AU2002318201A1 - Method for treating an animal carcass or plant material - Google Patents

Description

METHOD FOR TREATING AN ANIMAL CARCASS OR PLANT MATERIAL

Field of the Invention

This invention relates to an improved method for treating animal carcasses to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass.

Background of the Invention

Animals, such as, for example, poultry, red meat animals of all kinds, fish and crustaceans are killed and their carcasses are processed to produce food products for human consumption. Typically, the processing of such animals includes evisceration, which may contaminate the edible portion of the animal with unwanted bacteria, which may multiply depending upon the sanitary conditions employed in further processing steps. Bacterial contamination of the edible portions of the animal may cause spoilage of the edible portions and illness of consumers of the contaminated edible portions.

Treatment processes which involve contacting animal carcasses with aqueous solutions containing alkali metal phosphates and which are effective in reducing bacterial contamination and/or retarding bacterial growth without substantial detriment to the organoleptic properties of the carcasses are known, see, e.g., US 5,283,073. However, these processes tend to introduce relatively high amounts of phosphate compounds into treatment waste streams, which may be undesirable from an environmental perspective. What is needed in the art is a method for treating animal carcasses which is effective in reducing bacterial contamination and/or retarding bacterial growth without substantial detriment to the organoleptic properties of the carcasses and which does not produce a waste stream containing a high amount of phosphate compounds.

Summary of the Invention

In a first aspect, the present invention is directed to a method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with an aqueous solution comprising an effective amount of an alkali silicate.

In a second aspect, the present invention is directed to a method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with a substantially ethanol free aqueous solution comprising effective amounts of two or more of an alkali silicate, an alkali carbonate and an alkali hydroxide.

The treatment method of the present invention allows simple and economical washing of animal carcasses to reduce bacterial contamination of the carcass and/or retard bacterial growth on the carcass, without substantial detriment to the organoleptic properties of the carcass and without generating a waste stream that contains a high amount of phosphates.

In a third aspect, the present invention is directed to a method for treating edible plant materials to reduce bacterial contamination of the edible plant materials or retard bacterial growth on the edible plant materials, comprising contacting an edible plant material selected from fruits and vegetables with an aqueous solution comprising effective amount of an alkali silicate.

The treatment method of the present invention allows simple and economical washing of fruits and vegetables to reduce bacterial contamination of the fruits and vegetables or retard bacterial growth on the fruits and vegetables, without substantial detriment to the organoleptic properties of the fruits and vegetables and without generating a waste stream that contains a high amount of phosphates. Such treatment may extend the shelf life of the treated fruits and vegetables by providing improved control of microrganisms involved in spoilage of the fruits and vegetables.

Detailed Description of Invention and Preferred Embodiments

In a preferred embodiment, the treatment solution of the present invention is effective as a bacteriocide under the treatment conditions and killing bacteria is one mechanism by which the treatment of the present invention reduces bacterial contamination on the carcass.

As used herein, the terminology "reduce bacterial contamination or retard bacterial growth" refers generally to reducing bacterial contamination or retarding bacterial growth, as well as reducing bacterial contamination and retarding bacterial growth.

As used herein, the terminology "animal carcass" refers generally to the edible portion of any dead animal, including birds, fish, crustaceans, shellfish and mammals. Birds include for example, chickens, turkeys, geese, capon, game hens, pigeon, ducks, guinea fowl, pheasants, quail and partridges. Fish include, for example, catfish, trout, salmon, flounder, tuna, swordfish, and shark. Crustaceans include, for example, crayfish, shrimp, prawns, crabs and lobsters. Shellfish include clams, scallops, oysters and mussels. Mammals include cattle, pigs, sheep, lambs and goats.

In a preferred embodiment, the animal carcass is eviscerated, that is, the internal organs of the animal are removed from the carcass, prior to treatment with the aqueous treatment solution according to the method of the present invention. An eviscerated carcass typically comprises bones, skeletal muscle and associated fascia. In a preferred embodiment, the skin is not removed from the eviscerated carcass of a fish or a bird prior to treatment with the aqueous treatment solution according to the method of the present invention. In a preferred embodiment, the skin is removed from the eviscerated carcass of a mammal prior to treatment with the aqueous treatment solution according to the method of the present invention.

As used herein the terminology "edible plant materials" means plant materials selected from fruits and vegetables that are typically used as foods for humans. Suitable edible plant materials include, for example, lettuce, tomatoes, cucumbers, carrots, spinach, kale, chard, cabbage, broccoli, cauliflower, squash, beans, peppers, apples, oranges, pears, melons, peaches, grapes, plums and cherries.

A used herein, the term "organoleptic" means the sensory properties, including the appearance, texture, taste and smell, of food products made from the carcass.

The bacterial contamination addressed by the method of the present invention includes pathogenic bacteria, such as, for example, salmonellae, such as Salmonella typhimurium, S. choleraesuis and S. enteriditis, as well as E. coli, camphylobacter and spoilage bacteria, such as, for example, Pseudomonus aeruginosa.

In a preferred embodiment, the alkali silicate exhibits a solubility of greater than 0.5 percent by weight (wt%) more preferably greater than 3 wt%, in water.

Compounds suitable as the alkali silicate component of the treatment solution of the present invention are crystalline or amorphous alkali silicate compounds according to formula (1 ):

M₂O-m(SiO₂)-nH₂0 (1)

wherein:

M is sodium or potassium, m is a number, wherein 0.5 < m < 3.5, indicating the number of mole(s) of the Si0₂ moiety per 1 mole of M 0 moiety; and n indicates the water content, expressed as wt% water, wherein 0% < n < 55%.

Suitable alkali silicates include, for example, sodium disilicates, sodium metasilicates, potassium disilicates, and potassium metasilicates, and may be in anhydrous or hydrated form.

In a preferred embodiment, the alkali silicate comprises one or more metasilicates, which are crystalline products, according to M₂0-(Si0₂) -n'^O, wherein M is Na or K and n' is 0, 5, 6 or 9 and indicates the number of moles of water per Si0₂ moiety. In a preferred embodiment, the alkali silicate comprises one or more of anhydrous sodium metasilicate, anhydrous potassium metasilicate, sodium metasilicate pentahydrate, sodium metasilicate hexahydrate and sodium metasilicate nonahydrate. More preferably, the alkali silicate comprises one or more of anhydrous sodium metasilicate, anhydrous potassium metasilicate and sodium metasilicate pentahydrate. Even more preferably, the alkali silicate comprises one or more of anhydrous sodium metasilicate and anhydrous potassium metasilicate, and one or more of sodium metasilicate pentahydrate and potassium metasilicate pentahydrate.

