Although the safety of raw meat products has improved in recent decades, raw meat is still associated with a considerable incidence of foodborne illnesses and death. Standard raw meat antimicrobial interventions such as chemical sprays can reduce meat quality, and their effectiveness has plateaued. However, a new thermal pasteurization technology implementing direct steam injection into ground meat and subsequent chilling of the meat by expansion under vacuum has the potential to nearly eliminate pathogens in raw ground meat products while preserving the proteins in the raw state. An inoculation (
The primary pathogens of concern in the production of raw meat products are
Incidence of foodborne human infections, US. STEC, Shiga toxin-producing
In addition to the standard processes long employed by the meat industry, such as cooling and freezing, there are many intervention type technologies in use today in meat production, primarily focused on reducing STEC in beef and
For an antimicrobial intervention to be effective, it must come into contact with the microorganism. This can be a significant challenge when applying interventions to the whole carcass or to trimmings. A zero-moisture addition requirement for many raw meats, such that there can be no retention of the sprayed or dipped agents on the carcass or trim, typically limits the amount of agent that can be applied, making it difficult to achieve complete surface coverage by the antimicrobial. In addition, acids and chlorine will both reduce the quality of the meat to some degree. At low concentrations of acid (1% to 2%) or chlorine solutions (18 to 25 ppm of chlorine into chill water), the meat quality reduction is negligible. However, at higher concentrations—above 2%-acid solutions and above 25-ppm chlorine in chilled water, where these antimicrobial solutions may be more effective—the resulting treatment can have undesirable effects on the meat quality, including discoloration or bleaching, off-odor, and off-flavor attributes (
Although complete elimination of foodborne illness associated with raw meat is not possible, there are examples in other industries in which a technological leap has completely revolutionized food safety. The advent of milk pasteurization completely transformed the dairy industry and has practically eliminated the risk of foodborne illness associated with pasteurized dairy products. Today, unpasteurized milk products cause 840 times more illnesses and 45 times more hospitalizations than pasteurized products (
For this technology to be effective, it will have to overcome the limitations of the current technologies, namely, the inability to equally treat the entire product and to achieve the concentrations necessary for significant pathogen reductions without negatively impacting meat quality.
A direct steam injection and vacuum expansion chilling meat pasteurization system, referred to as refrigerated instantaneous temperature cycling (RITC), has been developed to inactivate microorganisms while preserving meat in the raw state. The process consists of 2 main steps: direct application of steam to meat to instantaneously raise the temperature beyond a minimum of 82.2°C, followed by equally instantaneous chilling of the meat by expansion under vacuum. The entire process, from the point steam contacts meat to the point meat is fully chilled under vacuum, takes only 0.3 s. This sophisticated form of thermal pasteurization can reduce microorganism populations by more than 5 log with only minimal and imperceptible changes to the sensory characteristics of the raw meat. The RITC process is similar to direct-heating ultra-high temperature (UHT) pasteurization of milk in common use today. However, typical direct-heating UHT treatments applied to meat would likely cause denaturing of proteins or other undesirable effects on the meat. There are several key distinctions that make the RITC process unique among UHT pasteurization processes and appropriate for use in raw meat.
Meat proteins, by nature, are more sensitive to high-temperature processing than milk proteins; therefore, it is important to minimize both the time and temperature during thermal pasteurization to maintain meat proteins in a native state and limit loss of color. For instance, heating meat proteins to 82.2°C using common direct-heating UHT milk pasteurization processes (Milk UHT) would likely cause the proteins to be cooked or denatured because of the longer time at high temperature. Typical Milk UHT process hold times range from 2.4 s to 6.7 s (
Pre-tempering, in which the product temperature is raised from a stable storage temperature to a consistent pre-injection temperature by indirect heat exchange, is common in UHT processes. In the RITC process for ground meats, the process of pre-tempering raises the product temperature to approximately 46°C prior to steam injection. A proprietary design heat exchanger using a single tube of small diameter ensures positive flow of all the product to be treated. This is important for precision temperature control and to minimize temperature variability throughout the product as it passes through the heat exchanger, resulting in even tempering without any overheating.
The steam injection step utilizes a patented (U.S. Patent No. 10,674,751) axial flow injector designed to promote rapid mixing without fouling. Fouling is a phenomenon common in pasteurization that refers to the formation of deposits on heat transfer surfaces as a result of reactions that take place as foods are heated (
The expansion chilling step uses a propriety design that creates an immediate, high-level exposure of the proteins to the vacuum environment, allowing instant boiling of the condensed water from the steam injection, which causes the rapid and equal chilling of all particles of the meat. The product entrance design limits the interaction of the product with the surface of the vessel, which prevents interference with the vacuum chilling or localized overheating due to contact with hot surfaces of the vessel.
