IL264292D0 - Advanced oxidative process for microbial reduction - Google Patents

Advanced oxidative process for microbial reduction

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Publication number
IL264292D0
IL264292D0 IL264292A IL26429219A IL264292D0 IL 264292 D0 IL264292 D0 IL 264292D0 IL 264292 A IL264292 A IL 264292A IL 26429219 A IL26429219 A IL 26429219A IL 264292 D0 IL264292 D0 IL 264292D0
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IL
Israel
Prior art keywords
ozone
apples
hydrogen peroxide
food
processing chamber
Prior art date
Application number
IL264292A
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Hebrew (he)
Original Assignee
Harpc Solutions Inc
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Publication date
Priority to US201762489180P priority Critical
Priority to PCT/CA2017/050818 priority patent/WO2018195643A1/en
Application filed by Harpc Solutions Inc filed Critical Harpc Solutions Inc
Publication of IL264292D0 publication Critical patent/IL264292D0/en

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Classifications

    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23LFOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/26Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by irradiation without heating
    • A23L3/28Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by irradiation without heating with ultra-violet light
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23BPRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B7/00Preservation or chemical ripening of fruit or vegetables
    • A23B7/005Preserving by heating
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23BPRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B7/00Preservation or chemical ripening of fruit or vegetables
    • A23B7/015Preserving by irradiation or electric treatment without heating effect
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23BPRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B7/00Preservation or chemical ripening of fruit or vegetables
    • A23B7/14Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10
    • A23B7/144Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23BPRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B7/00Preservation or chemical ripening of fruit or vegetables
    • A23B7/14Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10
    • A23B7/153Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of liquids or solids
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23BPRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B7/00Preservation or chemical ripening of fruit or vegetables
    • A23B7/14Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10
    • A23B7/153Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of liquids or solids
    • A23B7/157Inorganic compounds
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23LFOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/16Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by heating loose unpacked materials
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23LFOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3409Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23LFOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3409Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
    • A23L3/3445Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere comprising other gases in addition to CO2, N2, O2 or H2O
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23LFOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3454Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of liquids or solids
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23LFOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3454Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of liquids or solids
    • A23L3/358Inorganic compounds
    • AHUMAN NECESSITIES
    • A23FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23VINDEXING SCHEME RELATING TO FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES
    • A23V2002/00Food compositions, function of food ingredients or processes for food or foodstuffs

Description

W0 2018/195643 PCT/CA2017/050818 ADVANCED OXIDATIVE S FOR MICROBIAL REDUCTION FIELD OF THE ION The t invention relates generally to methods and systems for reducing microbial count in food. The methods and systems of the present invention are described herein with reference to apples in order to facilitate understanding of the ion. However, it should be clear to those skilled in the art that abiiity of said methods and systems is not limited to apples. Rather, said methods and systems can be adapted to reduce microbial count in other products susceptible to undesirable microbial ce, such as other fruits and vegetables.
DISCUSSION AND COMPARISON WITH RELEVANT PRIOR ART In December 2014, a multistate iisterlosis outbreak in the United States was linked to consumption of caramel-coated . Over the next few months, an investigation revealed that the Listeria originated on the e of the affected apples, which were subsequently introduced into the or of the apples when sticks to be used as handles punctured the apples during production. Although risk of listeriosis from candy apples can still be regarded as low, there is a need to appiy preventative measures during caramel apple production.
Washing apples in aqueous sanitizers is one e of such preventative measure. However, water wash s are not always practicai doc to cost and space limitations as well as concerns about bringing water into a manufacturing facility. Further, this sanitizing option was found to have limited efficacy in removing contamination (<1 log cfn reduction) and potentially can lead to cross-contamination (Perez-Rodriguez et al., 2014, “Study of the cross-contamination and survival of Salmonella in fresh apples”, International Journal of Food Microbiology, 184, 92-97, the entire disclosure of which is incorporated herein by reference). In addition, residual moisture on apples impedes coating of caramel on apples thereby creating dif?culties during production. uently, aqueous free approaches (for example, hydrogen peroxide vapor) are more compatible with candy apple production and er, have proven to be effective in decontaminating produce when compared to traditional post-harvest g (Back at al., 2014, “Effect of hydrogen peroxide vapor treatment for inactivating Salmonella Typhimnrium, Escherichia coli 01571H7 and Listeria monocytogenes on organic fresh lettuce” Food Control, 44, 78:85, the entire disclosure of which is orated herein by reference).
Ozone has been associated with antimicrobial activities and designated as Generally Recognized as Safe (GRAS) by the US. Food and Drug Administration. (See, e.g., Sharma and Hudson, “Ozone gas W0 2018/195643 PCT/CA2017/050818 is an effective and practical cterial agent”, Am J Infect Control. 2008 Oct; 36(8): 559-63, the entire disciosure of which is incorporated herein by nce). Processes of using soiution containing ozone for decontaminating food are described in, e.g., US. Patent Nos. 6,485,769 and 6,162,477. However, water is often the source of contamination in food manufacturing facilities. Moreover, as noted above aqueous free approaches are more compatible with certain types of food products including candy apples.
More recently, use of ozone gas was suggested. (See, e.g., Khadre et al., 2001, “Microbiological aspects of ozone applications in food: A review”, Journal of Food e, 66, 1262—1252, the entire disclosure of which is incorporated herein by nce). Previous studies have demonstrated that ozone introduced into the atmosphere of storage rooms can reduce microbial loading on fruit (Yaseen et ai., 2015, “Ozone for. post-harvest treatment of apple fruits”, Phytopathologia Mediterranea, 54, 94—103, the entire disclosure of which is incorporated herein by reference). However, ozone in storage rooms is applied at a low level (6.5— 2 ppm) to prevent excessive ion of gs and reduce hazards to workers. Consequently, an extended re time is required to achieve microbial reductions although contacting each individual apple ents a challenge.
