Effect of Ultrafiltration Combined with High-Pressure Processing on Safety and Quality Features of Fresh Apple Juice

Ultrafiltration (UF, 0.05 μm) with a ceramic membrane was combined with high-pressure processing (HPP) at 500 MPa/6 min and high-temperature short time (HTST) at 110 °C/8.6 s to process fresh apple juice. The aim of this study was to compare the effect of UF + HPP and UF + HTST on quality features of fresh apple juice and analyze the quality changes of the juice treated by UF + HPP and stored during 60 days at 4 °C. Applying UF, total plate count (TPC) and yeasts and molds (Y&M) significantly decreased by 0.29 and 0.28 log cycle, total phenols and ascorbic acid decreased by 33.50 and 26.52 %, and antioxidant capacity, using the DPPH and FRAP assay, significantly decreased by 26.40 and 25.37 %. Meanwhile, the juice clarity was 99.75?±?0.07 % and seven aroma compounds were changed. TPC and Y&M in juices treated by UF + HPP and UF + HTST were <1 log cycle. When compared to the juice treated by UF + HTST, the juice treated by UF + HPP showed lower browning degree and higher total phenols and clarity, and retained seven main volatile aroma compounds. Fresh apple juice processed by UF + HPP was microbiologically safe (TPC <1.8 log cycles and Y&M <1 log cycle) during 60 days of storage at 4 °C. The first-order model was a suitable model for all quality parameters of refrigerated fresh apple juice; however, rate constant k of first-order model was between ?0.0157 and 0.0350, showing the quality features of the refrigerated juice was stable.     

Extraction of allyl isothiocyanate from wasabi (Wasabia japonica Matsum) using supercritical carbon dioxide

The pungent flavor unique in wasabi is due to isothiocyanates including allyl isothiocyanate (AIT) which has outstanding antimicrobial activity. AIT is converted from sinigrin by enzymatic reaction in the presence of water. The optimum moisture content of wasabi root for supercritical CO₂ extraction (SCE) at 20 MPa and 35°C was found to be 125% dry basis. In the ranges of pressure (15–25 MPa) and temperature (35–55°C), yield of AIT by SCE increased as pressure increased and/or temperature decreased. The highest yield was 408 mg/100 g solid at 25 MPa and 35°C. SCE of AIT from the freeze-dried wasabi root, stem, and leaf at 20 MPa and 35°C resulted in the yields of 368, 39, and 11 mg/100 g solid, respectively. The moisture content of wasabi along with the pressure and temperature were the important parameters in SCE of AIT.     

Mushroom Blanch Water Concentration by Membrane Processes

Mushroom blanch water was concentrated by ultrafiltration (UF) and reverse osmosis (RO). UF prefiltration was essential in preventing severe fouling during the RO process. When the UF blanch water permeate was processed by RO, linear relationships between pressure and flux were observed at all concentrations tested. The blanch water was concentrated by UF/RO from 2% to 13% total solids at 60°C and 120 KPa/5000 KPa operating pressures with flux higher than 15 L/m² hr. Maximum concentration obtained was approximately 20% total solids with 90% recovery of the nonvolatiles. Recoveries of some major volatiles were above 50%. Panelists could not differentiate the original from the reconstituted blanch waters in sensory evaluations.     

Kinetic study of high pressure microbial and enzyme inactivation and selection of pasteurisation conditions for Valencia Orange Juice

Keeping quality of fresh orange juice is highly dependent on pectinolytic enzyme activity and the growth of spoilage microorganisms. The inactivation kinetics of indigenous pectin methylesterase (PME) and of the two more pressure resistant species of spoilage lactic acid bacteria (LAB) Lactobacillus plantarum and L. brevis in freshly squeezed Valencia orange juice under high hydrostatic pressure (100–500 MPa) combined with moderate temperature (20–40 °C) was investigated. PME inactivation followed first order kinetics with a residual PME activity (15%) at all pressure–temperature combinations used. The values of activation energy and activation volume were estimated at each pressure and at each temperature, respectively. Values of 90 kJ/mol and ?30 mL/mol at reference pressure of 300 MPa and reference temperature of 35 °C were estimated respectively. The corresponding z_T and z_P values of LAB inactivation were also estimated at all conditions tested. Values of 19.5 °C and 95 MPa at reference pressure of 300 MPa and reference temperature of 30 °C were estimated respectively for L. plantarum, while the corresponding values for L. brevis were 40 °C and 82 MPa, respectively, at the same reference conditions. Pressure and temperature were found to act synergistically both for PME and LAB inactivation. The PME and LAB inactivation rate constants were expressed as functions of the temperature and pressure process conditions. These functions allow the determination of the pressure/temperature conditions that achieve the target enzyme and microbial inactivation at a selected processing time. The process conditions of 350 MPa at 35 °C for 2 min are proposed as effective for Valencia orange juice cold pasteurisation.     

