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1.
J Dairy Sci ; 104(2): 1531-1547, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33309347

RESUMO

The effects of pressure, temperature, shear, and their interactions on selected quality attributes and stability of milk during ultra-shear technology (UST) were investigated. The UST experiments include pressure (400 MPa) treatment of the milk sample preconditioned at 2 different initial temperatures (25°C and 15°C) and subsequently depressurizing it via a shear valve at 2 flow rates (low: 0.15-0.36 g/s; high: 1.11-1.22 g/s). Raw milk, high-pressure processed (HPP; 400 MPa, ~40°C for 0 and 3 min) and thermal treated (72°C for 15 s) milk samples served as the controls. The effect of different process parameters on milk quality attributes were evaluated using particle size, zeta potential, viscosity, pH, creaming, lipase activity, and protein profile. The HPP treatment did not cause apparent particle size reduction but increased the sample viscosity up to 3.08 mPa·s compared with 2.68 mPa·s for raw milk. Moreover, it produced varied effects on creaming and lipase activity depending on hold time. Thermal treatment induced slight reduction in particle size and creaming as compared with raw milk. The UST treatment at 35°C reduced the effective diameter of sample particles from 3,511.76 nm (raw milk) to 291.45 nm. This treatment also showed minimum relative lipase activity (29.93%) and kept milk stable by preventing creaming. The differential effects of pressure, shear, temperature, and their interactions were evident, which would be useful information for equipment developers and food processors interested in developing improved food processes for dairy beverages.


Assuntos
Manipulação de Alimentos , Leite/química , Animais , Feminino , Leite/normas , Tamanho da Partícula , Pressão , Temperatura , Viscosidade
2.
Molecules ; 24(15)2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31390764

RESUMO

Different fractions of fully hydrogenated soybean oil (FHSBO) in soybean oil (10-30% w/w) and the addition of 1% salt (sodium chloride) were used to investigate the effect of high-pressure treatments (HP) on the crystallization behaviors and physical properties of the binary mixtures. Sample microstructure, solid fat content (SFC), thermal and rheological properties were analyzed and compared against a control sample (crystallized under atmospheric condition). The crystallization temperature (Ts) of all model fats under isobaric conditions increased quadratically with pressure until reaching a pressure threshold. As a result of this change, the sample induction time of crystallization (tc) shifted from a range of 2.74-0.82 min to 0.72-0.43 min when sample crystallized above the pressure threshold under adiabatic conditions. At the high solid mass fraction, the addition of salt reduced the pressure threshold to induce crystallization during adiabatic compression. An increase in pressure significantly reduced mean cluster diameter in relation to the reduction of tc regardless of the solid mass fraction. In contrast, the sample macrostructural properties (SFC, storage modulus) were influenced more significantly by solid mass fractions rather than pressure levels. The creation of lipid gel was observed in the HP samples at 10% FHSBO. The changes in crystallization behaviors indicated that high-pressure treatments were more likely to influence crystallization mechanisms at low solid mass fraction.


Assuntos
Gorduras/química , Lipídeos/química , Pressão , Cristalização , Ácidos Graxos/química , Estrutura Molecular , Óleo de Soja/química , Temperatura , Termodinâmica
3.
J Sci Food Agric ; 96(11): 3821-30, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26679559

RESUMO

BACKGROUND: A study was conducted to investigate the impact of high pressure (450 and 600 MPa at 30 °C) and thermal (72, 85 and 99 °C at 0.1 MPa) treatments on dispersive and aggregative characteristics of almond milk. Experiments were conducted using a kinetic pressure testing unit and water bath. Particle size distribution, microstructure, UV absorption spectra, pH and color changes of processed and unprocessed samples were analyzed. RESULTS: Raw almond milk represented the mono model particle size distribution with average particle diameters of 2 to 3 µm. Thermal or pressure treatment of almond milk shifted the particle size distribution towards right and increased particle size by five- to six-fold. Micrographs confirmed that both the treatments increased particle size due to aggregation of macromolecules. Pressure treatment produced relatively more and larger aggregates than those produced by heat treated samples. The apparent aggregation rate constant for 450 MPa and 600 MPa processed samples were k450MPa,30°C = 0.0058 s(-1) and k600MPa,30°C = 0.0095 s(-1) respectively. CONCLUSIONS: This study showed that dispersive and aggregative properties of high pressure and heat-treated almond milk were different due to differences in protein denaturation, particles coagulation and aggregates morphological characteristics. Knowledge gained from the study will help food processors to formulate novel plant-based beverages treated with high pressure. © 2015 Society of Chemical Industry.


