The effects of high hydrostatic pressure at subzero temperature on the quality of ready-to-eat cured beef carpaccio

We compared the application of high hydrostatic pressure (HHP) on unfrozen carpaccio (HHP at 20°C) and on previously-frozen carpaccio (HHP at -30°C). HHP at 20°C changed the color. The pressure increase from 400 to 650MPa and the time increment from 1 to 5min at 400MPa increased L* and b*. a* decreased only with 650MPa for 5min at 20°C. The prior freezing of the carpaccio and the HHP at -30°C minimized the effect of the HHP on the color and did not change the shear force, but increased expressible moisture as compared to the untreated carpaccio. HHP at 20°C was more effective in reducing the counts of microorganisms (aerobic total count at 30°C, Enterobacteriaceae, psychrotrophs viable at 6.5°C and lactic acid bacteria) than HHP at -30o C. With HHP at 20°C, we observed a significant effect of pressure and time on the reduction of the counts.     

Effects of High‐Hydrostatic Pressure on Inactivation of Human Norovirus and Physical and Sensory Characteristics of Oysters

The purpose of the study was to determine the effect of high‐hydrostatic pressure (HHP) on inactivation of human norovirus (HuNoV) in oysters and to evaluate organoleptic characteristics of oysters treated at pressure levels required for HuNoV inactivation. Genogroup I.1 (GI.1) or Genogroup II.4 (GII.4) HuNoV was inoculated into oysters and treated at 300 to 600 MPa at 25 and 0 °C for 2 min. After HHP, viral particles were extracted by porcine gastric mucin‐conjugated magnetic beads (PGM‐MBs) and viral RNA was quantified by real‐time RT‐PCR. Lower initial temperature (0 °C) significantly enhanced HHP inactivation of HuNoV compared to ambient temperature (25 °C; P < 0.05). HHP at 350 and 500 MPa at 0 °C could achieve more than 4 log₁₀ reduction of GII.4 and GI.1 HuNoV in oysters, respectively. HHP treatments did not significantly change color or texture of oyster tissue. A 1‐ to 5‐scale hedonic sensory evaluation on appearance, aroma, color, and overall acceptability showed that pressure‐treated oysters received significantly higher quality scores than the untreated control (P < 0.05). Elevated pressure levels at 450 and 500 MPa did not significantly affect scores compared to 300 MPa at 0 °C, indicating increasing pressure level did not affect sensory acceptability of oysters. Oysters treated at 0 °C had slightly lower acceptability than the group treated at room temperature on day 1 (P < 0.05), but after 1 wk storage, no significant difference in sensory attributes and consumer desirability was observed (P > 0.05).     

Effects of Different Chilling Methods on Hot Processed Vacuum Packaged Pork

Longissimus muscle (loin section) was removed from each side of 24 pork carcasses within 20 min postmortem. Each muscle was divided in half (N = 96 sections), vacuum packaged and allotted to one of four treatments: (1) normal chilling, (2) propylene glycol immersion, (3) crust freezing, or (4) high temperature conditioning and four storage intervals (N = 6) or 0, 7, 14 or 28 days. Rapid chilling with propylene glycol increased (P<0.05) purge. Shear force values were increased when loins were rapidly chilled (P<0.05) but few sensory differences were observed. Off-odor scores increased (P<0.05) with increasing storage time. Normal chilling resulted in lighter muscle color scores than rapidly chilled loin sections. Rapid chilling does not have a beneficial effect on palatability or shelf life of hot-processed fresh pork.     

Inactivation kinetics of Vibrio vulnificus in phosphate-buffered saline at different freezing and storage temperatures and times

Vibrio vulnificus (Vv) is a pathogen that can be found in raw oysters. Freezing can reduce Vv and increase the shelf life of oysters. The objective of this study was to develop predictive inactivation kinetic models for pure cultures of Vv at different frozen storage temperatures and times. Vv was diluted in phosphate-buffered saline (PBS) to obtain about 10(7) CFU/mL. Samples were frozen at -10, -35, and -80 °C (different freezing rates), and stored at different temperatures. Survival of Vv was followed after freezing and storage at -10 °C (0, 3, 6, and 9 d) and at -35 and -80 °C (every week for 6 wk). For every treatment, time-temperature data was obtained using thermocouples in blank vials. Predictive models were developed using first-order, Weibull and Peleg inactivation kinetics. Different freezing temperatures did not significantly (α = 0.05) affect survival of Vv immediately after freezing. The combined effect of freezing and 1 wk frozen storage resulted in 1.5, 2.6, and 4.9 log10 reductions for samples stored at -80, -35, and -10 °C, respectively. Storage temperature was the critical parameter in survival of Vv. A modified Weibull model successfully predicted Vv survival during frozen storage: log10 Nt = log 10No - 1.22 - ([t/10{-1.163-0.0466T}][0.00025T(2) + 0.049325]). N(o) and N(t) are initial and time t (d) survival counts, T is frozen storage temperature, Celsius degree. PRACTICAL APPLICATION: Vibrio vulnificus can be inactivated by freezing. Models to predict survival of V. vulnificus at different freezing temperatures and times were developed. This is the first step towards the prediction of V. vulnificus related safety of frozen oysters.     