In a preferred embodiment, the aqueous treatment solution comprises greater than or equal to 0.05 percent by weight (wt%) alkali silicate, more preferably from 0.1 wt% to saturation, still more preferably from 1 to 15 wt%, and even more preferably from 5 to 10 wt%, alkali silicate, wherein the ranges are calculated on the basis of the weight of the anhydrous alkali silicate. Either the anhydrous form or a hydrated form of the alkali silicate may be used to form the treatment solution, provided that the appropriate adjustment is made to compensate for the weight of any associated water of hydration. Unless otherwise specified, the concentrations of alkali silicates given herein are based on the weight of anhydrous alkali silicate.

In a highly preferred embodiment, the aqueous treatment solution comprises from 0.1 to 8 wt%, more preferably from 1 to 6 wt% and even more preferably from 2 to 4 wt% alkali silicate.

In a preferred embodiment, the aqueous solution comprises an amount of alkali silicate, typically from greater than 3 wt% to 6 wt%, more preferably from greater than 3 wt% to 5 wt% alkali silicate, effective to reduce bacterial contamination of the animal carcass. In the preferred embodiment, the method of the present invention is suitable as the primary step of a carcass processing line for reducing bacterial combination of the carcass below a target value.

In an alternative embodiment, the aqueous solution comprises an amount of alkali silicate, typically from 0.5 wt% to 4 wt% alkali silicate more preferably from 0.5 to 3 wt% alkali silicate, that is effective to retard bacterial growth on the animal carcass, but that is not necessarily sufficient to kill bacteria or otherwise reduce bacterial contamination of the carcass. In a preferred embodiment, the less concentrated alkali silicate solution is used in combination with other treatments, such as, for example, treating the carcass with aqueous lactic acid solution, washing the carcass with hot water, e.g., at a temperature of from about 160°F to about 180°F, or cleaning the carcass with steam and vacuum, wherein the series of treatments are, in combination, effective to reduce bacterial contamination of the animal carcass below a target value.

In a preferred embodiment, the aqueous treatment solution consists essentially of a solution of alkali silicate in water. In an alternative preferred embodiment, the aqueous treatment solution consists of a solution of alkali silicate in water. As used herein, the term "water" means tap water, that is, water as available onsite without requiring purification, that may contain minor amounts of components other than H₂0.

In a preferred embodiment, the treatment solution further comprises an alkali carbonate or alkali bicarbonate according to formula (2):

M_2-aH_aCθ₃-nΗ₂θ (2)

wherein: M' is sodium or potassium, a is 0 or 1 , and n" is a number wherein 0 < n" < fully hydrated.

Suitable alkali carbonates include sodium carbonate, potassium carbonate and may be in anhydrous or hydrated form. Suitable alkali bicarbonates include sodium bicarbonate and potassium bicarbonate. In a preferred embodiment, the treatment solution comprises one or more of sodium carbonate and potassium carbonate.

In a highly preferred embodiment, the treatment solution comprises greater than or equal to 0.05 wt%, more preferably from 0.1 wt% to saturation, more preferably from 0.2 to 15 wt% and still more preferably from 0.4 to 10 wt% alkali carbonate.

In an alternative embodiment, the aqueous treatment solution comprises from 0.2 to 5 wt%, and even more preferably from 0.4 to 1.0 wt%, alkali carbonate.

In a preferred embodiment, the treatment solution further comprises an alkali hydroxide according to formula (3):

M"OH (3)

wherein:

M" is sodium or potassium.

Suitable alkali hydroxides include, for example, sodium hydroxide, potassium hydroxide. Preferably, the hydroxide comprises sodium hydroxide. In a highly preferred embodiment, the treatment solution comprises greater than or equal to 0.05 wt%, more preferably from 0.5 to 5 wt%, still more preferably from 0.1 to 2 wt%, and even more preferably from 0.2 to 1 wt% of the alkali hydroxide.

In a preferred embodiment, the present invention is directed to a method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with an aqueous solution comprising greater than or equal to 0.05 wt% of an alkali silicate and greater than or equal to 0.05 wt% of an alkali carbonate.

In a more highly preferred embodiment, the treatment solution comprises from 0.1 wt% to saturation, more preferably from 0.5 to 10 wt% alkali silicate, and even more preferably from 3 to 8 wt% alkali silicate and 0.1 wt% to saturation, more preferably from 0.2 to 15 wt%, and even more preferably from 0.4 to 10 wt% alkali carbonate.

In a preferred embodiment, the aqueous treatment solution consists essentially of a solution of alkali silicate and alkali carbonate in water. In an alternative preferred embodiment, the aqueous treatment solution consists of a solution of alkali silicate and alkali carbonate in water.

In a preferred embodiment, the present invention is directed to a method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with an aqueous solution comprising greater than or equal to 0.05 wt% of an alkali silicate and greater than or equal to 0.05 wt% of an alkali hydroxide. In a more highly preferred embodiment, the treatment solution comprises from 0.1 wt% to saturation more preferably from 0.5 to 10 wt%, and even more preferably from 3 to 8 wt% alkali silicate and from 0.5 to 5 wt%, more preferably from 0.1 to 2 wt%, and even more preferably from 0.2 to 1 wt% of the alkali hydroxide.

In a preferred embodiment, the aqueous treatment solution consists essentially of a solution of alkali silicate and alkali hydroxide in water. In an alternative preferred embodiment, the aqueous treatment solution consists of a solution of alkali silicate and alkali hydroxide in water.

In a preferred embodiment, the present invention is directed to a method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with an aqueous solution comprising greater than or equal to 0.05 wt% of an alkali carbonate and greater than or equal to 0.05 wt% of an alkali hydroxide.

In a more highly preferred embodiment, the treatment solution comprises from 0.1 wt% to saturation, more preferably from 0.2 to 15 wt%, and even more preferably from 0.4 to 10 wt%, alkali carbonate and 0.5 to 5 wt%, more preferably from 0.1 to 2 wt%, and even more preferably from 0.2 to 1 wt% alkali hydroxide.

In a preferred embodiment, the aqueous treatment solution consists essentially of a solution of alkali carbonate and alkali hydroxide in water. In an alternative preferred embodiment, the aqueous treatment solution consists of a solution of alkali carbonate and alkali hydroxide in water. In a preferred embodiment, the present invention is directed to a method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with an aqueous solution comprising greater than or equal to 0.05 wt% of an alkali silicate, greater than 0.05 wt% of an alkali carbonate and greater than or equal to 0.05 wt% of an alkali hydroxide.

In a more highly preferred embodiment, the treatment solution comprises from 0.1 wt% to saturation, more preferably from 0.5 to 10 wt% alkali silicate, and even more preferably from 3 to 8 wt% alkali silicate, from 0.1 wt% to saturation, more preferably from 0.2 to 15 wt%, and even more preferably from 0.4 to 10 wt%, alkali carbonate and 0.5 to 5 wt%, more preferably from 0.1 to 2 wt%, and even more preferably from 0.2 to 1 wt% alkali hydroxide.

In a preferred embodiment, the aqueous treatment solution consists essentially of a solution of alkali silicate, alkali carbonate and alkali hydroxide in water. In an alternative preferred embodiment, the aqueous treatment solution consists of a solution of alkali silicate, alkali carbonate and alkali hydroxide in water.

