GB2087724A

GB2087724A - Bactericide or foods and food processing machines or utensils

Info

Publication number: GB2087724A
Application number: GB8129003A
Authority: GB
Original assignee: Ueno Seiyaku Oyo Kenkyujo KK
Current assignee: Ueno Seiyaku Oyo Kenkyujo KK
Priority date: 1980-09-26
Filing date: 1981-09-25
Publication date: 1982-06-03
Also published as: AU558019B2; JPS5758876A; JPS6228664B2; DE3138277A1; DE3138277C2; FR2490928A1; AU7560881A; FR2490928B1; CA1186218A; GB2087724B

Abstract

Previous techniques of sterilising foods and food processing machines or utensils suffer from a variety of disadvantages, such as causing a deterioration in the flavor or quality of the food. Such problems are now overcome by use of a bactericide comprising as active ingredients ethyl alcohol, and an organic acid or its salt and/or an inorganic acid or its salt. A food or a food processing machine or utensil can be sterilised by dissolving this bactericide in water, and contacting the resulting aqueous solution with the food or the food processing machine or utensil.

Description

SPECIFICATION Bactericide for foods and food processing machines or utensils This invention relates to an effective and safe liquid bactericide for foods and food processing machines or utensils, said bactericide comprising a combination of (1) ethyl alcohol and (2) an organic acid or its salt and/or an inorganic acid or its salt, and a method for killing noxious bacteria which adhere to foods and food processing machines or utensils to cause food poisoning or spoilage.

Nowadays, a variety of foods are processed in great quantities at fixed places and transported from thereto places of consumption. Accordingly, a long period of time elapses during transportation of the processed foods from the manufacturers to the consumers, and also until the consumers cook or eat them. During this time, various problems tend to arise. The greatest problem is the occurrence of food poisoning and spoilage owing to infecting microorganisms, and a great deal of efforts have been made to prevent it.

Food poisoning and spoilage are caused mainly by bacterial infection of raw materials, and bacterial infection during processing and distribution. In this regard, it is generally thought that seafood pastes, and hams and sausages have a high degree of safety because they undergo heat-treatment during processing. These foods, however, are susceptible to secondary contamination during a time period between the heat-treatment and packaging. In order to prevent food poisoning and spoilage of these foods, it is necessary to prevent secondary contamination.

Salads, Chinese foods, hambergs, meat balls, etc.

are among those processed foods which have recently shown a great demand in the Japanese market, and the demand for salads containing raw vegetables is especially high. It is known however that raw vegetables used for salads, such as cucumber, tomato, cabbage, Chinese cabbage, onion and celery, are frequently contaminated strongly by food-poisoning bacteria and spoiling bacteria. Presently, the noxious bacteria infecting vegetables is controlled by the blanching method.

This method, however, has the defect that because it involves immersing the vegetables in a liquid kept at a high temperature, the tissues of the vegetables will be destroyed by heat, and their flavor decreases markedly. Investigations have been undertaken, on the other hand, to remove the contaminating bacterra by an immersion or spraying technique using sodium hypochlorite, acetic acid, etc. However, since the chemicals must be used in high concentrations, they are likely to cause offensive odours, and adversely affect the flavor of foods and the health of the consumers.

Contamination of the human body (e.g., working personnel and cooks in food processing factories), seafoods, chickens (especially boilers), and chicken eggs by food-processing bacteria also poses a problem. For removal of these bacteria, it is the general practice to treat them with an aqueous solution of sodium hypochlorite in a concentration of less than 200 ppm (as available Cl,) but effect of this treatment is not sufficient. If the sodium hypochlorite is used in a concentration of 200 ppm or more, its odor remains in the chicken flesh, for example, and its flavor is drastically impaired.

Hydrogen peroxide has high bactericidal activity with little deleterious effects on foods when used in effective concentrations. However, since its carcinogenicity was discovered, it cannot be used in food treatment It is well known on the other hand that ethyl alcohol has been used widely as a medical disinfectant because of its high safety and strong antimicrobial activity. In some food processing plants, investigations are being made to utilize the bactericidal activity of ethyl alcohol, and to kill food-poisoning and spoiling bacteria of foods and increase their preserving effect by directly spraying ethyl alcohol to the foods or directly dipping them in ethyl alcohol.

In order to obtain a sufficient effect from ethyl alcohol alone, the concentration of ethyl alcohol should be at least 70%. Such a high ethyl alcohol concentration results in a strong smell of ethyl alcohol and markedly impairs of the flavor of foods.

Or it degenerates proteins to reduce the quality of foods and their discoloration. Inorganic acids such as phosphoric acid have a strong sterilizing effect, but for a sufficient effect, they have to be used in a concentration of more than 30%. At effective concentrations, the irritation and sour taste inherent to phosphoric acid remain in foods to reduce the paiatability of the foods. Organic acids such as lactic acid or acetic acid also exhibit a sterilizing effect in high concentrations In this case, too, their inherent irritating odors and sour tastes greatly impair the flavour of foods.The high-concentration ethyl alcohol, inorganic acids and organic acids are unsuitable as bactericides for foods processing machines because they also adversely affect the working environment by their inherent irritating odors.

In the circumstances, therefore, no effective means has been established yet for the removal and killing of noxious microorganisms adhering to foods, food processing machines or utensils etc., despite its utmost importance in food sanitation and food processing.

ft is an object of th is invention therefore to provide a bactericide for foods and food processing machines or utensils, which does not deteriorate the flavor, and quality of foods nor destroy the food processing environment, and has very low toxicity and high safety.

The present inventors have now found that an excellent synergistic bactericidal effect can be obtained by using a mixture of ethyl alcohol and at least one of organic acids, inorganic acids and salts of these, and contaminating bacteria can be killed at much lower concentrations than in the case of using the components of the mixture individually.

Thus, according to this invention, there is provided a liquid bactericide for foods and food processing machines or utensils, comprising as active ingredients (1) ethyl alcohol and (2) an organic acid or its salt and/or an inorganic acid or its salt.