The influence of controlled atmosphere and vacuum packaging upon chilled pork keeping quality

A total of 48 pork loin section (1 kg) with normal inherent muscle quality were utilized to evaluate and compare the effects of a vacuum packaging system and a CO(2) controlled atmosphere packaging system on keeping quality of chilled pork stored at -1·5°C. Results indicated based upon appearance CO(2) packaged porl loin had a storage life of greated than 15 weeks and vacuum packaged pork loid had a storage life of slightly over 12 weeks. However, off-flavor development coinciding with lactic acid bacteria reaching maximum numbers presently restricts the actual storage life of pork loin stored at -1·5°C to 9 weeks in both packaging treatments. Therefore, if microbial contamination on the commercial product can be reduced significantly to prevent spoilage organisms, including lactics, from rapidly growing to maximum numbers, storage life of pork loin at -1·5°C can be extended sufficiently to accomodate all domestic and export applications using either vacuum or CO(2) packaging.     

Reducing SO(2) in fresh pork burgers by adding chitosan

The use of 0.02 or 0.05% chitosan is proposed to reduce from 450 to 150mgkg(-1) the SO(2) required to preserve pork burgers aerobically packed and stored at 2°C for up to 21days under retail display conditions. The effects of chitosan and/or sulfite addition and the storage time were determined in fresh (color deterioration, lipid oxidation, pH, total viable counts, Escherichia coli and coliforms, Salmonella, appearance and odor) and cooked (appearance, odor, flavor and texture) burgers. The addition of either 0.02 or 0.05% chitosan was not detected by sensory analysis, and extended the shelf life of low-SO(2) burgers from 7 to 14days. Chitosan enhanced the preservative effects of sulfite at a low dose, acting on the main causes of meat deterioration (bacterial spoilage, color stability and lipid oxidation), and provided good sensory properties to fresh and cooked pork burgers.     

Effects of Potassium Sorbate, Sodium Acetate, Phosphates and Sodium Chloride Alone or in Combination on Shelf Life of Vacuum-Packaged Pork Chops

Microbiological and some physical and chemical effects of treating pork chop surfaces with sodium acid pyrophosphate, a commercial phosphate blend, potassium sorbate and phosphate/sorbate/sodium acetate solutions, with or without sodium chloride, before packaging were studied in pork chops vacuum-packaged and stored at 2–4°C for 10 weeks. All treatments containing potassium sorbate reduced (P<0.05) counts of mesophiles, psychrotrophs, EnterobacteriaCeae, facultative anaerobes, and lactobacilli. Treatment of chops with 10% phosphates/ 10% potassium sorbate solutions improved pork color and decreased purge. Potassium sorbate alone reduced microbial counts more than it did when combined with phosphates, but chops were darker and had more exudate (P<0.05). Combined use of 10% phosphates/10% potassium sorbate extended shelf life in vacuum-packaged fresh pork chops to 10 weeks at 2–4°C compared with 4 weeks for untreated pork and protected meat color.     

Evaluation of the storage life of vacuum packaged Australian beef

To establish the shelf-life of vacuum packaged Australian beef, 15 Strip-loins and 15 Cube-rolls for each Processor (A, B, and C) were evaluated at two week intervals (since wk 10 to 20). Steaks on the trays were placed in retail cabinets at 3 °C. Shelf-life evaluation was based on off-odor (only at week 10), microbial analysis, lipid oxidation, and color assessment by trained panelist and Hunter colorimeter. Panelists detected "slightly off-odor" in both primal cuts for Processors B and C (P<0.05). Processor A primal cut steaks displayed better color scores as well as CIE L*, a*, b*, Chroma and Hue values during storage and display period than steaks from the other processors. Also, primal cuts from Processor A showed lower microbial counts and TBARS values with respect to other processors during the trial. Processor A cuts showed improved shelf life attributes initially which helps to explain its slow shelf-life deterioration.     