Assuntos
Manipulação de Alimentos/métodos , Qualidade dos Alimentos , Substitutos do Leite/química , Nozes/química , Prunus dulcis/química , Algoritmos , Temperatura Alta/efeitos adversos , Humanos , Concentração de Íons de Hidrogênio , Cinética , Microscopia Confocal , Substitutos do Leite/isolamento & purificação , Valor Nutritivo , Nozes/economia , Ohio , Tamanho da Partícula , Pasteurização/métodos , Pigmentos Biológicos/análise , Proteínas de Vegetais Comestíveis/análise , Proteínas de Vegetais Comestíveis/química , Pressão/efeitos adversos , Desnaturação Proteica , Espectrofotometria Ultravioleta
4.
J Sci Food Agric ; 95(1): 174-8, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24752997

RESUMO

BACKGROUND: The effect of pressure-assisted thermal processing (PATP) on the inactivation of Geobacillus stearothermophilus spores was determined in deionized water, cooked ground beef, egg patty mince, whole milk and mashed potatoes at 105 °C under 500 and 700 MPa. RESULTS: The numbers of G. stearothermophilus spores in deionized water and milk were reduced by more than 6 log CFU mL(-1) at 700 MPa and 105 °C, whereas those in cooked beef were reduced by 4.27 log CFU g(-1). The inactivation patterns of G. stearothermophilus spores in all food matrices followed nonlinear behavior, showing that Weibull model fitted well to the inactivation curves of G. stearothermophilus spores in low-acid foods. CONCLUSION: The complex food matrices caused a protective effect on the inactivation of G. stearothermophilus spores during PATP. The results provide useful information in inactivation kinetics of bacterial spores for validating PATP-processed low-acid foods.


Assuntos
Conservação de Alimentos/métodos , Geobacillus stearothermophilus , Esporos Bacterianos , Animais , Bovinos , Ovos/microbiologia , Manipulação de Alimentos/métodos , Temperatura Alta , Carne/microbiologia , Leite/microbiologia , Pressão , Solanum tuberosum/microbiologia , Esporos Bacterianos/fisiologia , Microbiologia da Água
5.
Food Sci Biotechnol ; 32(14): 2025-2042, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37860738

RESUMO

In the present study encapsulation of ultrasound assisted red cabbage extract was carried out using four different carrier agents such as maltodextrin, gum arbic, xanthan gum, and gellan gum. Among the four hydrocolloids investigated, maltodextrin was found to have the least destructive effect on anthocyanin content (14.87 mg C3G/g dw), TPC (54.51 ± 0.09 mg GAE/g dw), TFC (19.82 Mg RE/g dw) and antioxidant activity (74.15%) upon freeze-drying. Subsequently a storage study was conducted using maltodextrin as carrier agent at 25-50 °C. The Clausius-Clapeyron equation was used to evaluate the net isosteric heat (qst) of water adsorption. The differential entropy (ΔS) and qst decreased from 82.298 to 38.628 J/mol, and 27.518 kJ/mol to 12.505 kJ/mol, respectively as the moisture content increased from 2 to 14%. The value of isokinetic energy and Gibb's free energy were found to be 364.88 and - 1.596 kJ/mol for freeze dried red cabbage.