Examples of the organic acids used in this inven tion and their salts include lactic acid, acetic acid, tartaric acid, gluconic acid, citric acid, ascorbic acid, malic acid, succinic acid, fumaric acid, and phytic acid and salts of these. Examples of the inorganic acids and their salts, on the other hand, include phosphoric acid, condensed phosphoric acids (e.g., acidic pyrophosphoric acid, hexametaphosphoric acid, ultraphosphoric acid, etc.), nitric acid, sulfuric acid, and hydrochloric acid, and their salts.

Generally, the bactericide of this invention preferably consists of 99.9 to 2.0% (WN) of ethyl alcohol and 0.1 to 98.0% (WN) of at least one acid or acid salt, although it varies depending upon the types of the acids and salts used. In addition to these active ingredients, the bactericide of the invention may contain small amounts of water and a polyhydric alcohol such as propylene glycol and glycerol. When the acid or its salt is not easily soluble in ethyl alcohol, the addition of a small amount of water is preferred in order to obtain a uniform liquid bactericide.

The bactericide of this invention is usually used as a solution in water, Despite the factthatthe bactericide of the invention contains the active ingredients in very low concentrations, it shows better bactericidal effects than the individual ingredients used separately. This synergistic effect can be seen from Experimental Examples and Examples given hereinbelow. For example, the concentrations of ethyl alcohol and the acid or its salt required for performing sterilization within 30 seconds using an aqueous solution can be decreased to 0.5 to 35% (WN), and 0.005 to 20% (WN), respectively.

The pH of the aqueous solution of the bactericide of the invention is preferably not more than 4.0.

When the bactericide of the invention consists of ethyl alcohol and at least one organic acid or salt, it preferably contains 99.4 to 20% (WN) of ethyl alcohol and 0.6 to 80% (WN) of the organic acid or its salt Usually, this bactericide is used in the form of an aqueous solution in which the concentration of ethyl alcohol is 35 to 5%, preferably lotto 5%, (WN) and the concentration of the organic acid or its salt is 20 to 0.5%, preferably 10 to 1% (WN).

When the bactericidal agent of this invention con sistsi of ethyl alcohol and at least one inorganic acid or salt, it preferably contains 99.9 to 20% (WN) of ethyl alcohol and 0.1 to 80% (won) of the inorganic acid or its salt. Usually, this bactericide is used in the form of an aqueous solution in which the concentration of ethyl alcohol is 35 to 5%, preferably 10 to 5% (WN) and the concentration of the inorganic acid or its salt is 0.005 to 20%, preferably 0.005 to 10%, (WN).

When the bactericide of the invention consists of ethyl alcohol, at least one organic acid or salt and at least one inorganic acid or salt, the bactericide preferably contains 98.0% to 2.3% (WN), 96.7 to 1.0% (WN) of the organic acid or its salt, and 96.7 to 1.0% (WN) of the inorganic acid or its salt Usually, this bactericide is used in the form ofan aqueous solution in which the concentration of ethyl alcohol is 18.6to 1%, preferably 14591%, (WN), the concent- ration of the organic acid or its salt is 31 to 0.3%, preferably 13.0 to 0.3 /O, (WI/I'), and the concentration of the inorganic acid or its salt is 10 to 0.03%, preferably 0.7 to 0.03%, ion).

The proportions and the effective concentrations of these components in these bactericides mentioned above are only examples which can effect sterilization within 30 seconds. They can be properly changed depending upon the type of foods to be sterilized, the contacttime, the contacting method, etc.

For sterilization, an aqueous solution of the bactericide of the invention is contacted with a food or food processing machine or utensil.

Examples of foods which can be sterilized suitably by the method of this invention includes seafood and meat products (such as fish pastes, sausage, ham, and bacon), vegetables, especially those eaten raw (such as cucumber, tomato, cabbage, onion, lettuce and celery), various types of noodles, spaghetti, macaroni, seafoods, meat, chicken, chicken eggs, and semi-dried or dried products of seafoods and meats.

Examples ofthe food processing machines and utensils include cooking plates, cooking knives, food containers, cleaning cloths, and various devices used in food processing plants such as agitators, mixers, homogenizers, automatic cutters, conveying containers and packing containers.

Contacting of foods or food processing machines and utensils with the bactericide can be effected, for example, by dipping, spraying, wiping, etc.

Since the bactericide of the invention has high bactericidal activity at low concentrations, sterilization can generally be achieved by effecting the contacting for less than 30 seconds. Longer contacting does not appreciably reduce the flavor and quality of foods, nor give rise any safety problem. Noxious bacteria adhering to the working personnel and cooks can be killed when they dip their hands in an aqueous solution of the bactericide of the invention, or wipe their hands with an absorbent cotton or gauze impregnated with the bactericide solution.

The use of the bactericide of the invention in this manner prevents food poisoning and increases the preservability of processed foods by inhibiting their spoilage for a prolonged period of time.

The following Experimental Examples and Examples illustrate the present invention more specifically.

In Experimental Examples 1 to 3, effective combinations of bactericidal components were determined in vitro usingEscherichiacoli(NlHJ-JC-2)which is a food-poisoning bacterium regarded as the most important contamination-indicated bacterium in food sanitation.

In Examples 1 to 7, bactericidal compositions prepared on the basis of the results of Experimental Examples 1 to 3 were used for foods and food materials to determine their bactericidal and bacteria removing effects.

All percentages in these examples are by (WN)%.

ExperimentalExample 1 (A) The following experiment was conducted in order to examine the bactericidal effect of a mixture of ethyl alcohol and an inorganic acid substance.

Escherichia coli (NIHJ-JC-2) was inoculated in a brain heart infusion broth (BHI), and cultivated at 37 C for 24 hours. The culture broth was diluted to 1/10 with sterilized physiological saline. The resulting Escherichia coli suspension was used as a sample. Phosphoric acid, acidic sodium pyrophosphate, sodium hexametaphosphate, sodium ultraphosphate and nitric acid were used as inorganic acid substances.

