Clarified Apple Juice Research Articles

Modeling the inactivation of Aspergillus fischeri and Paecilomyces niveus ascospores in apple juice by different ultraviolet light irradiances

The present work aimed to evaluate and to model the influence of UV-C light treatments with different irradiances (6.5, 13, 21, and 36 W/m2) on Aspergillus fischeri and Paecilomyces niveus ascospores inactivation in clarified apple juice. Approximately 5.0 and 6.0 log CFU/mL spores of P. niveus and A. fischeri, respectively, were suspended in 30 mL of clarified apple juice (pH 3.8, 12 ± 0.1°Brix) and exposed to UV-C light at different irradiances (as above) and exposure times (0 to 30 min). The first-order biphasic model was able to describe the experimental data with good statistical indices (RMSE = 0.296 and 0.308, R2 = 0.96 and 0.98, for P. niveus and A. fischeri respectively). At the highest irradiance level tested (36 W/m2), the UV-C light allowed the reduction of 5.7 and 4.2 log-cycles of A. fischeri and P. niveus ascospores, respectively, in approximately 10 min. P. niveus was the most UV-C resistant mould. The results showed that, to a defined UV-C fluence, a change in the level of either time or UV-C irradiance did not affect the effectiveness of UV-C light for A. fischeri and P. niveus inactivation. Thus, the modeling of the inactivation as a function of the UV-C fluence allowed the estimation of the primary model parameters with all experimental data and, consequently, no secondary models were needed. The model parameters were validated with experiments of variable UV-C fluences. Accordingly, experimental results allowed to conclude that UV-C treatment at the irradiances tested is a promising application for preventing A. fischeri and P. niveus spoilage of juices.

Mass transfer modelling of hollow fiber membrane contactor for apple juice concentration using osmotic membrane distillation

The present research study is based on theoretical and experimental investigation of hydrophobic porous hollow fiber membrane contactor (HFMC) module. The mass transfer diffusional model was developed for osmotic membrane distillation (OMD) and applied in apple juice concentration. The mathematical model was developed, taking into consideration the resistance-in-series concept for the mass transfer of water vapor molecules across the hydrophobic HFMC. The model was adapted to include the pore geometry, dimensionless numbers and concentration variation due to viscosity. The water vapor transport model was then simulated in MATLAB® and successfully validated with the experimental data. The model was applied to study the effects of driving forces for mass transfer and membrane porosity. Process parameters like juice concentration, stripping solution concentration, and Reynolds number were also studied to evaluate their effect on the overall mass transfer co-efficient and water vapor flux. The OMD experiments for the concentration of clarified apple juice were carried out in a laboratory-scale HFMC mini-module composed of two independent circuits, for stripping solution (CaCl2) and apple juice, respectively, in a total recycled mode. For the concentration of clarified apple juice, the evaporation flux ranged from 0.122 to 0.472 kgm−2h−1 resulting in a juice concentration of 30°Brix. The increase in pore diameter from 0.1 to 0.6 µm resulted in an increase in the mass transfer coefficient from 1.57 × 10−10 to 7.23 × 10−10 ms−1. Similarly, water vapor flux was increased from 0.02 to 0.50 kgm−2h−1, when the activity coefficient was changed from 0.1 to 0.5. Moreover, the results indicated that if the experimental parameters are carefully controlled, the simulation results can be used to predict the OMD process efficiency.

