Novel Intact Bitter Cassava: Sustainable Development and Desirability Optimisation of Packaging Films

Novel biomaterials and optimal processing conditions are fundamental in low-cost packaging material production. Recently, a novel biobased intact bitter cassava derivative was developed using an intrinsic, high-throughput downstream processing methodology (simultaneous release recovery cyanogenesis). Processing of intact bitter cassava can minimise waste and produce low-cost added value biopolymer packaging films. The objective of this study was to (i) develop and characterise intact bitter cassava biobased films and (ii) determine the optimal processing conditions, which define the most desirable film properties. Films were developed following a Box-Behnken design considering cassava (2, 3, 4 % w/v), glycerol (20, 30, 40 % w/w) and drying temperature (30, 40, 50 °C) and optimised using multi-response desirability. Processing conditions produced films with highly significant (p?<?0.05) differences. Developed models predicted impact of processing conditions on film properties. Desirable film properties for food packaging were produced using the optimised processing conditions, 2 % w/v cassava, 40.0 % w/w glycerol and 50 °C drying temperature. These processing conditions produced films with 0.3 %; transparency, 3.4 %; solubility, 21.8 %; water-vapour-permeability, 4.2 gmm/m²/day/kPa; glass transition, 56 °C; melting temperature, 212.6 °C; tensile strength, 16.3 MPa; elongation, 133.3 %; elastic modulus, 5.1 MPa and puncture resistance, 57.9 J, which are adequate for packaging applications. Therefore, intact bitter cassava is a viable material to produce packaging films that can be tailored for specific sustainable, low-cost applications.     

A New Chemical Marker-Model Food System for Heating Pattern Determination of Microwave-Assisted Pasteurization Processes

New chemical marker-model food systems with d-ribose and NaOH precursors as color indicators and gellan gels as chemical marker carrier were explored for the assessment of the heating pattern of in packaged foods processed in microwave-assisted pasteurization system (MAPS). In determining appropriate precursor concentrations, a solution of 2% (w/w) d-ribose and 60 mM NaOH was heated at 60–90 °C for 0–20 min. The solution absorbance at 420 nm increased linearly, while the color parameters L* decreased linearly with heating time at all processing temperatures. In storage, the produced brown color was stable at 4 and 22 °C within 7 days. The new chemical marker-model foods were prepared by mixing 2% (w/w) d-ribose and 60 mM NaOH with 1% (w/v) low-acyl gellan gum and 20 mM CaCl₂·2H₂O solution. The dielectric constant of the model food samples decreased with the addition of sucrose, and the loss factors increased with the addition of salt. After processing in the pilot MAPS, the heating pattern and cold and hot spots in the new chemical marker-model food system could be clearly recognized and precisely located through a computer vision method. This is the first time that the caramelization reaction was used as a time-temperature indicator in gellan gel model food. This study shows the possibility of using the new chemical marker-model food system for heating pattern determination of the MAPS.     

Deposit Generation During Camel and Cow Milk Heating: Microstructure and Chemical Composition

The aim of this study is to identify the chemical composition and the microstructure of the deposits obtained after heating camel and cow milks at 80 °C for 60 min using a laboratory-scale device. Like cow milk, camel milk was affected by heat treatment with the reduction of the non-casein nitrogen content reflecting the denaturation of camel whey proteins. The composition of the deposits generated during heating camel and cow milks at 80 °C for 60 min revealed that while camel deposit contained 57 % w/w protein, cow deposit showed a higher protein content of 69 % w/w. The mineral content was 35 % w/w for camel deposit which was higher than that of cow sample, which was 28 % w/w. SEM of both deposits showed a familiar structure of a protein deposit with large clumps composed of smaller aggregates. Camel deposit showed an amorphous structure due to its deficiency in β-lactoglobulin.     

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.     

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.     