One milliliter of the sample bacterial suspension was added to 9 ml of a test chemical solution prepared by adding physiological saline to ethyl alcohol and each of the inorganic acid substances so that the concentration of these compounds reached 1019 of the concentrations indicated in Table 1. They were immediately mixed, and maintained at 20 C. After a contact time of 30 seconds, one platinumloopfull of the mixture was inoculated in a fresh BHI broth, and cultivated at 375C for 48 hours. Growth of the bacterium in the culture broth was observed with the naked eyes. When no growth of the bacterium was noted, the result was evaluated as (-) which means that complete sterilization was possible, and when growth of the bacterium was noted, the result was evaluated as (+) which means that sterilization was impossible.The concentrations of the chemicals which were required for complete sterilization were measured. The results are shown in Table 1.

(B) The bactericidal effect of a combination of ethyl alcohol and an organic acid was examined in the same way as in (A) above. The organic acids tested were lactic acid, acetic acid, citric acid, tartaric acid, gluconic acid, malic acid, ascorbic acid and phytic acid. The results obtained with a contact time of 30 seconds are shown in Table 2.

Table 1

Type and concentration % Concentration of ethyl alcohol (%) ofthe inorganic acid 40 35 30 25 20 15 10 5 0 20 - - - - - - - - + 10 - - - - - - + + + Phosphoric 5 - - - - - - + + + acid 3 - - - - - + + + + 1 - - - - - + + + + 0.5 - - + + + + + + + 0 - + + + + + + + + 0.5 - - - - - + + + + Sodium 0.3 - - - - + + + + + ultra- 0.1 - - - + + + + + + phosphate 0.05 - - + + + + + + + O - + + + + + + + + 0.5 - - - + + + + + + Acidic 0.3 - - - + + + + + + sodium 0.1 - - + + + + + + + pyro- 0.05 - + + + + + + + + phosphate 0 - + + + + + + + + 0.5 - - - + + + + + + Sodium 0.3 - - + + + + + + + hexameta- 0.1 - + + + + + + + + phosphate 0.005 - + + + + + + + + O - + + + + + + + + 0.1 - - - - - - - - 0.05 - - - - + + + + + Nitric 0.03 - - - - + + + + + acid 0.01 - - - - + + + + + 0.005 - - - + + + + + + O - + + + + + + + + Table 2

Type and concentration (%) Concentration of ethyl alcohol (%) of the organic acid 40 35 30 25 20 15 10 5 0 20 - - - - - - - - + 10 - - - - - - - - + Lactic 5 - - - - - - - + + acid 3 - - - - - - - + + 1 - - - - - - + + + 0.5 - - - - - - + + + 0 - + + + + F + + + + 20 - - - - - - - - + 10 - - - - - - - - + Acetic 5 - - - - - + + + + acid 3 - - - - + + + + + 1 - - - - + + + + + 0.5 - - - + + + + + + 0 - + + + + + + + + 20 - - - + + + + + + 10 - - - + + + + + + Citric . 5 - - + + + + + + + add 3 - - + + + + + + + 1 - + + + + + + + + 0.5 - + + + + + + + + 0 - + + + + + + + + 20 - - - + + + + + + 10 - - - + + + + + + Tartaric 5 - - + + + + + + + acid 3 - - + + + + + + + 1 - - + + + + + + + 0.5 - + + + + + + + + 0 - + + + + + + + + 20 - - - + + + + + + 10 - - - + + + ± + + Gluconic 5 - - + + + + + + + acid 3 - - + + + + + + + 1 - - + + + + + + + 0.5 - + + + + + + + + 0 - + + + + + + + + 10 - - - - - + + + + Malic 5 - - - - + + + + + acid 3 - - - - + + + + + 1 - - - + + + + + + 0 - + + + + + + + + 7.5 - - - - - + ± + + Ascorbic 3.75 - - - - + + + + + acid 2.25 - - - + + + + + + 0.75 - - - + + + + + + 0 - + + + + + + + + 20 - - - - - - - - + 10 - - - - - - + + + 5 - - - - - - + + + Phytic 2.5 - - - - - + + + + acid 1.25 - - - - - + + + + 0.61 - - - - + + + + + 0.31 - - - - + + + + + 0.15 - - - - + + + + + 0 - + + + + + + + + The results given in Table 1 demonstrate that a marked synergistic effect was noted in a combination of ethyl alcohol with phosphoric acid. It is also seen from Table 2 that a combination of ethyl alcohol with lactic acid or acetic acid produces an excellent synergistic effect.

(C) Because a strong effect was noted in the combination of ethyl alcohol with phosphoric acid or lactic acid, a combination of ethyl alcohol, phosphoric acid and lactic acid was examined for bactericidal activity in the same way as in (A) above. The results obtained after a contact time of 30 seconds are shown in Table 3.

It is seen from Table 3 that the effect of the combination of these three chemicals was much stronger than that expected from the combination of ethyl alcohol and lactic acid or phosphoric acid.

The experimental results thus obtained show that when ethyl alcohol or the acids were individually used for sterilization, the various adverse effects mentioned hereinabove could not be avoided, whereas the combined use of ethyl alcohol and an organic acid and/or an inorganic acid, particularly the combined use of ethyl alcohol, lactic acid and phosphoric acid, greatly reduced the required concentrations of the individual chemicals and made possible effective sterilization without giving rise to problems of a sour taste, odor, degeneration, etc.

