was necessary 583 U kg^?1. In all tests, XYL-B was more efficient than XYL-F, but both improved the W value and P/L ratio. At 25 U kg^?1, GOX increased the development time (DT), as well as the ST and the P/L ratio. LAC, which is not a commonly used enzyme, significantly improved the ST and W values, being an interesting oxidant agent. Moreover, the ideal enzyme concentrations determined were compared with those suggested by the suppliers, with under and over dosages observed, especially for α-amylases and xylanases.     

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.     

Thermal transition and thermo-physical properties of potato (<Emphasis Type="Italic">Solanum tuberosum L</Emphasis>.) var. Russet brown

Potatoes are an important food in many regions of the world and are commonly used in a variety of food products. Thermal transition and thermo-physical properties of potatoes are important in order to design efficient food processes and select appropriate storage conditions. In this study, we determined the thermal transitions and thermophysical properties of raw and blanched/par-fried potato for a temperature range of ??32 to 21.1 °C. Using differential scanning calorimetry, we found an initial freezing point (T_f) at ??1.8?±?0.1 °C, an onset of melting (T_m^′) at ??9.9?±?0.2 °C and an unfreezable water content (X^′_w) for maximally freeze-concentrated raw potato at 0.21 kg water/kg potato. Corresponding values for blanched/par-fried potatoes were ??0.9?±?0.1 °C, ??11.0?±?0.2 °C and 0.18 kg water/kg potato. Results show that an increase in solids content decreased T_f of both raw and blanched potatoes. We modelled the relationship between them using the Chen model. The apparent specific heat (C_app) increased around T_f to 31.7?±?1.13 kJ/kg K for raw potato and 26.7?±?0.62 kJ/kg K for blanched/par-fried potato. For frozen raw potato at ??32 °C, thermal diffusivity (α) was 0.89?±?0.01?×?10?^?6 m²/s and thermal conductivity (k), 1.82?±?0.14 W/m K, respectively. These values were higher for frozen raw potato than for the unfrozen raw potato (0.15?±?0.01?×?10?^?6 m²/s and 0.56?±?0.08 W/m K, respectively at 21.1 °C). The apparent density (ρ) of frozen raw potato (992?±?4.00 kg/m³ at ??32 °C) was less than that for unfrozen raw potato (1053?±?4.00 kg/m³ at 21.1 °C), and a similar trend was obtained for blanched/par-fried potato (993?±?2.00 kg/m³ at ??32 °C and 1188?±?7.00 kg/m³ at 21.1 °C, respectively). This study established a correlation between thermo-physical properties and temperature. Findings may be used to inform the design and optimization of freezing processes and frozen storage for potato products.     

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.     

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).     

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.     

A Gompertz Model Approach to Microbial Inactivation Kinetics by High-Pressure Processing Incorporating the Initial Counts,Microbial Quantification Limit,and Come-Up Time Effects

During come-up time (CUT), the time to reach a desired processing pressure, isobaric-isothermal conditions cannot be assumed in the estimation of kinetic parameters for the design of commercial high-pressure processing (HPP) treatments. Since CUT effects on microbial population, enzyme activity, and chemical concentration are often ignored, kinetic models incorporating the non-isobaric and non-isothermal conditions prevailing during CUT were the objective of this work. The analysis of peer-reviewed data on the HPP inactivation of bacteria (counts observations n = 919, 60 survival curves) and bacterial spores (n = 273, 12 curves) showed that a Gompertz model (GMPZ) approach is an effective alternative. The GMPZ parameter A was fixed as the difference between the initial population (log₁₀ N _o ) and the lower quantification limit of microbial counts (log₁₀ N _lim), while exponential equations were used to describe pressure effects on the lag time (λ) and the maximum inactivation rate (μ_max). In low-acid media (pH > 4.5), λ decreased exponentially with pressure, allowing the identification of a theoretical pressure level (P _λ) sufficient to initiate microbial inactivation during CUT. The parameter μ_max exponentially increased with pressure for all evaluated datasets. Dynamic pressure effects during CUT were simplified by assuming isobaric conditions during CUT (t _CUT), allowing to obtain GMPZ parameter estimates using only nonlinear regression (R ² ～ 0.938, σ ² = 0.030–0.604). The proposed approach is a simpler, promising tool for a more informative analysis of the kinetics of microbial inactivation by HPP and should be further validated with additional experimental data.     