Previous attempts at pasteurization of meat proteins have taken the form of either carcass steam vacuuming systems or irradiation. Carcass steam vacuum systems work by delivering a stream of water at 7 to 10 pounds per square inch, between 88°C and 94°C, to an area 1.5 × 6.5 cm while simultaneously vacuuming the area around the stream of hot water (Dorsa, 1996). Steam delivered at approximately 45 psi continuously sanitizes the equipment while in use. The method of pasteurization in the RITC process differs from the previous attempts of using steam and vacuum in several regards. By using direct steam injection in RITC, the product temperature can be elevated instantaneously by latent heat transfer, which results in the shortest time possible for the thermal treatment process. By contrast, in carcass steam vacuum systems, the product temperature takes longer to be elevated since the only heat transfer effect is from the specific heat of the sprayed water resulting in a longer overall thermal treatment process. Similarly, the vacuum expansion in RITC causes the instantaneous chilling of the product, while the vacuum in the carcass steam vacuum systems is only intended to remove contamination from the carcass. Finally, since the entire product matrix is thermally treated during the RITC process, the log reductions of pathogen populations are representative of the entire matrix, whereas the log reductions achieved in steam vacuuming only apply to the small areas that are treated, typically areas of visible contamination.
An alternative method of meat pasteurization, irradiation, uses ionizing radiation from an energy source such as gamma rays or X-rays to achieve reduction in pathogen populations. Although irradiation is extremely effective in reducing microorganisms, the treatment produces a characteristic aroma and alters meat flavor, both of which negatively impact consumer acceptance (
Precedence for wide-scale commercial thermal pasteurization already exists for nondairy animal proteins, e.g., thermal pasteurization of liquid egg, which contains a low-viscosity protein in liquid phase (
The patent-pending RITC meat pasteurization technology was pioneered by empirical™ Innovations, Inc. (Dakota Dunes, SD) as part of the ground beef production process that it has developed using modern technologies. In this production process, the lean proteins from higher-fat beef cuts are separated into 2 phases, a fibrous component of protein and a component of protein in liquid phase (light protein). The 2 phases of protein are mixed back together to form the finished ground beef. The first application of the RITC technology was to the light protein. The low viscosity of the light protein made it easier to process and less susceptible to immediate fouling.
Throughout the development, there were several challenges that were difficult to predict or to model, therefore an empirical process of design, test, revise and retest was employed to rapidly understand and overcome the different challenges. A summary of some of the more significant challenges and solutions in developing the RITC process is presented here.
The steam and product must be mixed on the order of hundredths of a second in order to limit the time at high temperature to 0.3 s. Initial design and testing achieved minimal microorganism reductions because the mixing could not take place on the necessary timescale. The challenge to effective mixing is the penetration of the steam into the entire product mix without flow stagnation, which leads to overheating and fouling.
Two years of experimentation resulted in a robust understanding of the flow mechanics, leading to identification of several critical factors of instantaneous mixing: penetration depth, penetration angle, and flow velocity. Experimenting with the relationship between these factors led to the development of a specialized flow geometry that maximizes surface contact between the steam and the product while preventing flow stagnation.
Overheating during hold time causes fouling of the injector. The bulk fluid temperature is controlled by the ratio of steam added to the product, but localized overheating can occur where product contacts boundary surfaces, which absorb heat rapidly from the unmixed steam. After experimentation with a variety of techniques, the optimal solution involved controlling the heat flux through boundary surfaces. By using appropriate heat transfer media and channel design around the boundaries, the heat flux through the boundary surfaces can be maintained such that the heat is removed from the boundary surface prior to localized overheating. There is a balance between removing the necessary amount of heat to prevent overheating and removing too much heat, which causes the temperature achieved in the injector to fall below critical limits.
Direct chilling by expansion under vacuum is considered instantaneous if all of the product being processed is given equal access to the vacuum condition. Conventional processing techniques and vacuum expansion design do not immediately expose sufficient surface area to the vacuum, resulting in non-instantaneous chilling in much of the product. This wide range in chilling times would not be adequate in the RITC process due to the short timescale at high temperatures necessary for retaining meat quality.
An innovative, custom-designed vacuum expansion system closely integrated with steam injection and mixing was developed with the specific intent of maximizing the surface area of product when exposed to the vacuum condition. It was also important to minimize product contact with hot boundary surfaces of the vacuum system to prevent localized overheating. Together, these 2 design elements, properly implemented, facilitate instantaneous chilling of the product when exposed to the vacuum.
Figure
RITC thermal pasteurization of raw meat process. RITC, refrigerated instantaneous temperature cycling.
Time and temperature profile for RITC thermal pasteurization of raw meat process. RITC, refrigerated instantaneous temperature cycling.
The 2 key control attributes of the system are temperature control and mass differential control, both of which must be maintained within limits to ensure the effectiveness of the heat treatment and quality of the products.
A control volume and energy balance analysis determines the appropriate equations for controlling the temperature achieved in the steam injection step. The dashed line around the steam injector (5) in Figure
Control volumes for analysis of RITC thermal pasteurization of raw meat process. RITC, refrigerated instantaneous temperature cycling.
Terms and constants of the RITC thermal pasteurization of raw meat process
Term | Description | Source |
---|---|---|
mip | Mass flow of product into the control volume | Data |
ms | Mass flow of steam into the control volume | Data |
mm | Mass flow of temperature-controlled media | Data |
Δm | Difference of mass flow of product entering and leaving the control volume | Variable |
Tip | Temperature of product into the control volume | Data |
Tim | Temperature of temperature-controlled media into the control volume | Data |
Top | Temperature of product out of the control volume | Data |
Tom | Temperature of temperature-controlled media out of the control volume | Data |
Cpp | Specific heat of product | Table |
Cpm | Specific heat of temperature-controlled media | Table |
hf | Enthalpy of flashed water | Table |
hs | Enthalpy of steam input | Table |
hlatent | Enthalpy of vaporization of water | Table |
RITC, refrigerated instantaneous temperature cycling.