The treatment solution may, optionally, further comprise other components, such as for example, alkali metal salts, such as for example, NaCI, KCI, and surfactants suitable for food use.

In a preferred embodiment, the treatment solution of the present invention comprises less than 0.5 wt%, more preferably less than 0.2 wt%, ethanol. Even more preferably the treatment solution is substantially free, more preferably free, of ethanol. In one embodiment, the aqueous solution may further comprise less than 10 wt% alkali phosphate, preferably less than 5 wt% alkali phosphate and more preferably less than 2 wt% alkali phosphate, in order to provide an aqueous treatment solution with a reduced phosphate content compared to know alkali phosphate antimicrobial treatments.

In a preferred embodiment, the treatment solution of the present invention does not add any substantial amount of phosphates to the carcass processing waste stream and comprises, prior to use, less than 0.2 wt%, more preferably less than 0.1 wt%, trialkali phosphate. Even more preferably, the treatment solution is, prior to use, substantially free, more preferably free, of trialkali phosphate. Phosphates of animal origin may be present in used or recycled treatment solution and in carcass processing waste streams.

In a preferred embodiment, the treatment solution exhibits a pH of from about 11.5 to about 14, more preferably from about 12 to about 13.75, even more preferably from about 12.25 to about 13.5 and still more preferably from about 12.75 to about 13.25.

The treatment solution is made by dissolving the components of the solution in water.

In a preferred embodiment, the animal carcass is contacted with the treatment solution after slaughter, either prior to, during or after chilling, by dipping the carcass in the treatment solution or by spraying the treatment solution on the carcass. In a preferred embodiment, the animal carcass is contacted with the treatment solution by spraying the treatment solution under a gage pressure of greater than 2 pounds per square inch above atmospheric pressure (psig), more preferably from 2 to 400 psig, onto all accessible surfaces of the carcass. In a preferred embodiment, bird carcasses are contacted with the aqueous treatment solution by spraying the treatment solution onto the carcass at a pressure of from 3 to 40 psig. In a preferred embodiment, mammalian carcasses are contacted with the aqueous treatment solution by spraying the solution onto the carcass at a pressure of from 20 to 150 psig.

In a preferred embodiment, the treatment solution is at a temperature of from about 0 to about 85°C, more preferably from 0 to about 70 °C, still more preferably from about 10°C to about 50°C and even more preferably from about 20°C to about 40°C.

In a preferred embodiment, the animal carcass is contacted with the treatment solution for greater than or equal to about 1 second to about 5 minutes, more preferably from about 5 seconds to about 2 minutes, and even more preferably from about 15 seconds to about 1 minute. The preferred contact times refer to the duration of the active application process, for example, dipping or spraying, used to contact the aqueous treatment solution with the carcass. Once applied, the treatment solution can be immediately rinsed off of the carcass or, alternatively, allowed to remain on the carcass.

Animal carcasses that have been treated according to the present invention can, immediately after such treatment, be processed according to normal carcass process conditions, such as draining or chilling. Optionally, the treatment solution residue may be rinsed from the carcass prior to further processing.

In a preferred embodiment, the treatment solution is recovered and recycled. Preferably, the recovered treatment solution is filtered to remove solids prior to recycling. Preferably, the respective amounts of the one or more components of the treatment solution are monitored and the composition of the treatment solution is controlled by adding water and/or additional amounts of the metasilicate, carbonate and/or hydroxide components to the solution.

Example 1

Aqueous treatment solutions were made at 0.10, 0.20, 0.25, 0.30, 0.40, 0.50, 1.00, 2.50, 5.00, 10.0 and 20.0 % w/w of sodium hydroxide (NaOH), potassium hydroxide (KOH), AvGard™ TSP dodecahydrate (AVGARD), sodium carbonate (Na₂C0₃), sodium metasilicate nonahydrate, sodium chloride (NaCI) or potassium chloride (KCI). The weight percentages for the sodium metasilicate nonahydrate were calculated based on the total weight of sodium metasilicate nonahydrate, i.e., including the water of hydration. An equal mixture of E.coli ATCC 25922, E.coli ATCC 8739 and E.coli 0157:1-17 ATCC 43895 was prepared. The bacteria mixture was contacted with each of the respective treatment solutions by, in each case, adding a 1 ml sample of the bacteria mixture to a 99 ml sample of the respective treatment solution. In each case, the bacteria mixture was contacted with the respective treatment solution for 15 seconds. Following the 15 seconds contact time, samples of the treatment solution were subjected to a standard aerobic plate count. The baseline bacterial level when 1 ml of the bacteria mixture was added to 99 ml of sterile water was 850,000 colony forming units per ml (cfu/ml). Results following contact with the treatment solutions are reported in TABLES IA and 1 B below, in (cfu/ml). TABLE 1A

Colony Forming Units per Milliliter (cfu/ml)

Treatment Solution Concentration (%)

0.10 0.20 0.25 0.30 0.40 0.50

NaOH 140,000 60 - <10 <10 <10

KOH 640,000 22,000 - 300 <10 <10

Avgard 690,000 600,000 -- 550,000 280,000 110,000

Na₂C0₃ __ 540,000

Na Meta 700,000 100,000

Silicate

NaCI 720,000 —

KCI 800,000 ~ TABLE 1 B

Colony Forming Units per Milliliter (cfu/ml)

Treatment Solution Concentration (%)

1.00 2.50 5.00 10.00 15.00 20.00

NaOH <10 __ —

KOH <10 __ —

Avgard 150 __ ~

Na₂C0₃ 100,000 33,000 51 ,000 36,000 20,000

Na Meta 20 10 <10 <10 <10

Silicate

NaCI 680,000 810,000 770,000 770,000 780,000

KCI 930,000 880,000 690,000 800,000 1 ,000,000

Example 2

The procedure of Example 1 was repeated using a mixture of Salmonella typhimurium ATCC 14028, S. choleraesuis ATCC 4931 , and S. enteriditis ATCC 13076 in place of the E.coli mixture of Example 1. The baseline bacterial level when 1 ml of the Salmonella bacteria mixture was added to 99 ml of sterile water was at 630,000cfu/ml. Results are reported in TABLES 2A and 2B below, in cfu/ml.