6.
Curr Res Food Sci ; 6: 100439, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36691593

RESUMO

This study investigated the impact of ultra-shear technology (UST) processing on dairy-pea protein dispersions with different fat levels. Raw milk, skim milk, and cream, as well as model dispersions with combinations of dairy products and pea protein (i.e., raw milk with pea protein, skim milk with pea protein, and cream with pea protein) were employed as test samples. UST experiments were conducted at a pressure of 400 MPa and 70 °C shear valve exit temperature. The UST treatment increased the viscosity of the dispersions and the increases depended on the fat level. Dairy-pea protein dispersions from raw milk and skim milk were shear thinning and mathematically described by the power-law model defined by the consistency coefficient, K (Pa·sn) and the flow behavior index, n. UST treated cream + pea protein dispersions produced structures with gel-like characteristics. Microstructure and particle size analysis determined by laser scanning microscope revealed a reduction in particle size after UST treatment in raw milk + pea protein and skim milk + pea protein dispersions up to 7.55 and 8.30 µm, respectively. In contrast, the particle mean diameter of cream + pea protein dispersions increased up to 77.20 µm after the UST treatment. Thus, the effect of UST on the particle size and rheological behavior of the dispersions depended on the fat level. UST-treated dispersions were stable with no visible phase separation or sedimentation upon centrifugation at 4000×g for 30 min (4 °C). Heat treatment and freeze-thaw treatment of UST-treated samples showed stable blends immediately after the treatments, but subsequent centrifugation showed solid separation. Results from the study suggest that UST is a potential technology to produce stable dairy + pea protein liquids foods with different rheological characteristics for diverse applications.

7.
Int J Food Microbiol ; 378: 109838, 2022 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-35863173

RESUMO

Sanitation in dry food processing environments is challenging due to the exclusion of water. Superheated steam (SHS) is a novel sanitation technique that utilizes high temperature steam to inactivate microorganisms. The high sensible heat of SHS prevents condensation on surfaces. Here we evaluated SHS thermal inactivation of various vegetative and spore forming bacteria and fungi and determined the effect of food matrix composition on SHS efficacy. Capillary tubes with vegetative cells (Salmonella, E. coli O157:H7, Listeria monocytogenes, or Enterococcus faecium), Aspergillus fischeri ascospores, or B. cereus spores (100 µL) were SHS treated at 135 ± 1 °C for 1 or 2 s. After 1 s, SHS achieved a reduction of 10.91 ± 0.63 log10 CFU/mL for vegetative cells, 2.09 ± 0.58 log10 ascospores/mL for A. fischeri, and 0.21 ± 0.10 log10 spores/mL for B. cereus. SHS treatment achieved significant reductions in vegetative cells and fungal ascospores (p < 0.05), however B. cereus spores were not significantly reduced after 2 s and were determined to be the most resistant of the cell types evaluated. Consequently, peanut butter compositions (peanut powder, oil, and water) and milk powder (whole and nonfat) inoculated with B. cereus spores on aluminum foil coupons (2 × 3 × 0.5 cm) were tested. The D161°C values for B. cereus spores ranged from 46.53 ± 4.48 s (6 % fat, 55 % moisture, aw: 0.927) to 79.21 ± 14.87 s (43 % fat, 10 % moisture, aw: 0.771) for various peanut butter compositions. Whole milk powder had higher D161°C (34.38 ± 20.90 s) than nonfat milk powder (24.73 ± 6.78 s). SHS (135 ± 1 °C) rapidly (1 s) inactivated most common vegetative bacterial cells; however B. cereus spores were more heat resistant. B. cereus spore inactivation was significantly affected by product composition (p < 0.05). Compared to the log-linear model (R2 0.81-0.97), the Weibull model had better fit (R2 0.94-0.99). Finally, the ease of peanut butter removal from surfaces increased while the ease of non-fat dry milk removal decreased with the increasing SHS treatment duration. However, allergen residues were detectable on surfaces regardless of SHS treatment. The findings from this study can inform the development of pilot-scale research on SHS.


Assuntos
Escherichia coli O157 , Vapor , Alérgenos , Bacillus cereus , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Temperatura Alta , Pós , Esporos Bacterianos , Água
8.
J Food Prot ; 73(11): 2043-52, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21219716

RESUMO

The aim of this research was to study the effect of sucrose laurate ester (SL) on enhancing pressure-assisted thermal processing (PATP) inactivation of Bacillus amyloliquefaciens Fad 82 spores. B. amyloliquefaciens spores (∼108 CFU/ml) were suspended in deionized water, solutions of 0.1, 0.5, and 1.0% SL, and mashed carrots without or with 1% SL. Samples were treated at 700 MPa and 105°C for 0 (come-up time), 1, 2, and 5 min and analyzed by pour-plating and most-probable-number techniques. Heat shock (80°C, 10 min) was applied to untreated and treated samples to study the germination rates. Results were also compared against samples treated by high pressure processing (700 MPa, 35°C) and thermal processing (105°C, 0.1 MPa). Among the combinations tested, SL at concentrations of 1.0% showed the best synergistic effect against spores of B. amyloliquefaciens when combined with PATP treatments. In the case of high pressure and thermal processing treatments, SL did not enhance spore inactivation at the conditions tested. These results suggest that SL is a promising antimicrobial compound that can help reduce the severity of PATP treatments.