For the condition where the temperature of product out of the control volume is the temperature of the product out of the expansion vessel, then it is equal to the temperature of the vapor in the expansion vessel.
A control volume and energy balance analysis determines the appropriate equations for controlling the mass differential in the process. The dashed line around the steam injector (5) and expansion cooling vessel (9) in Figure
Moisture addition to the product during raw meat production processes is typically unacceptable. It is therefore important to have a simple and reliable method of tracking the mass change in order to ensure that all of the moisture added in the steam application stage is removed in the vacuuming chilling stage. The change in mass in the RITC process is given by
Temperature and moisture control of the system both rely on several sensor inputs that all inherently have a degree of uncertainty associated with the measurement. This impact of the uncertainty on the control formulas is taken into account by known methods, but care must be taken to identify all sources of uncertainty and set appropriate control limits. The temperature limit of the injector is maintained above the low limit by a 0.4°C margin of error. The change in mass of the product is maintained below limit by a margin of error of 0.1% of the product flow.
Full-scale production tests were conducted on the RITC system to verify the control scheme capability within the 6-Sigma framework. The mass differential during the RITC process was evaluated against upper (+0.5%Δm) and lower (−0.5%Δm) control limits bounding the desired variability on this process parameter. Process capability index (Cpk) values were calculated to describe the average and spread of the data with respect to the specification limits (
The product temperature out of the injector must be maintained within certain limits to achieve the desired microorganism reductions. Inoculated challenge studies were performed to determine the appropriate temperature limits to achieve a suitable reduction for high and low levels of inoculated non-pathogenic
Thermal inactivation of the 5 non-pathogenic
The 5 non-pathogenic
For the high population inoculation, 317.5 kg of light protein was inoculated with 3.5 L of the combined culture of the non-pathogenic
Mean populations (log cfu/g) of non-pathogenic
Mean ± SEM log cfu/g | Processed Samples Below Detection Limit | ||
---|---|---|---|
Replication | Control | Processed | |
6.3 ± 0.19 | 0.5 ± 0.00 | 3/5 | |
6.2 ± 0.13 | 0.5± 0.00 | 4/5 | |
6.2 ± 0.17 | 0.5 ± 0.06 | 5/5 | |
6.5 ± 0.11 | 0.5 ± 0.06 | 1/5 | |
6.2 ± 0.17 | 0.5 ± 0.00 | 5/5 | |
5.9 ± 0.21 | 0.5 ± 0.00 | 5/5 | |
6.5 ± 0.05 | 0.5 ± 0.00 | 5/5 | |
6.3 ± 0.06 | 0.5 ± 0.01 | 28/35 |
RITC, refrigerated instantaneous temperature cycling.
Number of processed samples below the detectable limit of the enumeration assay divided by total number of samples.
Lowercase letters indicate significant difference at
cfu, colony-forming units.
Mean populations (log cfu/g) of non-pathogenic
Mean ± SEM log cfu/g | Processed Samples Below Detection Limit | ||
---|---|---|---|
Replication | Control | Processed | |
4.1 ± 0.19 | 0.5 ± 0.00 | 5/5 | |
3.8 ± 0.13 | 0.5 ± 0.00 | 5/5 | |
3.7 ± 0.17 | 0.5 ± 0.06 | 4/5 | |
3.7 ± 0.11 | 0.5 ± 0.00 | 5/5 | |
3.8 ± 0.17 | 0.5 ± 0.00 | 5/5 | |
3.8 ± 0.05 | 0.5 ± 0.01 | 24/25 |
RITC: refrigerated instantaneous temperature cycling.
Number of processed samples below the detectable limit of the enumeration assay divided by total number of samples.
Lowercase letters indicate significant difference at
cfu, colony-forming units.
The light protein and inoculum mixture was recirculated for 30 min, and then 5 replicate control samples were taken. The RITC treatment was applied using a set point to reach a temperature of 85°C out of the injector for the high inoculation level and 82.2°C for the low inoculation level, and 5 replicate treated samples were collected. All of the samples, control and treated, were collected in sterile Whirl-Pak® (Uline, Pleasant Prairie, WI) bags and immersed in an ice-water bath within 5 s of collection. The ice water bath consisted of a standard meat tote with 4.5 kg of ice and approximately 4.5 kg of water. The samples were thoroughly chilled and transported to the laboratory, where they were analyzed within 24 h of collection.
The samples were homogenized and serially diluted in Butterfield’s Phosphate buffer (6.4% KH2PO4 suspended in deionized water, titrated to pH 7.2 and autoclaved) and enumerated using the method of Kang and Fung (
The high inoculation experiment was independently replicated 7 times, with 5 replicate control samples and 5 replicate treated samples for each independent replication. The low inoculation experiment was independently replicated 5 times, with 5 replicate control samples and 5 replicate treated samples analyzed for each independent replication. The microbial populations were converted to log colony forming units per gram, and descriptive statistics were computed using WINKS SDA software version 7.07 (TexaSoft;
The average populations for each replication of the control and processed samples are presented in Table Minimum reduction = [lowest population observed in control samples] − [highest population observed in processed samples]; log cfu/g. Average reduction = [average of population observed in control samples] − [average of population observed in processed samples], log cfu/g. Maximum reduction = [highest population observed in control samples] − [lowest population observed in processed samples]; log cfu/g.