Efficiency of apple juice clarification with using of nano-sized mineral oxides

Efficiency of apple juice clarification with using of nano-sized mineral oxides

Investigation of the migration of the least heating zone of clarified apple juice during heat treatment

When developing modes of food products thermal sterilization, it is necessary to determine the conditions for microorganisms test cultures and their spores guaranteed death in the least heating zone. The location of this zone is a critical parameter in thermal processes. At present, there are conflicting ideas about the localization and possible migration of the zone of least heating in the process of thermal sterilization of products with convective heat transfer. The kinetics of localization of the zone of least heating in the medium volume with convective heat transfer during heat treatment in conjunction with rheological properties was studied in the work. The clarified apple juice for baby food of domestic production was used as the object of study. The probe was placed so that the thermocouple was located on the vertical axis of the can at a geometric height of 3, 6, 9, 12, 18 and 24 mm. At each height value of the thermocouple, the jar with the sample was thermostated for 20 minutes, and then quickly cooled for 10 minutes. Heating was carried out at a thermostat temperature of 75, 80, 85, 90, and 95°C. The dynamics of rheological properties under isothermal conditions at temperatures of 30, 35, 40, 45, 50, 55, and 60°C and a range of shear rates from 0 to 700 s – 1 were also studied in the samples. As a result of the studies carried out, the presence of the migration of the zone of least heating during the heat treatment of single-phase media with convective heat transfer was determined experimentally, its kinetics was studied, the non-linear and reversible nature of the migration of the zone of least heating was established. The mechanism of the process of migration of the zone of least heating was proposed taking into account the dynamics of the rheology of the heated medium and the convective flows interaction.

Covalent immobilization of papain onto poly(hydroxyethyl methacrylate)-chitosan cryogels for apple juice clarification.

Enzyme immobilization appears as a remarkable technique to safely attach enzymes for several applications and cryogels stand as promising support materials to be used in such investigations. In this work, papain enzyme was immobilized onto an interpenetrating network obtained by cryogelation of N,N'-methylenebisacrylamide cross-linked 2-hydroxyethyl methacrylate and glutaraldehyde cross-linked chitosan. Cryogels were modified with -NH2 functionality and glutaraldehyde in order to attach papain covalently. Immobilization was carried out at 25 ℃ in 0.1 M pH 7.0 phosphate buffer at 1.0 mg/ml enzyme concentration for 5 h. The amount of papain immobilized onto cryogel was calculated to be 15.2 ± 2.54 mg/g cryogel. Macroporous structure and surface area were determined by scanning electron microscopy and Brunauer-Emmett-Teller techniques, respectively. Energy dispersive X-ray analysis showed that papain was bound to the cryogel and cryogel structure was composed of 2-hydroxyethyl methacrylate, chitosan, and glutaraldehyde. Proteolytic activities of free and immobilized papain were measured using casein as substrate. Optimum pH values and temperatures were 8.0 and 65 ℃ for free and immobilized enzymes and kinetic parameters were calculated at these conditions. Reusability and storage stability results indicated that immobilization enhanced the stability of papain compared to free form. Efficiency of immobilized papain was demonstrated by apple juice clarification study as an industrial use of the enzyme. Phenolic compound, protein, total soluble solid contents, and viscosity of apple juice before and after clarification were determined.

Effect of single and combined UV-C and ultra-high pressure homogenisation treatments on inactivation of Alicyclobacillus acidoterrestris spores in apple juice

Alicyclobacillus acidoterrestris is a spore-forming bacterium that can survive thermal pasteurization and acidic conditions. It produces changes in the odour and flavour of fruit juices leading to economical loses. A. acidoterrestris CECT 7094 spores were inoculated in clarified and cloudy apple juices (Golden delicious var.) in the range of 5–6 log10 spores/mL and submitted to different short-wave ultraviolet light (UV-C) doses (7.2–28.7 J/mL) and ultra-high pressure homogenisation (UHPH) treatments (100–300 MPa), including their combination. A. acidoterrestris could be inactivated in clarified apple juice at a level of 4.8 log10 CFU/mL by a 300 MPa-UHPH treatment when the inlet temperature was 80 °C. UV-C treatments showed to be more efficient achieving a lethality of 5.5 log10 CFU/mL with a dose of 21.5 J/mL at 20 °C. In cloudy apple juice (2357 NTU) UV-C treatments were less efficient with a maximum lethality of 4.07 CFU/mL after a dose of 28.7 J/mL. A previous application of UHPH contributed with UV-C to obtain higher reductions of A. acidoterrestris spores at the doses of 14.3 and 21.5 J/mL compared with UV-C single treatments. On the other hand, this previous treatment also changed the properties of particles in the matrix which apparently reduced the effectiveness of UV-C at 28.7 J/mL.