Isotope Ratio Mass Spectrometry Coupled to Element Analyzer and Liquid Chromatography to Identify Commercial Honeys of Various Botanical Types

The aim of the present work was to investigate whether honeys of various botanical characteristics could be discriminated and identified on the basis of the isotopic data. For this purpose, 45 commercial honey samples of various botanical types were analyzed using isotope ratio mass spectrometry (IRMS) coupled to element analyzer (EA) and liquid chromatography (LC). δ ¹³C values of honey; corresponding extracted protein and individual sugars (sucrose, glucose, and fructose) of honey; reducing sugar; and sucrose contents were determined and utilized to demonstrate the authenticity of commercial honeys of different botanical types. Results indicated that a very strong correlation (δ ¹³C_protein = 0.862δ ¹³C_honey + 0.800, R ² = 0.944) was observed between δ ¹³C honey values and δ ¹³C protein values of real honey samples. δ ¹³C_honey and δ ¹³C_protein should range from ?27.2 to ?23.5 and ?26.9 to ?23.6‰ for pure honeys of various botanical types investigated in this study. The use of isotopic compositions and some systematic differences as authenticity criterion permits the honey samples of various botanical types to be reliably detected.     

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.     

Effect of Tannin Extracts on Biofilms and Attachment of <Emphasis Type="Italic">Escherichia coli</Emphasis> on Lettuce Leaves

Lettuce is often involved in foodborne outbreaks caused by pathogenic Escherichia coli. Current control strategies have often proved ineffective to ensure safe food production. For that reason, the present study compared the efficacy of tannin extracts and chlorine treatments on the reduction of E. coli ATCC 25922 adhered to lettuce leaves. E. coli was inoculated artificially on leaf surfaces of fresh crisp lettuce. Effectiveness of water, chlorine (200 mg/L), and three commercial available tannin extracts from Acacia mearnsii De Wild. (tannin AQ (2 %, w/v), tannin SG (1 %, v/v) and tannin SM (1 %, v/v)) treatments was evaluated using the viable plate count method and scanning electron microscopy (SEM). SEM results revealed that bacterial cells are attached as individual cells and in clusters to the leaf surface after 2 h of incubation. Biofilm formation was observed after 24 h of incubation. The tannin SM treatment was able to reduce counts in approximately 2 log CFU/cm² on leaf segments. However, treatment was less effective in the reduction of E. coli counts after 24 h of incubation when compared to 2 h incubation of the same extract. The results suggest that the tannin SM extract diminishes E. coli counts adhered to and under biofilm formation on lettuce leaves and its effect is similar to the use of chlorine solutions.     

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.     

Quantification of <Emphasis Type="Italic">Penicillium nalgiovense</Emphasis> on Dry-Cured Sausage ‘Salchichón’ Using a SYBR Green-Based Real-Time PCR

To evaluate the effective implantation of a specific protective culture of Penicillium nalgiovense, a real-time quantitative PCR (qPCR) using SYBR Green methodology was developed. Two specific primers were designed on the basis of the published partial sequences of the Internal Transcribe Spacer (ITS)1–5.8S-ITS2 region of various strains of P. nalgiovense. Using the developed method, a PCR product of 51 bp with a T _m value 81.34 °C was detected. T _m values of the amplified product allowed specific differentiation between P. nalgiovense and the remaining mould species tested. The developed qPCR method was tested on inoculated slices of dry-cured sausage (‘salchichón’) showing an efficiency of 97.24 %, a R ² value of 0.99 and a detection limit of P. nalgiovense of 1 log colony-forming units (cfu)/cm². The qPCR method demonstrated that the protective strain of P. nalgiovense grew and competed against an ochratoxin A (OTA)-producing Penicillium verrucosum strain on commercial dry-cured sausage. This qPCR method provides a specific, accurate and sensitive detection and quantification of P. nalgiovense on dry-cured sausage salchichón in order to estimate its colonization during their processing. This assay will improve strategies to prevent and control unwanted mould colonization and OTA risk in dry-cured meat commodities.     

Effect of Thermosonic Pretreatment and Microwave Vacuum Drying on the Water State and Glass Transition Temperature in <Emphasis Type="Italic">Agaricus bisporus</Emphasis> Slices

This study aimed to understand the micromechanism of thermosonic pretreatment and microwave vacuum drying on Agaricus bisporus. The water state and glass transition temperature (T _g ) of fresh and thermosonically treated Agaricus bisporus slices during microwave vacuum drying were studied using differential scanning calorimetry (DSC), low-field nuclear magnetic resonance (LF-NMR), and magnetic resonance imaging (MRI). Results showed that four population groups were contained in the initial distribution of transverse relaxation time (T ₂) data of fresh A. bisporus slices: T ₂₁ (0.38–7.05 ms), T ₂₂ (9.33–32.75 ms), T ₂₃₁ (37.65–265.61 ms), and T ₂₃₂ (305.39–811.13 ms). Thermosonic pretreatment significantly decreased the initial free water content of A. bisporus sample but was accompanied by a sharp increase in its immobilized water. “Semi-bound water transfer” appeared during microwave vacuum drying (MVD) at moisture contents (X _w ) of 0.70 and 0.60 g/g (wet basis (w.b.)) for untreated and thermosonically treated samples, respectively. MVD caused dramatic changes in the water state and enhanced the T _g by decreasing the content and mobility of immobilized water in A. bisporus tissues. The mobility of semi-bound water for thermosonically and MVD-treated samples was higher than for MVD-untreated samples, resulting in T _g values decreasing by approximately 2–11.5 °C, but the uniformity of water distribution in thermosonic-treated and MVD-treated samples was better at X _w  ≤ 0.52 g/g (w.b.).     

