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).     

Roasting and Colouring Curves for Coffee Beans with Broad Time-Temperature Variations

The effects of time and temperature on change in bean colour and kinetics of coffee roasting covering pre-roasting and over-roasting condition were investigated. Arabica coffee beans (Colombia Excelso) were dried or roasted in an oven at constant temperatures (140, 180, 200, 220, 260, and 300 °C) to obtain the profiles of mass loss and colour change. Changes in roasting rate from the first stage (high rate) to the second (low rate) were found to occur at different levels of roast loss for different roasting temperatures. Roasting curves were obtained by normalising the data of mass reductions, which comprised solid and moisture, to the initial solid mass. Changes in bean colour were found to follow a certain path regardless of the roasting temperature, as shown by the characteristic colouring curve, and were less affected by the temperature compared to the roast loss. A method of predicting the bean colour during roasting was also presented by analysing the relationships among the L*, a* and b* values.     

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.     

Uncertainty of Trypsin Inhibitor Activity Measurement of Legume Crops Using Microtiter Plate Method

Trypsin inhibitors could limit utilization of legumes in human nutrition, but they could also have beneficial health effects. The objective of this study was to measure trypsin inhibitor activity (TIA) of different legumes using microtiter plate method and to identify factors that contribute to uncertainty of TIA measurement. TIA measurements were performed on seeds of faba bean, pea, common vetch, soybean, and common bean cultivars. The significant effect of legume crop on TIA measurement uncertainty was confirmed with P = 0.045. Certain sources of measurement uncertainty were related with the content of trypsin inhibitors (Tis) in legume seeds. In respect to that, significant effect of level of sample dilution (P ? 0.001) was confirmed. Significant influence of the repeated absorbance measurement of sample reaction mixture on uncertainty of TIA measurement was identified (P ? 0.001), and it took 60% of overall TIA measurement uncertainty for soybean cultivars. TIA of soybean cultivars exceeded 90 TUI/mg. Repeated absorbance measurement of positive control reaction mixture took 70% of TIA measurement uncertainty of cultivars with TIA lesser than 4.5 TUI/mg. Graduated cylinder used for preparation of the final sample solutions took the range from 45 to 90% of overall TIA measurement uncertainty of the cultivars whose TIA were in the middle of previously mentioned. The uncertainty of TIA measurement of legume crops was not studied before; thus, this study pointed out that acquiring insight into factors contributing to uncertainty of TIA measurement could give directions for improvement of TIA testing if microtiter plate method is used.     

Bioactive compounds and antioxidant activities of sprout soybean fermented with <Emphasis Type="Italic">Irpex lacteus</Emphasis> mycelia

To enhance the biological activities of sprout soybean, beans were treated with steaming (SS), germinating (GS), or roasting (RS) prior to fermentation with Irpex lacteus mycelia for 20 days. The total phenolic, flavonoid, isoflavone, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of each fermented bean preparation were examined every 5 days for 20 days. The total phenolic content of SS, GS, and RS preparations was 9.61, 10.23, and 10.46 mg/g, respectively, after 15 days of fermentation. These concentrations were approximately 4–5 folds higher compared to initial levels. The total flavonoid content was 8–9 folds higher than initial levels. The isoflavone content was highest in the RS sample (6.84 mg/g). The DPPH radical scavenging activity of beans fermented with I. lacteus mycelia was increased 2–8 folds after 20 days of fermentation. These results indicate that antioxidant activity components were increased by fermentation of I. lacteus mycelia irrespective of soybean treatments.     

