Patent Application
20090214725
This invention relates to equipment and methods for processing seafood, poultry, and other animal-source food products to reduce microbial flora on the product and promote extension of shelf life.
Seafood, poultry, and other meat products are considered at-risk foods for carrying food-borne pathogens and other spoilage microorganisms. Due to the high volume processing and the ubiquitous nature of microbes, they are often present in the end consumer food supply and pose a significant health risk to the consumer. Product is often transported and sold fresh, without ever undergoing a freeze process, causing these items to have the highest risk for harboring food-borne pathogens. However, due to the inherent properties of some microorganisms, such as Listeria, frozen products are not without risk and additional control measures in the processing and packaging phases of both fresh and frozen production is warranted.
Ozone is an allotropic form of the element oxygen but in pure form is unstable and usually only minute amounts are present in nature due to its extremely short lifetime (half-life in water is about 20 min.). Ozone is the most chemically active form of oxygen as an oxidizing agent. Ozone may be produced artificially, for example, by passing dry oxygen between two electrodes connected to an alternating high voltage source. Ozone is used commercially for various applications such as a disinfectant and decontaminant for air and water, as a bleaching agent for waxes, oils, and other organic compounds, and as an anti-microbial agent in food processing. Ozone as a reactive oxidizing agent has an oxidizing potential of 2.07 compared with the hydrogen peroxide oxidizing potential of 1.77 and the chlorine gas oxidizing potential of 1.36. Due to this high oxidizing potential, ozone is considered to be an excellent disinfectant, in particular for water treatment.
Short-wave ultraviolet (UV) radiation (i.e., wavelength of 254 nm) can reduce the microbial activity dramatically in air and on hard surfaces that are free from food residues, and can eliminate or significantly reduce pathogens from potable water. UV irradiation at germicidal wavelengths (230-280 nm) causes adjacent thymine molecules on DNA to dimerize, and if enough of these defects accumulate on a microorganism's DNA its replication is inhibited, thereby rendering it harmless (even though the organism may not be killed outright). UV irradiation may thus serve as an effective viricide and bactericide when used appropriately.
Ultraviolet (UV) irradiation and antimicrobial constituents in processing water and ice are combined in a system and method for processing animal-source food products to reduce harmful microbial flora. Water used in the process, to make ice and to dip and wash the product, is irradiated with UV at germicide wavelengths. In addition, a peroxygen component such as peracetic acid is included with irradiated water in the formation of ice used in packaging the food product. Also, irradiated water is chilled and ozonated to provide immersion liquid in which the food product is initially dip-washed. Thereafter, the food product is subjected to one or more pressurized spray washes with the UV-irradiated water containing the peroxygen component, and then air-dried prior to final packaging in frozen or fresh-iced form for retail distribution.
Referring now to the plan view of
Sprayed unit portions are then conveyed through a drying station 22 at which filtered and purified air is delivered by an ‘air knife’ at high velocity over the surfaces of the unit portions in order to remove excess antimicrobial solution clinging to the surfaces. Thereafter, the dried unit portions are conveyed to the packaging station for freezing or fresh-packed, film-wrapped processing in preparation for retail distribution.
The environment 26 within which the unit portions progress through the processing equipment is maintained in sanitized condition using HEPA filters through which approximately 30-40% of the internal air volume is exchanged per hour, at temperatures not exceeding about 41° Fahrenheit. That is, air is exhausted and replaced by outside air that is filtered before entering the environment 26. Supporting equipment such as chillers and ozone generators and chemical injectors and air-processing apparatus (not shown) is housed externally to the processing environment 26.
More specifically, and with reference to the flowchart of
Water from supply 29 is treated 31 with ultraviolet at wavelengths within the germicidal range (i.e., approximately 230-280 nm) to provide sterilized water for formation of ice 33 and for chilling 35 to serve as dipping and spray-washing water.
The ice formation 33 incorporates a peroxygen component such as peracetic acid at a concentration in the range from about 50 to about 150 ppm. This ice provides a continuous supply of the peroxygen component to the food product as packaged or as otherwise in contact with the ice as it melts, for example, during shipment to a facility at which processes of the present invention are performed.
The chilled water is aerated 37 with ozone to provide chilled, disinfectant water for the initial dip washing 39 of product. Thereafter, the disinfected and chilled product is pressure-sprayed 41, 43 one or more times with chilled water 45 that also incorporates a peroxygen component such as peracetic acid (PAA) in a concentration of about 50 to 150 ppm. Of course, successive stages of spray washing 41, 43 may be accomplished with chilled water having different concentrations, different peroxygen components, and different spray parameters for enhanced disinfection of the processed product. For example, the initial spray washing 41 may be performed with a solution of about 120-150 ppm PAA from an elevation of about six inches height above the product. A successive spray washing 43 may be performed with a solution of about 60-80 ppm PAA from an elevation of about 10 inches height above the product.
After the stages of spray washing 41, 43, the disinfected product is air dried 48 using filtered air delivered at high velocity to the product in order to remove excess water and debris adhering to the surface of the product. The product is then packaged, for example, by freezing or by packing in ice 33 containing a peroxygen component for retail distribution.