Magnetic Biocatalysts of Pectinase: Synthesis by Macromolecular Cross-Linker for Application in Apple Juice Clarification

SUMMARYResearch backgroundPectinase enzyme has become a valuable compound in beverage industry. One of the most significant concepts to overcome the drawbacks of using industrial enzymes is their immobilization. In the present study, magnetic chitosan microparticles were utilized as a substrate for pectinase immobilization. New methods of enzyme immobilization involve the use of non-chemical cross-linkers between the enzyme and the substrate. The aim of this study is to immobilize the pectinase enzyme using polyaldehyde kefiran as a macromolecular cross-linker on magnetic particles.Experimental approachPectinase was immobilized in four steps: relative oxidation of kefiran and its application as a cross-linker, production of magnetic iron(II) iron(III) oxide (Fe3O4) microparticles, coating of magnetic Fe3O4 microparticles with chitosan, and immobilization of the enzyme on the substrate, prepared by the use of oxidized kefiran cross-linker. Parameters such as cross-linking concentration, time and ratio of chitosan magnetic microparticles to enzyme were optimized. Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering, transmission electron microscopy, and vibrating sample magnetometer were used to identify the groups and investigate the structures. The biochemical properties (stability of enzyme activity at different pH, temperature and time), enzyme reusability, kinetic parameters (Km and νmax) and apple juice turbidity, using free and immobilized pectinase enzymes, were also measured.Results and conclusionsCross-linker concentration, cross-linking time and the ratio of magnetic Fe3O4 microparticles with chitosan to enzyme were important factors in activity recovery of pectinase. FTIR analysis correctly identified functional groups in the structures. The results showed that after enzyme stabilization, the particle size and molecular mass, respectively, increased and decreased the magnetic saturation strength. According to the thermal kinetic study, the activity of the immobilized pectinase was higher than of its free form. The findings of this study indicate excellent stability and durability of the immobilized pectinase. Finally, a magnetic pectinase micro-biocatalyst was used to clarify apple juice, which reduced turbidity during processing.Novelty and scientific contributionThis study investigates the usage of kefiran oxidized as a new cross-linker for the immobilization of pectinase enzyme. Magnetic pectinase micro-biocatalyst has a good potential for industrial applications in the food industry, with high thermal stability.

Purification and Thermodynamic Characteristics of an Exo-Polygalacturonase from Trichoderma Pseudokoningii

Polygalacturonases (PGs) are necessary to degrade the insoluble viscous pectin components during the clarification process of fruit juice and are produced by some plants and various microbes, such as bacteria, yeasts and fungi. In this study, an exo-polygalacturonase (exo-PGP4a) was purified from T. Pseudokoningii using DEAE-Sepharose and Sephacryl S-200 columns. We show that the enzyme produced in this study by solid-state fermentation of citrus Orange peel was purified 20-fold with 12.8% recovery. The apparent molecular mass of the enzyme was determined to be 25 kDa using gel filtration and SDS-PAGE. The optimum temperature and pH of the exo-PGP4a were 45and#176;C and 6, respectively. The exo-PGP4a showed half-lives of 50.95 and 21.32 min at 55 and 75and#176;C, respectively. The activation energy for denaturation (Ea*) was 42.596 kJ/mol. The Km value of the enzyme for PGA hydrolysis was 2 mg/ml, and the Vmax was 3.27 and#181;mol min-1 mg-1. Several metal cations, such as Cu2+and Zn2+, were found to enhance the enzymatic activity of the exo-PGP4a, while Pb2+, Ca2+, Ni2+, Cd2+, Co2+ and Hg2+ ions were found to be inhibitory. In this study, we suggest the exo-polygalacturonase has potential role of the clarification of Orange, Apple, Grape, and Peach juices in the food industry.