Assuntos
Bacillus/fisiologia , Daucus carota/microbiologia , Manipulação de Alimentos/métodos , Sacarose/análogos & derivados , Bacillus/efeitos dos fármacos , Contagem de Colônia Microbiana , Relação Dose-Resposta a Droga , Contaminação de Alimentos/prevenção & controle , Germinação , Temperatura Alta , Pressão , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/crescimento & desenvolvimento , Sacarose/farmacologia , Temperatura , Fatores de Tempo
9.
J Food Prot ; 72(4): 775-82, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19435226

RESUMO

Pressure-assisted thermal processing (PATP) is an emerging sterilization technology in which a combination of pressure (500 to 700 MPa) and temperature (90 to 120 degrees C) are used to inactivate bacterial spores. The objective of this study was to examine the role of pressurization rate and pressure pulsing in enhancing PATP lethality to the bacterial spore. Bacillus amyloliquefaciens TMW 2.479 spore suspensions were prepared in deionized water at three inoculum levels (1.1 x 10(9), 1.4 x 10(8), and 1.3 x 10(6) CFU/ml), treated at two pressurization rates (18.06 and 3.75 MPa/s), and held at 600 MPa and 105 degrees C for 0, 0.5, 1, 2, 3, and 5 min. Experiments were carried out using custom-fabricated, high-pressure microbial kinetic testing equipment. Single and double pulses with equivalent pressure-holding times (1 to 3 min) were investigated by using the spore suspension containing 1.4 x 10(8) CFU/ml. Spore survivors were enumerated by pour plating, using Trypticase soy agar after incubation at 32 degrees C for 2 days. During short pressure-holding times (< or = 2 min), PATP treatment with the slow pressurization rate provided enhanced spore reduction over that of the fast pressurization rate. However, these differences diminished with extended pressure-holding times. After a 5-min pressure-holding time, B. amyloliquefaciens population decreased about 6 log CFU/ml, regardless of pressurization rate and inoculum level. Double-pulse treatment enhanced PATP spore lethality by approximately 2.4 to 4 log CFU/ml, in comparison to single pulse for a given pressure-holding time. In conclusion, pressure pulsing considerably increases the efficacy of PATP treatment against bacterial spores. Contribution of pressurization rate to PATP spore lethality varies with duration of pressure holding.


Assuntos
Bacillus/fisiologia , Temperatura Alta , Pressão Hidrostática , Esporos Bacterianos/fisiologia , Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Esterilização
10.
J Food Prot ; 71(1): 102-8, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18236669

RESUMO

High-pressure processing (HPP) of Turkish white cheese and reduction of Listeria monocytogenes, total Enterobacteriaceae, total aerobic mesophilic bacteria, total molds and yeasts, total Lactococcus spp., and total Lactobacillus spp. were investigated. Cheese samples were produced from raw milk and pasteurized milk and were inoculated with L. monocytogenes after brining. Both inoculated (ca. 10(7) to 10(8) CFU/g) and noninoculated samples were subjected to HPP in a high-pressure food processor at 50 to 600 MPa for 5 and 10 min at 25 degrees C. Reductions in L. monocytogenes, total aerobic mesophilic bacteria, Lactococcus spp., and Lactobacillus spp. in both pasteurized- and raw-milk cheese samples and reductions in total molds and yeasts and total Enterobacteriaceae counts in raw-milk cheese samples increased with increased pressure (P < or = 0.05). The maximum reduction of the L. monocytogenes count, ca. 4.9 log CFU/g, was obtained at 600 MPa. Because of the highly inhibitory effect of pasteurization, the total molds and yeasts and total Enterobacteriaceae counts for the cheese samples produced from pasteurized milk were below the detection limit both before and after HPP. There was no significant difference in inactivation of L. monocytogenes, total aerobic mesophilic bacteria, Lactococcus spp., and Lactobacillus spp. under the same treatment conditions for the raw milk and pasteurized milk cheeses and for 5- and 10-min treatment times (P > 0.05). No significant change was detected in pH or water activity of the samples before and after HPP. Our findings suggest that HPP can be used effectively to reduce the microbial load in Turkish white cheese.