Simultaneous Determination of Alkaloids in Green Coffee Beans from Ethiopia: Chemometric Evaluation of Geographical Origin

The alkaloid compositions of 99 green coffee (Coffea arabica L.) bean samples comprising eight varieties (Harar, Jimma, Kaffa, Wollega, Sidama, Yirgachefe, Benishangul and Finoteselam) from the major production regions of Ethiopia were investigated. High performance liquid chromatography was applied for the simultaneous determination of four coffee alkaloids in the aqueous extracts of the beans. The limits of detection for the method were established as 13 mg kg^?1 for trigonelline, 7 mg kg^?1 for theobromine, 8.5 mg kg^?1 for caffeine and 4 mg kg^?1 for theophylline in the dry coffee beans. Theophylline was not detected in any of the samples. The determined concentrations (% w/w dry coffee beans) ranged from 0.98 to 1.32 % for trigonelline, 0.0048 to 0.0094 % for theobromine and 0.87 to 1.38 % for caffeine. The concentrations of the alkaloids varied significantly, depending on the geographical origin of the beans. Theobromine was not detected in coffee beans from the East (Harar coffees), and its absence in samples can be used to ascertain whether the coffee originates from this region. Coffee beans from the Northwest were characterized by higher concentrations of caffeine. Application of linear discriminant analysis provided 75 % correct classification of samples into the respective production regions, with a 74 % prediction success rate. The moderate classification efficiency obtained when using alkaloid data demonstrates the potential of using this class of compounds in discriminant models for determination of the geographical origin of green coffee beans from Ethiopia.     

Comparison of the Diatheva STEC FLUO with BAX System Kits for Detection of O157:H7 and Non-O157 Shiga Toxin-Producing <Emphasis Type="Italic">Escherichia coli</Emphasis> (STEC) in Ground Beef and Bean Sprout Samples Using Different Enrichment Protocols

The aim of this study was to assess the performance of the Diatheva STEC FLUO and BAX System real-time PCR assays for detection of Shiga toxin-producing Escherichia coli (STEC) (stx1/stx2 and eae target genes) and O-group identification in ground beef and bean sprout samples. Ground beef (325 g or 25 g) and mung bean sprout (25 g) samples were inoculated with ~?10 CFU of the “top five” STEC (O157:H7, O26, O103, O111, and O145 as specified in EU regulation ISO13136:2012), enriched using different broths and incubation temperatures, and tested using the Diatheva and BAX real-time PCR assays. In ground beef, both molecular methods were able to detect the “top five” STEC, and lower Ct values were observed for the Diatheva kits compared to BAX System. The O111-contaminated samples gave negative results with both methods using mTSB?+?novobiocin for enrichment. In bean sprouts, both methods provided positive results, although detection was not possible using mTSB?+?acriflavin/cefsulodin/vancomycin for enrichment. In conclusion, the Diatheva and BAX methods detected the “top five” STEC in ground beef and bean sprouts when inoculated at low levels. Both assays provided equivalent results in terms of performance and reliability. Thus, the Diatheva kits are comparable to reference STEC-detection methods and could be used by the food industry to reliably detect the “top five” STEC.     

Polymerase chain reaction for the detection of<Emphasis Type="Italic"> Phaseolus vulgaris</Emphasis> beans in chestnut purée

A method based upon polymerase chain reaction (PCR) for the detection of Phaseolus vulgaris beans in chestnut purée was developed. The method involves DNA isolation by the GeneSpin kit and PCR with primers oriented to a sequence of a nuclear gene encoding PvLEA-18, a late embryogenesis-abundant protein of beans. The PCR method was shown to be specific for Ph. vulgaris, producing a 100 bp fragment with six Ph. vulgaris cultivars, and negative results with four non-Ph. vulgaris Phaseolus samples and five non-Phaseolus legumes. When evaluated with model mixtures of Ph. vulgaris beans and the chestnut purée, a detection limit of 1% was determined.     

