Method for preserving fresh food

Abstract

The invention relates to a new method for preserving fresh food, in particular fresh agricultural products, by applying an alkaline solution and subsequently an acidic solution to the fresh food.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, particularly the preservation of fresh foods such as fresh agricultural products like fruits, vegetables, and herbs. Background of the Invention

[0003] Food preservation involves preventing the growth of unwanted microorganisms, slowing oxidation, and inhibiting and / or reversing processes that lead to visual deterioration, such as browning reactions in fresh foods, particularly freshly cut produce, especially vegetables, fruits, and herbs. Many processes are known for food preservation, encompassing a wide range of methods. In many processes, the appearance and taste characteristics of the food are substantially altered. In contrast, in many cases, it is desirable to make foods more durable and extend their shelf life while preserving as many characteristics as possible, such as flavor, texture, aroma, and optical appearance. Furthermore, many known processes address only one or a selected aspect of food preservation, such as preventing browning or slowing oxidation, without simultaneously inhibiting microorganisms such as bacteria and yeast, or vice versa. In particular, for the preservation of fresh produce such as fresh fruits, vegetables, and herbs, it is desirable to provide preservation processes that simultaneously address the most relevant preservation aspects: reducing oxidation, anti-browning treatment, and inhibiting or reducing microorganisms such as bacteria, fungi, and / or yeast. On the one hand, undesirable browning can occur in fresh produce due to oxidation or enzymatic reactions (also known as enzymatic browning). On the other hand, undesirable browning can be observed after preservation treatment due to discoloration caused by tissue damage.

[0004] EP3338563A1 describes a method for preserving fresh produce, particularly cut fruits and vegetables, using an aqueous solution containing potassium carbonate and at least one ascorbate and / or isoascorbate ion source in a very specific molar ratio ranging from 1.00:0.95 to 1.00:0.50 to prevent browning. The solution, in the form of a mixture of all components, is applied to fresh produce to preserve freshness and extend the shelf life of processed fruits and vegetables. The mixture described herein is not intended to prevent microbial spoilage but possesses antioxidant and anti-browning properties.

[0005] Patent KR101848788B1 describes fruit processing, including a fruit preparation step, a disinfection step, cutting or removing fruit parts according to fruit type, a pretreatment step of removing the peel, a washing step of immersing the pretreated fruit in a soaking solution and washing it, and a dehydration step of washing the fruit. Specifically, disinfection includes applying 200 ppm of chlorine, and the washing step includes applying a mixture containing an aqueous solution of ascorbic acid and sodium bicarbonate.

[0006] Patent US2012 / 0045555A1 describes a process for preserving freshly cut fruit by applying a fresh fruit preservation solution containing water, ascorbic acid, calcium ascorbate, carbohydrates, sodium chloride, magnesium chloride, potassium bicarbonate, and malic acid.

[0007] Patent application WO94 / 12041 describes a process for preserving freshly cut fruits or vegetables to maintain their natural appearance, comprising briefly immersing the cut fruits or vegetables in a diluted aqueous solution containing sodium and / or potassium ions, calcium ions, chloride ions, ascorbic acid or ascorbate ions (or isomers or derivatives thereof) and citric acid or citrate ions or malic acid or malic acid ions (or isomers or derivatives thereof).

[0008] JP06-181684, EP0141875, and WO00 / 30460 also disclose the use of ascorbic acid metal salts or combinations of ascorbic acid and metal salts in the treatment of fruits, vegetables, and other foods for reducing microbial contamination, preventing discoloration, and preservation. These solutions must contain ascorbic acid or its salts, sodium carbonate or potassium carbonate, citric acid or its salts, and sulfite or bisulfite compounds, each in a concentration of 10% to 40%. The solutions described herein contain all components in a single mixture.

[0009] US2012 / 045555A1 relates to preservatives for fresh fruit, particularly by reducing oxidation of the exposed cut surface of the fruit. Preservatives include single mixtures of ascorbic acid, calcium ascorbate, carbohydrates, sodium chloride, magnesium chloride, potassium bicarbonate, and malic acid.