Alternative to ozone, UV has been known to elicit antimicrobial activity through photons directly damaging DNA of the target microbe. Although UV has been widely used for ection of water and other clear liquids, so far UV treatment of foodstuff surfaces remain problematic due to shading effects caused by irregular rs and/or presence within biotiims or ceil clumps.
The present invention addresses the above described shortcomings of prior art methods and . systems by combining UV treatment with oxidizing agents such as ozone or hydrogen peroxide or ations thereof. For instance the inventors propose combining ozone treatment with a process termed Advanced Oxidative s (AOP) (combination of hydrogen peroxide and UV), which s is useful for treating turbid waters and carton packaging.
W0 2018/195643 PCT/CA2017/050818 SUMMARY OF THE INVENHON The present invention provides for a method for inactivating bacteria on a food product susceptibie to (surface, sub—surface and internal) microbial presence, which comprises contacting the food product to be treated .with ultravioiet C (UV—C) iight, hydrogen peroxide and/or ozone, as weli as heat, which method can se nse of a system comprising means of providing each of said UV—C Eight, hydrogen peroxide andfor ozone, and heat.
W0 2018/195643 PCT/CA2017/050818 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: Schematic of UV: en peroxide reactor set up for Experiment 1 and ment 2.
Figure 2: shows vation of Listeria monocytogenes on and within apples by UV:hydrogen peroxide from 1-6%. Inoculated apples were placed in the chamber and ent concentrations of hydrogen peroxide red. All treatments were performed for 603 at 48°C.
Figure 3: shows inactivation of Listeria znonoeytogenes on the surface and core of apples using UVzozone with or without 6% hydrogen peroxide at 48°C from 30 to 120 seconds.
Figures 4A and 4B: Listeria monocymgenes counts on the surface and core of candy apples stored at 22°C. The apples were inoculated with Listeria the d using a combination of ozone (up to 50 ppm) foliowed by AOP. The apples were then coated with caramel-chocolate — red apple (Fig. 4A) or caramel- green apple (Fig. 48) with 3 units of each being removed at the ent sampling points.
Figure 5: shows log count reduction of E. colt on whole lettuce heads treated with hydrogen peroxide vapor (2 and 4%) for 30, 60, and 120 seconds. The log count reduction (LCR) was calculated by subtracting the average iog survivors (3 units of each being removed at the different ng points) from those recovered on non—treated fruit.
' Figure 6: shows iog count reduction of E. co? on whole lettuce heads treated with ozone and AOP at high and low humidity. The log count reduction (LCR) was caiculated by subtracting the average log ors (3 units of each being removed at the different sampling points) from those recovered from 1'eated fruit.
Figure 7: shows average log count reductions of E. coli on whole lettuce heads treated with ozone gas for 5 minutes alone, and in combination with H202, UV, and chlorine dioxide. The log count reduction (LCR) ' was calculated by cting the average log survivors (3 units of each being removed at the different sampling points) from those recovered on non-treated fruit.
Figure 8: shows shelf-life of whole heads of lettuce inoculated with E. 0011?, treated with ozone gas for 5 minutes alone, and in combination with H202, U V, and chlorine dioxide (Figure 7) as wet] as an untreated control group at storage days 0, 2, 5, 8, and 10.
W0 2018/195643 PCT/CA2017/050818 DETAILED DESCRJPTION While aspects of the invention described herein are described with reference to reducing microbial count in fruit, in particular apples, it should be appreciated that the described methods, systems and related lies can be used to reduce microbial count in other types of food or products. .
Further, speci?c embodiments and examples of the methods and systems described herein are illustrative, and many variations can be introduced on these embodiments and examples without departing from the spirit of the disclosure or from the scope of the appended claims. Elements and/or features of different illustrative embodiments andx’or examples may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims.
DEFINITIONS As used , and unless stated otherwise, each of the following terms shall have the ion set forth below.
As used herein, “about” in the context of a numerical value or range means $1096 of the numerical value or range recited or claimed. By any range disclosed herein, it is meant that all hundredth, tenth and integer unit amounts within the range are ically disclosed as part of the invention.
Accordingly, “about” a recited value speci?cally includes that recited value. For example, a range of about 20 minutes refers to all measurements within the range of 321004 of 20 minutes, including 20 minutes.
To overcome shortcomings associated with prior art treatment of foodstuff to reduce microbial count therein, the present ion proposes combining UV treatment with oxidizing agents such as ozone or hydrogen peroxide or combinations thereof. In the proposed AOP process, hydrogen peroxide is ed by UV photons to form short-lived, antimicrobial free radicals that can penetrate into shaded areas on the e of the uff to be treated.
AOP was demonstrated to decontaminate fresh produce. The critical parameters for supporting AOP processes are temperature and hydrogen peroxide concentration. Speci?cally, the reaction to generate radicals is favored at 48°C but less so at the l room ature (approximately 22°C).
Further, AOP processes have an optimum hydrogen peroxide concentration, since too low levels of en peroxide will result in insuf?cient radical generation, while an excess of hydrogen peroxide can cause y of ls to become too high such that they ultimately combine, and are thereby as- W0 2018/195643 2017/050818 neutralized.