Application of Near-Infrared Hyperspectral Imaging with Variable Selection Methods to Determine and Visualize Caffeine Content of Coffee Beans

Hyperspectral imaging covering the spectral range of 874–1734 nm was used to determine caffeine content of coffee beans. Spectral data of 958.24–1628.89 nm were extracted and preprocessed. Partial least squares regression (PLSR) model on the preprocessed full spectra obtained good performance with coefficient of determination of prediction (R ² _p ) of 0.843 and root mean square error of prediction (RMSEP) of 131.904 μg/g. In addition, 10 variable selection methods were applied to select the best optimal wavelengths. The PLSR models on the different optimal wavelengths obtained satisfactory results. The PLSR model on the wavelengths selected by random frog (RF) performed the best, with R ² _p of 0.878 and RMSEP of 116.327 μg/g. The RF wavelength selection combined with the PLSR model also achieved satisfactory visualization of caffeine content between different coffee beans. The overall results indicated that optimal wavelength selection was an efficient method for spectral data preprocessing, and hyperspectral imaging was illustrated as a potential technique for real-time online determination for caffeine content of coffee beans.     

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.     

Combined Application of Fluorescence Spectroscopy and Chemometrics Analysis in Oxidative Deterioration of Edible Oils

Combined methods of fluorescence spectrometry with chemometrics were used to monitor oxidation deterioration of edible oil. Synchronous and three dimensional fluorescence spectroscopy techniques were proposed for monitoring palm oil, camellia oil, sunflower oil and perilla oil during oven accelerated oxidation. Principal component analysis plot of fluorescence intensity (λex = 320–700 nm) clearly showed oxidative evolution of oils over heating time. High saturated or monounsaturated oils exhibited high regression coefficients between peroxide values and fluorescence intensity (R ²  = 0.973 for 400 nm in palm oil; R ²  = 0.956 for 370 nm in camellia oil). High diunsaturated oil exhibited high regression coefficient between nonpolar carbonyl compounds and fluorescence intensity (R ²  = 0.970 for 370 nm in sunflower oil). High triunsaturated oil exhibited high regression coefficient between p-anisidine value and fluorescence intensity (R ²  = 0.938 for 665 nm in perilla oil). In conclusion, Fluorescence spectroscopy is a rapid and green nondestructive method for oxidation monitoring. Differences of fatty acid compositions played key rules in formation of oxidation products and evolution of fluorescence spectra.     

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.     

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.     

Stabilization of Refrigerated Avocado Pulp: Chemometrics-Assessed Antibrowning Allium and Brassica Extracts as Effective Lipid Oxidation Retardants

The effectiveness of Allium and Brassica extracts to inhibit the evolution of lipids oxidation in avocado pulp under refrigeration (storage at 4 °C) was studied. Onion, garlic, scallion, white cabbage, cauliflower, and Brussels sprouts extract were tested as preserving agents in refrigerated avocado pulp. Allium extracts promoted almost a 60% retention of the intrinsic anti-radical capacity of the pulps. Considering secondary oxidation effects, extinction coefficient at 270 nm shows that all treated pulps (except those with scallion addition) were acceptable at the 30th storage day (K ₂₇₀ < 0.22), but they were all significantly less oxidized than the untreated samples (K ₂₇₀ = 1.8) (P < 0.05). Garlic-treated avocado showed the highest antioxidant effectiveness, based on C=CH cis proportion (I _cis = 108.3), while samples with white cabbage extract presented the highest C=CH trans (I _trans = 5.7) proportion after 30 days. The PCA method was discriminant enough since 83.6% of the variance was explained by the first two principal components, allowing the samples to be grouped according to storage time and extract type. This study confirmed that the addition of garlic, onion, and cauliflower extracts enhanced lipid antioxidant properties in refrigerated avocado pulps.     

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%).     