[0010] KR20130141017 describes a liquid composition for preventing browning of fruit, the composition comprising 1.5 wt% vitamin C, 0.3 wt% potassium carbonate and 98.2 wt% water, resulting in a molar ratio of potassium cations to ascorbate anions of 1:1.96, wherein the components are present in a single mixture.

[0011] Therefore, existing technologies primarily provide methods for preserving fresh produce, in which a single preservative solution is applied to the fresh produce in a single step. Known one-step preservative mixtures may contain ascorbate and / or isoascorbate, typically in combination with carbonates or bicarbonates. Such compositions are particularly effective at preventing oxidation and browning of fresh produce, but less effective at preventing microbial spoilage. If any, such known and described preservatives possess only weak disinfectant properties and may exhibit buffering or side effects in the mixture, contrary to strong antimicrobial activity. Furthermore, combining active ingredients in a single solution to simultaneously induce several very different effects, such as antimicrobial, antioxidant, and anti-browning effects, presents problems in the preparation of suitable and effective formulations. Additionally, solutions used to preserve fresh produce from microbial spoilage utilize active disinfectants or disinfectant compounds that may be potentially hazardous and are not permitted for food preservation worldwide, such as chlorine-based disinfectants. Such potent disinfectants are also often unacceptable to consumers. It is also essential to avoid creating undesirable residues on the processed food that affect its taste. Known preservation compositions fail to address the antimicrobial properties during their processing and only provide compositions for the final solution. Typically, food is sterilized with common disinfectants and then treated with ascorbate solutions.

[0012] For example, food preservation methods using two or more separate processing steps having two or more different preservative solutions are known from WO2013 / 079903, EP1574135A1, US6,500,476 and US5,919,507.

[0013] WO2013 / 079903 discloses a method for preventing enzymatic browning by using a solution of calcium ascorbate and an enzyme inhibitor, the solution being an acidifier capable of lowering the pH to below 4. The method may optionally include a first step of pre-soaking the agricultural product in a solution containing a chelating agent.

[0014] EP1574135A1 describes a two-step preservation process in which a first acidic solution with a pH of 1.5 to 4.5 is applied to the produce to reduce the concentration of microorganisms, followed by a second anti-browning treatment by applying a solution containing chelating agents and antioxidants with a pH of 7 to 9.

[0015] While WO2013 / 079903 does not provide any treatment to inhibit or reduce microbial spoilage, EP1574135A1 uses acidic solutions to inhibit microorganisms. This acid treatment results in undesirable effects on the flavor of the treated produce and provides only insufficient antimicrobial efficacy. Furthermore, both methods require the use of chelating agents, which is undesirable due to food administration reasons and the very limited acceptability of food processing in the EU.

[0016] US 6,500,476 describes a three-step preservation process, comprising: first, contacting mushrooms with a high-pH alkaline solution (pH 10.5 to 11.5) to reduce microbial growth; second, neutralization with a neutralization buffer and salts of organic acids; and third, anti-browning treatment with antioxidants, a calcium source, and a chelating agent. The first alkaline solution is preferably prepared using carbonates and bicarbonates. The second neutralization solution is substantially free of isoascorbic acid and sodium isoascorbate. The third anti-browning solution contains sodium isoascorbate, isoascorbic acid, ascorbic acid, or calcium ascorbate (or L-cysteine) as a browning inhibitor. Therefore, the process described herein requires additional washing and neutralization steps prior to the anti-browning treatment.

[0017] Similarly, US 5,919,507 describes a preservation process for reducing microorganisms using a high-pH alkaline solution of pH 9.5 to 11.0, employing a two-step treatment. The second treatment step involves washing and neutralizing the treated mushrooms with a pH-neutralizing solution of isoascorbic acid and sodium isoascorbate in a specific ratio of 1:4. Similar to US 6,500,476, the two-step process described in US 5,919,507 preferably uses carbonates and bicarbonates to prepare the alkaline solution, and preferably incorporates EDTA as a chelating agent into the second neutralization and anti-browning solution.