Assuntos
Queijo/microbiologia , Contaminação de Alimentos/análise , Manipulação de Alimentos/métodos , Pressão Hidrostática , Listeria monocytogenes/crescimento & desenvolvimento , Animais , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Enterobacteriaceae/crescimento & desenvolvimento , Microbiologia de Alimentos , Fungos/crescimento & desenvolvimento , Leite , Temperatura , Fatores de Tempo , Turquia , Leveduras/crescimento & desenvolvimento
11.
Int J Food Microbiol ; 113(3): 321-9, 2007 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-17196696

RESUMO

The combined pressure-thermal inactivation kinetics of spores from three strains of anaerobic (Clostridium sporogenes, C. tyrobutylicum, and Thermoanaerobacterium thermosaccharolyticum), and six strains of aerobic (Bacillus amyloliquefaciens and B. sphaericus) bacteria were studied. Spores of these bacteria were prepared in deionized water and treated in a custom-made kinetic tester over various pressure (0.1 and 700 MPa) and thermal (105 and 121 degrees C) combinations. Survivor data were modeled using log-linear and Weibull models to obtain relevant kinetic parameters. In comparison to thermal treatment alone, the combined pressure-thermal conditions accelerated the inactivation of the spores tested. A measurable fraction of spore populations was inactivated during the pressure come-up time. Pressure-assisted thermal processing (PATP) at 700 MPa and 121 degrees C for 1 min inactivated up to 7-8 log for some of spores tested. Among bacteria evaluated, based on survivor curve data T. thermosaccharolyticum, B. amyloliquefaciens Fad 82, and Fad 11/2 were found to produce the most PATP-resistant spores. PATP inactivation plots showed characteristic upward curvature, which is indicative of the tailing behavior. Since both log-linear and Weibull kinetic models did not consider microbial reduction during process come-up time, our results demonstrated that the estimated model parameters were not adequate to compare combined pressure-thermal resistance of various bacterial spores tested.


Assuntos
Bactérias Aeróbias/crescimento & desenvolvimento , Bactérias Anaeróbias/fisiologia , Microbiologia de Alimentos , Temperatura Alta , Pressão Hidrostática , Bactérias Aeróbias/fisiologia , Bactérias Anaeróbias/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Cinética , Modelos Lineares , Modelos Biológicos , Esporos Bacterianos/crescimento & desenvolvimento
12.
J Agric Food Chem ; 55(22): 9311-7, 2007 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-17907780

RESUMO

Pressure-assisted thermal processing (PATP) is being widely investigated for processing low acid foods. However, its microbial safety has not been well established and the mechanism of inactivation of pathogens and spores is not well understood. Fourier transform infrared (FT-IR) spectroscopy was used to study some of the biochemical changes in bacterial spores occurring during PATP and thermal processing (TP). Spore suspensions (approximately 10(9) CFU/mL of water) of Clostridium tyrobutyricum, Bacillus sphaericus, and three strains of Bacillus amyloliquefaciens were treated by PATP (121 degrees C and 700 MPa) for 0, 10, 20, and 30 s and TP (121 degrees C) for 0, 10, 20, and 30 s. Treated and untreated spore suspensions were analyzed using FT-IR in the mid-infrared region (4000-800 cm(-1)). Multivariate classification models based on soft independent modeling of class analogy (SIMCA) were developed using second derivative-transformed spectra. The spores could be differentiated up to the strain level due to differences in their biochemical composition, especially dipicolinic acid (DPA) and secondary structure of proteins. During PATP changes in alpha-helix and beta-sheets of secondary protein were evident in the spectral regions 1655 and 1626 cm(-1), respectively. Infrared absorption bands from DPA (1281, 1378, 1440, and 1568 cm(-1)) decreased significantly during the initial stages of PATP, indicating release of DPA. During TP changes were evident in the bands associated with secondary proteins. DPA bands showed little or no change during TP. A correlation was found between the spore's Ca-DPA content and its resistance to PATP. FT-IR spectroscopy could classify different strains of bacterial spores and determine some of the changes occurring during spore inactivation by PATP and TP. Furthermore, this technique shows great promise for rapid screening PATP-resistant bacterial spores.