Table3

Phosphoric Lactic Concentration of ethyl alcohol (%) acid acid (%) (%) 40 36 30 25 20 15 10 5 3 1 0.5 0 20 - - - - - - - - + + + + 10 - - - - - - - + + + + 5 - - - - - - - + + + + + 0 3 - - - - - - - + + + + + 1 - - - - - - + + + + + + 0.5 - - - - - - + + + + + + O - + + + + + + + + + + + 20 - - - - - - - - - - + + 10 - - - - - - - - - - + + 5 - - - - - - - - - + + + 0.1 3 - - - - - - - - - + + + 1 - - - - - - + + + + + + 0.5 - - - - - - + + + + + + O - - + + + + + + + + + + 20 - - - - - - - - - - - + 10 - - - - - - - - - - - + 5 - - - - - - - - - - - + 0.5 3 - - - - - - - - - + + + 1 - - - - - - - + + + + + 0.5 - - - - - - + + + + + + O - - + + + + + + + + + + 20 - - - - - - - - - - - + 10 - - - - - - - - - - - + 5 - - - - - - - - - - - + 1.0 3 - - - - - - - - - - - + 1 - - - - - - - - - + + + 0.5 - - - - - - - - + + + + O - - - - - + + + + + + + Experimental Example 2 Since lactic acid and phosphoric acid are acidic substances, the pH of the bactericidal solution which is decreased as a result of using these acids presumably contributes also to the bactericidal acitvity of the solution. To confirm this, the following experi me nut was performed.

A mixture of ethyl alcohol, phosphoric acid and lacitic acid was prepared. The concentrations of ethyl alcohol and phosphoric acid were fixed at 10% and 0.1%, respectively, whereas the concentration of lactic acid was varied within the range of 3 to 20% as shown in Table 4. The pH of the mixture was adjusted to 5-1 with 1 N-NaOH or HC1 at the time of application. The bactericidal effect of the mixture was examined in the same way as in Experimental Example 1, (A). The time of contact between the sample bacterial suspension and the sample bactericidal mixture was varied between 30 seconds and 10 minutes. The results are shown in Table 4. These results show that a pH of 4.0 or below is desirable.

Accordingly, organic acids and inorganic acids other than lactic acid and phosphoric can fully exhibit a bactericidal effect by using them together with ethyl alcohol. For example, a combination of ethyl alcohol, lactic acid and another organic acid or salt, a combination of ethyl alcohol and, phosphoric acid and another inorganic acid or salt, or a combination of ethyl alcohol, another organic acid and another inorganic acid is effective when a solution of such a combination is adjusted to not more than 4.0. Table4

pHofthe Contacting time solution during Lactic acid 30 1 5 10 contact (%) seconds minute minutes minutes 3 - - - 5 - - - - 1 and 2 10 - - - 15 - - - - 20 - - - 3 - - - - 5 - - - - 3 10 - - - - 15 - - - - 20 - - - - 3 + + + 5 + + - 4 10 + - - 15 - - - - 20 - - - - 3 + + + + 5 + + + + 5 10 + + + + 15 + + + - 20 + + + - (Note): Ethyl alcohol 10%; phosphoric acid 0.1%.

Experimental Example 3 Three mixtures having the following compositions were prepared on the basis of the results of Experimental Examples 1 and 2, and examined for bactericidal effect in the same way as in Example 1, (a). The results are shown in Table 5.

Mixture A Ethyl alcohol 87.0 % Latic acid 8.7 % Phosphoric acid 4.3 % Total 100 % Mixture B Ethyl alcohol 61.7 % Lactic acid 37.0 % Phosphoric acid 1.3 % Total 100 % Mixture C Ethyl alcohol 37.0 % Lactic acid 61.7% Phosphoric acid 1.3 % Total 100 % Table 5

Concentrations of the ingredients in the aqueous solution { /OJ Contacting time Concen tration Ethyl Lactic Phosphoric 30 1 5 10 Chemicals (%) alcohol acid acid seconds minute minutes minutes 10 8.70 0.87 0.43 - - - - 7 6.09 0.609 0.301 - - - - Mixture A 5 4.35 0.435 0.215 + + + 3 2.61 0.261 0.129 + + + ~ 1 0.87 0.087 0.043 + + + + 10 6.17 3.70 0.13 - - - 7 4.32 2.59 0.091 - - - - Mixture B 5 3.09 1.85 0.065 - - - - 3 1.85 1.11 0.039 + + + - 1 0.617 0.370 0.013 + + + + 10 3.70 6.17 0.13 - - - 7 2.59 4.319 0.091 - - - - Mixture C 5 1.85 3.085 0.065 - - - - 3 1.11 1.851 0.039 + + + - 1 0.370 0.617 0.013 + + + + Lactic acid 20 + + + + Phosphoric 20 acid + + + + 40 Ethyl 35 + + + + alcohol 30 + + + + 20 + + + + Not added 0 + + + + As shown in Table 5, the bactericidal effect was strongest with the mixture C and least strong with the mixture A, and the mixture B comes in between.

Each of the mixtures showed a bactericidal effect when the concentrations of ethyl alcohol, lactic acid and phosphoric acid were much smaller than the effective concentrations of these components used individually. Thus, a marked synergistic effect was noted.

Example 1 The bactericidal effects of each of the chemicals shown in Table 6 on bacteria adhering to "crab leglike fish-cake (kamaboko-like product)" whose infection by coliform bacteria is especially notabie were examined.

Refrigerated Alaska pollack 1 kg Salt 30 g L-giutamic acid 100 g Crab flavor 5g Potato starch 50 g Ice water 300 g Total 1485 g A minced flesh of the above composition was molded into a block having a weight of about 1 kg and attached to a plate. The product was held at 40 C for 1 hour, and its surface was colored with natural red dye. The product was steamed at 90 C for 1 hour and cooied.

The plate was removed from the resulting product, and dipped for 10 seconds in a suspension of Escherichia coli (NIHJ-JC-2) to cause the bacteria to adhere fully. The contaminated block was then dipped for 30 seconds in a water solution of each of the mixtures A, B and C in the concentrations shown in Table 6. Immediately then, it was withdrawn. The standard plate count was measured by a conventional plate dilution method using a standard agar culture medium. The numberofcoliform organisms was measured by the plate dilution method using a desoxycholate agar culture medium. For comparison, the number of bacteria was measured in the same way immediately after dipping of the block in the bacterial suspension, or after further dipping it in hydrogen peroxide or ethyl alcohol solution. The results are summarized in Table 6.