Evaluation of Consumer Acceptance and Quality of Thermally and High Hydrostatic Pressure Processed Blueberries and Cherries Subjected to Cellulose Nanofiber (CNF) Incorporated Water-Resistant Coating Treatment

This study evaluated the influence of cellulose nanofiber (CNF) incorporated layer-by-layer water-resistant coating on consumer acceptance of blueberries and cherries processed in light syrup thermally (TP, 97 °C for 7 min) or non-thermally (high hydrostatic pressure (HHP), 414 MPa for 10 min). The coating technique was validated on canned blueberries in a commercial canning operation. Consumers (n?=?75 and 77 for blueberry and cherry study, respectively) scored overall, color, aroma, and texture likeness of coated and uncoated processed fruits using a 9-point hedonic scale and firmness intensity using a 5-point just about right (JAR) scale. Coating treatment significantly (P?<?0.05) increased aroma and texture liking scores of TP and HHP blueberries compared with uncoated ones, but did not impact overall and color liking scores. Coated TP (2.67) and HHP (2.96) blueberries received closer to JAR score in firmness that uncoated ones (1.88 and 2.57, respectively). Informing consumers about the benefit of developed coatings altered consumers’ attitude from negative (~?80 and ~?57% gave “neutral” and “disliking” scores on TP and HHP samples, respectively) into positive status (“I would like the overall appearance”). Coating treatment resulted in higher aroma liking scores in HHP cherries, but decreased (P?<?0.05) overall and color liking scores on both TP and HHP cherries due to the presence of visible coating substances onto fruit surface. In commercial canning process, coated blueberries showed great retention of bioactive compounds and firmness. This study demonstrated that CNF incorporated layer-by-layer coating is promising to produce high quality of processed fruits in light syrup.     

"Chilled" pork-Part I: Sensory and physico-chemical quality

Chilled meat exportation comprises chilling within 48h post-mortem to temperatures <0°C without freezing and holding under these conditions for several weeks. The effects of this ageing on sensory quality of pork are unknown and hence the objective of this study was to compare the sensory quality of Canadian pork as found in an export (Japan) market and locally. Regardless that the Japanese market's quality criteria were met, pork sorted on-line differed (P<0.05) from that for the domestic market only for lightness, exudate and cooking loss; no differences in intramuscular fat content were observed. Overall, a trained panel scored weaker pork and meat flavours and odours in the export than the domestic pork as a result of either the quality by selection if roasted or the ageing (-1.7°C, 43days exported chilled or 3.1°C, 5days domestic) if grilled or shabu shabu. Grilled pork was also more tender, sweeter and had stronger caramel flavour with the chilled ageing.     

"Chilled" pork - Part II. Consumer perception of sensory quality

The objective of this study was to compare consumer perception of the sensory quality of grilled Canadian pork destined for Japanese and domestic markets, with particular reference to export selection criteria imposed by Japanese importers and transportation conditions. Consumers from Quebec, Canada tasted local and export quality pork subjected to "chilled" (aged 43days at -1.7°C) or conventional ageing (5days at 3.1°C). Consumers' scores (out of 10) were higher (P<0.05) in the "chilled" than conventionally aged pork for tenderness (6.8 vs 5.7), juiciness (6.6 vs 6.0), taste liking (6.4 vs 5.9) and overall acceptability (6.7 vs 6.1). When informed that the conventionally aged, domestic quality pork was destined for the domestic market, consumer scores increased significantly (P<0.05). No effect of information was observed on the perception of the 'chilled' export quality meat, perhaps a consequence of the high sensory quality observed prior to labelling.     