Reverse Osmosis and Flavor Retention in Apple Juice Concentration

Plate-and-frame (PF) and spiral-wound (SW) membrane configurations were used to study influence of reverse osmosis (RO) on flavor compounds in apple juice permeate and retentate. Low temperature (20°C) and high pressure (50 bar) were most effective operating parameters for flavor recovery. Non-volatile flavor component RO losses were due to permeation. However, loss of volatile compounds through permeation was minor compared with equipment processing losses. Flavor compounds showed more rejection by polyamide than poly-ether-urea thin-film composite membranes. The SW configuration demonstrated greater flavor losses than did PF. Chemical structure of aldehydes and esters appeared to affect flavor compound retention. Volatile losses modified the flavor profile of RO concentrated apple juice.     

超滤法澄清西番莲果汁的研究

以寻求提高西番莲原汁超滤时的渗透通量为目的，用国产芳香聚酰胺膜平板超滤器进行试验，对超滤操作条件，果汁预处理，膜的清洗进行研究。结果表明，西番莲原汁超滤时渗透通量最高的操作压力为0．15MPa，最佳进料速度为22mL/s，操作温度为室温；原汁经海藻酸钠—碳酸钠澄清剂预处理后可以明显增大渗透通量；超滤处理后。原汁的西番莲固有滋味和品质得到较好保留。采用超滤澄清法生产高质量的西番莲原汁是可行的。     

EFFECT OF SUPERCRITICAL CARBON DIOXIDE ON MICROBIAL POPULATIONS IN SINGLE STRENGTH ORANGE JUICE1

The effect of supercritical carbon dioxide on aerobic total plate count (TPC) of fresh-squeezed and quick-frozen single strength orange juice from Valencia oranges was studied. Orange juice was treated with SC CO₂ at different temperatures (35° to 60°C) and pressures (8.3 to 33.1 MPa). SC CO₂ treatment at 35°C reduced the TPC by 2 log cycles after 1 h treatment at 33 MPa. At 45°C and 33 MPa 2 log cycles reduction required 45 mins, and 15 mins treatment was sufficient at 60°C. D values of temperature control samples decreased as temperature increased, while that of supercritically treated juice decreased as pressure increased. D values at 35, 45 and 60°C of the supercritically treated juice at 33.1 MPa were calculated as 28, 22.6 and 12.7 min, respectively. The calculated values of z were 180°C, 167°C and 72°C at 8.3 MPa, 20.7 MPa and 33.1 MPa, respectively.     

Purification and Concentration of Betalaines by Ultrafiltration and Reverse Osmosis

Beet juices prepared by solid-liquid extractions were processed by ultrafiltration (UF) and reverse osmosis (RO) to 30°Brix at 20°C. De Danske Sukkerfabrikker (DDS) UF/RO Lab Module-20 plate-and-frame system was used having a 0.72-m² effective membrane area and pressures from 50-40 bar. After prefiltering, pectinase treated juices were sequentially processed through 20,000 and 6,000 (UF) molecular weight (MW) cut-off membranes. The UF purified products were then concentrated by RO processes on several types of cellulose acetate (CA) membranes, one with a 500 MW cut-off and 70% NaCl permeability provided colorants that were separated from a majority of soluble solids. Addition of invertase to pectinase-treated juices decreased flux but yielded a three-fold increase in betalaine concentration on a dry weight basis. Betalaine concentration by UF and RO processes also halved nitrate level and greatly reduced flavor.     

Inactivation of Lactobacillus fructivorans in physiological saline and unpasteurised sake using CO2 microbubbles at ambient temperature and low pressure

The ability of carbon dioxide microbubbles (MB‐CO₂) to inactivate Lactobacillus fructivorans suspended in physiological saline and unpasteurised sake at ambient temperature and a pressure lower than 2.0 MPa was investigated. The number of L. fructivorans cells in physiological saline solution containing 15% ethanol showed a 6‐log reduction following MB‐CO₂ treatment at 40 °C and 2.0 MPa for 50 min. The effectiveness of the treatment increased concomitantly with temperature, pressure and ethanol concentration of the sample solution but was unaffected by the glucose concentration in the sample solution. Furthermore, the number of L. fructivorans cells showed a 5‐log reduction in sake after MB‐CO₂ treatment at 40°C and 2.0 MPa for 60 min. Sensory evaluation revealed no significant difference between MB‐CO₂‐treated sake and unpasteurised sake. These results indicated that MB‐CO₂ treatment was highly effective for the inactivation of L. fructivorans and might become a practical method for pasteurising sake at ambient temperature.     