The results show that the bactericidal agent of the invention can perform complete sterilization at an extremely low concentration which was 1/10 to 1/14 of the effective concentration of ethyl alcohol alone.

The concentration of the required concentration of ethyl alcohol in the mixtures was much lower, and is about 1/11 to 1/38 of that required when ethyl alcohol is used alone. The same can be said with regard to the other components. This means that the combination of chemicals in accordance with this invention produces a marked synergistic effect, and therefore, can simultaneously solve the conventional problems of the quality of foods, the working - environment, safety, etc.

Table 6 (fish-cake product)

Concentrations {o/o) After dipping treatment Concen trations Standard Numberof ofthe Phos- plate coliform chemicals Ethyl Lactic phoric count organisms Chemicals (%) alcohol acid acid (cellslg) (cellslg) Non-treated (immediately after attachment 9.9x104 1.3 x 103 of bacteria) Distilled water 3.0 x 103 2.1 x 102 Hydrogen peroxide 0.05 2.1 x 103 1.1 x 102 10 8.70 0.87 0.43 0 0 7 6.09 0.609 0.301 0 0 Mixture A 5 4.35 0.435 0.215 9.2 x 102 6.3 x 10 3 2.61 0.261 0.129 2.5 x 103- 1.80 x 102 1 0.87 0.087 0.043 2.7 x 103 1.90 x 102 10 6.17 3.70 0.13 0 0 7 4.32 2.59 0.091 0 0 Mixture B 5 3.085 1.85 0.065 0 0 3 1.851 1.11 0.039 8.1 x 102 5.2 x 10 1 0.617 0.370 0.013 2.6 x 103 2.11 x 102 10 3.70 6.17 0.13 0 0 7 2.59 4.319 0.091 0 0 Mixture C 5 1.85 3.085 0.065 0 0 3 1.11 1.851 0.039 2.5x102 6.1 x 10 1 0.370 0.617 0.013 2.7 x 102 1.75 x 102 70 0 0 Ethyl alcohol 60 2.5 x 103 1.5 x 102 In order to examine the effects of the bactericidal agent of the invention on the flavor of foods, a paste product produced as above was removed from the plate, and immediately then, dipped for 30 seconds in an aqueous solution of each of various chemicals.

It was then subjected to an organoleptictest by a panel often persons for an unusual taste or an unusual odor. The results are shown in Table 7.

It is seen from Table 7 that the bactericides of the invention show no effect on the flavor of foods when their concentrations were not more than 30%. Since the concentration of 30% is much higher than the effective concentrations shown in Table 6, it is clear that the bactericides of the invention can be used without any deleterious effect on the flavour of foods.

Table 7 (fish-cake product)

Concen- Number of the trations panelists who felt an of the unusual taste or an Chemicals chemicals unusual oder out of (%) 10 Distilled water \ 0 Hydrogen peroxide 0.05 0 Mixture A 40 4 30 \ 0 Mixture B 40 5 30 0 Mixture C 40 8 30 0 30 1 0 Ethyl alcohol 1 70 # 10 60 8 Example 2 In this Example, the bactericidal effects of each of the chemicals shown in Table 8 and 9 on onion (about 100 g) and cucumber (about 100 g)whose infection by noxious bacteria was heaviest among edible vegetables were examined in the same way as in Example 1. The results are shown in Tables 8 and 9.

The cucumber was subjected to an organoleptic test in the same way as in Example 1. The results are shown in Table 10.

Table 8 (onion)

Concentrations (%) After dipping treatment Concen trations Phos- Standard Numberof of the Ethyl Lactic phoric plate coliform Chemicals chemicals alcohol acid acid count organisms (ole) (cellslg) (cellslg) Non-treated (immediately - 5.3 x 106 1.7 x 104 after attachment of bacteria) Blanching (*) - 2.5 x 10 0 Distilled water - 2.25 x 106 8.4 x 104 Hydrogen peroxide 0.02 3.3 x 106 3.0 x 102 10 8.70 0.87 0.43 0 0 7 6.09 0.609 .0.301 4.4 x 104 0 Mixture A 5 4.35 0.435 0.215 2.5 x 106 6.7 x 103 3 2.61 0.261 0.129 2.11 x 106 5.4 x 104 1 0.87 0.087 0.043 2.80 x 106 6.9 x 104 10 6.17 3.70 0.13 0 0 7 4.319 2.59 0.091 0 0 Mixture B 5 3.085 1.85 0.065 0 0 3 1.851 1.11 0.039 2.30 x 10 5.2 x 10 1 0.677 0.370 0.013 2.18 x 106 6.7 x 104 10 3.70 6.17 0.13 0 0 7 2.59 4.319 0.091 0 0 Mixture C 5 1.85 3.085 0.065 0 0 3 1.11 1.851 0.039 5.1 x 10 5.9 x 10 1 0.370 # 0.617 0.013 # 2.12 x 106 8.2 x 104 Ethyl alcohol 70 3.8 x 10 1.3 x 10 (*) Dipped in warm water at 80 C for 30 seconds.