TLC-Digital Image-Based Fluorometric Analysis of Ergosterol and Chitin Content in Food Grains Artificially Infested with <Emphasis Type="Italic">Aspergillus flavus</Emphasis> and <Emphasis Type="Italic">Fusarium verticillioides</Emphasis>

Novel thin-layer chromatography-digital image-based analytical methods were developed for the quantitation of ergosterol and chitin content in six food matrices (rice, wheat, maize, sorghum, groundnut, and sunflower), artificially infested with Aspergillus flavus (MTCC 6513)/Fusarium verticillioides (MRC 826). For ergosterol, single-step method, based on liquid/liquid extraction, was followed by thin-layer chromatography (TLC). Chitin was solubilized using lithium chloride (5%) in dimethyl acetamide and converted to chitosan using 5 N NaOH and subsequently complexed with calcofluor white dye. The absorption and emission maxima of chitosan-calcofluor complex were recorded at λ 350/230 and 430 nm, respectively. The sensitivity based on the limit of detection (LOD) was found to be 100 ng both for ergosterol and chitin analysis. Based on ergosterol and chitin analysis, groundnut and maize were found to be suitable substrates for A. flavus (p?<?0.013 and p?<?0.01), while sorghum followed by groundnut and sunflower were found to be ideal for F. verticillioides (p?<?0.01 and p?<?0.0001) and rice was established as poor substrate as there was no growth on it up to 12 days of incubation. A strong correlation was found between ergosterol and chitin contents with regression (r ²) values of 0.974 and 0.997 in food grains inoculated with A. flavus and F. verticillioides, respectively, during the period of infection. The authenticity of the two methods developed was further confirmed by applying them to commercial food grains and flours. Thus, ergosterol in combination with chitin analysis could be successfully used as an index of fungal contamination employing TLC-digital-based analytical methods.     

Formulation and Stability Characterization of Rutin-Loaded Oil-in-Water Emulsions

In this work, formulation and characterization of oil-in-water (O/W) emulsions loaded with rutin were successfully overhead. We investigated the effect of homogenization pressure on the mean droplet size, droplet size distribution, physical stability, and rutin retention of these emulsions. O/W emulsions with a mean droplet size (d _3,2) of about 150 nm and a span of nearly the unit were formulated by microfluidization at the homogenization pressure 20–150 MPa. The O/W emulsion droplets loaded with rutin were physically stable in terms of variations of d _3,2 and span during 30 days of storage in the dark condition at 4 and 25 °C. The creaming velocity was characterized using centrifugal method showing a relative good shelf life. HPLC analysis demonstrated that 71–85% of initial rutin was retained in the fresh O/W emulsions and declined to 22–35% (w/w) for 30-day storage at 25 °C. Antioxidant activity assays confirmed that rutin-loaded emulsion participated in the antioxidant activity after encapsulation similarly to pure rutin. These results indicate that O/W emulsion systems can function as potential delivery systems to enhance bioavailability to encapsulate liposoluble antioxidant rutin for potential applications in the food industry.     

Effects of chitosan and collagen containing α-tocopherol on the oxidative stability in bulk oil and oil-in-water emulsion

To provide efficient antioxidant capacities, proper carriers are needed to protect antioxidants against oxidative stress. Collagen mesh structure or chitosan gel was loaded with α-tocopherol and their effects were evaluated in bulk corn oil or oil-in-water (O/W) emulsion at 60 °C. Added collagen and chitosan enhanced oxidative stability in corn oil and O/W emulsions at 60 °C compared to corn oils without carriers or with addition of α-tocopherol (p < 0.05). Stability of α-tocopherol in corn oil loaded in collagen or chitosan was significantly enhanced compared to that in oils without carriers (p < 0.05). In O/W emulsions, α-tocopherol loaded collagen showed higher antioxidant properties than α-tocopherol loaded chitosan (p < 0.05). Collagen mesh structure and chitosan gel retarded the rates of lipid oxidation efficiently in both food matrices when α-tocopherol was not loaded. Collagen mesh structure and chitosan gel can be useful carriers for α-tocopherol in bulk oil or O/W emulsion.     

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.     

Determination of Seven <Emphasis Type="Italic">N</Emphasis>-nitrosamines in Agricultural Food Matrices Using GC-PCI-MS/MS