An added advantage is obtained when a combination of ozone and hydrogen peroxide vapor is used. Due to presence of en peroxide vapor in the chamber, relative humidity surrounding the halt to be d is increased so that susceptibility of microbial cells to the lethal effects of ozone is also expected to increase r et ai., 2013, “A review on ozone-based treatments for fruit and vegetables preservation”, Food Engineering Reviews, 5, 71-106 and de Candia et al., 2015, “Eradication of high viable loads of Listeria monocytogenes contaminating food-contact surfaces. Frontiers in Microbiology, 6, 12, the entire disclosure each is incorporated herein by reference).
Through a series of experiments, the inventors of the methods and systems described herein showed that Listeria can be killed on produce, in particular apples, by treating them with various combinations of UViC Eight, en peroxide, heat and ozone. in this series of experiments, the results ranged from a 0-log to a 6—log kill. Each “log” reduction tes the extent of the kill by a factor of 10.
That is to say there was 99% (2-log) to 99.999% (S-log) kill of Listeria. The system used in these experiments comprises a reactor, which reactor has a treatment chamber with UV-C and/or ozone lamps located therein, as well as means for providing hydrogen peroxide vapor and heat to the processing chamber. The distance from lamps, acid concentration, acid ?ow rate, temperature and dwell time are ail controlled. initial positive laboratory results suggested that a commercial scale application test was warranted. Accordingly, a uous conveyor unit for transporting apples through the processing chamber was built to replace the sealed chamber design.
Accordingly, in one embodiment of the present invention, a system for vating bacteria and/or reducing microbiai count on a food product susceptible to e and internal ial presence is provided, said system sing a chamber which is operably connected to means for producing andfor suppling to the foodstuff each of UV-C light, hydrogen peroxide and/or ozone, and heat. In a preferred embodiment, the system comprises means for producing and/or supplying to the foodstuff each of UV-C light, hydrogen peroxide and ozone. It is possible to use ozone gas or even introduce ozonated water containing peroxide. in an embodiment of the system as described herein, the system further comprises a means for transporting the product be d, e.g., a conveyor, and/or a ature sensor. A continuous or can ailow food product to be treated to ?ow continuously through the processing r, such that the treatment can be on small (1—5 lb./hour), medium (5-500 lehour) or large scale (>500 lehour). In a r embodiment, the methods and systems described herein can be adapted for removal of pesticide from food products.
W0 95643 PCT/CA2017/050818 In an embodiment, the chamber has capacity to hold at toast 1, at least 10, at least 100 or at least 200 lbs of food product.
In an embodiment of the method as described herein, the bacteria is Listeria. In another embodiment, the bacteria is Sahnonella or E.Co|i.
In one embodiment, the food product is a fruit or a vegetable. in another embodiment, the food product is apple, melon, lettuce, mushroom, zucchini or cucumber (whole or core). In another embodiment, the food product is avocado, peaches, lemon, cantaloupe, pepper, tomato or mango. in yet another ment, the food product is seed, spice, tea, or grain.
In one embodiment, the processing chamber is kept at a predetermined humidity during treatment of the food product, which humidity is about 60-100%. In another embodiment, the system is con?gured such that the product has a dwelt time in the processing chamber of from 5 seconds to 2 minutes, or more.
In an embodiment, process parameters of the d method for inactivating bacteria on a food product susceptible to microbial presence areas s: UV light: The total e can be up to 10,000W. For example, the UV lights can be configured as foliows: up to 400 x UV-C 23W lamps emitting at 254nm (wavelength range between 290nm and 100nm); or 3 x 17W == 51W total, or 4 baths x 46W t 2 bulbs on sides x 34W per bulb = 252W total.
Ozone: (if t) up to 400 x ozone tight bulbs emitting at 17'4nm (wavelength range .
Approximately 95% of the ultraviolet energy emitted from the germicidal lamps used by the inventors is at the mercury resonance wavelength of 254 nanometers. This wavelength is in the region of maximum germicidai effectiveness and is highly lethal to virus, ia, protozoa and mold. Ultraviolet wavelengths shorter than 200 nanometers are capable of producing ozone from Oxygen (02) in the air.
The ozone lamps used by the inventors, in addition to emitting germicidal ultraviolet output at 254 nanometer wavelength, also emit ozone producing rays at 185 nanometer wavelength.
Although oniy 7% of the lamp’s totai energy output, the 185 nanometer wavelength energy has the unique capability to destroy organics by oxidation of the organic to carbon dioxide gas. The extent of the microbial reduction is ent on both ultraviolet puri?er sizing (expressed as dosage level units in att—seconds per square centimeter).
W0 2018/195643 PCT/CA2017/050818 ce offood t from bulbs: between 1cm and 200cm.
Hydrogen peroxide concentration: (if present) between 1% and 12% volnmefvolume aqueous solution, preferably 1-6 %, and more preferably 24%.
Hydrogen peroxide flow rate: {if present) between 0 and 10 liters per minute.
Temperature in the processing chamber: between 22°C and 60°C, preferably 40-55°C, most preferably . - about 48°C.
Processing chamber Dwell Time: between 5 seconds and 2 minutes.
Humidity inside processing chamber: between 60% to 100%.
Size of processing chamber: 1’ x 6”}: 6” to 60’ x 30’ x 20’.
An ozone monitor can be optionally installed in the room, which is mmed to automatically shut off the chamber and start the exhaust fan if (Lippm ozone is detected.
The systems and methods of the present invention are ageous over previously known sanitation methods in that it is coo-friendly. Specifically, the method of the subject invention does not use water, thereby conserving fresh water and avoids creation of chemical water ef?uent with harsh sanitizing chemicais like chlorine or ammonia. In addition, ozone gas decomposes into oxygen, leaving no dangerous or l lay-products.