Minimum, average, and maximum reduction (log cfu/g) in the populations of non-pathogenic
Replication | Minimum | Average | Maximum |
---|---|---|---|
5.3 | 5.8 | 6.3 | |
5.4 | 5.7 | 6.1 | |
5.1 | 5.6 | 6.2 | |
5.3 | 6.0 | 6.2 | |
5.4 | 5.8 | 6.2 | |
5.0 | 5.4 | 6.1 | |
5.8 | 6.0 | 6.1 | |
5.3 ± 0.09 | 5.8 ± 0.08 | 6.2 ± 0.03 |
RITC, refrigerated instantaneous temperature cycling.
Minimum reduction = [lowest population observed in control samples] − [highest population observed in processed samples]; log colony-forming units per gram (cfu/g).
Average reduction = [average of population observed in control samples] − [average of population observed in processed samples], log cfu/g.
Maximum reduction = [highest population observed in control samples] − [lowest population observed in processed samples]; log cfu/g.
Mean ± SEM; log cfu/g.
Minimum, average, and maximum reduction (log cfu/g) in the populations of non-pathogenic
Replication | Minimum | Average | Maximum |
---|---|---|---|
3.3 | 3.6 | 3.8 | |
2.8 | 3.3 | 3.8 | |
2.5 | 3.2 | 3.5 | |
3.0 | 3.2 | 3.4 | |
3.0 | 3.3 | 3.6 | |
2.9 ± 0.13 | 3.3 ± 0.07 | 3.6 ± 0.07 |
RITC, refrigerated instantaneous temperature cycling.
Minimum reduction = [lowest population observed in control samples] − [highest population observed in processed samples]; log colony-forming units per gram (cfu/g).
Average reduction = [average of population observed in control samples] − [average of population observed in processed samples], log cfu/g.
Maximum reduction = [highest population observed in control samples] − [lowest population observed in processed samples; log cfu/g.
Mean ± SEM; log cfu/g.
The average across the 7 replicates of the high inoculation experiments were 5.3, 5.8, and 6.2 for the minimum, average, and maximum log reductions. The minimum log reduction recorded was for replication 6, for which the minimum log reduction was 5.0. The average across the 5 replicates of the low inoculation experiments were 2.9, 3.3, and 3.6 for the minimum, average, and maximum log reductions. The minimum log reduction recorded was for replication 3, for which the minimum log reduction was 2.5. It is important to note, while interpreting the results of the low inoculation experiments, that 24 of the 25 treated samples that were analyzed had populations below the detectable limit of the assay (log 0.5 cfu/g) and that the minimum detection limit was entered for all of those 24 samples. The one treated sample that did have a population above the detection limit had a population of log 0.8 cfu/g. Because of this, the determining factor in calculating the log reduction was the initial population in the control samples.
Based on the average log reductions achieved at the different temperature set points of the high inoculation and low inoculation, maintaining the temperature achieved in the injection step above 85°C is sufficient to achieve a 5 log microorganism reduction and above 82.2°C is sufficient to achieve a 3 log microorganism reduction.
Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) analysis demonstrated the protein profile of soluble proteins in samples with and without the incorporation of the RITC process. Independent samples (∼250 mL) were collected to represent the protein profile with (
Representative SDS-PAGE gel of light protein. MW molecular weight marker; SDS-PAGE, sodium dodecyl sulfate -polyacrylamide gel electrophoresis; W with refrigerated instantaneous temperature cycling thermal pasteurization process; WO without refrigerated instantaneous temperature cycling thermal pasteurization process.
SDS-PAGE was conducted as described, and the distinct gel slices (Figure
Protein profile—based on the primary bands in the SDS-PAGE analysis—was not altered by the RITC process (
Effect of treatment on abundance (percentage of protein bands in each sample) of primary protein bands separated by SDS-PAGE
Mean ± SEM Abundance of Band | |||
---|---|---|---|
Band | With RITC Thermal Pasteurization Process | Without RITC Thermal Pasteurization Process | |
6.10 ± 0.21 | 5.75 ± 0.27 | 0.32 | |
3.06 ± 0.06 | 3.14 ± 0.11 | 0.54 | |
8.95 ± 0.14 | 9.10 ± 0.12 | 0.41 | |
6.92 ± 0.13 | 7.03 ± 0.09 | 0.50 | |
4.00 ± 0.06 | 4.02 ± 0.06 | 0.78 | |
4.54 ± 0.07 | 4.50 ± 0.07 | 0.68 | |
4.43 ± 0.08 | 4.41 ± 0.07 | 0.83 | |
2.25 ± 0.04 | 2.38 ± 0.07 | 0.12 | |
5.26 ± 0.11 | 5.40 ± 0.07 | 0.31 | |
6.23 ± 0.12 | 6.31 ± 0.08 | 0.56 |
Band label corresponds to bands labeled in Figure
Abundance of selected bands based on percentage of total bands in lane (
Independent
RITC, refrigerated instantaneous temperature cycling.
SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Proteins identified in distinct bands (labeled A–K in Figure
Band | Total PSMs | Accession | Description | Coverage, % | No. Peptides | No. PSMs | Percentage of Total PSMs | No. Unique Peptides | No. AAs | MW, kDa | Calc. pI | Score Mascot: Mascot |
---|---|---|---|---|---|---|---|---|---|---|---|---|
A | 24,147 | Q9BE40 | Myosin-1 | 63 | 146 | 2,924 | 12.11 | 13 | 1,938 | 222.9 | 5.72 | 38,244 |
F1MRC2 | Myosin-2 | 63 | 149 | 2,912 | 12.06 | 0 | 194 | 223.2 | 5.8 | 36,089 | ||
Q9BE41 | Myosin-2 | 63 | 147 | 2,875 | 11.91 | 0 | 1,940 | 223.2 | 5.8 | 35,638 | ||
F1MM07 | Myosin-7 | 61 | 142 | 2,369 | 9.81 | 54 | 1,935 | 223.1 | 5.74 | 29,412 | ||
F1N2G0 | Myosin heavy chain 6 | 42 | 98 | 1,828 | 7.57 | 3 | 1,938 | 223.5 | 5.67 | 22,905 | ||
E1BP87 | Myosin heavy chain 4 | 45 | 104 | 1,924 | 7.97 | 1 | 1,935 | 222.4 | 5.73 | 20,476 | ||
F1N775 | Myosin heavy chain 8 | 42 | 95 | 1,842 | 7.63 | 1 | 1,937 | 222.6 | 5.77 | 22,423 | ||
B | 8,232 | B0JYK6 | Alpha-1,4 glucan phosphorylase | 67 | 59 | 1,565 | 19.01 | 48 | 842 | 97.2 | 7.14 | 11,996 |
Q3ZC55 | Alpha-actinin-2 | 68 | 52 | 603 | 7.33 | 33 | 894 | 103.7 | 5.45 | 8,041 | ||
Q0III9 | Alpha-actinin-3 | 68 | 51 | 453 | 5.50 | 37 | 901 | 103.1 | 5.45 | 6,213 | ||
Q0VCY0 | Sarcoplasmic/endoplasmic reticulum calcium ATPase 1 | 44 | 43 | 525 | 6.38 | 31 | 993 | 109.2 | 5.29 | 6,325 | ||
C | 1,449 | P02769 | Serum albumin | 83 | 64 | 5,330 | 36.89 | 7 | 607 | 69.2 | 6.18 | 43,076 |
B0JYQ0 | ALB protein | 82 | 62 | 4,608 | 31.89 | 5 | 607 | 69.2 | 6.33 | 32,206 | ||
D | 7,706 | A0A452DI31 | Beta-enolase | 66 | 32 | 2,271 | 29.47 | 24 | 444 | 48.3 | 7.72 | 21,075 |
P68138 | Actin, alpha skeletal muscle | 67 | 19 | 400 | 5.19 | 10 | 377 | 42 | 5.39 | 3,522 | ||
F1MB08 | Alpha-enolase | 35 | 15 | 759 | 9.85 | 9 | 500 | 54.1 | 9.1 | 7,880 | ||
P60712 | Actin, cytoplasmic | 41 | 14 | 312 | 4.05 | 4 | 375 | 41.7 | 5.48 | 2,562 | ||
E | 10,131 | P68138 | Actin, alpha skeletal muscle | 81 | 22 | 1,705 | 16.83 | 3 | 377 | 42 | 5.39 | 12,254 |
Q3T0P6 | Phosphoglycerate kinase 1 | 75 | 27 | 587 | 5.79 | 19 | 417 | 44.5 | 8.27 | 6,716 | ||
Q3ZC07 | Actin, alpha cardiac muscle 1 | 75 | 20 | 1,624 | 16.03 | 1 | 377 | 42 | 5.39 | 10,037 | ||
A0A452DI31 | Beta-enolase | 54 | 23 | 539 | 5.32 | 20 | 444 | 48.3 | 7.72 | 7,082 | ||
P60712 | Actin, cytoplasmic 1 | 63 | 18 | 1,053 | 10.39 | 7 | 375 | 41.7 | 5.48 | 8,712 | ||
F | 7,786 | Q9XSC6 | Creatine kinase M-type | 69 | 29 | 3,230 | 41.48 | 28 | 381 | 43 | 7.12 | 32,122 |
A6QLL8 | Fructose-bisphosphate aldolase | 78 | 24 | 372 | 4.78 | 21 | 364 | 39.4 | 8.19 | 4,106 | ||
Q3T0P6 | Phosphoglycerate kinase 1 | 65 | 22 | 195 | 2.50 | 22 | 417 | 44.5 | 8.27 | 2,165 | ||
G | 7,828 | A6QLL8 | Fructose-bisphosphate aldolase | 93 | 41 | 3,315 | 42.35 | 37 | 364 | 39.4 | 8.19 | 27,194 |
Q9XSC6 | Creatine kinase M-type | 74 | 22 | 488 | 6.23 | 22 | 381 | 43 | 7.12 | 4,746 | ||
A0A3S5ZPB0 | Fructose-bisphosphate aldolase | 20 | 8 | 424 | 5.42 | 4 | 510 | 55.6 | 8.47 | 2,684 | ||
H | 7,417 | P10096 | Glyceraldehyde-3-phosphate dehydrogenase | 92 | 32 | 2,857 | 38.52 | 29 | 333 | 35.8 | 8.35 | 19,209 |
A0A3Q1M5R4 | L-lactate dehydrogenase | 51 | 22 | 580 | 7.82 | 17 | 341 | 37.4 | 6.25 | 4,272 | ||
P19858 | L-lactate dehydrogenase A chain | 71 | 21 | 280 | 3.78 | 16 | 332 | 36.6 | 8 | 1,985 | ||