Identification of equivalent processing conditions for pasteurization of strawberry juice by high pressure,ultrasound, and pulsed electric fields processing

The objective of this study was to evaluate the effectiveness of high pressure processing (HPP), ultrasound (US) and pulsed electric fields (PEF) for the pasteurization of strawberry juice (SJ). Acid-adapted Escherichia coli was used to inoculate SJ prior to treatment with HPP, US, and PEF. HPP was applied at several pressures (200–400 MPa) up to 2 min while US (120 μm, 24 kHz) was conducted at 25, 40, and 55 °C up to 10 min in continuous pulsing mode. In order to avoid excessive use of SJ, PEF was performed using a model solution (MS) basically composed of citric acid (8 g/L), fructose (35 g/L), glucose (35 g/L), Na₂HPO₄ (0.2 M) and NaCl (5%) to simulate the SJ electrical conductivity, pH, and total soluble solid (TSS). A face-centered composite design was conducted for PEF processing at different electric field intensities (EFI) (25–35 kV/cm) and treatment times (5–27 μs). Processing conditions were selected that resulted in 5-log CFU/mL inactivation of E. coli. HPP at 300 MPa for 1 min, and US at 55 °C (thermosonication) for 3 min reduced E. coli in SJ by 5.75 ± 0.52 and 5.69 ± 0.61 log CFU/mL, respectively. PEF treatment at 35 kV/cm, 27 μs treatment time, 350 mL/min flow rate, and 2 μs pulse width in monopolar mode resulted in 5.53 ± 0.00 log reduction of E. coli in MS. Likewise, E. coli population in SJ was also reduced by 5.16 ± 0.15 log after applying the same PEF conditions to SJ. No E. coli was detected in SJ subjected to conventional thermal pasteurization at 72 °C for 15 s. All technologies reduced the natural microbiota below 2 log CFU/mL in terms of the total aerobic bacteria and yeast-mold counts. Thus, this study identified the equivalent conditions for the SJ pasteurization by three nonthermal processing technologies.Industrial relevanceConsumers have an increasing interest towards fresh-like food products with desirable nutritional and sensorial attributes. High pressure, ultrasound and pulsed electric field are three relevant novel nonthermal technologies as alternatives to conventional thermal treatments. This study identified the processing conditions of these three nonthermal technologies for the pasteurization of strawberry juice based on equivalent inactivation of acid-adapted E. coli. From an industrial point of view, the established processing conditions are useful references for the development of novel berry juices. In addition to microbiological safety, this study on equivalent processing allows direct efficacy and quality comparisons of a given juice pasteurized by the three nonthermal technologies under consideration.     

Concentration of Skim Milk by a Cascade Comprised of Ultrafiltration and Nanofiltration: Investigation of the Nanofiltration of Skim Milk Ultrafiltration Permeate

In order to reach a high volume reduction ratio (VRR) prior to drying of skim milk, a membrane cascade comprising of an ultrafiltration (UF) coupled with a nanofiltration (NF) can be applied. The present study investigated the impact of processing (filtration temperature, transmembrane pressure (TMP)) and product (feed pH) parameters on the NF of skim milk UF permeate. It could be shown that a low filtration temperature of 10 °C is more advantageous in terms of flux stability and rejection of the solute fraction as compared to higher filtration temperatures up to 45 °C. The solution pH did not affect permeate flux and lactose retention. However, in order to avoid calcium losses, it is more favorable to conduct the concentration at a pH of 6.8 instead of at a lower pH of 5. The application of a higher TMP (up to 4 MPa) enhances permeate flux and VRR as well as solute rejection during concentration of UF permeate. It was also shown that the retention of solutes decreases towards the end of the concentration process. As a consequence, the achievement of high final VRR must be weighed against increased product losses at the end.     