Finaliy, the ation of any embodiment or feature mentioned herein with one or more of any of the other separately mentioned embodiments or features is contemplated to be within the scope of the instant invention.
Experiments Materials andMethods Suitability ofLacrebacillirs?zrcfivomns as a arefor Listeria aronocyrogenes The ve resistance of antobac?ins to ozone compared to L. monocyfogerzes, was ed using inoculated appies placed inside a biobubble in which the antimicrobial gas was introduced. It was found that the extent of vation of acilhrs and L. Irrorrocymgenes by ozone treatment was dependent on the applied time (ozone concentration). in relative terms there was no signi?cant difference W0 2018/195643 PCT/CA2017/050818 (P>0.05) in the log ions of L. monocytogenes compared to Lactobncill'us receiving the same ozone exposure. Therefore, the Laclobacilius strain is a suitable ate for L. monocyroganes that can be applied in commercial trials for accessing the efficacy of ozone treatment.
Bacteria used and inocufofion ofappies Listeria monocytogenes inoculation suspension was prepared as follows:Lisreria monocytogenes serotype 4b (isolated from fresh e) and Lacrobaci?ns ?rzrctivomns (isolated from wine) were used throughout the study. L. monocytogenes was cultivated in 50 ml tryptic soy broth (TSB) for 24 h at 30°C with Lacrobaeiilus being ated in MRS broth at 30°C for 48b. The cells were harvested by centrifugation (5000g for 10 min) and pellet re-suspended in saline to a final cell density of 8 log cfnfml.
For one set of experiment, an apple slice (30g) was cut from a whole fruit and the skin surface inoculated with 0.1 ml of Listeria culture to give a final cell density of 7 log cfn. The apple slices were incubated at 4°C for 16 it before being treated with UV or UV and hydrogen peroxide. After the treatment, Listeria was red from the apple slice by snbmerging in saline to give a final ratio of 1:10 then homogenized by stomaching. A dilution series was prepared in saline then plated out onto Modi?ed I Oxford (MOX) formula agar that was ted at 30°C for 48h.
For whole apples, the fruit was steeped inoculated in suspensions containing 7 log cfu/ml for 20 rains. The apples were then removed and placed in a vacuum r then subjected to 3 x 30 s cycles to in?ltrate the Listeria into the core rface. The apples were removed and stored ght at 4°C then used the next day. To recover cells from the treated apples, the core was initially removed using a sterile corer and placed in a sterile bag along with saline to give a 1:10 dilution. The core was homogenized by stomaching for 303 then a serial dilution prepared in saline. The remainder of the apple was placed into another sterile pouch containing 100 ml of saline and Listeria released by massaging. Again, a dilution series was prepared in saline that was plated onto M02; agar then incubated at 30°C for 43h.
The UVReactor The UV reactor includes an iolet fixture (Sani-RayTM- ess steel, 24”.): 9” x S”, 120v 50/60Hz) isingél x 23W lamps (measured at 254nm at 100 hours and 30°C) that were 24” long and 15mm in diameter with a UV output of 8.5, emitting at 254nm that were held a distance of 16 ml from the conveyor surface. Standard UV lamps (serial it 05-1348) and ozone lamps (ii 05-1349, ozone output of 2.3) were both used (2 of each). A UVX radiometer (UVPTM ated to +/- 5% according to manufacturer instructions) was used to monitor the lamps intensity to ensure consistency. .9- W0 2018/195643 PCT/CA2017/050818 The hydrogen peroxide (obtained from Aldrichm, 30% solution) was prepared at varying concentrations (fl-4% v/v) and was pie-warmed in a hot water bath to 22 or 48°C then placed in the reservoir of an atomizer/vaporizer. The processing chamber was pro-warmed with a fan heater that was switched offjust prior to placing the inoculated apples into the unit. The apples were held in the center of the unit for the allotted time period removed at the opposite end. The set-up can be seen from the schematic of Figure 1.
With reference to Figure l, labels in the ?gure designates the following elements: 1: en PeroxideVaporizer. 2: UV Light. 3: Tray of . 4: Heated Tunnel.
: Conveyor.
Parocetic acid Peracetic Acid (obtained from Sigma—AldrichTM, 40% in acetic acid: water) was diluted to various concentrations from 20—70 ppm was used either as a wash or a spray.
Veri?cation ofCombined Ozone andAOP Process to l L. monocytogenes Apples were spot inoculated (5 iogm CPU/apple) at the calyx of apples with a ?ve strain cocktail of L. togenes as described above. The apples were transferred to a cold room and held overnight prior to ent. Batches of 13 apples were placed in the ozone reactor and treated for 40 minutes. The apples were then dried for a further 50 minutes without ozone then directly transferred to the AOP unit.
The AOP treatment was performed g the apples within the r with the calyx facing the UV- C: Ozone lamp. Hydrogen peroxide vapor was generated from a 6% v/v solution pro-warmed to 48°C.
Treatment was performed for 30' seconds after which a wooden stick was inserted into the calyx before coating with caramel maintained at 80°C. For the red apples, an additional chocolate layer was added.
The apples were then stored on trays within a room ined at 22°C. Control groups of apples were prepared at the same time as apples to be treated, and stored in the same manner. However instead of being treated with ozone and hydrogen peroxide, they were only exposed to air and water (at otherwise same flow rates and temperatures to mimic the process).