TABLE 2A

___ Colony Forming Units per Milliliter (cfu/ml)

Treatment Solution Concentration (%) 0.10 0.20 0.25 0.30 0.40 0.50

NaOH 220,000 20 10 <10 <10

KOH 550,000 46,000 40 <10 <10

Avgard 720,000 540,000 420,000 74,000 4,800

Na₂C0₃ — — — — 350,000

Na Meta — — 640,000 — ~ 97,000

Silicate

NaCI — — 640,000

KCI — — 740,000 TABLE 2B

Colony Forming Units per Milliliter (cfu/ml)

Treatment Solution Concentration (%)

1.00 2.50 5.00 10.00 15.00 20.00

NaOH <10 ~ __

KOH <10 __ __

Avgard 200 __ —

Na₂C0₃ 32,000 4,200 4,500 4,900 - 4,300

Na Meta <10 <10 <10 <10 - <10

Silicate

NaCI 700,000 — 640,000 570,000 690,000 500,000

KCI 610,000 — 600,000 590,000 700,000 630,000

Example 3

Samples of an equal mixture of Salmonella typhimurium ATCC 14028, S. choleraesuis ATCC 4931 , and S. enteriditis ATCC 13076 were contacted with each of the respective treatment solutions set forth in TABLES 3A to 3M by, in each case, adding a 1 ml sample of the bacteria mixture to a 99 ml sample of the respective treatment solution. The aqueous treatment solutions were made by dissolving the following components: sodium metasilicate nonahydrate and NaOH (TABLES 3A and 3B), sodium metasilicate nonahydrate and KOH (TABLE 3C), sodium metasilicate nonahydrate and sodium carbonate (TABLES

3D, 3E and 3F), sodium metasilicate nonahydrate and NaCI, KCI or AVGARD

(TABLE 3G),

NaOH and sodium carbonate (TABLES 3H and 31), sodium carbonate and KOH (TABLE 3J), sodium carbonate and KCI or NaCI (TABLE 3K),

NaOH and KCI (TABLE 3L), and

AVGARD and KCL (TABLE 3 M), in the amounts set forth in the respective TABLES, in water. The weight percentages for the sodium metasilicate nonahydrate were calculated based on the total weight of sodium metasilicate nonahydrate, i.e., including the water of hydration. In each case, the bacteria mixture was contacted with the respective treatment solution for 15 seconds and then subjected to a standard aerobic plate count Results are given below TABLES 3A to 3M in cfu/ml. The baseline bacteria level for each test was determined by contacting 1 ml of the bacteria mixture to 99 ml of sterile water and is given in the 0.0%/0.0% data cell of each of the TABLES 3A to 3M.

TABLE 3A

NaOH (%)

Na Metasilicate 0.00 0.05 0.10 0.15 0.20

(%)

0.00 230,000 160,000 110,000 22,000 390

0.20 150,000 200,000 1 ,600 640 <10

0.40 100,000 21 ,000 1 ,200 <10 <10

0.60 19,000 2,400 10 <10 <10

0.80 420 <10 <10 <10 <10

1.00 40 <10 <10 <10 <10

TABLE 3B

NaOH (%)

Na Metasilicate 0 0.05 0.1 0.15 0.2

(%)

0 900,000 820,000 370,000 20,000 <10

0.2 790,000 550,000 29,000 <10 <10

0.4 560,000 18,000 <10 <10 <10

0.6 320,000 30 <10 <10 <10

0.8 6,300 <10 <10 <10 <10

1 <10 <10 <10 <10 <10 TABLE 3C

KOH (%)

Na Metasilicate 0.00 0.10 0.20 0.30

(%)

0.00 110,000 130,000 18,000 200

0.20 130,000 120,000 800 <10

0.40 110,000 180,000 <10 <10

0.60 90,000 250 <10 <10

0.80 3,500 <10 <10 <10

1.00 <10 <10 <10 <10

TABLE 3D

SODIUM CARBONATE (%)

Na 0.00 0.20 0.25 0.50 1.00 2.00 5.00 10.00 Metasilicate (%)

0.00 730,000740,000680,000550,000120,000 16,000 28,000 30,000

0.20 630,000400,000190,000 26,000 8,000 2,200 25,000 28,000

0.40 350,000 12,000 2,000 120 410 2,800 34,000 31,000

0.60 8,600 180 170 <10 <10 110 3,800 20,000

0.80 <10 <10 <10 <10 <10 <10 4,400 16,000

1.00 <10 <10 <10 <10 <10 <10 1,100 4,200

TABLE 3E

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 1.00 2.00 5.00 10.00

Metasilicate

(%)

0.00 1 ,100,0 870,000 840,000 160,000 13,000 6,200 6,300

00

0.20 910,000 430,000 35,000 7,700 2,600 10,000 10,000

0.40 590,000 18,000 870 260 1 ,300 2,900 6,800

0.60 160,000 60 20 <10 80 no data 7,600

0.80 400 <10 <10 <10 10 2,200 4,400

1.00 <10 <10 <10 <10 <10 340 2,500

TABLE 3F

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00

Metasilicate

(%)

0.00 820,000 940,000 580,000 300,000 110,000 9,000 6,700 6,400

0.20 970,000 600,000 56,000 5,000 2,400 1 ,800 6,600 4,700

0.40 860,000 20,000 1,400 150 680 1 ,200 3,200 4,800

0.60 270,000 1,500 <10 <10 <10 <10 4,200 3,500

0.80 24,000 <10 <10 <10 <10 <10 550 4,600

1.00 140 <10 <10 <10 <10 <10 30 3,000 TABLE 3G

NaCI KCI Avgard (%) (%) (%)

Na Metasilicate 0.00 20.00 20.00 0.25 0.50 (%) 0.00 650,000 520,000 580,000 440,000 71,000 0.20 780,000 200,000 140,000 100,000 1,800 0.40 340,000 150,000 110,000 3,300 360 0.60 8,300 6,600 44,000 70 10 0.80 110 49,000 8,800 <10 <10 1.00 <10 24,000 6,300 <10 <10

TABLE 3H

NaOH (%)

Sodium 0.00 0.05 0.10 0.15 0.20

Carbonate

(%)

0.00 1 ,100,000 1 ,200,000 650,000 72,000 80

0.25 950,000 350,000 1 ,200 <10 <10

0.50 790,000 12,000 <10 <10 <10

1.00 260,000 8,600 <10 <10 <10

2.00 47,000 6,300 10 <10 <10

5.00 58,000 28,000 6,600 20 <10

10.00 39,000 25,000 9,200 4,300 110 TABLE 31

NaOH (%)

Sodium Carbonate 0 0.05 0.1 0.15 0.2

(%)

0 920,000 1 ,100,000 260,000 20,000 940

0.25 880,000 280,000 510 <10 <10

0.5 650,000 7,000 70 <10 <10

1 340,000 4,600 10 <10 <10

2 44,000 5,700 30 <10 <10

5 39,000 19,000 2,800 40 <10

10 28,000 21 ,000 11,000 2,600 770

TABLE 3J

KOH (%)

Sodium Carbonate 0.00 0.10 0.20 0.30

(%)

0.00 940,000 970,000 58,000 <10

0.25 930,000 75,000 40 <10

0.50 880,000 1 ,800 <10 30

1.00 280,000 1 ,700 <10 <10

2.00 40,000 6,400 <10 <10

5.00 45,000 18,000 150 <10

10.00 35,000 25,000 7,500 700

TABLE 3K

KCI NaCI

(%) (%)