The quantitative analytical methods for seven N-nitrosamines including N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodibutylamine (NDBA), N-nitrosopiperidine (NPIP), N-nitrosopyrrolidine (NPYR), and N-nitrosomorpholine (NMOR) were established for agricultural food matrices. Four food matrices were used for the method development: rice soup as a fatless solid matrix, apple juice as a fatless liquid matrix, corn oil as a fat-rich liquid matrix, and 20 % alcohol as an alcohol matrix. A combination of solid-supported liquid-liquid extraction (SLLE) using Extrelut NT and a solid phase extraction (SPE) using Florisil was employed for fatless matrices. For an alcohol matrix, only SLLE was used without SPE, and liquid-liquid extraction (LLE) was established for a fat-rich matrix. The extract was analyzed by gas chromatography-positive chemical ionization-tandem mass spectrometry (GC-PCI-MS/MS) using ammonia gas as an ion source. Linearity, recovery, repeatability, inter-day precision, reproducibility, and uncertainty were evaluated for method validation using four matrices. Method detection limits for all of the investigated N-nitrosamines were ranged from 0.10 to 0.18 μg/kg for the rice soup, from 0.10 to 0.19 μg/kg for the apple juice, 0.10 μg/kg for the corn oil, and from 0.10 to 0.25 μg/kg for 20 % alcohol, depending on N-nitrosamines. Established methods were applied to determine seven N-nitrosamines in some agricultural food products.     

Verification of 5-Methyltetrahydrofolic Acid in Nutritional Products

A simple method for the verification of supplemental (6R,S)-5-methyl-5,6,7,8-tetrahydrofolic acid, “5-MTHF,” in nutritional products is described. Nutritional product samples are prepared for the liquid chromatographic/fluorescence detection (LC/FLD) determination of 5-MTHF by buffer dilution, 10-min centrifugation, and syringe filtration. Method performance has been defined by assessments of 5-MTHF linearity (r ² averaged 0.9999 ± 0.0001, and all relative calibration errors averaged ≤0.6%, for ten consecutive six-point standard curves), intermediate precision (rsd = 1.1%, n = 9, for three products fortified at ～1.73 μmol/kg = ～795 μg/kg, tested on each of 3 days), accuracy (spike recovery average = 92.8 ± 1.0%, n = 9, for nutritional products spiked with 5-MTHF at ～1.73 μmol/kg, or ～795 μg/kg), and selectivity (absence of interference from reagent blanks, and from four compounds structurally related to 5-MTHF). The 5-MTHF recovery, as % of unheated controls, from a simulated heat treatment (20 min at 120 °C) averaged 99.1 ± 0.6%, n = 4. The limits of 5-MTHF detection (S/N = 3) and quantification (S/N = 10) were experimentally determined to be 10 μg/kg (～0.020 μmol/kg) and 30 μg/kg (～0.060 μmol/kg), respectively (<10× the expected fortification rate). The method provides a simple and inexpensive means for verifying proper fortification, and for assessing the stability to processing and storage conditions, of free 5-MTHF in nutritional products. A finding of interest is the indication that liquid nutritional products may comprise a stable matrix for 5-MTHF fortification.     

Chitosan Controls Postharvest Decay and Elicits Defense Response in Kiwifruit

Chitosan is an eco-friendly alternative to synthetic fungicides for managing postharvest decay of fruits and vegetables. The ability of chitosan to enhance resistance to postharvest gray (Botrytis cinerea) and blue mold (Penicillium expansum) in kiwifruit was investigated. The gene expression and activity of antioxidant enzymes, and total phenolic compounds were determined. Results showed that chitosan at 5 g/L significantly inhibited gray and blue mold in kiwifruit stored at 25 and 4 °C. Chitosan significantly induced the gene expression of catalase, superoxide dismutase, and ascorbate peroxidase, as well as increased the enzyme activity. Moreover, chitosan markedly increased the content of total phenolic compounds in kiwifruit. Importantly, chitosan also exhibited beneficial effects on fruit quality. Taken together, the ability of chitosan to reduce mold in stored kiwifruit may be associated with the elicitation of host defense response. These results have practical implications for the application of chitosan to reduce postharvest losses.     

Preserving Melons by Osmotic Dehydration in a Ternary System Followed by Air-Drying

In this study, the effect of different osmotic solution concentrations (20–60% w/w of sucrose with 10% w/w NaCl salt), fruit to solution ratios (1:9–1:3), immersion times (0.5–4 h), and temperatures (15–55°C) on the mass transfer kinetics during osmotic dehydration of melons (Curcumis melo L.) in ternary solution namely sucrose–salt–water followed by air-drying were investigated. The effective diffusion coefficients for sucrose and water during osmotic dehydration were determined, assuming osmotic dehydration to be governed by Fickian diffusion. The estimated parameters allowed optimizing the system to reduce total processing time. The optimum treatments were with 50% sucrose and 10% NaCl salt concentration, fruit to solution ratio of 1:4 for 1 h at 45°C. Samples non-treated and pre-treated in optimized conditions were dried in a hot-air dryer at 60°C until equilibrium was achieved after 2.5 h. Pre-treatment reduced the air-drying period in up to 6.8 h.     