W0 2018/195643 PCT/CA2017/050818 ically, candy apples (n=3) were transferred for microbiological analysis. Here, the core was removed using a sterile corer and placed in a sterile bag then re»suspended in tep ment broth to a 1:10 dilution. The core was homogenate in a stomacher for 60 seconds. The part of the stick that was embedded in the apple was manually massaged in the homogenate to release any attached Listeria. The remainder of the apple was submerged in 100 ml of One step enrichment broth and manually massaged to release the candy: caramel layers.
The samples were plated onto MOX formula media that was incubated at 30°C for 48 hours. In parallel, the homogenates were enriched at 37°C for 24 hours then streaked onto MOX agar that was incubated at 30°C for 48 hours. A presumptive positive colony from each plate was subjected to ation using API test strips.
Bacteria Recovery and Enumeration Lettuce After treatment, lettuce heads were ChOpped, suspended in 500 ml of saline and stomached for 1 minute, a dilution series was ed in saline. To ate STEC, the samples were then spread plated onto MacConkey Sorbitol agar (CT-SMAC) and chromogenic culture media agar) incubated at 37°C for 24 hours. L. monocytogenes was plated onto MOX Agar incubated at 35°C for 24 — 48 hours.
Apples After having nges recovering pathogens from apples in the same manner as lettuce, baseline s were performed in order to determine the optimal method for recovering Listeria from the surface of apples. The apples were spot inoculated with 100 pl of Listeria [8~log CFU] then allowed to attach for 4 hours. The Listeria was then recovered by one of three methods to evaluate the ef?ciency of each method. The methods were as follows: method (1) whole apples were placed in sterile plastic pouches and suspended in 100 ml of saline and manually rubbed for 1 minute. For method (2) a peeler was used to remove the apple peel which was then placed in 50 ml of saline and usly shaken for 1 minute.
Lastly. method (3) was the same as described for (2) except the peel was homogenized using a lab top blender. Regardless, of the method of recovery, a dilution series was prepared in saline then spread plated onto MOX Agar incubated at 35°C for 24 — 48 hours. Presumptive positive es were counts being reported a log CPU. .11- W0 2018/195643 2017/050818 E?ect ofListeria hermetic}? Temperature on Attachment To determine if the incubation temperature of Listeria is important for its attachment to appies, the bacteria was cultivated at both 25°C (were Listeria express ?agella) and at 37°C (Le. no ?ageila expressed). The bacteria were ailowed time to adhere to the apple before being removed (method 1) as described above.
Statisticaf Analysis Each experiment was repeated at least three times with triplicate samples being ed. The bacterial counts transformed into logm values with differences between means performed Using ANOVA in combination with the Tukey test.
EXPERIMENT 1: UV:Hydrogen peroxide treatment - Baseline studies determined the effect of time, hydrogen peroxide concentration (in 1.5%) and temperature (22°C to 48°C) on the decontamination of appies inoculated with L. monocytogenes. To increase the ivity of the assay and avoid geometric effects, apple haives were used instead of whole apples. From the results it was found that UV alone supported a high log reduction of Listeria compared to when used in tow concentrations of hydrogen peroxide (Table i). The results can be attributed to direct inactivation of ia in the absence of shading effects.
With en peroxide aione, negligible log reductions of Listeria were observed although the ' efficacy couidlbe enhanced by ing the unit at 48°C ed to 22°C. A more distinct effect of temperature was observed when UV was combined with hydrogen peroxide l). Here, there were signi?cantly higher iog reductions when the unit was run at 48°C compared to 22°C. The highest log ion was obtained with using a hydrogen peroxide concentration of 1.5% vlv introduced into the unit at 48°C with a 303 residence time. The results can be explained by the AOP ding to a greater extent at 48°C compared to 22°C. At lower trations of hydrogen peroxide the lower ed iethality was due to insuf?cient radicals being formed from the UV decomposition of H202. Yet, presence of ' hydrogen peroxide was sufficient to absorb the UV photons thereby providing a protective effect to the Listeria on the surface of apple.
W0 2018/195643 PCT/CA2017/050818 Table 1: Inactivation of Listeria monocytogenes on inoculated appie haives by using different UVzhydrogen peroxide combinations.
Initiai Lo_ Count Reduction Treatment Time Loading 22°C 48°C L"c: n5:" gE 7,340.12 c‘4' [—1. U1 to Lad E: all I.) C:- on w 7:: 43- H202 1% l— U: w ~0.95?:0. 19 0.97i0.70 -0.44i0.l3 0.3823111 Hie-11.5% 123 —0.21:E0.01 _—_-0.02:t0.29 23mm —___ 21%_— 1.29:1;020 238 —303 0.92i0.06 >303 z iSS 1.71i0.71 3.6421206? l.5% 303 2.25:1:0.83 >4.40 vation ofListeria monocytogenes introduced on and within whole apples In practical terms, the treatment of whole apples is challenging due to the shading caused by the physical shape of the apple, in addition to Listeria being potentially present within the sob—surface of core. e of the aforementioned shading effects the use of UV alone would be limited. This was indeed found in the current case where UV applied to inocniated whole apples resulted in < 1 log cfu reduction of Listeria on the surface of apples and no average reduction in levels of the pathogen within the internal core (-0.2ii0.69). When UV was used in combination with hydrogen peroxide the LCR of Listeria was increased up to 4% via H202 beyond which did not support higher reductions of the pathogen (Figure 2) However, there was a correlation between hydrogen peroxide concentration and reduction in Listeria introduced into core tissue of apples (Figure 2). Here it was found that 6% hydrogen peroxide used in combination with UV could support a 0.86 log cfu reduction in ia ieveis that represents a reduction of 84% of the original population.