[0018] As stated above, due to regulatory restrictions, the use of chelating agents to achieve anti-browning is less desirable, especially in the treatment of fresh produce. Furthermore, the inventors of this invention have found that antimicrobial treatments with solutions at pH 11.5 or lower, as described in US 6,500,476 and US 5,919,507, provide only limited antimicrobial efficacy. Even if these prior art documents provide good total microbial plate count results, this has only limited significance for the shelf life of the product, as products with high total microbial counts can still be marketable. US 5,919,507 explains in column 2, lines 62-66, that highly alkaline preservative treatments are limited by the upper pH limit and that solution exposure time must be carefully controlled to optimize bacterial destruction while avoiding counterproductive overexposure to extreme pH levels, which could lead to chemical damage to tissues.

[0019] The invention described herein combines two aspects—anti-browning / antioxidant and microbial inhibition—in a more effective and cost-efficient two-step process. Furthermore, the invention allows for the provision of a preservative process without the negative aspects of common disinfectants, such as the degradation of the physical and characteristic properties of treated produce, and without the regulatory restrictions of common anti-browning chelating agents. Surprisingly, the inventors of the invention have further discovered that, with the novel process described herein, a more alkaline, antimicrobially effective solution with a pH > 11.5 can be applied to fresh produce without causing degradation or chemical damage as anticipated by the teachings of US 5,919,507. In particular, the method of the invention avoids undesirable browning caused by discoloration due to tissue damage after preservation treatment.

[0020] Problems to be solved

[0021] Increased transport distances and the demands for providing and storing convenience foods, particularly freshly cut produce in places like schools, cafeterias, or fast-food restaurants, necessitate extended shelf life. Microbial contamination limits shelf-life extension due to ineffective antimicrobial pretreatment. Furthermore, extended shelf life and preservation against spoilage involve protecting fresh produce from visual and textural deterioration, such as due to oxidation, shrinkage, and undesirable browning. Therefore, there is a need for an improved and effective antimicrobial pretreatment that does not alter the texture, taste, and appearance of food to an unacceptable degree and extends the shelf life of fresh produce.

[0022] The problem this invention aims to solve is to provide an improved method for preserving fresh produce. Specifically, it is necessary to control microbial contamination while avoiding undesirable effects on appearance, taste, and texture, such as undesirable browning reactions due to discoloration caused by tissue damage following oxidation or preservation treatment, changes in structure, crispness, residues affecting taste, and similar changes. On the other hand, it is desirable to provide an efficient preservation process that combines the two most important aspects of fresh produce processing, simultaneously providing highly effective antimicrobial treatment and anti-browning / antioxidant treatment. This preservation process should avoid undesirable browning caused by discoloration due to tissue damage following preservation treatment. This means that a specific object of the invention relates to providing a novel, highly efficient food preservation process that balances a highly alkaline pH to achieve highly effective antimicrobial activity and avoids undesirable changes in texture or structure of the treated produce, such as erosion, chemical damage, or discoloration (browning).

[0023] The process should be easy to apply and therefore cost-effective. It should also be suitable for avoiding regulatory restrictions, particularly by achieving anti-browning even without the use of chelating agents. In a specific aspect, the new process should provide a highly efficient preservation method that is effective not only against bacteria but also against microbial spoilage caused by yeast.