Effects of High Hydrostatic Pressure on the Physical,Microbial, and Chemical Attributes of Oysters (Crassostrea virginica)

The change in the quality attributes (physical, microbial, and chemical) of oysters (Crassostrea virginica) after high hydrostatic pressure (HHP) treatment at 300 MPa at room temperature (RT, 25 °C) 300, 450, and 500 MPa at 0 °C for 2 min and control oysters without treatment were evaluated over 3 wk. The texture and tissue yield percentages of oysters HHP treated at 300 MPa, RT increased significantly (P < 0.05) compared to control. Aerobic and psychrotrophic bacteria in control oysters reached the spoilage point of 7 log CFU/g after 15 d. Coliform counts (log MPN/g) were low during storage with total and fecal coliforms less than 3.5 and 1.0. High pressure treated oysters at 500 MPa at 0 °C were significantly higher (P < 0.05) than oysters HHP treated at 300 MPa at 0 °C in lipid oxidation values. The highest pressure (500 MPa) treatment in this study, significantly (P < 0.05) decreased unsaturated fatty acid percentage compared to control. The glycogen content of control oysters at 3 wk was significantly higher (P < 0.05) when compared to HHP treated oysters [300 MPa, (RT); 450 MPa (0 °C); and 500 MPa (0 °C)]. HHP treatments of oysters were not significantly different in pH, percent salt extractable protein (SEP), and total lipid values compared to control. Based on our results, HHP prolongs the physical, microbial, and chemical quality of oysters.     

Factors influencing death and injury of foodborne pathogens by hydrostatic pressure-pasteurization

The key objective of hydrostatic pressure-pasteurization of food is the destruction of pathogenic bacterial cells at a high level (8log cycles) without adversely affecting the acceptance characteristics of a food. To achieve these goals, hydrostatic pressure-pasteurization may best be conducted at a moderate pressure, which alone will not kill the desired level of pathogens. However, along with hydrostatic pressure other parameters, namely pressurization-time, temperature and bactericidal compounds, such as bacteriocins, can be used to enhance bactericidal effects of pressurization.Our results with four pathogens indicated that viability loss at 25°C were minimal up to 207MPa, then increased at a rapid rate. However, even above 483MPa, not all species had 8log cycles viability loss. At and above 276MPa a large number of survivors were injured. At 207MPa and 25°C, pressurization for 30min did not greatly enhance viability loss and injury of the four pathogens. However, pressurization temperatures beyond 35°C greatly increased cell death and injury. By pressurizing the cells in the presence of a mixture of pediocin AcH and nisin viability loss of the pathogens was increased by an additional 1.3 to 5.1log cycles. This increase was due to the bactericidal effect of the two bacteriocins on sensitive and injured cells. These results indicated that at moderate pressure, a high level of destruction of pathogens can be induced within a short time by using moderate temperature in combination with bactericidal preservative(s).     

Sensitivity of Staphylococcus aureus and Lactobacillus helveticus in ovine milk subjected to high hydrostatic pressure.

Ovine milk, standardized to 6% fat, was inoculated with Staphylococcus aureus CECT 534 and Lactobacillus helveticus CECT 414 at a concentration of 10(7) cfu/ml and treated by high hydrostatic pressure. Treatments consisted of combinations of pressure (200, 300, 400, 450, and 500 MPa), temperature (2, 10, 25, and 50 degrees C), and time (5, 10, and 15 min). Staphylococcus aureus was highly resistant to pressure; only pressurizations at 50 degrees C of 500 MPa for 15 min achieved reductions of > or = 7.3 log units. For L. helveticus, the number of surviving cells was reduced considerably at pressures of 400 MPa or more (up to 4.5 log units at 50 degrees C for 15 min), and pressure was more effective at low (2 and 10 degrees C) and moderately high (50 degrees C) temperatures than at room temperature (25 degrees C). Both species showed first-order kinetics of destruction in the range 0 to 60 min. The D values for S. aureus were 20 min (2 degrees C at 450 MPa) and 16.7 min (25 degrees C at 450 MPa), and D values for L. helveticus were 7.1 min (2 degrees C at 450 MPa) and 9.1 min (25 degrees C at 450 MPa). Lactobacillus helveticus showed higher rates of survival of pressure than those reported in previous studies for other Lactobacillus spp.     