EXPERIMENT 2: Efficac of a combination of UV h dro_en eroxide and ozone to decontaminate apples Ozone was generated by replacing one of the UV-C lamps with one that emits at 174 nm with hydrogen de being introduced via a vapor at 48°C. It was found that for a 303 treatment time the ion of Listeria on the surface of appies was signi?cantly higher when UV:ozone:peroxide was \ W0 2018/195643 PCT/CA2017/050818 applied ed to UV:ozone treatment. When longer treatment times were applied the extent of inactivation of Listeria on the surface of apples was not signi?cantly different between UV:Ozone:peroxide and UV:ozone (Fig. 3). The log reduction of Listeria on the surface of appies was ndent of the ent time suggesting that the residual ors were in tive niches.
Similar to the trend of log reductions on the surface of apples, the inactivation of the pathogen within the core was icantly higher for UVzozonezperoxide compared to UV:ozone at 303 of treatment (Fig However, the extent of Listeria inactivation by UV:ozone:peroxide did not increase _ 12). with extended treatment times. In contrast, the log ion of Listeria within the core by UV:ozone did increase with time and was not significantiy different from UV:ozone:peroxide at 1203.
The results suggest that action of UV:ozone:peroxide results in rapid inactivation of Listeria compared to when UV:ozone are applied without H202.
Conclusions UV:Hydrogen peroxide ent using 6% H202 at 48°C for 60s can cantly reduce Listeria monocytogenes on the surface and within the core of . The treatment could be enhanced through combining UV:peroxide with ozone.
MENT 3: Veri?cation of Combined Ozone and AOP Process to l Listeria monecyrogenes ' on Candy Apples The object of this experiment is to evaluate the combined effect of ozone and AOP (UVzhydrogen peroxide:Ozone) to control L. monocyrogenes on apples and fate of survivors on candy apples stored at 22°C.
' Materials and Methods Apples were spot inocuiated (5 log cfu/apple) at the calyx of apples with a ?ve strain cocktail of L. monocyfogenes. The apples were transferred to a cold room and held overnight prior to treatment.
Batches of 13 apples were placed in the ozone reactor and treated for 40 mins. The apples were then dried for a further 50 mins without ozone then directly transferred to the AOP unit. The AOP treatment was performed placing the apples within the chamber with the calyx facing the UV-C:Ozone lamp. Hydrogen peroxide vapor was generated from a 6% v/v solution pro-warmed to 48°C. Treatment was performed for 30s after which a wooden stick was inserted into the calyx before coating with caramel maintained at 80°C. For the red apples, an additional chocolate layer was added. The apples were then stored on trays W0 2018/195643 PCT/CA2017/050818 within a room maintained at 22°C.
Periodically, candy apples (n=3) were transferred for microbiological analysis. Here, the core was removed usinga sterile corer and placed in a sterile bag then rte-suspended in One-step enrichment broth to a 1:10 dilution. The core was homogenate in a stomacher for 603. The part of the stick that was embedded in the apple was manually ed in the homogenate to release any ed Listeria. The remainder of the apple was submerged in 100 ml of One step enrichment broth and manually massaged to release the candyzcaramel layers.
The samples were plated onto MOX a media that was incubated at 30°C for 48h. In parallel, the homogenates were enriched at 37°C for 24h then streaked onto M02; agar that was incubated at 30°C for 4811. A presumptive positive colony from each plate was ted to con?rmation using API test strips.
Results Results of this experiment are shown in Figure 4 and Tables 2A and ZB below.
Table 2A and ZB: Listeria monocytogenes recovered from Candy Apples over a 19 Day Shelf-life at 22°C. Data from Figure 4.
Table 2A (Caramel Chocolate —- red a- le) Log efulApple ' osmve b.- I ment/Total testedI Storage Day Candy Apples from Non—treated Candy Apples from Ozone & AOP control Red A has Treated Red A )les Core (0/3) (U3) (0/3) (1(3) 0.12 3.64:1:033 0 ' (0/3 (0/3) 8 4.33i0.06 4.39i0 16 0.5 0.50:l:0.87 ' (U3) (113) (1/3) (2/3) W0 95643 PCT/CA2017/050818 Table 213 (Caramel .._ reen a le) ' ositive b ment?‘otal tested Storage Day Candy Apples from Non-treated Candy Apples from Ozone & AOP at 22°C control Green A lies Treated Green A les 0/3) (113) (0/3) (113) 0 a (0/3) (1/3 (U3) (1/3) .12 3 10:02] assoc? 0 (113) (0/3) . 3.63:1:0.16 4.40i0.19 1.00:|:0.87 O (2/3) (0X3) The Listeria levels on control non-treated apples (green and red) was 5 log cfu and numbers decreased by 0.4- 0.9 log cfu by the caramel coating process. In candy apples prepared from non~treated green apples, ia counts at the end of the 19 day Shelli-life did not vary signi?cantly (P>0.05) compared to Day E (Figure 4A; Table 2A). However, Listeria with the core of non-treated apples did increase in levels foilowing a 3 day lag period and was signi?cantly (P<0.05) higher at the end of the 19 day shelf—iife (Figure 4A; Table 2A).
Listeria counts on the e of candy apples prepared from untreated green apples decreased by approximately 1 log oft: over the initial 3 day shelf-life but then remained constant for the remaining 16 day storage period (FigurellB; Table 2B). The L. manaeyiogenes counts within the core of candy apples stored at 22°C fluctuated over the 19 day shelf-life with no overall signi?cant change in counts at the end, compared to Day 1 (Fignre 43; Table 2B).