Sodium Carbonate 0.00 20.00 20.00

(%) 0.00 930,000 1 ,000,000 980,000

0.25 870,000 300,000 650,000

0.50 1 ,200,000 220,000 400,000

1.00 120,000 140,000 310,000

2.00 44,000 100,000 180,000

5.00 39,000 39,000 88,000

10.00 18,000 7,200 41 ,000

TABLE 3L

1 b8 KCI (%)

NaOH (%) 0.00 20.00

0.00 1 ,000,000 110,000

0.05 1 ,000,000 140,000

0.10 420,000 19,000

0.15 1 ,800 4,300

0.20 280 400

TABLE 3M

1 b9 KCI (%)

Avgard (%) 0.00 20.00

0.00 590,000 610,000

0.25 470,000 160,000

0.50 65,000 33,000 Example 4

The procedure of Example 3 was repeated, except that the aqueous treatment solutions used in Example 4 were made by dissolving the following components: sodium metasilicate nonahydrate, sodium carbonate and NaOH (TABLES 4A, 4B) sodium metasilicate nonahydrate, sodium carbonate and KCI (4C and 4D), sodium metasilicate nonahydrate, NaOH and KCI (TABLES 4E and 4F), sodium carbonate, NaOH and KCI (TABLES 4G and 4H), sodium metasilicate nonahydrate, sodium carbonate, NaOH and KCI (TABLES 41 and 4J), in the amounts set forth in the TABLES, in water. The weight percentages for the sodium metasilicate nonahydrate were calculated based on the total weight of sodium metasilicate nonahydrate, i.e., including the water of hydration. Results are given below TABLES 4A to 4J in cfu/ml. The baseline bacteria level for each test was determined by contacting 1 ml of the bacteria mixture to 99 ml of sterile water and is given in the 0.0%/0.0% data cell of each of the TABLES 4A to 4J.

TABLE 4A

AH Below @ 0.05% NaOH

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00 Metasilicate

(%) 0.00 1,100,00068,0005,1002,800 1,300 800 5,700 14,000

0.20 520,000 2,300 470 <10 20 1,200 3,600 10,000

0.40 12,000 30 <10 <10 <10 20 no data 3,400

0.60 20 <10 <10 <10 <10 <10 4,100 5,600

0.80 <10 <10 <10 <10 <10 <10 2,100 3,500

1.00 <10 <10 <10 <10 <10 <10 180 2,500

TABLE 4B

All Below @0.10% NaOH

SODIUM CARBONATE (%)

Na Metasilicate 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00

(%) 0.00 340,000 370 <10 10 <10 70 3,400 4,600

0.20 42,000 <10 <10 <10 <10 <10 970 4,000

0.40 <10 <10 <10 <10 <10 <10 <10 1,100

0.60 <10 <10 <10 <10 <10 <10 <10 2,000

0.80 <10 <10 <10 <10 <10 <10 <10 1,900

1.00 <10 <10 <10 <10 <10 <10 <10 2,900 TABLE 4C

All Below @ 10.00% KCI

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00

Metasilicate

(%)

0.00 840,000 85,000 65,000 72,000 63,000 34,000 17,000 8,500

0.20 51 ,000 45,000 39,000 43,000 35,000 21 ,000 11 ,000 8,100

0.40 22,000 25,000 21 ,000 17,000 21 ,000 19,000 11 ,000 6,000

0.60 5,200 9,000 11 ,000 14,000 11 ,000 9,300 3,600 4,200

0.80 6,700 3,400 23,000 3,300 4,700 4,600 6,100 3,100

1.00 2,200 3,600 5,000 4,900 4,700 2,800 2,700 4,600

TABLE 4D

All Below @ 20.00% KCI

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00 Metasilicate

(%)

0.00 910,000 150,000 80,000 60,000 48,000 29,000 14,000 8,200

0.20 29,000 26,000 20,000 22,000 22,000 19,000 9,100 10,000

0.40 8,000 16,000 5,400 14,000 9,100 11 ,000 12,000 3,700

0.60 5,700 11 ,000 4,200 12,000 9,000 8,600 9,300 2,400

0.80 4,100 23,000 5,100 10,000 5,600 2,900 2,300 2,500

1.00 1 ,700 16,000 3,500 10,000 3,800 2,900 3,000 2,800 TABLE 4E

All Below @ 10.00% KCI

NaOH (%)

Na Metasilicate 0 0.05 0.1 0.15 0.2

(%)

0 820,000 2,800 1 ,100 <10 <10

0.2 120,000 9,200 1 ,000 540 <10

0.4 19,000 1 ,800 30 30 <10

0.6 270 350 160 30 <10

0.8 50 160 10 30 <10

1 30 10 <10 <10 <10

TABLE 4F

All Below @ 20.00% KCI

NaOH (%)

Na Metasilicate 0 0.05 0.1 0.15 0.2

(%)

0 890,000 50,000 20,000 480 740

0.2 84,000 39,000 11 ,000 4,400 1 ,800 0.4 38,000 10,000 5,700 200 470 0.6 46,000 6,600 3,000 1 ,800 180 0.8 16,000 4,400 2,200 1 ,800 30

1 13,000 3,800 1 ,200 1 ,800 1 ,400 TABLE 4G

All Below @ 10.00% KCI

NaOH (%)

Sodium Carbonate 0 0.05 0.1 0.15 0.2

(%)

0 560,000 43,000 1 ,700 <10 40

0.25 270,000 40,000 4,300 30 30

0.5 170,000 61 ,000 7,300 230 250

1 160,000 78,000 19,000 900 510

2 210,000 61 ,000 16,000 4,100 1 ,200

5 23,000 32,000 9,500 11 ,000 710

10 30,000 30,000 11 ,000 7,800 900

TABLE 4H

All Below @ 20.00°/ , KCI

NaOH (%)

Sodium Carbonate 0 0.05 0.1 0.15 0.2

(%)

0 730,000 47,000 11 ,000 200 70

0.25 400,000 55,000 40,000 1,100 320

0.5 310,000 34,000 19,000 9,700 810

1 270,000 44,000 27,000 12,000 2,400

2 87,000 no data 13,000 12,000 2,600

5 28,000 52,000 23,000 9,500 2,600

10 30,000 23,000 11 ,000 11 ,000 2,900 TABLE 41

All Below @ 0.10% NaOH and 10.0%KCI

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00 Metasilicate

(%)

0.00 290 3,300 5,000 2,500 6,90047,00012,00012,000

0.20 1,600 140 1,500 1,400 4,800 3,800 9,600 4,000

0.40 no data.290 1,900 540 1,700 4,300 3,500 5,300

0.60 190 1,200 1,800 270 760 2000 3,400 3,500

0.80 30 530 1,200 290 50 1,800 2,000 4,200

1.00 40 <10 20 30 40 60 2,800 1,900

TABLE 4J

All Below @ 0.10% NaOH and 20.00% KCI

SODIUM CARBONATE (%)