Quality of fresh retail pork cuts stored in modified atmosphere under temperature conditions simulating export to distant markets

The effect of storage temperature on microbial and sensory quality of retail cuts of pork was determined on samples stored under temperature regimens designed to simulate conditions that could be encountered in accessing distant markets with retail-ready product. Samples were packaged in modified atmosphere with 100% CO(2) and <200 ppm O(2) in plastic film with extremely low gas transmission rates. All samples were stored at -1·5°C for three weeks. Reference samples were held at -1·5°C for the duration of the study; experimental samples were transferred to 4°C (-1·5 4° C ) or 7°C (-1· 517° C ) and analyzed for microbial content and sebsory attributes including appearance, confinement and meat odours. Storage life of reference samples at -1·5°C was seven weeks before rejection for loss of acceptable appearance. With transfer of samples to 4 and 7°C after three weeks at -1·5°C, samples remained acceptable for retail sale for two weeks and one week, restpectively. The microbial flora was dominated by lactic acid bacteria under all three storage conditions. Appearance of the cuts was the principal criterion limiting storage life. Discoloration of the meat was not a problem in this study, but purge and odour, including sour and sulphur notes, became a problem with time. The study indicated that export of retail-ready pork cuts to distant markets with a three-week time for delivery to market at -1·5°C can be achieved with one to two weeks of marketing time at retail market at 4 to 7°C.     

Effect of freezing temperature, thawing and cooking rate on water distribution in two pork qualities

The effects of freezing temperature (-20 versus -80°C) in combination with long-term freezer storage (-20°C) on water mobility and distribution in pork of two qualities (normal and high ultimate pH) were explored using low-field NMR T(2) relaxometry. A marked effect of freezing temperature on the characteristics of intra- and extramyofibrillar water (T(2) relaxation times) in the thawed pork was demonstrated, implying that the freezing temperature in combination with prolonged freezer storage affects the distribution and chemical-physical state of water in the thawed meat. Determination of technological properties (thawing and cooking loss) revealed that the observed T(2) variations related to water distribution and water properties, which were found to be consistent with the degree of structural damage assessed by light microscopy, also were reflected in the technological quality of the meat. Low freezing temperature in combination with prolonged freezer storage was associated with increased thawing and cooking loss. In addition, pH in the fresh meat had a pronounced effect on the distribution of myofibrillar water, as a more homogenous pore size distribution was evident in meat with high pH compared with normal pH. A clear effect of cooking rate on the T(2) relaxation characteristics in the cooked pork was also demonstrated, probably reflecting a cooking rate-induced effect on the myofibrillar structures. The effect of cooking rate on water distribution resulted in a significantly lower cooking loss upon a slow cooking rate (0.5°C/min from 25 to 65°C and 0.3°C/min from 65 to 80°C) compared with a fast cooking rate (1°C/min).     

USE of HYDROSTATIC PRESSIJRE to PRODUCE HIGH QUALITY and SAFE FRESH PORK SAUSAGE

The effects of high hydrostatic pressure (HHP) on the survival of microor ganisms and quality changes of fresh pork sausages were investigated. Pork sausage inoculated with Listeria monocytogenes at 1O⁷ CFU/gram was prepared and subjected to HHP at 414 and 552 MPa, at treatment temperatures of 25 and SOC. for various time intervals to examine pressure effects on inactivation of bacteria. At a pressure of 414 MPa and SOC for 2 min, the microorganisms in fresh pork sausages were completely inactivated. Partial discoloration of meat was observed after 10 min of pressurization above 414 MPa at either temperature.
The effect of HHP treatment on the physical and rheological properties of sausage was also studied. the sausages increased infirinness with an increase in the pressure applied. the pressure-treated sausages were generally lighter in color as compared with the heat-treated sausages.
The optimal pressure/temperature/time conditions that resulted in minimum quality changes with microbiologically safe fresh pork sausages was 414 MPa and SOC for 2 min.     

Shelf life of pork from five different quality classes

A total of 117 loins were selected on the cutting line at 24 h post-mortem to study the long term shelf life (35 days, 4 °C) of vacuum packaged pork from five different quality classes (PSE: pale, soft, exudative; PFN: pale, firm, non-exudative; RSE: red, soft, exudative; RFN: red, firm, non-exudative; and DFD: dark, firm, dry). The microbial load at 0 d was not significantly different (P > 0.05) among the pork quality classes, indicating that the initial microflora was influenced by the dressing conditions at the plant, not by the meat quality class. But after 35 d of storage, total aerobic mesophilic and presumptive lactic acid bacteria counts were higher (P < 0.05) in DFD pork due to its higher ultimate pH. RSE was the second quality class most susceptible to spoilage, whereas PFN, RFN and PSE pork had similar microbial loads. Further research is needed to elucidate the causes of the shorter shelf life in RSE pork.     