Table 9 (cucumber)

Concentrations (%) After dipping treatment Concen trations Phos- Standard Number of of the Ethyl Lactic phoric plate coliform Chemicals chemicals alcohol acid acid count organisms (%) (cellsig) (cellsig) Non-treated 7.9 x 105 2.4 x 104 (immediately after attachment of bacteria) Blanching (*) 0 0 Distilled water - 1.45 x 10 4.1 x 10 Hydrogen peroxide 0.02 3.9 x 104 9.2 x 10 10 8.70 0.87 0.43 0 0 7 6.09 0.609 0.301 0 0 Mixture A 5 4.35 0.435 0.215 5.3 x 10 4.6 x 10 3 2.61 0.261 0.129 8.9 x 104 3.9 x 10 1 0.87 0.087 0.043 1.29 x 105 4.0 x 10 10 6.17 3.70 0.13 0 0 7 4.319 2.59 0.091 0 0 Mixture B 5 3.085 1.85 0.065 0 0 3 1.831 1.11 0.039 6.9 x 10 2.9 x 10 1 0.617 0.370 0.013 7.2 x 104 3.8 x 10 10 3.70 6.17 0.13 0 0 7 2.59 4.319 0.091 0 0 Mixture C 5 1.85 3.085 0.065 0 0 3 1.11 1.851 0.039 7.3 x 104 3.7 x 10 1 0.370 0.617 0.013 1.32 x 105 3.7 x 10 Ethyl alcohol 70 8.8 x 10 9.0 x 10 (*) Dipped in warm water at 80 C for 30 seconds.

Table 10 (cucumber)

Number of pane Concen- lists who felt an tration unusual taste or an Chemicals (%) unusual odor out of 10 Blanching 5 Distilled water - 0 Hydrogen peroxide 0.05 0 Mixture A 40 4 30 0 MIxture B 40 6 30 0 Mixture C 40 9 30 1 20 0 Ethyl alcohol 70 10 60 9 Example 3 In this Example, the mixture B shown in Experimental Example 3 was used to kill bacteria adhering to vegetables.

Cucumber and cabbage cut into four were washed with water, and dipped in each of the chemicals shown in Table 11, and the number of bacteria was examined by the conventional plate diluting method in the same way as in Example 1. The results are shown in Table 11.

Table Ii

After dipping treatment Concen tration Standard Number of of the Dipping plate coliform chemical time count organisms Vegetable Chemical (%) (minutes) (cellsig) (cellsig) Only washed with water 1.0 x 106 1.56 x 10 2% 10 3.9 x 105 0 Cucumber 20 7.2 x 104 0 (*) Mixture B 30 5.4 x 104 0 1% 30 2.4 x 104 0 Sodium hypochlorite (as available Cl) 200 ppm 30 2.4 x 105 8.5 x 10 Only washed with water 3.1 x 105 1.3 x 105 1.0% 30 7.9 x 105 0 Cabbage 0.7% 30 3.2 x 10 0 (*) Mixture B 0.5% 30 2.8 x 10 5.0 x 10 (*) The cucumber was sliced at the surface portion, and the cabbage was the one sampled at random from many cabbages. The number of bacteria per gram was examined using 10 g each ofthese samples.

Example 4 The bactericidal effects of each of the chemicals shown in Table 12 on bacteria adhering to the surface of chicken (broiler) were examined.

The test was carried out in the same way as in Example 1 using about 51 g of the flesh taken from nearthe wing of a chicken. The results are shown in Table 12, and demonstrate the marked effects of the bactericides of the invention.

When the above test was repeated exceptthat the whole flesh of a chicken wes used instead of the flesh near the wing. Bacteria (general bacteria and coliform organisms) were not detected when the mixture A was used in an amount of 5%, the mixture B, in an amount of 3%, and the mixture C, in an amount of 3%. At lower concentrations than those shown in Table 12, an effect of complete sterilization was obtained.

By the same tests as above, it was confirmed that the bactericides of the invention are equally effective for beef, pork and fresh seafoods.

Table 12 (chicken)

Concentration ofthe Concen- ingredients (%) After dipping treatment tration ofthe Phos- Number of chemical Ethyl Lactic phoric Standard coliform (%) alcohol acid acid plate count organisms Chemical (cells/10 x 10cm2) (cells/lO x 10 cm Non-treated (immediately - 6.3 x 106 3.8 x 104 after bacteria attachment) Distilled water - 4.2 x 106 3.5 x 104 Sodium hypochlorite 0.02 3.7 x-106 3.9 x 104 10 8.70 0.87 0.43 , 0 7 6.09 0.609 0.301 0 .-0 0 Mixture A 5 4.35 0.435 0.215 3.9x 105 8.7 x 102 3 2.61 0.261 0.129 3.8 x 106 2.9 x 104 1 0.87 0.087 0.043 4.1 x 106 3.7 x 104 10 6.17 3.70 0.13 0 - 0 7 4.319 2.59 0.091 0 0 Mixture B 5 3.085 1.85 0.065 0 0 3 1.851 1.11 0.039 ,5.1x10' 7gK2 1 0.617 0.370 0.016 3.9 x 106 2.9 x 104 10 3.70 6.17 0.13 0 0 7 2.59 4.319 0.091 0 0 Mixture C 5 1.85 3.085 0.065 0 4 0 3 1.11 1.851 0.039 4.8 X-104 6.7 x 102 1 0.370 0.617 0.013 3.7 x 106 - - 3.2 x 104 Ethyl alcohol 70 Example 5 The bactericidal effects of the chemicals shown in Table 13 were tested on chicken eggs.

Escherichia coli was caused to adhere to about 67 g of eggs in the same way as in Example 1, and the eggs were then dipped for 30 seconds in an aqueous solution of each of the chemicals. Then, the surfaces of the eggs were wipped off, and the standard plate count and the number of coliform organisms were measured. The results are shown in Table 13.

It is seen from table 13 that the bactericides of the invention show a marked effect as a bactericidal treating agent for eggs.