Assuntos
Temperatura Alta , Espectroscopia de Infravermelho com Transformada de Fourier , Esporos Bacterianos/química , Bacillus/química , Clostridium tyrobutyricum/química , Pressão , Esporos Bacterianos/classificação
13.
J Microbiol Biotechnol ; 17(3): 524-9, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18050959

RESUMO

Pressure inactivation behavior of Bacillus amyloliquefaciens spores was investigated in deionized water. The spores of B. amyloliquefaciens were subjected to 105 degrees C and 700 MPa. The magnitude of the decrease in viability after pressure treatment was similar to that after pressure treatment followed by heat shock. The increase of dipicolinic acid (DPA) release was correlated with the spore inactivation, and the hydrophobicity did not significantly change during the pressure-assisted thermal processing (PATP). Lag phase duration increased with increasing pressure process time. The mechanisms of spore germination and inactivation during the PATP were related to a complex physiological process.


Assuntos
Bacillus/fisiologia , Pressão Hidrostática , Esterilização/métodos , Bacillus/crescimento & desenvolvimento , Bacillus/isolamento & purificação , Bacillus/metabolismo , Pão/microbiologia , Contagem de Colônia Microbiana , Interações Hidrofóbicas e Hidrofílicas , Microbiologia Industrial/métodos , Cinética , Ácidos Picolínicos/metabolismo , Esporos Bacterianos/metabolismo , Esporos Bacterianos/fisiologia
14.
J Microbiol Biotechnol ; 17(4): 616-23, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18051273

RESUMO

The effects of initial concentration and pulsed pressurization on the inactivation of Clostridium sporogenes spores suspended in deionized water were determined during thermal processing (TP; 105 degrees C, 0.1 MPa) and pressure-assisted thermal processing (PATP; 105 degrees C and 700 MPa) treatments for 40 min and 5 min holding times, respectively. Different inoculum levels (10(4), 10(6), and 10(8) CFU/ml) of C. sporogenes spores suspended in deionized water were treated at 105 degrees C under 700 MPa with single, double, and triple pulses. Thermally treated samples served as control. No statistical significances (p > 0.05) were observed among all different inoculum levels during the thermal treatment, whereas the inactivation rates (k1 and k2) were decreased with increasing the initial concentrations of C. sporogenes spores during the PATP treatments. Double- and triple-pulsed pressurization reduced more effectively the number of C. sporogenes spores than single-pulse pressurization. The study shows that the spore clumps formed during the PATP may lead to an increase in pressure-thermal resistance, and multiple-pulsed pressurization can be more effective in inactivating bacterial spores. The results provide an interesting insight on the spore inactivation mechanisms with regard to inoculum level and pulsed pressurization.


Assuntos
Clostridium/fisiologia , Microbiologia de Alimentos , Conservação de Alimentos/métodos , Temperatura Alta , Pressão Hidrostática , Esporos Bacterianos/fisiologia
15.
Food Chem ; 237: 461-470, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28764021

RESUMO

A study was conducted to identify optimal ultrasound processing conditions (ultrasound energy density and temperature) to maximize the extraction of anthocyanin colorants from black carrot pomace. The treatment maximized the yield of five different anthocyanin compounds from black carrot pomace with cyanidin-3-xyloside-galactoside-glucoside-ferrulic acid (C3XGGF, 60.85-74.22mg/L) as the most abundant anthocyanin compound, followed by cyanidin-3-xyloside-galactoside (C3XG, 49.56-70.12mg/L). The response surface models predicted that if extraction conditions were conducted at 183.1J/g energy density and 50°C, the yield of various anthocyanin compounds would be maximized from the black carrot pomace. Response surface models were developed correlating anthocyanin yield with ultrasonication treatment parameters. The study showed the synergy of combining ultrasonication and temperature for the extraction of anthocyanin pigments from black carrot pomace. Results of the study also further demonstrate the potential of ultrasonication technology as a tool for the extraction of valuable components waste products from fruits and vegetables juice industry.