Effect of Single‐ and Two‐Cycle High Hydrostatic Pressure Treatments on Water Properties,Physicochemical and Microbial Qualities of Minimally Processed Squids (Todarodes pacificus)

This study investigated the effect of single‐ and two‐cycle high hydrostatic pressure (HHP) treatments on water properties, physicochemical, and microbial qualities of squids (Todarodes pacificus) during 4 °C storage for up to 10 d. Single‐cycle treatments were applied at 200, 400, or 600 MPa for 20 min (S‐200, S‐400, and S‐600), and two‐cycle treatments consisted of two 10 min cycles at 200, 400, or 600 MPa, respectively (T‐200, T‐400, and T‐600). HHP‐treated samples had higher (P < 0.05) content of P_2b (immobilized water) and P₂₁ (myofibril water), but lower P₂₂ (free water) than those of control. The single‐ and two‐cycle HHP treatments at the same pressure level caused no significant difference in water state of squids. The two‐cycle HHP treatment was more effective in controlling total volatile basic nitrogen, pH, and total plate counts (TPC) of squids during storage, in which TPC of S‐600 and T‐600 was 2.9 and 1.8 log CFU/g at 10 d, respectively, compared with 7.5 log CFU/g in control. HHP treatments delayed browning discoloration of the squids during storage, and the higher pressure level and two‐cycle HHP were more effective. Water properties highly corresponded with color and texture indices of squids. This study demonstrated that the two‐cycle HHP treatment was more effective in controlling microbial growth and quality deterioration while having similar impact on the physicochemical and water properties of squids in comparison with the single‐cycle treatment, thus more desirable for extending shelf‐life of fresh squids.     

Effectiveness of Dipping with Phosphate, Lactate and Acetic Acid Solutions on the Quality and Shelf-life of Pork Loin Chop

Extending the shelf‐life of pork loin chops by dipping in 2% acetic acid (AA), 10% sodium lactate (SL), or 10% trisodium phosphate (TSP), compared to the undipped control (CONT), was demonstrated. TSP had the highest pH and water‐holding capacity. However, TSP had a dry and dark visual appearance on the loin chop surface, while AA was similar to pale, soft, and exudative (PSE) pork. CONT and SL had obvious putrid odor with TPC exceeding 10⁷ CFU/g at d 6 and d 9, respectively. Pork loin chops dipped in 10% sodium lactate solution resulted in better visual appearance and lower microbial counts, suggesting a possible extension of the shelf‐life to 6 d under refrigeration.     

Meat quality and cooking attributes of thawed pork with different low field NMR T(21)

A relationship of low field NMR T(2) components to meat quality and cooking attributes of pork was investigated. Longissimus muscle was removed from 23 pig carcasses at 24h postmortem for meat quality measurements and cooking test. Frozen samples were classified into three groups by LF-NMR T(21) of thawed samples: A (<40ms), B (40-44ms) and C (>44ms). There were significant differences (P<0.05) in pH, lightness (L* value) and pressing loss among the three groups. Cooking time to attain 70°C was slightly lower in group C than the other groups. Shear force value of cooked samples was not affected by T(21). The component T(21) correlated (P<0.05) with L* value, muscle pH and pressing loss, while L* value correlated (P<0.05) with thawing loss and muscle pH. Therefore, combined LF-NMR and color measurements could be a good way to differentiate water holding capacity of pork.     

Effect of enrobing and antioxidants on quality characteristics of precooked pork patties under chilled and frozen storage conditions

Enrobed or coated pork patties containing a (50:50) mixture of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) at a level of 100 ppm in the batter mix and meat emulsion were cooked and stored chilled (4±1?°C) and frozen (-18±1?°C) for evaluation of quality. Test samples were compared to control patties (neither enrobed nor antioxidant treated). After 35 days of refrigerated storage no significant difference (P>0.05) was found in pH, 2-thiobarbituric acid (TBA) and Warner-Bratzler shear force (WBSF) values between uncoated and treated samples. Similarly, enrobed patties showed no significant (P<0.05) decrease in TBA values compared to control patties, but had lower relative moisture loss at the 45th day of frozen storage. However, control patties had significantly (P<0.05) higher overall shear values than coated patties under the same storage conditions. Coated samples had higher microbial loads but below the acceptable limit. Total plate counts (TPC) in enrobed and control patties were around 3.48 and 3.05 log(10) cfu/g, respectively, whereas in frozen stored samples these numbers were 2.77 and 2.69 log(10) cfu/g at the end of storage. Sensory scores viz appearance and color, flavor, juiciness, texture, and overall acceptability were higher in treated samples than controls during the entire storage period.