I | 7,686 | P19858 | L-lactate dehydrogenase A chain | 88 | 35 | 1,653 | 21.51 | 29 | 332 | 36.6 | 8 | 10,492 |
P10096 | Glyceraldehyde-3-phosphate dehydrogenase | 67 | 18 | 557 | 7.25 | 16 | 333 | 35.8 | 8.35 | 4,313 | ||
P04272 | Annexin A2 | 66 | 26 | 650 | 8.46 | 26 | 339 | 38.6 | 7.31 | 8,342 | ||
A0A3Q1M5R4 | L-lactate dehydrogenase | 50 | 21 | 589 | 7.66 | 16 | 341 | 37.4 | 6.25 | 4,090 | ||
J | 3,441 | A0A1K0FUF3 | Myoglobin | 99 | 28 | 1,925 | 55.94 | 25 | 154 | 17.1 | 7.46 | 14,383 |
K | 8,709 | D4QBB4 | Globin A1 | 97 | 28 | 2,675 | 30.72 | 14 | 145 | 15.9 | 7.59 | 23,519 |
P01966 | Hemoglobin subunit alpha | 100 | 19 | 2,022 | 23.22 | 18 | 142 | 15.2 | 8.44 | 14,011 | ||
D4QBB3 | Hemoglobin beta | 97 | 17 | 1,756 | 20.16 | 3 | 145 | 16 | 6.89 | 16,721 |
AA, amino acid; ALB, albumin; ATPase, adenosine triphosphatase; Calc. pI, calculated isoelectric point; MW, molecular weight; PSM, peptide spectrum match; RITC, refrigerated instantaneous temperature cycling.
Proteins identified in distinct bands (labeled A–K) from sample without RITC thermal pasteurization (
Band | Total PSMs | Accession | Description | Coverage, % | No. Peptides | No. PSMs | Percentage of Total PSMs | No. Unique Peptides | No. AAs | MW, kDa | Calc. pI | Score Mascot: Mascot |
---|---|---|---|---|---|---|---|---|---|---|---|---|
A | 26,215 | F1MRC2 | Myosin-2 | 64 | 154 | 3,400 | 12.97 | 0 | 1,940 | 223.2 | 5.8 | 40,897 |
Q9BE40 | Myosin-1 | 64 | 149 | 3,282 | 12.52 | 15 | 1,938 | 222.9 | 5.72 | 42,806 | ||
Q9BE41 | Myosin-2 | 64 | 152 | 3,365 | 12.84 | 0 | 1,940 | 223.2 | 5.8 | 40,585 | ||
F1MM07 | Myosin-7 | 62 | 145 | 2,950 | 11.25 | 57 | 1,935 | 223.1 | 5.74 | 37,515 | ||
E1BP87 | Myosin heavy chain 4 | 47 | 108 | 2,378 | 9.07 | 3 | 1,935 | 222.4 | 5.73 | 25,836 | ||
F1N775 | Myosin heavy chain 8 | 43 | 101 | 2,111 | 8.05 | 2 | 1,937 | 222.6 | 5.77 | 25,420 | ||
F1N2G0 | Myosin heavy chain 6 | 43 | 100 | 2,081 | 7.94 | 3 | 1,938 | 223.5 | 5.67 | 27,846 | ||
B | 10,197 | B0JYK6 | Alpha-1,4 glucan phosphorylase | 67 | 59 | 2,044 | 20.05 | 49 | 842 | 97.2 | 7.14 | 14,736 |
Q3ZC55 | Alpha-actinin-2 | 65 | 51 | 738 | 7.24 | 33 | 894 | 103.7 | 5.45 | 9,215 | ||
A0A3Q1M2X5 | Alpha-actinin-3 | 62 | 49 | 548 | 5.37 | 36 | 888 | 101.7 | 5.44 | 6,711 | ||
A5D7D1 | Alpha-actinin-4 | 59 | 47 | 354 | 3.47 | 27 | 911 | 104.9 | 5.44 | 3,484 | ||
Q0VCY0 | Sarcoplasmic/endoplasmic reticulum calcium ATPase 1 | 38 | 40 | 556 | 5.45 | 28 | 993 | 109.2 | 5.29 | 6,479 | ||
C | 16,683 | P02769 | Serum albumin | 85 | 66 | 5,923 | 35.50 | 7 | 607 | 69.2 | 6.18 | 49,541 |
B0JYQ0 | ALB protein | 83 | 64 | 5,139 | 30.80 | 5 | 607 | 69.2 | 6.33 | 38,408 | ||
D | 8,856 | A0A452DI31 | Beta-enolase | 70 | 33 | 2,027 | 22.89 | 23 | 444 | 48.3 | 7.72 | 18,387 |
P68138 | Actin, alpha skeletal muscle | 67 | 19 | 628 | 7.09 | 2 | 377 | 42 | 5.39 | 4,769 | ||
Q3ZC07 | Actin, alpha cardiac muscle | 66 | 18 | 606 | 6.84 | 1 | 377 | 42 | 5.39 | 4,337 | ||
F1MB08 | Alpha-enolase | 39 | 15 | 586 | 6.62 | 8 | 500 | 54.1 | 9.1 | 6,439 | ||
P60712 | Actin, cytoplasmic 1 | 49 | 15 | 457 | 5.16 | 6 | 375 | 41.7 | 5.48 | 3,674 | ||
E | 8,919 | P68138 | Actin, alpha skeletal muscle | 70 | 21 | 1,476 | 16.55 | 2 | 377 | 42 | 5.39 | 13,377 |
Q3T0P6 | Phosphoglycerate kinase 1 | 79 | 29 | 694 | 7.78 | 21 | 417 | 44.5 | 8.27 | 8,593 | ||