Assuntos
Daucus carota , Antocianinas
16.
J Agric Food Chem ; 65(39): 8578-8585, 2017 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-28929757

RESUMO

Effects of high-pressure processing (HPP, 100-600 MPa for 3 min at 30 °C) on the glucosinolate content, conversion to isothiocyanates, and color changes during storage in fresh broccoli sprouts were investigated. A mild heat treatment (60 °C) and boiling (100 °C) were used as positive and negative controls, respectively. Glucosinolates were quantified using liquid chromatography-mass spectrometry, and isothiocyanates were quantified using high-performance liquid chromatography-photodiode array detection. A formation of isothiocyanates was observed in all high-pressure-treated sprouts. The highest degree of conversion (85%) was observed after the 600 MPa treatment. Increased isothiocyanate formation at 400-600 MPa suggests an inactivation of the epithiospecifier protein. During storage, color changed from green to brownish, reflected by increasing a* values and decreasing L* values. This effect was less pronounced for sprouts treated at 100 and 600 MPa, indicating an influence on the responsible enzymes. In summary, HPP had no negative effects on the glucosinolate-myrosinase system in broccoli sprouts.


Assuntos
Brassica/química , Manipulação de Alimentos/métodos , Glucosinolatos/metabolismo , Isotiocianatos/metabolismo , Plântula/química , Brassica/enzimologia , Glucosinolatos/análise , Glicosídeo Hidrolases/metabolismo , Temperatura Alta , Isotiocianatos/análise , Pressão
17.
J Agric Food Chem ; 54(26): 10300-6, 2006 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-17177574

RESUMO

The efficacy of microbial inactivation techniques is currently tested using time-consuming and labor-intensive plate count methods, which are the principal rate-limiting steps in developing inactivation kinetic parameters for alternative food processing technologies. Fourier transform infrared (FT-IR) spectroscopy combined with multivariate analysis was used to quantify viable spores and identify some biochemical changes in samples treated by autoclaving, pressure-assisted thermal processing (PATP), and thermal processing (TP). Spore suspensions ( approximately 109 CFU/mL) of Bacillus amyloliquefaciens TMW 2.479 Fad 82, B. amyloliquefaciens TMW 2.482 Fad 11/2, B. sphaericus NZ 14, B. amyloliquefaciens ATCC 49764, and Clostridium tyrobutyricum ATCC 25755 were treated by PATP (121 degrees C and 700 MPa) for 0, 10, 20, and 30 s and by TP (121 degrees C) for 0, 10, 20, and 30 s. The concentrations of spores in treated samples were determined by plating (reference method). Models developed using partial least-squares regression (PLSR) for predicting spore levels in treated samples had correlation coefficients (r) of >0.99 and standard errors of cross-validation ranging between 100.2 and 100.5 CFU/mL. Changes in dipicolinic acid (DPA) and secondary structure of proteins were found to occur during inactivation of spores by PATP and TP. FT-IR spectroscopy could rapidly estimate viable bacterial spore levels in PATP- and TP-treated spore suspensions, providing an accurate analytical tool for monitoring the efficacy of sterilization techniques in inactivating spore-forming microorganisms.


Assuntos
Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Espectroscopia de Infravermelho com Transformada de Fourier , Esporos Bacterianos/fisiologia , Bacillus/fisiologia , Clostridium/fisiologia , Temperatura Alta , Pressão
18.
J Agric Food Chem ; 54(3): 739-46, 2006 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-16448177