No Listeria was recovered from candy apples prepared from green or red fruit treated with Ozone then AOP (Figure 4; Table 2). With regards to the core samples, for both red and green apples, two ofthe three replicates tested negative for Listeria by enrichment following ozone and AOP treated (Figure 4; Table 2). Therefore, the l log reduction of Listeria was 4—5 log chi/apple in the case of both candy apple varieties.
In the course of e, Listeria was sporadically recovered from the surface of candy apples prepared from d red apples but levels of the en did not increase in numbers. Listeria within the core of red apples was sporadically recovered over the I9 Day storage period with no overall increase -15..
W0 2018/195643 PCT/CA2017/050818 in numbers being observed (Fignre 4A; Table 2A). With treated green apples, surface counts on candy apples increased following after storage Day 5 attaining 1 log cfufappie at the end of the 19 day storage period (Figure 4B; Table 2B). In contrast, surviving Lisierio within the core of green apples decreased over the shelf—life with none of the samples taken passed Day 8 testing positive for the pathogen (Figure 413; Table 2B).
Decontamination uce Heads Using Gas Phase entions The rationale of the research approach was to inactivate pathogens on lettuce heads with the assumption that contamination would be restricted to the surface. This in effect would reduce the reliance of post~harvest washing and also minimize the risk of disseminating pathogens through the processing fine. The two treatments evaluated were ozone and a treatment based on using a combination of hydrogen peroxide and UV (AOP).
Hydrogen Peroxide: UV Lettuce heads were placed in the UV reactor chamber and sprayed with hydrogen peroxide (2 or 4%) with and without illumination with UV-C. As a control group inoculated apples were treated with H20 vapor in place of the H202. The exact amount of vapor that comes in contact with the product is impossible to pin point exactly due to the nature of the e or type system where vapor enters a chamber from above as the produce . However after the process is ?nished the e is dried by the circulation fans. Although 4% H202 is more effective in reducing E. colt on whole iettuce heads for ' shorter term treatments, 2% ed higher ions after 2 minutes (Figure 5). When replacing H202 with water, as a l, the treatment is just as effective. Iliumination with UV alone supported the lowest log reductions with no increase in ef?cacy with treatment times > 60 seconds. Testing the treated apples with a catatase assay, there was no hydrogen peroxide residues detectable (ievel of ion > 1 Oppm).
Ozone Ozone applied under high humidity conditions resulted in the highest tog reductions (just over 1 tog CFUfg), slightly more than AOP process under the same humidity conditions e 6). Overall the treatment achieved minimal log ions.
Efficacy of 0 Combination of UV, fr?rfrogen Peroxide, Ozone and Chlorine dioxide to Decontaminore Lettuce W0 2018/195643 PCT/CA2017/050818 A combined sequentiai treatment of ozone, 6 % H202 and 50 ppm chlorine dioxide achieved nearly 4 log CFUIg reduction (Figure 7). The combined treatment s (FigureS) resulted in lettuce with very low E. coli levels, which was maintained throughout the 10-day shelf life, when compared to the untreated group which maintained a steady level of the pathogen (Figure 8).
Conclusion/Discassion ‘ On Candy apples prepared from apples that had been inoculated with Listeria but not treated, the pathogen levels decreased, did not signi?cantly change or increased during the 19 day storage period at 22°C. L. monocytogenes was found to increase in the core of non-treated red apples attaining levels of >6 log ple.
By using a combination of ozone and AOP is was possible to achieve a 4-5 log cfu reduction of Listeria monocyfogenes. With Candy apples prepared from red , the Listeria counts within the core or surface of the candy apple did not significantly change when the candy apples held at 22°C for 19 days. In a similar manner, Listeria within the core of treated green apples decreased over the life.
There was evidence of ry of ia on the e of candy apples prepared from treated green apples. However, levels were low and only detected by enriching the samples.
From the studies performed along with those published by others, the fate of L. monocytogenes on candy apples depends on several factors. Speci?cally, the greatest risk posed by L. monocytogenes is introduced into the core as opposed to the surface of apples.
The extent to which L. monocytogenes grows onlwithin candy apples is more ent on if the pathogen has been pie-stressed more so than the storage temperature. In this respect, the application of ozone gas and then AOP would lead to sed stress of L. monocyfogenes that could explain the restricted growth of the pathogen with candy apples held at room temperature.
In conclusion, by implementing the ozone gas treatment and AOP, it is possible to reduce levels of L. monocytogenes on and within apples ed for candy apply production. Based on the fact that both entions are aqueous free there is little risk of actively growing L. monocytogenes contaminating the product. Therefore, collectively the ce presented indicates that storing apples at 4°C as opposed to room temperature does not bring signi?cant bene?ts to L. monocytogenes control. Consequently, candy apples prepared as described can be stored at room temperature without any additional risk of being contaminated or supporting the growth of L. monocytogenes.
W0 2018/195643 PCT/CA2017/050818 EXPERIMENT 4: Decontamination of Different Fruit and ables using a Combination of UV/Ozone/Hydrogen Peroxide This experiment was conducted to determine the log count reduction of Listeria monocytogenes introduced on different produce types and d with a combination of UVIOzonenydrogen peroxide.
Methods Bacteria and e conditions Listeria monocytogenes (serotypes 4a, 4b, 112b, lf2a, and 3a) was cultivated overnight in TSB at 37°C and cells harvested by centrifugation. The pellet was suspended in saline to a ?nal celi density of 8 log ofu/ml (013590 - 02). The col! suspension was held at 4°C for up to 12 hours prior to use.