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.     

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%).     

Optimization of Extraction Parameters of Total Phenolics from <Emphasis Type="Italic">Annona crassiflora</Emphasis> Mart. (Araticum) Fruits Using Response Surface Methodology

In this study, response surface methodology was used to optimize the extraction temperature (25–75 °C) and ethanol concentration (0–70 %, ethanol/water, v/v) to maximize the extraction of total phenolic compounds (TPC) from araticum pulp. The efficiency of the extraction process was monitored over time, and equilibrium conditions were reached between 60–90 min. A second-order polynomial model was adequately fit to the experimental data with an adjusted R ² of 0.9793 (p < 0.0001) showing that the model could efficiently predict the TPC content. Optimum extraction conditions were ethanol concentration of 46 % (v/v), extraction temperature of 75 °C and extraction time of 90 min. Under the optimum conditions, the araticum pulp showed high TPC content (4.67 g GAE/100 g dw) and also high antioxidant activity in the different assays used (46.56 μg/mL, 683.65 μmol TE/g and 1593.72 μmol TE/g for DPPH IC₅₀, TEAC and T-ORAC_FL, respectively). From our extraction procedure, we successfully recovered a significantly higher amount of TPC compared to other studies in the literature to date (1.5–22-fold higher). Furthermore, TPC and antioxidant activity were present in the fruit in levels that are difficult to find in other common fruits. These results expose a potential approach for improving human health through consumption of araticum fruit.     

Evaluation of <Emphasis Type="Italic">eryC</Emphasis> as a Molecular Marker for the Quantitative Detection of <Emphasis Type="Italic">Brucella</Emphasis> Spp. by Real-Time PCR in Food Samples

We evaluated the capacity of the Brucella sp. eryC gene as a diagnostic marker for brucellosis by quantitative real-time PCR. eryC gene encodes the enzyme d-erythrulose-1-phosphate dehydrogenase that plays an important role in the erythritol metabolism and is related with the Brucella survival in the intracellular environment of the macrophage. The assay includes an internal amplification control (IAC) in order to avoid false negative results. It was 100% specific, with an analytical sensitivity of 1 genome equivalent (GE) in 43% of the reactions, being the quantification highly linear (R ² > 0.9953) and efficient (PCR efficiency >0.8820) over a 6-log dynamic range, down to 10 GE. Finally, the applicability of this assay was evaluated with artificially contaminated biological matrices implicated in the transmission of this bacterium such as sheep raw milk and pig blood. The eryC-IAC real-time PCR assay allowed detection of as few as ten Brucella cells per 25 ml of sheep raw milk or per 1 ml of pig blood. In conclusion, we present an alternative for the detection of Brucella genus and therefore facilitate the establishment of preventive and prophylactic measures in food and farm environments.     

Comparative Study on the Inactivation and Photoreactivation Response of <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> Seafood Isolates and a <Emphasis Type="Italic">Listeria innocua</Emphasis> Surrogate after Pulsed Light Treatment

The inactivation and photoreactivation response of six seafood-isolated Listeria monocytogenes and one Listeria innocua strain after pulsed light (PL) treatment was evaluated. The lower inactivation levels found after exposure of treated samples to daylight during the first 90 min of storage confirmed that both L. innocua and L. monocytogenes have the capability to photorepair PL-induced DNA damage upon appropriate conditions. Photoreactivation levels from 0.2 to 2.1 log CFU cm^?2 were observed depending on treatment intensity (fluence) and Listeria strain. Complete photorepair of PL-caused damage was not found even after treatments inducing low inactivation levels. Photoreactivation increased up to 2.1 log with the applied fluence up to a threshold able to cause between 2.4 and 5.4 log reductions under dark storage. Photorepair was not avoided but lower photoreactivation was observed after higher fluence inducing more than 6 log reductions under dark storage. Both L. innocua and L. monocytogenes serotype 1/2b exhibited the highest photoreactivation levels whereas serotypes 1/2a showed the lowest ones. The overall inactivation and photoreactivation responses of tested Listeria strains were comparable indicating that L. innocua may be a good surrogate for the safe evaluation, optimization and validation of PL technology to control L. monocytogenes in food products and food processing facilities.