Na 0.00 0.25 0.50 0.75 1.00 2.00 5.00 10.00 Metasilicate

(%)

0.00 12,00012,00011,00014,000 17,00022,00011,00012,000

0.20 5,100 7,500 11,00011,000 11,000 9,500 8,200 7,500

0.40 3,400 2,300 3,800 3,300 1,100 4,700 6,300 2,700

0.60 1,400 2,900 3,400 1,900 1,200 5,400 2,800 1,300

0.80 2,700 200 1,100 700 1,200 400 1,700 700

1.00 2,700 600 900 600 500 800 900 2,400 Example 5

Aqueous solutions were made by dissolving the components:

NaOH (TABLE 5A), sodium metasilicate nonahydrate and sodium carbonate (TABLE 5B) and sodium metasilicate nonahydrate and sodium carbonate/NaOH (TABLE 5C) were in the amounts set forth in the respective TABLES, in water. The weight percentages for the sodium metasilicate nonahydrate were calculated based on the total weight of sodium metasilicate nonahydrate, i.e., including the water of hydration. The pH of each solution was measured. Results are set forth below in TABLES 5A to 5C.

TABLE 5A

NaOH (%)

0.00 0.05 0.10 0.15 0.20

PH 7.21 11.39 11.61 12.01 12.2

TABLE 5B

All Below @ 0.10% NaOH

PH

Sodium Carbonate (%)

Na Metasilicate 0.00 0.25 0.75 2.00

(%)

0.00 7.21 12.05 12.15 12.41

0.20 12.08 12.14 12.26 12.98

0.60 12.20 12.34 12.56 13.01 TABLE 5C pH

Sodium Carbonate (%)

Na Metasilicate 0.00 0.50 0.75 1.00 2.00

(%) 0.00 7.21 11.02 11.22 11.32 11.43

0.60 11.97 12.03 12.06 12.22 12.76

1.00 12.15 12.23 12.46 12.78 13.02

Example 6

Aqueous treatment solutions were prepared, at concentrations of 4,

7, 10 and 13 wt%, from the following mixtures of dry ingredients:

Sodium metasilicate (Mixture A),

80 wt% sodium metasilicate and 20wt% TSP (Mixture B), 30 wt% sodium metasilicate and 70 wt% sodium carbonate

(Mixture C),

60 wt% sodium metasilicate and 40 wt% sodium carbonate

(Mixture D),

94 wt% sodium carbonate and 6 wt% sodium hydroxide (Mixture E), and

97 wt% sodium carbonate and 3 wt% sodium hydroxide (Mixture

F), and in addition at concentrations of 1%, 2% and 3% for the sodium metasilicate (Mixture A). The pentahydrate form of sodium metasilicate was used to make the treatment solutions. The weight percentages for the sodium metasilicate pentahydrate were calculated based on the total weight of sodium metasilicate pentahydrate, i.e., including the water of hydration.

Chicken carcasses were taken from a commercial chicken processing line after having been eviscerated and washed with water, with carcasses for each set of tests being removed from the processing line over the course of 7 hours over several days.

Each carcass was submerged by hand in a 5 gallon container of test solution for 15 seconds, withdrawn from the test solution, allowed to drip for 30 seconds, placed in a plastic bag and rinsed. The carcasses were each rinsed by adding 400 milliliters of Butterfield's buffer (which had first been acidified with HCI to a pH of from about 2 to about 3, in order to allow neutralization of any residual alkalinity of the treated carcass) to the plastic bag containing the carcass and then shaking the carcass in bag of buffer solution for 1 minute. Samples of rinse solutions were then immediately removed from the bag and chilled by placing containers of the samples on water ice in shipping containers. The chilled samples of rinse solution were then shipped overnight on water ice, without being frozen themselves, to a lab for microbiological testing.

The tests were run in cycles, using one carcass per test, with each cycle beginning with a control sample and proceeding through the test solutions in order of increasing concentration of test solution and then returning to the control solution to begin the next cycle. Clean sterile rubber gloves were used for removing the chickens from the processing line and for the dipping procedure. The gloves were changed between carcasses.

E. coli counts were determined by subjecting rinse solution to £. co///coliform count plate testing (Petrifilm™ (3M)) according to AOAC Official Method 991.14. Results are reported as the number of colonies per milliliter (CFU/mL). Salmonella counts were determined by subjecting 55 gram samples of rinse solution, with three broth enrichment steps to colorimetric deoxyribonucleic acid hybridization testing (GENE-TRAK™ (Neogen Corporation)) according to AOAC Official Method 990.13. Presumptive positive results were, in general, confirmed according to FDA-BAM (8^th Edition Revision A, 1998). Results are reported as the percentage of positive results, calculated as: ((number of positive results in the test series/total number of samples in the test series) x 100).

In each case, an "Incident Rate" is reported as a percentage calculated according to: ((number of positive results in the test series/total number of samples in the test series) x 100). In the case of E. Coli results, an average value ("Ave.") is reported as the arithmetic average of the results for all days of the test series.

In TABLE 6A, for each set of results for a given test procedure, the results for days 1 , 2, 3 and 4 are each based on a sample size of 25 carcasses. In TABLE 6B, for each set of results for a given test procedure, the results for day 1 are each based on a sample size of 11 carcasses, the results for days 2 and 3 are each based on a sample size of 17 carcasses, the results for days 4 and 5 are each based on a sample size of 20 carcasses and the result for day 6 is based on a sample size of 15 carcasses. In TABLES 6C-6H, for each set of results for a given test procedure, the results for days 1 , 2, 3, 4 and 5 are each based on a sample size of 17 carcasses and the result for day 6 is based on a sample size of 15 carcasses.

Treatment with aqueous solutions of mixtures A - F did not, within the range of concentrations used, result in any substantial detriment to the visual appearance of the treated chicken carcasses.

TABLE 6C: Results for Mixture A (Sodium Metasilicate)

Control 10%TSP 4% Mixture A 7% Mixture A 10% Mixture A 13% Mixture A

Day E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella

1 <836 71% <68 12% <51 29% <30 18% <34 24% <23 6%

2 248 12% <25 0% <17 6% <24 0% <43 6% <12 0%

3 <106 53% <17 12% <26 12% <32 0% <76 12% <12 0%

4 343 18% <90 6% <46 0% < 118 6% <75 0% <25 0%

5 536 88% <92 41% <63 29% <54 29% <76 24% <16 24%

6 1307 20% <27 0% <45 0% <19 7% <13 0% <11 0%

Ave. <563 - < 53 - < 41 - < 46 - < 53 - < 16 -

Incident 97% 44% 61% 12% 54% 13% 56% 10% 47% 11% 25% 5% rate

TABLE 6D: Results for Mixture B (80% Sodium Metasilicate / 20%TSP) I I

C i

Control 10%TSP 4% Mixture B 7% Mixture B 10% Mixture B 13% Mixture B 1

Day E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella

1 < 88 24% < 39 6% < 16 6% < 88 0% < 15 0% < 11 0%

2 228 65% < 25 35% < 73 29% < 18 41% < 32 18% < 17 18%

3 279 76% < 24 18% < 22 18% < 31 24% < 12 29% < 10 12%

4 <401 82% < 54 59% < 26 41% < 42 47% < 42 47% < 16 24%

5 110 76% < 58 53% < 16 24% < 48 47% < 903 35% < 14 18%

6 74 53% < 16 13% < 23 13% < 11 13% < 23 20% < 10 7%

Ave. <197 — < 36 — < 29 ... < 40 ... < 171 ... < 13 ...