The test vegetable and fruit were spot inoculated on the surface to skin, around the tOp of the fruit, with 100 pl of the test bacterium at a concentration of 8~log 10 CPU/mi. The apples were then dried in a biosafety cabinet for 20 minutes to 4 hours, before being erred to 4°C storage for a maximum of 24 hours: To alize the ia, 1 ml of the suspension was added to the stem crevice and put under a vacuum for } , removed from the vacuum and left for 1 minute, before being vacuumed once more for another minute.
Reactor The UV reactor consisted of an ultravioiet ?xture (Sani-Ray'ii't stainless steel, 24” x 9” x S”, 120v 50/60Hz) containing 4 x 25W lamps (measured at 254nm at 100 hours and 80°C) that were 24” long and 15mm in diameter with a UV output of 8.5 were held a distance of 16 cm from the conveyor surface.
Standard UV lamps (serial it 8) and ozone lamps (a 05-1349, ozone output of 2.3) were both used (2 of each). A UVX radiometer (UVPTM calibrated to +l~ 5% according to manufacturer ctions) was used to monitor the iamps intensity to ensure consistency. The hydrogen peroxide (obtained from Sigma- Aldrich“, 30% solution) was prepared at varying concentrations (24% v/v) and pre—warmed in a hot water bath to 22 or 48°C then placed in the reservoir of an atomizer/vaporizer. The processing chamber was pro—warmed with a fan heater that was switched offjust prior to placing the inoculated apples into the unit. The apples were held in the center of the unit for the allotted time period d at the opposite end. #19- W0 2018/195643 PCT/CA2017/050818 Resufts Results are shown below in Table 3.
TABLE3 ___—— Produce Type Log Count %Retluction Reduction .7mm __— _——_- ___lm_ ———__ 6.84m.” __- _—4.7mm 2.16%.91 99.259 -—_1.33i058 swims 99999 7.10i0.06 __— ——2.98i025 4.12i025 : 99.992 -_—_—99.999 __——— 1030.09 __— —_4.26i023 ' 2.76i023 99.330 _—3.9mm 3.1mm 99-924 __——— .34i0.16 __- m {113150.03 30.320 __5.1mm .03 39—744 —__—— 6.69i0.07 __— _—5.6mm 1.07%.08 59.262 __5.34i032 Lam-32 74.295 ————— 110mm __— ——3.8%029 3.71i029 99.933 _—2.10mi? 5.00%.” 99.999 Zucchini (core) 6.1mm __— _—6303:0351 02210.31 _—6.10i0‘38 0.4%038 61.981 _———— _—_—_ i021 1.89M: 93.712 __439mm maze-06 99-339 _——_— 4.33:1:094 - __— _—4.53i0.45 (14810.45 — -_—1mm 1.22i026 _ _—__— 6.5mm __— _—6.37%.10 0.1mm _ __620mm .49 — ——_—_ _———— ——2.5%026 2.50i026 — __—_- .20.. 108 0 R

Claims (17)

:
1. l. A method for inactivating bacteria and/or reducing ial count on a food product susceptible to microbial presence, said method comprising continuously passing said food product h a processing chamber to subject the food product to exposure with ultraviolet C (UV-C) light, hydrogen peroxide vapor, ozone, and heat, for a processing time in the processing chamber of between 5-120 seconds, wherein the hydrogen peroxide vapor is present at up to 12% v/v solution, and the ature inside the processing chamber is ined between about 220C and 600C.
2. The method of claim 1, wherein the bacteria is Listeria.
3. The method of claims 1 or 2, wherein the food product is a fruit, preferably apple.
4. The method of any one of claims 1-3, wherein the ozone and the hydrogen peroxide vapor are provided by two separate sources.
5. The method of any one of claims 1-4, wherein wavelength range of the UV-C light is between 290nm and 100nm.
6. The method of any one of claims 1-5, wherein concentration of the hydrogen peroxide vapor is between 2-6% v/v.
7. The method of any one of claims 1-6, wherein ?ow rate of the en peroxide vapor is n 0 and 10 liters per minute.
8. The method of any one of claims 1-7, wherein ozone is provided by ozone light bulbs emitting at a wavelength of range of 125-225 nm.
9. The method of any one of claims 1-8, wherein hydrogen peroxide vapor is provided by a hydrogen peroxide atomizer or vaporizer.
10. The method of any one of claims 1-9, wherein humidity inside the processing chamber is ined at between 60% to 100% relative humidity.
11. The method of any one of claims 1-10, said method excluding a step of contacting an ozone-containing liquid with the food product.
12. A system for vating bacteria and/or reducing microbial count on a food product susceptible to microbial presence, said system comprising a processing chamber and a means for uously transporting the food product through the processing chamber, i) a means for generating UV-C light, ii) a means for generating hydrogen peroxide vapor, iii) means for ting ozone, iv) a heat source, wherein each of i)-iv) is operably connected to the processing chamber.
13. The system of claim 12, wherein the means for generating hydrogen peroxide vapor and the means for generating ozone are separate.
14. The system of any one of claims 12-13, further comprising means for maintaining humidity within the chamber.
15. The system of any one of claims 12-14, wherein the processing chamber has a size of about 1’ x 6”x 6” to 60’ x 30’ x 20’.
16. The system of any one of claims 12-15, con?gured such that a distance of the food product to the means for generating UV-C light in the processing chamber between lcm and 200cm.
17. The system of any one of claims 12—16, comprising lamps emitting wavelength range n 290nm and 100nm for ting UV and lamps emitting wavelength of less than 20 mm, preferably about 185 nm, for generating ozone. 12 0 R
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