P62739 | Actin, aortic smooth muscle | 70 | 20 | 1,326 | 14.87 | 2 | 377 | 42 | 5.39 | 10,943 | ||
P60712 | Actin, cytoplasmic 1 | 66 | 19 | 946 | 10.61 | 9 | 375 | 41.7 | 5.48 | 9,697 | ||
A0A452DI31 | Beta-enolase | 62 | 27 | 383 | 4.29 | 19 | 444 | 48.3 | 7.72 | 5,477 | ||
F | 7,824 | Q9XSC6 | Creatine kinase M-type | 72 | 33 | 2,412 | 30.83 | 32 | 381 | 43 | 7.12 | 22,683 |
A6QLL8 | Fructose-bisphosphate aldolase | 80 | 25 | 351 | 4.49 | 23 | 364 | 39.4 | 8.19 | 4,240 | ||
Q3T0P6 | Phosphoglycerate kinase 1 | 70 | 25 | 274 | 3.50 | 25 | 417 | 44.5 | 8.27 | 3,357 | ||
G | 7,566 | A6QLL8 | Fructose-bisphosphate aldolase | 97 | 42 | 2,877 | 38.03 | 36 | 364 | 39.4 | 8.19 | 20,640 |
Q9XSC6 | Creatine kinase M-type | 66 | 23 | 397 | 5.25 | 22 | 381 | 43 | 7.12 | 4,186 | ||
A0A3S5ZPB0 | Fructose-bisphosphate aldolase | 21 | 10 | 421 | 5.56 | 4 | 510 | 55.6 | 8.47 | 2,078 | ||
H | 8,425 | P10096 | Glyceraldehyde-3-phosphate dehydrogenase | 90 | 31 | 2,759 | 32.75 | 28 | 333 | 35.8 | 8.35 | 19,955 |
A0A3Q1M5R4 | L-lactate dehydrogenase | 62 | 25 | 780 | 9.26 | 19 | 341 | 37.4 | 6.25 | 6,433 | ||
P19858 | L-lactate dehydrogenase A chain | 74 | 23 | 385 | 4.57 | 18 | 332 | 36.6 | 8 | 2,497 | ||
I | 7,338 | P19858 | L-lactate dehydrogenase A chain | 88 | 36 | 1,559 | 21.25 | 31 | 332 | 36.6 | 8 | 9,079 |
P10096 | Glyceraldehyde-3-phosphate dehydrogenase | 62 | 18 | 542 | 7.39 | 15 | 333 | 35.8 | 8.35 | 4,565 | ||
P04272 | Annexin A2 | 66 | 26 | 531 | 7.24 | 26 | 339 | 38.6 | 7.31 | 6,413 | ||
A0A3Q1M5R4 | L-lactate dehydrogenase | 48 | 20 | 563 | 7.67 | 16 | 341 | 37.4 | 6.25 | 3,411 | ||
J | 3,618 | A0A1K0FUF3 | Myoglobin | 92 | 22 | 2,205 | 60.95 | 22 | 154 | 17.1 | 7.46 | 17,595 |
K | 10,084 | D4QBB4 | Globin A1 | 97 | 24 | 2,480 | 24.59 | 8 | 145 | 15.9 | 7.59 | 26,483 |
P01966 | Hemoglobin subunit alpha | 100 | 18 | 2,077 | 20.60 | 17 | 142 | 15.2 | 8.44 | 14,123 | ||
D4QBB3 | Hemoglobin beta | 97 | 16 | 1,692 | 16.78 | 3 | 145 | 16 | 6.89 | 20,671 |
AA, amino acid; ALB, albumin; ATPase, adenosine triphosphatase; Calc. pI, calculated isoelectric point; MW, molecular weight; PSM, peptide spectrum match; RITC, refrigerated instantaneous temperature cycling.
To evaluate the impact of the process on the meat color, samples of finished ground beef were taken from the empirical™ production process both with and without incorporation of the RITC process on the light protein. There is natural variability of the concentration of the protein between fibrous and liquid phases during the production process which can affect finished ground beef color. To eliminate this variability from the analysis, the concentration of the protein in liquid phase was maintained at 40% of the finished ground beef during sample collection. A total of 6 sample batches each with and without the incorporation of the RITC process were collected on 3 different production days. Five samples were taken from each batch, and the beef was ground and prepared into a retail tray. Pictures of the sample tray preparation for batches of ground beef made with and without the incorporation of the RITC process are depicted in Figure
Photograph of tray preparation of batches of ground beef with and without the incorporation of the refrigerated instantaneous temperature cycling thermal pasteurization process.