Alcohol Determination in Distilled Alcoholic Beverages by Liquid Phase Fourier Transform Mid-Infrared and Near-Infrared Spectrophotometries

Fourier transform mid-infrared spectrophotometry (FT-MIR), 1180–950 cm^?1, and near-infrared spectrophotometry (NIR), 1720–1660 nm, have been used complementarily for the direct determination of ethanol and methanol in distilled alcoholic beverages. In mid-infrared ethanol and methanol identified separately, hence, it has been used to confirm the absence or presence of methanol. In the absence of methanol, both were used to determine the alcoholic strength independently; however, near-infrared was used without diluting the samples. Ethanol and methanol contents were evaluated using the calibration curves established by a plot of peak height or peak area versus concentration % (w/w). The linearity range for ethanol was up to 15 and 50 % (w/w) for mid- and near-infrared, respectively. The developed methods are simple, fast, precise, and accurate. Moreover, the results obtained were in excellent agreement with the results obtained from gas chromatographic measurements. No sample preparation was required at all, and in all samples, methanol was not detected.     

Determination of Total Sugar Content in Soy-Based Drinks Using Infrared Spectroscopy and Chemometrics

Partial least square (PLS) regression models were developed and compared in order to determine the total sugar content in soy-based drinks using an infrared spectroscopy technique known as attenuated total reflectance Fourier transform infrared (ATR-FTIR). On a spectrophotometer set for analyzing on the middle infrared region, spectral band of 1900 to 900 cm^?1, commercial samples of soy beverage were analyzed, as well as samples with crescent water additions of 5, 10, and 20% v/v. Reference data for total sugars were obtained using the Lane-Eynon method. To construct regression models, algorithms of interval partial least square (iPLS) and synergy of interval partial least square (siPLS) were applied using iToolbox package on Matlab 8.1 environment. Kennard-Stone algorithm was used to the selection of calibration and prediction sets. Two models have been the best obtained: the first was an iPLS with seven latent variables, which selected the spectral band of 1399–900 cm^?1 and presented root mean square error of cross-validation (RMSECV)?=?0.1678% (w/w). The second best model was siPLS with six latent variables, which selected spectral bands of 1025–1150 and 1151–1476 cm^?1 and presented RMSECV?=?0.1963% (w/w). The proposed method presents advantages such as a small-required amount of sample for spectrum achievement, no sample destruction, and a high analytical frequency.     

Effect of Microfluidization Condition on Physicochemical Properties and Inhibitory Activity of Nanoemulsion Loaded with Natural Antibacterial Mixture

The main objective of this study was to investigate the effects of the microfluidic pressure (600–1200 bar) and cycles (2–4) on the inhibitory activity and physicochemical properties of the nanoemulsion loaded with a natural antibacterial mixture (i.e., citral, trans-2-hexen-1-ol, and linalool, 1:1:1 w/w). The current study showed that the microfluidization at 1000 bar for 4 cycles resulted in the most stable antibacterial nanoemulsion with the smallest droplets. In most cases, the cycle had the more significant effect than the pressure on the physicochemical properties of the antibacterial nanoemulsion. The minimal inhibitory concentrations (MICs) for Salmonella Typhi, Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes were 2500, 5000, 1250, and 5000 μg/ml, respectively. In general, the microfluidization condition did not significantly affect the ξ-potential and inhibitory activity of the antibacterial nanoemulsion. The microfluidization at 1350 bar and 3 cycles was the overall optimum preparation condition. There was an insignificant (p?>?0.05) difference between the experimental and predicted optimum point. This verified the adequacy of the response surface models fitted for explaining the properties of antibacterial nanoemulsion as a function of microfluidization condition.     