[0024] This invention addresses this problem by providing a novel method for preserving fresh produce, comprising the application of two different solutions in a two-step process as described in detail herein. This novel process allows for improved resistance to microbial contamination, including antibacterial and anti-yeast activity, thereby extending shelf life while maintaining texture and crispness, as well as flavor properties and a good optical appearance. Foods treated with the claimed process show a reduction of yeast, bacteria, and fungi by up to 3 logarithms. Simultaneously, their sensory properties are significantly improved compared to conventional processing techniques. Surprisingly, when applied to fresh produce, such as, in particular, cut fruits, vegetables, and herbs, this novel process not only inhibits undesirable browning but also reverses browning to some extent. Therefore, it is surprising to find that this novel process provides a highly efficient preservation method that allows for the avoidance of undesirable browning due to tissue damage following preservation treatment. The solutions applied in this novel process are specifically designed to perform their specific functions to maximize efficiency and do not perform multiple functions simultaneously like many other single solutions. Furthermore, this novel process allows for more efficient and safer use of the preservative solutions and enables them to be stored stably for extended periods without deterioration, for example, due to precipitation of active compounds. Invention Details

[0026] This invention relates to a method for preserving fresh food, such as, in particular, fresh agricultural products, the method comprising the following steps:

[0027] (a) Provide an aqueous solution (1), wherein solution (1) is an alkaline solution with a pH value ≥ 10.0;

[0028] (b) Provide an aqueous solution (2) containing 0.5% to 25% w / w ascorbate and / or isoascorbate ions;

[0029] (c) Apply solution (1) to fresh food; and

[0030] (d) In a subsequent step, solution (2) is applied to the same fresh food.

[0031] The fresh food of this invention is preferably a fresh agricultural product.

[0032] Solution (1) is an alkaline solution with a pH value >10.0, preferably >10.5, more preferably >10.9, even more preferably >11.0, even more preferably >11.5, and most preferably >12.0. The pH of the most preferred alkaline solution (1) is >11.0, more preferably >11.5, and most preferably >12.0. The alkaline solution (1) must be configured to be effective in sterilizing fresh foods, especially fresh agricultural products, and should prevent further microbial contamination, delay microbial growth, and reduce microbial contamination on fresh foods to a certain extent. The alkaline solution (1) should be effective against one or more of the bacteria, yeast, and fungi groups, and it is desirable that it is effective against at least bacteria and yeast. Results show that sufficient anti-yeast activity can be obtained by using an alkaline solution with a pH >11.0, preferably >11.5, and most preferably >12.0.

[0033] In the context of this invention, the pH value of the solution is measured at room temperature (20℃±5℃) using a standard laboratory aqueous solution pH meter, utilizing the electrochemical determination of pH.

[0034] Suitable alkaline compounds for preparing alkaline solution (1) may be selected from alkali metal or alkaline earth metal salts or mixtures thereof. Preferred alkali metal or alkaline earth metal salts for preparing solution (1) are sodium, potassium, calcium, and magnesium salts or mixtures thereof. More preferably, sodium or potassium salts or mixtures thereof are used. Preferably, hydroxides, carbonates, and bicarbonates are used to prepare solution (I).

[0035] Among alkaline compounds, hydroxides are preferred, such as sodium hydroxide and potassium hydroxide in particular, as they are the strongest, most stable, and most soluble bases among hydroxides. Due to their high antimicrobial and disinfection potential, the use of strong bases ensures minimal microbial contamination of processed foods.

[0036] A preferred embodiment of the present invention relates to a method for preserving fresh food, wherein the solution (1) contains at least one hydroxide selected from the group consisting of calcium hydroxide, sodium hydroxide, and potassium hydroxide, or mixtures thereof, preferably sodium hydroxide and potassium hydroxide, or mixtures thereof. Although the alkaline solution (1) may contain the at least one hydroxide mixed with one or more carbonates, in a preferred embodiment, the solution (1) does not contain carbonate compounds.

[0037] The at least one hydroxide in solution (1) is preferably used at a concentration of at least 0.01% w / w, preferably at least 0.1%, more preferably at least 0.5% w / w, and most preferably at least 1.0% w / w.

[0038] The upper limit of the at least one hydroxide in solution (1) is preferably 5.0% w / w, more preferably 4.0% w / w, more preferably 3.0% w / w, and most preferably 2.0% w / w.