Purification and Thermodynamic Characteristics of an Exo-Polygalacturonase from Trichoderma Pseudokoningii

Polygalacturonases (PGs) are necessary to degrade the insoluble viscous pectin components during the clarification process of fruit juice and are produced by some plants and various microbes, such as bacteria, yeasts and fungi. In this study, an exo-polygalacturonase (exo-PGP4a) was purified from T. Pseudokoningii using DEAE-Sepharose and Sephacryl S-200 columns. We show that the enzyme produced in this study by solid-state fermentation of citrus Orange peel was purified 20-fold with 12.8% recovery. The apparent molecular mass of the enzyme was determined to be 25 kDa using gel filtration and SDS-PAGE. The optimum temperature and pH of the exo-PGP4a were 45and#176;C and 6, respectively. The exo-PGP4a showed half-lives of 50.95 and 21.32 min at 55 and 75and#176;C, respectively. The activation energy for denaturation (Ea*) was 42.596 kJ/mol. The Km value of the enzyme for PGA hydrolysis was 2 mg/ml, and the Vmax was 3.27 and#181;mol min-1 mg-1. Several metal cations, such as Cu2+and Zn2+, were found to enhance the enzymatic activity of the exo-PGP4a, while Pb2+, Ca2+, Ni2+, Cd2+, Co2+ and Hg2+ ions were found to be inhibitory. In this study, we suggest the exo-polygalacturonase has potential role of the clarification of Orange, Apple, Grape, and Peach juices in the food industry.

Study of thermal stability of ascospores Aspergillus (Neosartorya) fischeri depending on the concentration of soluble solids in apple juice

Kinetic studies of the thermal inactivation of test crop spores are necessary to develop optimal heat treatment regimes for fruit juices. The purpose of the work is to study the dynamics of changes in the thermal stability parameters DT and z depending on changes in the soluble solids content in canned fruit products using the example of certain types of apple juice products with a pH of 3.80. The regularity of thermal inactivation of ascospores of the mesophilic mold Aspergillus fischeri in concentrated apple juice (JAC) with a soluble dry matter (RSV) content of 70%, in restored apple juice with RSV – 11.2%, and in restored apple juice with pulp with RSV – 16% was studied. The parameters of thermal stability were determined by the capillary method at temperatures of 80, 85, 90, and 95 °C. It was experimentally established that the heat resistance of A. fischeri spores in clarified apple juice was DT 95 °С = 0.16 min, and the parameter value z = 6.76 °C, in apple juice with pulp parameters: DT 95 °C = 0.24 min, z – 7.12 °C, in YaKS – DT 95 °C = 0.39 min, and z – 7.8 °C. The dynamics of thermal stability parameters D and z of A. fischeri mold fungus spores (test cultures) versus RSV concentration of juice products was established. The research results showed that with an increase in the concentration of RSV, the thermal stability of spores increases exponentially. The rate of increase in thermal stability decreases with increasing concentration of RSV. Since the concentration of RSV affects the rheological properties of the product (viscosity), this leads to a change in the kinetics of heating in products with convection heat transfer. Therefore, an increase in the concentration of RSV should inevitably lead not only to an increase in the thermal stability of spores of microorganisms, but also to a shift in the region of optimal modes of heat treatment of products toward an increase in the thermal load to ensure regulatory requirements for microbiological safety.