Enterohemorrhagic <Emphasis Type="Italic">Escherichia coli</Emphasis> (EHEC) in water from karst springs: detection with real-time PCR and isolation of strains

Within 2 months, two water sources in a karst area in Switzerland were sampled 9 times each, and analyzed by real-time PCR for 6 EHEC O-types, Shiga-like-toxin (stx1 and stx2) and intimin (eae) genes. With the exception of O111, 5 O-types were recorded regularly and at high frequencies (O26: 33.3 %; O157: 33.3 %; O104: 66.6 %; O103: 72.2 %; O145: 94.4 %). Genes for Shiga-like-toxins and intimin were almost omnipresent (stx1: 77.8 %; stx2: 83.3 %; eae: 77.8 %). Strain isolation was undertaken for O-groups 26, 103, 104, 145 and 157. Sample selection for strain isolation was based on Cq-values for the O-groups and stx1, stx2 and eae. From selected samples, frozen enrichment cultures were cultivated on EHLY-agar and 50 typical colonies screened for the O-type and genes encoding for stx1, stx2 and eae. With this approach, only one virulent EHEC-strain could be isolated (Escherichia coli O103, stx1 +; stx2 ?; eae +). We carried out one extensive testing with 800 colonies of O-group O145, and no virulent strain was isolated. Our findings showed that PCR-results are not sufficient to formulate epidemiological conclusions and that the isolation of strains is necessary. However, as the detection procedure of EHEC in foods is cumbersome and expensive, the appropriateness of such an approach in official food control is a matter of debate.     

Resistance of rubberwood (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis>) treated with chitosan or silane against surface molds

The aim of this study was to determine the efficacy of chitosan and methoxysilane in the prevention of surface mold growth on rubberwood. Three different chitosan samples were tested; C1 (Mw 37 kDa), C2 (Mw 5.4 kDa) and C3 (Mw 3.5 kDa). Radial growth inhibition assay of the chitosan samples was investigated at concentrations ranging from 0.063 to 0.5 %w/v against Aspergillus niger BAM 4 and Penicillium decumbens CBS 121928. Chitosan samples C1 and C3 exhibited strong antifungal activity against both molds. Rubberwood samples were either vacuum or dip treated with varying concentrations of chitosan or silane solution. The content of chitosan in wood showed that after the leaching test, chitosan was well retained in both vacuum and dip treated wood. The concentration of silicon in wood showed similar results. The vacuum treated wood samples with chitosan C1 and C3 at 1 %w/v concentration had strong resistance against A. niger BAM 4. However, dip treated rubberwood samples with 2 %w/v chitosan solutions showed lower resistance against A. niger BAM 4. On the other hand, both vacuum and dip treated rubberwood samples with chitosan had no resistance against P. decumbens CBS 121928. The silane treated wood samples showed no resistance to fungal growth.     

Encapsulation of Holy Basil Essential Oil in Gelatin: Effects of Palmitic Acid in Carboxymethyl Cellulose Emulsion Coating on Antioxidant and Antimicrobial Activities

The challenge of using essential oils possessing antioxidant and antimicrobial properties in food industry is to maintain their chemical stability. This research examined the roles of emulsion coating in preventing the degradation of holy basil essential oils (HBEO) during storage. The uncoated HBEO-loaded gelatin microcapsules and those coated with 1, 2, and 3 % palmitic acid emulsified in carboxymethyl cellulose, denoted as UC, C-1P, C-2P, and C-3P, respectively, had HBEO contents of 76.35, 76.09, 68.96, and 59.39 % with the surface oils of 1.31, 0.65, 0.65, and 0.84 %, respectively. The increase in the palmitic acid concentrations caused a significant increase in the L ^* values (p?<?0.05). After 90 days of storage at 30 °C, the surface oils of UC, C-1P, C-2P, and C-3P significantly increased to 3.65, 2.43, 2.15, and 3.03 %, respectively, coincident with the decrease in the L ^* values. X-ray diffraction studies revealed that the crystalline structures of the microcapsules were influenced by gelatin renaturation and palmitic acid polymorphism. The antioxidant activities, expressed as IC₅₀, of the free and encapsulated HBEO before storage were 0.30 mg/ml. After storage, IC₅₀ of only C-2P remained constant, while those of the rest significantly increased (p?<?0.05). The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of all the samples against pathogenic bacteria did not change over storage. C-3P exhibited the strongest antimicrobial activity of MIC of 0.625 mg/ml and MBC of 1.25 mg/ml. These findings suggest that the emulsion coating enables shelf life extension of HBEO-loaded gelatin microcapsules.     

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.).