Table 13 (chicken eggs)

Concentration of the Concen- ingredients (%) After dipping treatment tration of the Phos- Number of chemical Ethyl Lactic phoric Standard coliform (%) alcohol acid acid plate count organisms Chemical (cells/10 x 10cm2) (cells/lO x 10cm2) Non-treated (immediately - 5.5 x 104 7.5 x 102 after bacteria attachment) Distilled water - 2.8 x 104 5.8 x 10 Sodium hypochlorite 0.02 8.1 x 103 4.1 x 102 10 8.70 0.87 0.43 0 0 7 6.09 0.609 0.301 0 / 0 Mixture A 5 4.35 0.435 0.215 2.7 x 103 9.8 x 10 3 2.61 0.261 0.129 2.5 x 104 5.3 x 102 1 0.87 0.087 0.043 2.5 x 104 5.2 x 102 10 6.17 3.70 0.13 0 0 7 4.319 2.59 0.091 0 0 Mixture B 5 3.085 1.85 0.065 0 0 3 1.851 1.11 0.039 5.1 x 102 9.7 x 10 1 0.617 0.370 0.013 3.1 x 104 4.9 x 102 10 3.70 6.17 0.13 0 0 0 7 2.59 4.319 0.091 0 0 Mixture C 5 1.85 3.085 0.065 0 0 3 1.11 1.851 0.039 4.8 x 103 5.8 x 10 1 0.370 0.617 0.013 8.0 x 10' 4.2 x 102 Ethyl alcohol 70 3.9 x 10 5.1 x 10 Example 6 In this Example, the bactericidal effects of each of the chemicals shown in Table 14 on bacteria adhering to the surface of ham were tested.

Salt (1.5%), 120 ppm of sodium nitrite, 550 ppm of sodium ervthrobate and 0.3% of sodium tripolyphosphate were uniformly injected into about 2 kg of meat taken from the ham portion of a hog.

The meat was then rubbed and kneaded, wrapped with a cotton cloth and tied with a thread. It was then dried at40"Cfor3 hours and smoked at 57 C for 4 hours to produce a ham. The ham was stored at 0 C -overnight, and used as a test sample.

A pre-cultivated suspension-of Escherichia coli and Lactobaclllus vulgaricus was suspended in physiological saline to prepare a bacterial suspension.

The ham sample was cut into blocks each weighing about 200 g. The blocks were dipped for 5 seconds in the bacterial suspension to cause the bacteria to adhere to the surface of the blocks. The blocks were then dipped in each of the bactericidal solutions shown in Table 14 for a predetermined period of time, and withdrawn. Then, the surface portion of each block was cut off asepticaliy, and homogenized. The number of bacteria was measured. The results are shown in Table 14.

Table 14

Dipping time versus bacteria count Treatment Bacteria 30 seconds # I minute # 5 minutes coliform organisms 5.1 x 10 4.2 x 10 1.55 x 104 Dipping in water only lactic acid bacteria 4.3 x 104 2.6 x 104 5.2 x 104 standard plate count 3.7 x 104 2.2 x 104 5.3 x 104 5% coliform organisms 1.4 x 10 1.6 x 10 lactic acid bacteria 4.3 x 10 6.8 x 10 3.0 x 10 standard plate count 2.9 x 10 4.7 x 10 3.5 x 10 Mixture B coliform organisms - - 10% lactic acid bacteria 6.9 x 10 4.2 x 10 1.1 x 10 standard plate count 2.1 x 10 1.75 x 10 3.8 x 10 coliform organisms 3.8 x 10 7.5 x 10 Sodium 500 ppm lactic acid bacteria 6.6 x 104 5.8 x 10 (as available Cl) standard plate count 42 K 104 6.4 K 10 coliform organisms 3.9 x 10 1.6 x 10 1.2 x 10 60% lactic acid bacteria # 1.8 x 103 # 3.4 x 102 # 1.5 x 102 standard plate count 1.8 x 10 5.4 x 10 5.1 x 10 Ethyl alcohol coliform organisms 2.0 x 10 1.4 x 10 70 % lactic acid bacteria 7.8 x 10 6.1 x 10 1.1 x 10 standard plate count 2.2 x 10 1.9 x 10 5.5 x 10 The bacterial count is the number of bacteria per g, (-) represents "negative".

Example 7 In the process of producing Vienna sausage, before packaging, the heat-treated sausage is usually (1) cooled and carried to a clean room, (2) cut by a drum cutter, (3) carried on a conveyor, (4) sent to an aligner, and (5) put into a bucket.

In this Example, the following two tests were con ducted in order to examine the bactericidal effect of the bactericide (mixture B) of the invention.

In the first test showing a conventional process, the standard plate count, the number of lactic acid bacteria, and the presence or absence (positive or negative) of coliform organisms were determined with regard to the sausage (1) in the clean room, and the sausages (6) which was passed through the drum cutter (2), conveyor (3), the aligner (4), and bucket (5).

In the second test showing the process of the invention, the same test as above was carried out with regard to the sausage (1') treated with the bactericide and placed within the clean room, the drum cutter (2') treated with the bactericide, the conveyor (3') treated with the bactericide, the aligner (4') treated with the bactericide, and the bucket (5') treated with the bactericide. The same measurement as above was carried out with regard to the sausage which passed through the sterilized bucket (5').

The results are shown in Table 15. The data regarding the deviced (2) to (5) and (2') to (5') were obtained with regard to a sterilized gauze which was used to swab a 30 cm x 30 cm zone of each of these devices.

Table 15

Standard Lactic Sites inspected plate acid Coloform count bacteria organisms (1) Surface of Vienna sausage in the clean 2.5x102 1.8x102 + room (cells for each sausage) (2) That portion of the drum cutter which 2.0 x 102 8.8 x 102 + contacted with sausage (3) Surface of the C conveyor (4) Aligner 7.2 x 102 5.3 x 103 + o (5) Bucket 1.3 x 104 2.5 x 104 + u (6) The surface ofthe sausage which passed 8.5 x 10' 5.7 x 104 + (1') Vienna sausage (sprayed with a 10% - - solution of the bac tericide) in the clean room (2') The product-contacting portion ofthe drum - - 0 o cutter sprayed with a c 10% solution of the bactericide (3') Surface of the conveyor c sprayed with a 10% - ~ solutionofthe bactericide o (4') Aligner sprayed with X a 10% solution of the the bactericide (5') Bucket sprayed with a 10% solution ofthe - - bactericide (6') The surface of the sausage with passed - - through the bucket (5') -: negative, +: positive

Claims

1. A food orfood processing machine or utensil which has been sterilised by an aqueous bactericide comprising (1) ethyl alcohol and (2) at one least organic or inorganic acid or salt thereof.