Clarification of Apple Juice Using New Generation Nanocomposite Membranes Fabricated with TiO2 and Al2O3 Nanoparticles

To enhance anti-fouling properties of polymeric membranes during apple juice clarification, PSF/PEI (20/2 wt%) ultrafiltration (UF) membranes were modified with TiO2 and Al2O3 nanoparticles using the phase inversion method. Turbid apple juice samples were clarified using cross-flow membrane filtration system. All fabricated nanocomposite UF membranes had higher apple juice flux values than PSF/PEI membrane. Membrane prepared with 0.01% TiO2 (UFT1) had the highest apple juice flux (at steady state, 44.6 L/m2h). The FRR (%) value of TiO2 and Al2O3 incorporated UF membranes was between 90.9–94.0% and 79.6–97.6%, respectively, and these FRR values were higher than that of PSF/PEI membrane (UF2, 60.3%). Porosity and hydrophilicity of the UF membranes significantly increased with the addition of nanoparticles and the highest porosity and hydrophilicity was achieved in the 0.01% TiO2 incorporated UF membrane (UFT1) membrane. Higher flux recovery ratio (FRR) and lower relative flux reduction (RFR) values of Al2O3 and TiO2 incorporated nanocomposite membranes, compared with the unmodified membrane, demonstrated the enhancement in the anti-fouling properties of the PSF/PEI membrane. SEM images of the nanocomposite membranes also proved the nanoparticle incorporation to the PSF/PEI matrix. Color, turbidity, total soluble solid, total phenolic content, and antioxidant capacity of the samples using nanocomposite membranes were better than that of clarified using both commercial and unmodified membranes. TiO2 incorporated nanocomposite membranes had superior performance than Al2O3 incorporated nanocomposite membranes and among these membranes, the ones prepared with the addition of 0.01 wt% TiO2 exhibit the best performance in terms of clarification of apple juice.

Statistical optimisation of laccase production by isolated strain Aspergillus flavus PUF5 utilising ribbed gourd peels as the substrate and enzyme application on apple juice clarification

ABSTRACT In the current study laccase was produced by the isolated strain Aspergillus flavus PUF5 through solid-state fermentation (SSF) using waste ribbed gourd peels as substrate. During the statistical optimisation process, influencing fermentation factors among eleven selected variables were identified using Plackett–Burman design. Among them, fermentation time (144–192 h), medium pH (3.0–7.0), concentration of starch (0.5–1%) and concentration of peptone (0.2–0.8%) were vital influencing parameters. Furthermore, the shared effects of those variables were studied following Box–Behnken design. Optimised states of selected variables were fermentation time (168 h), medium pH (4.9), concentration of starch (0.61%) and peptone (0.51%) with predicted and observed activity of laccase 174.3 and 168.9 U/g, respectively. This laccase production under optimised condition was about 3.5-fold more that the unoptimised medium. The laccase obtained through SSF was tested for its suitability in the clarification of apple juice. During enzymatic oxidation, the changes in colour, turbidity, phenolics and flavonoids in apple juice were estimated and compared with untreated sample. Results showed a significant reduction in phenolic and flavonoid content in the fruit juice during the oxidation process. The turbidity in the juice was also decreased, which indicated the suitability of the laccase form A. flavus PUF5 in fruit juice clarification.

Apple juice clarification by a purified polygalacturonase from Calonectria pteridis

Polygalacturonases are extensively used in food industries for pectic substances degradation. They are essential for fruit juice clarification due the degradation of insoluble viscous pectinacious compounds. Polygalacturonase production by the fungus Calonectria pteridis was performed on submerged fermentation and, after purification, the enzyme showed a molecular weight of 68kDa. The highest polygalacturonase activity occurred at pH 4.0, and the enzyme preserved more than 70 % of its activity at pH values between 3.6 and 6.0. The optimum temperature was 60°C. The half-life values at 50 and 60°C were 260 and 66min, respectively. The KM value was 0.52mg/mL for the substrate polygalacturonic acid and the presence of Hg+2 and SDS completely inhibited the enzyme activity. The purified polygalacturonase was applied for apple juice clarification and it resulted in a volume and an amount of reducing sugars released increase of 10.65 and 40.93 %, respectively.