Incident 97% 63% 56% 31% 49% 22% 53% 29% 50% 25% 29% 13%

Rate

TABLE 6E: Results for Mixture C (30 % Sodium Metasilicate / 70% Sodium Carbonate)

Control 10% TSP 4% Mixture C 7% Mixture C 10% Mixture C 13% Mixture C

Day E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella

1 < 226 53% < 54 47% < 57 29% < 46 29% < 44 18% < 55 24%

2 < 107 65% < 11 35% < 16 65% < 29 53% < 39 35% < 44 29%

3 < 428 53% < 15 18% < 32 29% < 89 6% < 552 29% < 17 6%

4 254 40% < 103 20% < 53 30% < 97 30% < 227 0% 997 10%

5 469 35% < 30 20% < 39 10% < 36 30% < 19 20% < 21 0%

6 < 255 32% < 24 21% < 28 26% < 33 21% < 15 16% < 31 5%

Ave. < 208 ... < 29 ... < 29 ... < 44 ... < 134 ... < 126 —

Incident 92% 46% 59% 27% 74% 31% 73% 28% 73% 21% 62% 12%

Rate

1

TABLE 6F: Results for Mixture D (60% Sodi ium Metasilicate / 40% Sodium Carbonate) LO

1

Control 10% TSP 4% Mixture D 7% Mixture D 10% Mixture D 13% Mixture D

Day E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella

1 < 51 65% < 11 12% < 11 24% < 94 35% < 14 35% < 11 29%

2 < 350 41% < 32 6% < 44 18% < 130 29% < 28 6% < 20 0%

3 < 89 71% < 12 35% < 27 41% < 26 47% < 13 35% < 18 18%

4 < 56 82% < 12 24% < 18 41% < 21 35% < 11 65% < 23 29%

5 1 ,437 88% < 22 24% < 36 35% < 19 24% < 25 29% < 11 0%

6 < 97 87% < 25 33% < 13 53% < 47 40% < 12 47% < 11 53%

Ave. < 122 — < 19 ... < 25 ... < 56 _- < 17 ... < 16 ...

Incident 92% 72% 49% 22% 54% 35% 64% 35% 39% 36% 30% 22%

Rate

TABLE 6G: Results for Mixture E (94% sodium carbonate / 6% Sodium Hydroxide)

Control 10% TSP 4% Mixture E 7% Mixture E 10% Mixture E 13% Mixture E

Day E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella

1 < 79 35% < 28 15% < 15 35% < 53 15% < 32 15% < 15 5%

2 109 64% < 11 36% < 76 50% < 24 43% < 11 36% < 12 29%

3 < 286 29% < 362 29% < 44 35% < 36 12% < 39 6% < 15 18%

4 < 99 41% < 18 0% < 32 18% < 58 18% < 28 6% < 18 18%

5 < 74 24% < 11 0% < 40 6% < 22 6% < 26 6% < 25 0%

6 < 25 20% 117 33% < 41 53% < 53 33% < 15 27% < 66 27%

Ave. < 112 ... < 91 ... < 41 ... < 41 — < 25 ... < 25 ...

Incident 85% 36% 56% 19% 74% 33% 68% 21% 51% 16% 52% 16%

Rate

1

TABLE 6H: Results for Mixture F (97% Sod ium Carbonate / 3% Sodium Hydroxide) LO

1

Control 10% TSP 4% Mixture F 7% Mixture F 10% Mixture F 13% Mixture F

Day E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella E. coli Salmonella

1 410 65% < 44 29% < 29 35% < 39 35% < 18 35% ^' < 21 41%

2 211 53% < 15 18% < 22 18% < 80 18% < 33 18% < 16 6%

3 < 101 47% < 35 41% < 21 35% < 27 47% < 14 24% < 13 18%

4 < 55 12% < 11 6% < 29 6% < 19 12% < 17 12% < 12 12%

5 99 94% < 22 35% < 56 59% < 28 53% < 21 53% < 19 29%

6 < 50 33% < 38 13% < 19 27% < 17 20% < 35 40% < 13 0%

Ave. < 141 ... < 28 ... < 29 — < 35 ... < 23 ... < 16 ...

Incident 94% 51% 51% 24% 71% 30% 71% 31% 56% 30% 48% 18%

Rate

The treatment method of the present invention allows simple and economical washing of animal carcasses to reduce bacterial contamination of the carcass and/or retard bacterial growth on the carcass, without substantial detriment to the organoleptic properties of the carcass and without generating a waste stream that contains a high amount of phosphates.

Example 7

The method of the present invention was applied to vegetables. Aqueous treatment solutions were made with 2% w/w sodium metasilicate pentahydrate (pH = 13.20) and 10% w/w sodium metasilicate pentahydrate (pH = 13.71 ) in cold tap water. The weight percentages for the sodium metasilicate pentahydrate were calculated based on the total weight of sodium metasilicate pentahydrate, i.e., including the water of hydration. All wash solutions were allowed to mix for 15 minutes on a stir plate. Stainless steel trays (approximately 25 x 35 x 5 mm) were sanitized with 200 PPM sodium hypochlorite and rinsed to be used as treatment wash basins. The aqueous treatment solutions were then added to the sanitized trays.

Bolthouse carrots (obtained in 1 pound commercial packages) were separated into 140 gram samples. Each of the samples was washed in 2000 grams of one of the aqueous treatment solutions or of cold tap water by submerging the sample in the liquid for 10 minutes with occasional mixing. After 10 minutes each sample was rinsed under cold running tap water for 2 minutes in a sanitized stainless steel funnel. Rinsed carrots were allowed to drain for 10 minutes on perforated plastic weigh boats.

Contaminant organisms were enumerated by grinding samples of the treated carrots into Butterfield's phosphate buffer to make a 1 :10 dilution. This was then spread plate onto Standard Plate Count (SPC) agar. Plates were incubated aerobically for 48 hours at 30°C.

The remaining treated carrots were transferred into sterile Whirlpak bags and stored at 4°C for 1 month. Each week a sample was taken and tested for the number of contaminants present.