Effects of organic acid pretreatment on microstructure,functional and thermal properties of unripe banana flour

Starch availability has been implicated in unripe matured banana (Musa species), which when processed yields flour suitable for application in low gluten and composite wheat formulations. Unripe Musa species: Williams, Luvhele, Mabonde and Muomva-red obtained from fruit bunch were pretreated with ascorbic, citric and lactic acids, processed into 50 g of flour and characterised for their functional and thermal properties. Scanning electron microscope of unripe banana flour (UBF) showed varying micrographs of flour, with polygonal for Luvhele, oval for Mabonde, elongated for Muomva-red and between polygonal and spherical for Williams. The bulk density of UBF samples was within the range of 0.66–0.84 g/mL for all organic acid pretreatment while citric acid pretreated UBF had the least browning index. Significant difference (p < 0.05) was recorded in swelling power with no significant difference in water solubility index except for Mabonde UBF. Thermal properties showed single endothermic transition for all UBF samples at various pretreatment concentration. The onset temperature (To) of UBF ranges from 49.82 to 65.59 °C, peak temperature (Tp) from 60.11 to 76.71 °C, conclusion temperature (Tc) from 70.36 to 94.16 °C and enthalpy of gelatinization (ΔH) from 2.61 to 32.24 J/g. Short amylopectin chains present in starch of UBF was attributed to low To, Tp, Tc and ΔH values recorded for Mabonde cultivar, while the contribution of heat-moisture treatment rather than organic acid pretreatment of UBF samples was attributed to different gelatinization and transition temperatures recorded for all cultivars examined.     

Real-Time Monitoring of Organic Carrot (var. Romance) During Hot-Air Drying Using Near-Infrared Spectroscopy

The worldwide consumption of dried carrot (Daucus carota L.) is on a growing trend. Conventional methods for drying carrots include hot-water blanching followed by hot-air drying, which is usually uncontrolled and therefore prone to product quality deterioration. Thus, there is a need for innovative drying systems that yield high-value end products. In this study, the efficacy of NIR spectroscopy for the non-destructive monitoring of physicochemical changes and drying behaviour in organic carrot slices during 8-h hot-air drying at 40 °C was demonstrated using Partial least squares (PLS) regression and PLS discriminant analysis (PLS-DA). The impact of hot-water blanching pre-treatment (at 95 °C for 1.45 min) for enzyme inactivation on performances of both regression and classification models was also evaluated. PLS regression models were successfully developed to monitor changes in water activity (R ² = 0.91–0.96), moisture content (R ² = 0.97–0.98), total carotenoids content (R ² = 0.92–0.96), lightness for unblanched carrots (R ² = 0.80–0.83) and hue angle for blanched samples (R ² = 0.85–0.87). Soluble solids content prediction was poor for both treatments (RMSEP = 3.43–4.40). Classification models were developed to recognise dehydration phases of carrot slices on the basis of their NIR spectral profile using K-means and PLS-DA algorithms in sequence. The performance of each PLS-DA model was defined based on its accuracy, sensitivity and specificity rates. All of the selected models provided from good (> 0.85) to excellent (> 0.95) sensitivity and specificity for the predefined drying phases. Feature selection procedures yielded both regression and classification models with performances very similar to models computed from the full spectrum.     

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.).     

Textural properties of mung bean starch gels prepared from whole seeds

The textural properties of mung bean starch gels (MSG) made by starches purified from whole seeds of Dahyeon were investigated to improve the quality of Korean traditional starch gel, cheongpomuk. Based on our investigation, the protein and dietary fiber contents of starch from whole mung beans (WM) were significantly higher than those from hulled mung beans (HM); however, apparently, WM had lower amylose contents than HM (their respective apparent amylose contents were 32.42 and 33.09%). The fresh gels (WMSG and HMSG), stored gels (WMSG-S4 and HMSG-S4), and reheated gels (WMSG-R4 and HMSG-R4) were also compared. The stored gels showed the highest L and b values, translucence, hardness, and gumminess. While HMSG showed a denser network structure than WMSG, the structure of stored gels was recovered after reheating. The fresh gels showed V type crystallinity, but the stored gel changed into B type crystallinity. WMSG showed higher sensory bending properties and smoothness than HMSG, but more similarities in the overall qualities.     

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.