RESUMO

Immunoglobulin-rich foods may provide health benefits to consumers. To extend the refrigerated shelf life of functional foods enriched with bovine immunoglobulin G (IgG), nonthermal alternatives such as high-pressure processing (HPP) may offer advantages to thermal processing for microbial reduction. To evaluate the effects of HPP on the immunoactivity of bovine IgG, a soymilk product enriched with milk protein concentrates, derived from dairy cows that were hyperimmunized with 26 human pathogens, was subjected to HPP or heat treatment. To achieve a 5 log reduction in inoculated Escherichia coli 8739, the HPP or heat treatment requirements were 345 MPa for 4 min at 30 degrees C or for 20 s at 70 degrees C, respectively. To achieve a 5 log reduction in natural flora in the enriched soymilk, the HPP or heat treatments needed were 552 MPa for 4 min at 30 degrees C or for 120 s at 78.2 degrees C, respectively. At equivalent levels for a 5 log reduction in E. coli, HPP and heat treatment caused 25% and no detectable loss in bovine IgG activity, respectively. However, at equivalent levels for a 5 log reduction in natural flora, HPP and heat resulted in 65 and 85% loss of bovine IgG activity, respectively. Results of combined pressure-thermal kinetic studies of bovine milk IgG activity were provided to determine the optimal process conditions to preserve product function.


Assuntos
Manipulação de Alimentos/métodos , Alimentos Fortificados/microbiologia , Imunoglobulina G/imunologia , Leite/imunologia , Leite de Soja , Animais , Antígenos de Bactérias/imunologia , Bovinos , Contagem de Colônia Microbiana , Escherichia coli/imunologia , Temperatura Alta , Pressão , Salmonella enteritidis/imunologia
19.
J Food Prot ; 69(4): 853-60, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16629029

RESUMO

Bacillus amyloliquefaciens is a potential surrogate for Clostridium botulinum in validation studies involving bacterial spore inactivation by pressure-assisted thermal processing. Spores of B. amyloliquefaciens Fad 82 were inoculated into egg patty mince (approximately 1.4 x 10(8) spores per g), and the product was treated with combinations of pressure (0.1 to 700 MPa) and heat (95 to 121 degrees C) in a custom-made high-pressure kinetic tester. The values for the inactivation kinetic parameter (D), temperature coefficient (zT), and pressure coefficient (zP) were determined with a linear model. Inactivation parameters from the nonlinear Weibull model also were estimated. An increase in process pressure decreased the D-value at 95, 105, and 110 degrees C; however, at 121 degrees C the contribution of pressure to spore lethality was less pronounced. The zP-value increased from 170 MPa at 95 degrees C to 332 MPa at 121 degrees C, suggesting that B. amyloliquefaciens spores became less sensitive to pressure changes at higher temperatures. Similarly, the zT-value increased from 8.2 degrees C at 0.1 MPa to 26.8 degrees C at 700 MPa, indicating that at elevated pressures, the spores were less sensitive to changes in temperature. The nonlinear Weibull model parameter b increased with increasing pressure or temperature and was inversely related to the D-value. Pressure-assisted thermal processing is a potential alternative to thermal processing for producing shelf-stable egg products.


Assuntos
Bacillus/fisiologia , Ovos/microbiologia , Temperatura Alta , Pressão Hidrostática , Contagem de Colônia Microbiana , Cinética , Modelos Lineares , Esporos Bacterianos/crescimento & desenvolvimento
20.
Annu Rev Food Sci Technol ; 6: 435-62, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25747234

RESUMO

High pressure processing (HPP) has emerged as a commercially viable food manufacturing tool that satisfies consumers' demand for mildly processed, convenient, fresh-tasting foods with minimal to no preservatives. Pressure treatment, with or without heat, inactivates pathogenic and spoilage bacteria, yeast, mold, viruses, and also spores and extends shelf life. Pressure treatment at ambient or chilled temperatures has minimal impact on product chemistry. The product quality and shelf life are often influenced more by storage conditions and packaging material barrier properties than the treatment itself. Application of pressure reduces the thermal exposure of the food during processing, thereby protecting a variety of bioactive compounds. This review discusses recent scientific advances of high pressure technology for food processing and preservation applications such as pasteurization, sterilization, blanching, freezing, and thawing. We highlight the importance of in situ engineering and thermodynamic properties of food and packaging materials in process design. Current and potential future promising applications of pressure technology are summarized.


Assuntos
Manipulação de Alimentos/métodos , Indústria Alimentícia , Pressão , Microbiologia de Alimentos
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