Immobilization of pectinase on chitosan-magnetic particles: Influence of particle preparation protocol on enzyme properties for fruit juice clarification

Magnetic-chitosan particles were prepared following three different protocols enabling the preparation of particles with different sizes – nano (Nano-CMag, Micro (Micro-CMag) and Macro (Macro-CMag) – and used for pectinase immobilization and clarification of grape, apple and orange juices. The particle size had a great effect in the kinetic parameters, Nano-CMag biocatalyst presented the highest Vmax value (78.95 mg. min−1), followed by Micro-CMag and Macro-CMag, with Vmax of 57.20 mg.min−1 and 46.03 mg.min−1, respectively. However, the highest thermal stability was achieved using Macro-CMag, that was 8 and 3-times more stable than Nano-CMag and Micro-CMag biocatalysts, respectively. Pectinase immobilized on Macro-CMag kept 85% of its initial activity after 25 batch cycles in orange juice clarification. These results suggested that the chitosan magnetic biocatalysts presented great potential application as clarifying catalysts for the fruit juice industry and the great importance of the chitosan particles preparation on the final biocatalyst properties.

Enhanced bacterial inactivation in apple juice by synergistic interactions between phenolic acids and mild food processing technologies

This study demonstrated an innovative processing approach based on synergistic antimicrobial activity of two phenolic acids with mild thermal and non-thermal processing technologies. The two selected model phenolic acids were gallic acid (GA; 10 mM) and ferulic acid (FA; 1 mM). The processing technologies evaluated for processing of a model clarified apple juice were UV-A light, mild heat (55 °C) and moderate pressure (250 MPa), with processing times ranging from 1 to 30 min. The results demonstrated that combinations of selected phenolic acids and a mild physical processing were able to lower E. coli O157:H7 and Listeria innocua counts from 6-log CFU mL −1 to below the detection limit of 1-log CFU mL −1 . Bacterial inactivation was significantly enhanced by the combination of UV-A light processing and FA, where 10 min of treatment enhanced bacterial inactivation by 5-log as compared to light processing alone, which presented no bacterial inactivation. In contrast, the combination of GA and mild-temperature thermal processing (55 °C) or mild-levels of high-pressure processing (250 MPa), enhanced bacterial inactivation by 4-log as compared to the physical treatments alone, which presented only 1-log of inactivation. The influence of these synergistic combinations on bacterial membrane damage was assessed by selective plating technique under osmotic pressure. Furthermore, the total intracellular thiol content was also measured to assess for thiol oxidation. Overall, the results demonstrated enhanced bacterial inactivation based on synergistic interactions of selected phenolic acids with both mild-thermal and non-thermal technologies in a model food system and illustrate potential to create diversity of novel antimicrobial strategies for food processing. This study showed that the presence of naturally-based compounds can significantly reduce intensity levels of physical processing required to inactivate model gram-positive and gram-negative bacteria in apple juice. In this study two phenolic acids, ferulic acid and gallic acids were selected as these compounds are naturally present in many fruits and other food products including grains. Furthermore, the levels of these natural phenolic acids used in this study are comparable to the levels naturally present in some of the food materials. • Ferulic acid plus UV-A and gallic acid plus 55 °C or pressure showed synergistic inactivation in apple juice. • Ferulic acid at 1 mM resulted in 5-log CFU/mL bacterial inactivation with UV-A exposure. • Gallic acid at 10 mM resulted in 4-log CFU/mL bacterial inactivation with 55 °C or 250 MPa exposure. • Combination of gallic acid with heat or pressure increased intracellular thiol oxidation. • All observed synergistic combinations showed damage to bacterial membranes.

Immobilization of Aspergillus quadrilineatus RSNK-1 multi-enzymatic system for fruit juice treatment and mannooligosaccharide generation

Aspergillus quadrilineatus RSNK-1 produced a multi-enzymatic system containing (U/gds) β-mannanase (1021), endo-xylanase (1 9 1), α-galactosidase (3.42), β-xylosidase (0.07) and β-glucosidase (0.28) on low-cost copra meal (CM) in SSF. The enzyme preparation was covalently immobilized on aluminum oxide pellets (3 mm) under statistically optimized conditions leading to 73.17% immobilization yield. The immobilized enzyme (Man-AOP) displayed enhanced thermal and pH stability. Man-AOP was characterized by FTIR, SEM and PXRD revealing a covalent interaction. The bio-conjugate was successfully recycled for mannooligosaccharide (MOS) generation from locust bean gum (LBG) up to 10 cycles, yielding an average of 0.95 mg MOS/cycle. Man-AOP was also effective in clarification of apple, kiwi, orange and peach juices and enhanced their reducing sugar content. The bio-conjugate was useful in generation of MOS from mannan and enrichment of fruit juices.