It is believed that the integrity of the plasma or cytoplasmic membranes of eukaryotic and prokaryotic cells of microbial contaminants is essential for cell viability, and that organic solvents, such as a peroxygen compound, disrupt the hydrophobic bonds between the fatty acids of the lipid bilayers and dissolve the membranes. However, less harsh conditions, such as altering the pH or temperature of the environment can kill cells due to their effects on membrane protein structure. Because protein secondary, tertiary, and quaternary structures are highly dependent upon many non-covalent but highly specific ionic, hydrogen, and hydrophobic bonds between amino acids, agents that disrupt these bonds and denature the membrane proteins can be lethal to the microbial contaminants. For example, acidic pH, produced by the addition of a peroxygen compound, protonates amino acids with negatively charged R groups, like aspartate and glutamate. If an ionic bond between an aspartate residue and a positively charged amino acid like lysine is essential for protein structure, this bonding will be disrupted at low pH, and the protein will not function. Hydrogen bonds are similarly disrupted by changes in pH. Therefore, denaturation in accordance with the processes of the present invention essentially destroys the cell structure of the microbial contaminants through the continued manipulations of the cell environment.
Individual sealed packaging units of unfrozen processed protein products are regulated by FDA guidelines to provide a packaging film with specified oxygen transmission rates. This allows for diffusion of oxygen through the packaging film to prevent the formation of anaerobic conditions leading to a favorable environment for the proliferation of dangerous pathogens such as Clostridium botulinum. Packaging film of this type promotes oxygen transfer at a rate of approximately 0-10,000 cc/m2/24 hours in ambient pressure at a temperature of 70° F. Thus, processed and frozen animal-source protein products are vacuum-packed in such packaging films and show favorable sensory qualities and extended shelf life. Also, the probability for cross contamination of products due to the volume of product traveling through the processing facility and the ubiquitous nature of microorganisms is significantly diminished in accordance with the present invention, and containment in individual packaging after undergoing the microbial reduction processing of the present invention mitigates risk of cross contamination from contact with food-contacting surfaces and/or other contaminated products.
In accordance with the present invention, it is believed that utilizing UV pre-treated process water 31, and utilizing two process-water systems (i.e., one containing an antimicrobial constituent at defined concentrations 45, and the other an ozonated water supply at prescribed concentrations 37), and storing product between harvesting and processing on ice 33 containing an antimicrobial constituent, and submerging product in dip tank 39 containing antimicrobial constituent or ozonated water, and a pressure spray process 41, 43 all significantly reduce microbial loads on seafood, poultry, and other meat products. This is because processing according to the present invention maintains low core temperature of the product, corrupts bacterial genetic material by creation of thymine dimers, disrupts bonding properties and disrupts bacterial membranes by oxidation mechanisms.
Ideally in accordance with the present invention, seafood, poultry, and other meat products are maintained on antimicrobial ice 33 during transport from harvest to the processing stages. All process water in the present invention that comes into contact with animal food product (including water used to create antimicrobial ice 33) is exposed to UV treatment 31, and is either used along with an antimicrobial constituent or undergoes ozonation 37 prior to coming into contact with product. Product emerging from the final stage of processing is conveyed into a separate controlled environment (not shown), with filtered air and ambient temperature reduced below 5 degrees Celsius where the product is loaded onto packaging line for individual portion packaging.
In the course of processing animal food products in accordance with the embodiment of the present invention described herein, the ambient temperature in which the processing is performed directly correlates with microbial growth and hence is a parameter that is controlled in the operating environment of the food processing area to within the range between 34-38 degrees Fahrenheit in order to reduce the growth rates of most mesophilic organisms. Also HEPA-filtered air is exchanged throughout the processing environment at a rate of about 10-40% per hour. That is, air is exhausted and replaced by outside air that is filtered before entering the environment 26.
Product being processed is transported by conveyor through dip tank 39 containing the chilled and ozonated water at a temperature between 35-41 Fahrenheit and containing ozone at a concentration in the range of about 0.1-1.5 ppm at point of contact with product. The rate of conveyance and the length of the dip tank are determined to provide immersion of product for about 1-60 seconds. Exposure to highly oxidative ozone molecules contained in the process water destroys microorganisms by reacting with oxidizable cellular components, particularly those containing double bonds, sulfhydryl groups, and phenolic rings. Therefore, membrane phospholipids, intracellular enzymes, and genomic material react with the ozone to cause cell damage and death of the microorganisms.
From the dip wash 39, product is transported via conveyor beneath one or more successive spray apparatus 41, 43 utilizing process water 45 containing an antimicrobial peroxygen component such as peroxy acid at concentration in the range of about 50-150 ppm.
The subject matter of this application relates to the subject matter of application Ser. No. 12/035,589, entitled “Batch Processing of Animal-Source Food Product,” filed on Feb. 22, 2008, which subject matter is incorporated herein in the entirety by this reference thereto.