The results of the microbiological testing are set forth in TABLE 7 as Colony Forming Units/gram of carrot (CFU/g)

TABLE 7: Contaminant Count for Treated Carrots (All counts are an average of two samplings)

Sample Time Control 2% Sodium 10%) Sodium

(CFU/g) Metasilicate Metasilicate

(CFU/g) (CFU/g)

Initial - Day 0 36,000 2,200 400

Week l 1 ,600,000 120,000 52,000

Week 2 9,700,000 14,000 1 ,100

Week 3 15,000,000 18,000,000 1 ,800

Week 4 12,000,000 100,000,000 1 ,000,000

After washing the two sodium metasilicate wash water basins contained an orange tinge apparently from removal of the outer layer of carrot. The 10% solution was a stronger color. The carrots from the 10% treatment were slightly soft or mushy on the outside, the 2% treatment were slightly softer than the water wash control, but did not appear objectionably softer. At the end of 1 month the control water wash carrots had a pale white outer layer in spots, they appeared to have a dried out surface. The two samples of carrots from the sodium metasilicate wash still remained orange and appeared moist. The treatment method of the present invention allows simple and economical washing of edible plant materials to reduce bacterial contamination of the edible plant materials and/or retard bacterial growth on the edible plant materials, without substantial detriment to the organoleptic properties of the edible plant materials and without generating a waste stream that contains a high amount of phosphates.

Claims (30)

1. A method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the carcass with an aqueous solution comprising an effective amount of an alkali silicate.

2. The method of claim 1 , wherein the alkali silicate comprises one or more crystalline or amorphous alkali silicate compound according to the formula: M₂O-m(SiO₂)-nH₂0 wherein:

M is sodium or potassium, m is a number, wherein 0.5 < m < 3.5, indicating the number of mole(s) of the Si0₂ moiety per 1 mole of M₂0 moiety; and n indicates the water content, expressed as wt% water, wherein 0% < n

< 55%.

3. The method of claim 1 , wherein the alkali silicate comprises one or more crystalline metasilicate according to M₂0(Si0₂) -n'HaO, wherein M is Na or K and n' is 0, 5, 6 or 9 and indicates the number of moles of water per Si0₂ moiety.

4. The method of claim 1 , wherein the alkali silicate comprises one or more of anhydrous sodium metasilicate, anhydrous potassium metasilicate, sodium metasilicate pentahydrate, sodium metasilicate hexahydrate and sodium metasilicate nonahydrate.

5. The method of claim 1 , wherein the aqueous solution comprises greater than or equal to 0.05 percent by weight alkali silicate.

6. The method of claim 1 , wherein the aqueous solution comprises from 1 to 15 percent by weight alkali silicate.

7. The method of claim 1 , wherein the aqueous solution further comprises one or more of alkali carbonates and alkali hydroxides.

8. The method of claim 7, wherein the aqueous solution comprises one or more alkali carbonate or alkali bicarbonate compound according to formula:

M z-aHaCOg-n'HzO wherein:

M' is sodium or potassium, a is 0 or 1 , and n" is a number wherein 0 < n" < fully hydrated .

9. The method of claim 7, wherein the aqueous solution comprises an alkali carbonate selected from sodium carbonate, potassium carbonate sodium bicarbonate and potassium bicarbonate, each of which may be in anhydrous or hydrated form, and mixtures thereof.

10. The method of claim 7, wherein the aqueous solution comprises greater than 0.05 percent by weight alkali silicate and greater than 0.05 percent by weight alkali carbonate.

11. The method of claim 7, wherein, the aqueous solution comprises from from 0.5 to 10 percent by weight alkali silicate and from 0.2 to 15 percent by weight alkali carbonate.

12. The method of claim 7, wherein the aqueous solution comprises an alkali hydroxide according to formula:

M'OH wherein: M" is sodium or potassium.

13. The method of claim 7, wherein the aqueous solution comprises sodium hydroxide as the alkali hydroxide.

14. The method of claim 7, wherein the aqueous solution comprises greater than 0.05 percent by weight alkali silicate and greater than 0.05 percent by weight alkali hydroxide.

15. The method of claim 7, wherein the aqueous solution comprises from 0.5 to 10 percent by weight alkali silicate from 0.1 to 2 percent by weight alkali hydroxide.

16. The method of claim 7, wherein the aqueous solution comprises greater than or equal to 0.05 percent by weight alkali silicate, greater than or equal to 0.05 percent by weight alkali carbonate and greater than or equal to 0.05 percent by weight alkali hydroxide.

17. The method of claim 7, wherein the aqueous solution comprises from 0.5 to 10 percent by weight alkali silicate, from 0.2 to 15 percent by weight alkali carbonate and from 0.1 to 2 percent by weight alkali hydroxide.

18. The method of claim 1 , wherein the animal carcass is contacted with the aqueous solution after slaughter of the animal and prior to, during or after chilling the carcass, by dipping the carcass in the treatment solution or by spraying the treatment solution on the carcass.

19. The method of claim 18, wherein the duration of the dipping or spraying is from about 1 second to about 5 minutes.

20. The method of claim 1 , wherein the animal carcass is contacted with the aqueous solution by spraying the aqueous solution onto the carcass under a gage pressure of greater than 2 pounds per square inch.

21. The method of claim 1 , wherein the animal carcass is contacted with the aqueous solution by spraying the aqueous solution onto the carcass under a gage pressure of 3 to 40 pounds per square inch.

22. The method of claim 1 , wherein the aqueous solution is at a temperature of from 0 to about 85°C

23. The method of claim 1 , wherein the aqueous solution is at a temperature of from 0 to about 70 °C.

24. The method of claim 1 , wherein the aqueous solution is recovered after contacting the carcass and is recycled.

25. A method for treating animal carcass to reduce bacterial contamination of the carcass or retard bacterial growth on the carcass, comprising contacting the animal carcass with a substantially ethanol free aqueous solution comprising effective amounts of two or more of an alkali silicate, an alkali carbonate and an alkali hydroxide.

26. The method of claim 25, wherein the aqueous solution comprises greater than or equal to 0.05 percent by weight alkali carbonate and greater than or equal to 0.05 percent by weight alkali hydroxide.

27. The method of claim 25, wherein the aqueous solution comprises from 0.1 percent by weight to saturation of alkali carbonate and from 0.5 to 5 percent by weight alkali hydroxide.

28. A method for treating edible plant materials to reduce bacterial contamination of edible plant materials or retard bacterial growth on the edible plant materials, comprising contacting the edible plant materials with an aqueous solution comprising effective amount of an alkali silicate.

29. The method of claim 28, wherein the aqueous solution comprises greater than or equal to 0.05 percent by weight alkali silicate.

30. The method of claim 28, wherein the alkali silicate comprises one or more crystalline or amorphous alkali silicate compound according to the formula: M₂O-m(SiO₂)-nH₂0 wherein:

M is sodium or potassium, m is a number, wherein 0.5 < m < 3.5, indicating the number of mole(s) of the Si0₂ moiety per 1 mole of M₂0 moiety; and n indicates the water content, expressed as wt% water, wherein 0% < n

< 55%.