Increased Resistance of Salmonella enterica Serovar Typhimurium and Escherichia coli O157:H7 to 222-Nanometer Krypton-Chlorine Excilamp Treatment by Acid Adaptation.

In this study, we examined the change in resistance of Salmonella enterica serovar Typhimurium and Escherichia coli O157:H7 to 222-nm krypton-chlorine (KrCl) excilamp treatment as influenced by acid adaptation and identified a mechanism of resistance change. In addition, we measured changes in apple juice quality indicators, such as color, total phenols, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, during treatment. Non-acid-adapted and acid-adapted pathogens were induced by growing the cells in tryptic soy broth without dextrose (TSB w/o D) at pH 7.3 and in TSB w/o D at pH 5.0 (adjusted with HCl), respectively. For the KrCl excilamp treatment, acid-adapted pathogens exhibited significantly (P < 0.05) higher D5d values, which indicate dosages required to achieve a 5-log reduction, than those for non-acid-adapted pathogens in both commercially clarified apple juice and phosphate-buffered saline (PBS), and the pathogens in the juice showed significantly (P < 0.05) higher D5d values than those for pathogens in PBS because of the UV-absorbing characteristics of apple juice. Through mechanism identification, it was found that the generation of lipid peroxidation in the cell membrane, inducing cell membrane destruction, was significantly (P < 0.05) lower in acid-adapted cells than in non-acid-adapted cells for the same amount of reactive oxygen species (ROS) generated at the same dose because the ratio of unsaturated to saturated fatty acids (USFA/SFA) in the cell membrane was significantly (P < 0.05) decreased as a result of acid adaptation. Treated apple juice showed no significant (P > 0.05) difference in quality indicators compared to those of untreated controls during treatment at 1,773 mJ/cm2IMPORTANCE There is a need for novel, mercury-free UV lamp technology to replace germicidal lamps containing harmful mercury, which are routinely utilized for UV pasteurization of apple juice. In addition, consideration of the changes in response to antimicrobial treatments that may occur when pathogens are adapted to the acid in an apple juice matrix is critical to the practical application of this technology. Based on this, an investigation using 222-nm KrCl excilamp technology, an attractive alternative to mercury lamps, was conducted. Our study demonstrated increased resistance to 222-nm KrCl excilamp treatment as pathogens adapted to acids, and this was due to changes in reactivity to ROS with changes in the fatty acid composition of the cell membrane. Despite increased resistance, the 222-nm KrCl excilamp achieved pathogen reductions of 5 log or more at laboratory scale without affecting apple juice quality. These results provide valuable baseline data for application of 222-nm KrCl excilamps in the apple juice industry.

Immobilization and some application of α-amylase purified from Rhizoctonia solani AG-4 strain ZB-34

Abstract Background Aim of the study was to immobilize the α-amylase produced earlier from the mesophilic fungus Rhizoctonia solani AG-4 strain ZB-34 by solid-state fermentation and investigate the suitability of immobilized enzymes for some industries. Materials and methods A novel α-amylase from R. solani AG-4 strain ZB-34 was immobilized in chitosan by covalent binding and Ca-alginate by entrapment. Results The efficiency of chitosan and Ca-alginate immobilization was 67.9% and 59.6%, respectively. The immobilized enzymes showed the highest activity in the presence of starch. Optimum values for chitosan and Ca-alginate immobilized enzymes were pH 4.50 and 40°C and pH 5.50 and 60°C, respectively. It was found that immobilized enzymes were highly stable in terms of thermal and pH stabilities. When the chitosan immobilized enzyme was used with detergents, chocolate stains on dirty laundry was better cleaned. Chitosan immobilized R. solani AG-4 strain ZB-34 α-amylase was found to have a higher desizing effect at 40°C in tap water. As a result of Ca-alginate immobilization, the enzyme clarified apple juice more than the free enzyme. Conclusion The results showed that immobilized enzymes might have potential applications in industry. This is the first report immobilizing an α-amylase produced from the fungus R. solani.