2. Afood or food processing machine or utensil according to claim 1 which has been sterilised by contact with said bactericide for one minute or less.

3. Afood or food processing machine or utensil according to claim 2 wherein contact has been for 30 seconds or less.

4. A food or food processing machine or utensil according to any one of the preceding claims wherein the unsterilised food or food processing machine or utensil has been dipped in, sprayed with or wiped with the bactericide.

5. Afood or food processing machine or utensil according to claim 1 substantially as hereinbeforedescribed in any one of Examples 1 to 7.

6. A liquid bactericide for foods and food processing machines or utensils, said bactericide comprising as active ingredients ethyl alcohol, and organic acid or its salt and/or an inorganic acid or its salt.

7. The bactericide of claim 6 which comprises as active ingredients ethyl alcohol, the organic acid or its salt, and the inorganic acid or its salt.

8. The bactericide of claim 6 which comprises ethyl alcohol and the organic acid or its salt as active ingredients.

9. The bactericide of claims 6 which comprises ethyl alcohol, and the inorganic acid or its salt as active ingredients.

10. The bactericide of any one of claims 6 to 8 wherein the organic acid is selected from the group consisting of lactic acid, acetic acid, tartaric acid, gluconic acid, citric acid, ascorbic acid, malic acid, succinic acid, fumaric acid and phytic acid, and the organic acid salt is selected from sodium, potassium, calcium and magnesium salts of these organic acids.

11. The bactericide of any one of claims 6,7 and 9 wherein the inorganic acid is selected from the group consisting of phosphoric acid, condensed phosphoric acid (acidic pyrophosphoric acid, hexametaphosphoric acid, ultraphosphoric acid, etc), hydrochloric acid, sulfuric acid and nitric acid, and the inorganic acid salt is selected from the group consisting of sodium, potassium, calcium and magnesium salts of these inorganic acids.

12. The bactericide of any one of claims 6,7, 10 and 11 which comprises 99.9 to 2.0% (WN) of ethyl alcohol, and 0.1 to 98.0% (WN) of the organic acid or its salt and/or the inorganic acid or its salt.

13. The bactericide of any one of claims 6, 7, 10, 11 and 12 which comprises 98.0 to 2.3% (won) of ethyl alcohol, 1.0 to 96.7% (won) of the organic acid or its salt, and 1.0 to 96.0% (WN) ofthe inorganic acid or its salt.

14. The bactericide of any one of claims 6,7, 10, 11, 12 and 13 wherein the organic acid is lactic acid and the inorganic acid is phosphoric acid.

15. The bactericide of claims 6, 8, or 10 which comprises 99.4 to 20% (WN) of ethyl alcohol and 0.6 to 80% (won) of the organic acid or its salt.

16. The bactericide of any one of claims 6, 8, 10 and 15 wherein the organic acid is lactic acid, acetic acid or phytic acid.

17. The bactericide of claims 6,9 or 11 which comprises 99.9 to 20% (WN) of ethyl alcohol and 0.1 to 80% (won) of the inorganic acid or its salt

18. The bactericide of any one of claims 6,9, 11 and 17 wherein the inorganic acid is phosphoric acid, ultraphosphoric acid nor nitric acid.

19. A method for sterilizing a food or a food processing machine or utensil, which comprises dissolving a liquid bactericide comprising ethyl alcohol, an organic acid or its salt and/or an inorganic acid or its salt as active ingredients in water, and contacting the resulting aqeuous solution with the food or the food processing machine or utensil.

20. The method of claim 19 wherein the bactericides comprises ethyl alcohol, the organic acid or its salt and the inorganic acid or its salt as active ingredients.

21. The method of claim 19 wherein the liquid bactericide comprises ethyl alcohol and the organic acid or its salt as active ingredients.

22. The method of claim 19 wherein the liquid bactericide comprises ethyl alcohol and the inorganic acid or its salt as active ingredients.

23. The method of any one of claims 19 to 21 wherein the organic acid is selected from the group consisting of lactic acid, acetic acid, tartaric acid, gluconic acid, citric acid, ascorbic acid, malic acid, succinic acid, fumaric acid and phytic acid, and its salt is selected from the group consisting of sodium, potassium, calcium and magnesium salts of these organic acids.

24. The method of any one of claims 19, 20 and 22 wherein the inorganic acid is selected from the group consisting of phosphoric acid, acidic phyrophosphoric acid, hexametaphosphoric acid, ultraphosphoric acid, hydrochloric acid, sulfuric acid and nitric acid, and its salt is selected from the group consisting of sodium, potassium, calcium and magnesium salts of these inorganic acids.

25. The method of any one of claims 19, 20, 23 and 24 wherein the aqueous solution of the bactericide contains 0.5 to 35% (WN) of ethyl alcohol and 0.005 to 20% (won) of the organic acid or its salt and/or the inorganic acid or its salt.

26. The method of any one of claims 19, 20, 23, 24 and 25 wherein the aqueous solution of the bactericide contains 1 to 18.6% (won) of ethyl alcohol, 0.3 to 31% (WN) of the organic acid or its salt, and 0.03 to 10% (WN) of the inorganic acid or its salt.

27. The method of any one of claims 19, 20, 23, 24, 25 and 26 wherein the organic acid is lactic acid, and the inorganic acid is phosphoric acid.

28. The method of any one of claims 19, 21, 23 and 25 wherein the aqueous solution of the bactericide contains 5 to 35% (WN) of ethyl alcohol and 0.5 to 20% (WN) of the organic acid or its salt.

29. The method of any one of claims 19, 22, 24 and 25 wherein the aqueous solution of the bactericide contains 5 to 35% (won) of ethyl alcohol and 0.005 to 20% (won) of the inorganic acid or its salt

30. The method of any one of claims 19 to 29 wherein the aqueous solution of the bactericide has a pH of not more than 4.0.