Color measurements of ground beef samples
Mean ± SEM | |||
---|---|---|---|
Color Trait | With RITC | Without RITC | |
51.33 ± 0.78 | 50.25 ± 0.90 | 0.37 | |
19.26 ± 0.27 | 22.45 ± 0.34 | <0.001 | |
14.92 ± 0.22 | 15.66 ± 0.31 | 0.06 |
RITC, refrigerated instantaneous temperature cycling.
Independent
The
An independent, third-party sensory research provider developed a protocol to measure the acceptance of ground beef patties produced exclusively using an empirical™ system (including the RITC pasteurization of the light protein) compared with retail-available ground beef patties known not to contain any empirical™ ground beef as a component. The 3 products tested were Great Value™ 100% Pure Beef Burgers produced at Establishment 18076 (Jensen Meat Company, Inc., San Diego, CA), Great American™–All Natural Beef Burgers produced at USDA Establishment 1899 (American Foods Group, Green Bay, WI), and 100% empirical™ ground beef patties produced at USDA Establishment 19872 (empirical Foods, Inc., South Sioux City, NE). All 3 products tested were one-quarter-pound and 80% lean, 20% fat blend patties cooked to 74°C on a flat grill. The consumer sample consisted of 105 adults who are primary grocery shoppers and primary food preparers, have eaten hamburgers at least once per month that were cooked at home with ground beef purchased from a grocery store (frozen or refrigerated), and are willing to try 100% ground beef patties cooked well done. Participants were served 3 test products in a fully rotated and balanced monadic-sequential presentation and were asked their like or dislike and rating of specific attributes (Table
Ground beef patty consumer preference ranking
Preference | Great Value™ | empirical™ | Great American™ |
---|---|---|---|
61 | 34 | 5 | |
31 | 50 | 19 | |
8 | 16 | 76 | |
1.5 | 1.8 | 2.7 |
Mean rank refers to weighted mean preference ranking of the 3 patties.
Lowercase letter superscripts indicate significant differences between mean ranks at
Product information: Great Value™ (Jensen Meat Company, Inc., San Diego, CA); empirical™ (empirical Foods, Inc., South Sioux City, NE); Great American™ (American Foods Group, Green Bay, WI).
Ground beef patty liking attributes
Mean Liking Attributes | Great Value™ | empirical™ | Great American™ |
---|---|---|---|
6.9 | 6.2 | 4.2 | |
6.8 | 6.5 | 5.2 | |
6.9 | 6.9 | 5.8 | |
6.7 | 6.8 | 6.3 | |
6.9 | 6.2 | 4.5 | |
6.5 | 6.1 | 4.7 | |
6.7 | 5.7 | 3.6 | |
6.9 | 6.0 | 3.9 |
Liking attributes were scored on a scale of 9 different selections ranging from 1 (Dislike Extremely) to 9 (Like Extremely).
Lowercase letter superscripts indicate significant differences between mean ranks at
Product information: Great Value™ (Jensen Meat Company, Inc., San Diego, CA); empirical™ (empirical Foods, Inc., South Sioux City, NE); Great American™ (American Foods Group, Green Bay, WI).
Ground beef patties produced exclusively using an empirical™ system (including the RITC pasteurization of the light protein) was the second most preferred patty tested (Table
Due to vast differences in protein composition and viscosity of meat products, adapting the RITC technology to other species (including poultry and pork) will require customizations at every step of the process. The process is complex, and inferring the design requirements for other types of meat products is impractical. Developing the appropriate customizations to the process for other meat products will require robust, trial-and-error experimentation and redesign. The experimentation and redesign processes will focus on several aspects: Optimizing steam injection penetration and mixing Identifying friction-reducing and flow-promoting geometries/surfaces to accommodate high-viscosity proteins Defining relevant microorganisms and suitable target reductions for different products Controlling heat flux at boundary layer surfaces Ensuring the effectiveness of vacuum expansion cooling and moisture removal
The RITC process is consistent with current regulatory pasteurization descriptions, namely, retaining a raw appearance after receiving a process that achieves a 5 log reduction of pathogens (
Non-refrigerated distribution and sale of milk and milk products (shelf-stable milk) were historically accomplished by in-container sterilization processes that produced significant chemical changes in the milk and milk products. Milk UHT was developed as an alternative method of shelf-stable milk that has substantially fewer chemical changes in the milk than traditional in-container sterilization (
Since RITC technology is based on similar principles as Milk UHT, it is reasonable to expect that the technology could be used to extend the refrigerated shelf life of raw meat products and even further developed to achieve non-refrigerated distribution and sale of raw meat products. The important first step in production of shelf-stable raw meats is the prevention of the presence of pathogenic organisms in meat during the time prior to consumption.
Daily tests for the presence of generic
Meat pasteurization using direct steam injection and expansion chilling under vacuum overcomes the limitations of current intervention technologies in use in the industry; namely, it significantly reduces the microbiological populations of the entire product with only minimal, imperceptible changes to the sensory characteristics of the raw meat. Development of the technology has largely been oriented toward a specific production process of ground beef in use by empirical™; however, there is great potential to use the technology to significantly reduce microbiological risk associated with any raw ground meat products as well as other beneficial impacts such as increased shelf life.