Optimization and purification of cellulase produced by Penicillium decumbens and its application

Background and objectives Cellulases are an enzyme group based on catalytic action. They include endocellulase, exocellulase, beta glucosidase, cellulose phosphorylases, and oxidative cellulases. This work was aimed at the production of cellulase by fungal strains from Penicillium sp. Selection of the best organism that gives the highest productivity of the enzyme, examination of the cellulase production under the optimum conditions, purification of cellulase, identification by high-performance liquid chromatography, and its application in clarification and yield increase of apple juice were also studied. Materials and methods Three strains of Penicillium sp. were examined using the method of Congo red for cellulase production. The factors affecting cellulase production by fungus Penicillium decumbens were identified. Cellulase produced by P. decumbens was purified using ammonium sulfate precipitate (80% saturation) followed by ion exchange chromatography by Sephadex G-200. High-performance liquid chromatography technique was used to measure the purity of cellulase produced from P. decumbens. The cellulase enzyme was used to increase the yield of apple juice and apple juice clarification, as examples of its application in the food industry. Results and conclusion The P. decumbens colony proved to have the largest decolorization zone, and the cellulase produced was a large amount (21.5 U/ml). The highest activity of cellulase was seen in the media containing 50% carboxymethylcellulose and 50% dates molasses waste (Dibs) as carbon source after incubation for 6 days, and the optimum pH and temperature for the production cellulase were pH 4.0 at 30°C. Utilization of 80% ammonium sulfate gave pure enzyme cellulase (38.25 U/ml) and has a high degree of specific activity (25.5 U/mg protein). Cellulase activity of 42 U/ml and the degree of specific activity of 46.6 U/mg protein, with a 4.3-fold purification of cellulase, with 42% recovery from the crude cellulase, was obtained with Sephadex G-200. The results revealed an increase in the quantity of produced apple juice treated by cellulase enzyme.

Application and optimization of solid-state fermentation process for enhancing polygalacturonase production by Penicillium expansum

Penicillium expansum 3.5425 was applied in solid-state fermentation (SSF) of agricultural wastes for polygalacturonase biosynthesis. Among various carbon additives, apple pomace was most suitable for the biosynthesis of polygalacturonase (1440.57 U/g). Optimization of medium parameters using rotational orthogonal design (ROD) experiment combined with optimal fermentation conditions resulted in a 2.72-fold increase in the polygalacturonase production. By using ammonium sulphate precipitation, ion-exchange and gel-permeation chromatography, the polygalacturonase produced by P. expansum 3.5425 was finally purified which had specific activity of 19269 U/mg and molecular weight of 30 kDa. The enzyme was remarkably active in the pH range of 3-5 and at 50°C, which makes it more acceptable in the industrial application. Besides, partially purified polygalacturonase (875.15 U/mL) was used for apple juice clarification and the clarity at 0.4 mL/kg was maximum, which reveals a great potential of polygalacturonase in food industry. Keywords: solid-state fermentation (SSF), polygalacturonase, Penicillium expansum, juice clarification, agricultural wastes DOI: 10.25165/j.ijabe.20181106.3673 Citation: Zhu M M, He H J, Fan M T, Ma H J, Ren H W, Zeng J, et al. Application and optimization of solid-state fermentation process for enhancing polygalacturonase production by Penicillium expansum. Int J Agric & Biol Eng, 2018; 11(6): 187–194.