OCC制浆造纸废水的膜处理技术研究

运用聚醚砜超滤膜对OCC造纸废水二级生化出水进行了处理,旨在将处理后的出水回用于纸机系统。通过考察废液通量、总固形物去除率、CODcr去除率等指标,得出了OCC废水膜处理的优化工艺,即截留相对分子量1000,压力0.3MPa,温度20℃,转速200rpm,最佳透过比为95%。结果表明,在最佳操作条件下废水的通量为27.6L/（m^2·h）,总固形物（TS）从6.96g/L降低到4.32g/L,CODcr从812mg/L降低到117mg/L,阳离子需求量（CD）从1.7532meq/L降低到0.0158meq/L,色度由2381倍降低到25倍,可满足纸机水回用的要求。     

Pecan Oil Recovery and Composition as Affected by Temperature, Pressure, and Supercritical CO2 Flow Rate

Effects of supercritical CO₂ flow rate, extraction temperature, and pressure were studied on oil recovery, fatty acid composition, and factors that control solute extraction from intact pecan halves. After an initial solubility dominant period, extraction was influenced by diffusion of oil from within the pecan. The effective diffusion coefficient was 9.76 × 10^-12 m²/s. In the first 105 min, more oil was extracted as CO₂ flow increased from 1.0 to 7.5 standard L/min (slpm). Beyond 120 min, increasing CO₂ flow from 4 to 7.5 slpm produced negligible differences in amounts of extracted oil. At 2.5 slpm CO₂ flow and 45–75°C, the oil extracted increased by 60% when pressure increased from 41.3 to 55.1 MPa and yielded slightly more at 66.8 MPa. Temperature, pressure, micrometering valve temperature, cultivar (but not extraction time) affected fatty acid (palmitic, stearic, oleic, linoleic, and linolenic) composition of pecan oil.     

Effect of extrusion conditions and storage temperature on texture,colour and acidity of butter

The effect of extruder shear rate (500, 750, 1125, 1500 and 1750/s), feed temperature (5, 7, 10, 13 and 15 °C) and storage temperature (5, 7, 10, 13 and 15 °C) on the acid value, colour (L*, a* and b*values) and texture (hardness and adhesiveness) of organic butter was examined. The optimised conditions in terms of extruder shear rate, feed temperature and storage temperature were 1345/s, 13 °C and 7 °C, respectively. At the optimised conditions; the predicted responses were determined as hardness 42.5 g/cm, work softening 67.2%, adhesiveness 42.5 gf/cm, acid value 3.4 mg KOH/kg and L* value 99.57.     

Oscillatory High Pressure Processing Applied to Mechanically Recovered Poultry Meat for Bacterial Inactivation

The effect of oscillatory high pressure processing on mesophile and psychrotroph populations of mechanically recovered poultry meat (MRPM) was evaluated. Vacuum‐packaged samples were subjected to cycles by alternating moderate pressure (60 MPa) and high pressure (450 MPa) at 20 °C, once or several times so that the total time under high pressure was 15 min. A continuous treatment at 450 MPa for 15 min at 20 °C was also performed. Oscillatory treatments did not generate significantly higher decreases in counts of both populations than continuous pressurization. Reductions from 3.2 to 3.8 log CFU g^–1 were found for mesophiles. Psychrotrophs proved more sensitive: one of the cyclic treatments induced a lethality of 5.2 log CFU g ^–1. Pressurization improves the microbiological quality of MRPM.     

Ultrafiltration and Reverse Osmosis of the Waste Water from Sweet Potato Starch Process

The primary waste water discharged from pilot plant scale sweet potato starch manufacturing was processed by ultrafiltration (UF). The UF permeate was then concentrated by reverse osmosis (RO). Growth of microorganisms in waste water would reduce the flux of UF. When the feed velocity of UF was higher than 2.5 m/sec, its positive effect on permeation rate was no longer existent. Relationships between transmembrane pressure and permeate flux were linear at all tested concentrations. UF filtered protein and calcium reduced two-thirds of the biochemical oxygen demand (BOD) and half the chemical oxygen demand (COD) at weight concentration ratio (WCR) of 5. With RO the rest of the components were recovered and BOD and COD were reduced more than 99% and 98%, respectively, at a WCR of 6.     

Effect of Modified Manufacturing Parameters on the Quality of Cheddar Cheese made from Ultrafiltered (UF) Milk

Cheddar cheese was made from milk concentrated twofold by ultrafiltration (UF). Lowering the cooking and cheddaring temperature from 39°C to 35°C resulted in faster acid development, promoted more proteolysis, caused faster degradation of lactose, and contributed smoother body and texture to the cheese. Starter culture at 2% by weight of unconcentrated milk in combination with low cooking and cheddaring temperature reduced pH at faster rate and shortened the cheese making time by approximately 45 min, compared to cheese made using the traditional temperature (39°C). For the traditional temperature (39°C) of cooking and cheddaring, the addition of 0.2 mL/ kg rennet of unconcentrated milk produced the same rate of proteolysis in both control and cheese made from UF retentate. Composition (fat, protein, salt and moisture) and yield of the UF cheeses with modified temperature treatments were not significantly different from control.