[0039] In a further preferred embodiment, the solution (1) contains at least one hydroxide at a concentration of 0.01% to 5.0% w / w, preferably 0.1% to 4.0% w / w, more preferably 0.5% to 3.0% w / w, and most preferably 1.0% to 2.0% w / w. A suitable range from the lower and upper limits can be selected depending on the specific process conditions, the composition of the solution (2), and the food to be processed.

[0040] On the one hand, these concentration ranges and limits allow for sufficient reduction of microbial contamination in processed foods, and on the other hand, do not cause irreversible damage or flavor deterioration in processed foods.

[0041] The selected concentration range provides a good balance between preservative activity of processed foods and protection against textural or sensory degradation.

[0042] Further preferably, the solution used in the method of the present invention is free of potentially harmful and corrosive disinfectants, and the method does not include disinfection steps using such undesirable disinfectants. Undesirable and avoided disinfectants particularly include chlorine-based disinfectants, such as sodium chlorite and other salts of chlorite, hypochlorites, hypochlorous acid, and chlorine dioxide, as well as peracetic acid, quaternary ammonium compounds, ethanol, isopropanol, formaldehyde, and hydrogen peroxide. Such undesirable disinfectants are potentially harmful to food or consumers. The solution used in the present invention preferably does not contain these compounds.

[0043] Solution (2) contains 0.5% to 25.0% w / w ascorbate and / or isoascorbate ions.

[0044] Preferably, the solution (2) contains at least 0.5%, at least 0.75%, at least 1.0%, at least 1.5%, at least 0.75%, at least 2.0% w / w of ascorbate and / or isoascorbate ions.

[0045] The upper limit of ascorbate and / or isoascorbate ions in solution (2) is 25.0% w / w, preferably 24.0%, 23.0%, 22.0%, 21.0%, 20.0%, 19.0%, 18.0%, 17.0%, 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%, 7.0%, 6.0% w / w.

[0046] More preferably, the solution (2) contains 1.0% to 15.0% w / w, even more preferably 1.5% to 10% w / w, and most preferably 2.0% to 6.0% w / w ascorbate and / or isoascorbate ions.

[0047] A suitable range can be selected from the lower and upper limit values according to specific process conditions, the composition of solution (1) and the food to be treated.

[0048] In principle, ascorbate and / or erythorbate ions can be derived from ascorbic acid and erythorbic acid. Preferably, salts of ascorbic acid and / or erythorbic acid are used to prepare the solution of the present invention, such as preferably alkali metal or alkaline earth metal salts of ascorbic acid or erythorbic acid, or mixtures thereof. Preferred salts are selected from calcium ascorbate, calcium erythorbate, potassium ascorbate, potassium erythorbate, sodium ascorbate, magnesium erythorbate, and mixtures thereof. It is particularly preferred to use potassium ascorbate, potassium erythorbate, sodium ascorbate, sodium erythorbate, or mixtures thereof. In particular, these alkali metals and alkaline earth metals are essential nutrients required by organisms to perform functions necessary for life, as they cannot be biochemically synthesized by the human body. Therefore, the use of these ascorbates and / or erythorbates is beneficial. In addition, cherries can be used as a source of ascorbate ions or any other suitable source rich in ascorbic acid (vitamin C).

[0049] Derivatives of ascorbates and / or erythorbates can also be used, such as ascorbic acid esters or ethers, in particular for example ascorbyl palmitate or ascorbyl ethyl ether.

[0050] The preferred pH of solution (2) is < pH 8.0, preferably < pH 7.5, more preferably < pH 7.0, more preferably < pH 6.5, more preferably < pH 6.0, more preferably < pH 5.5, more preferably < pH 5.0, more preferably < pH 4.5, even more preferably < pH 4.0, and most preferably the pH is between 3.0 and 5.0.

[0051] Solution (2) produces a neutralizing effect on the alkaline solution, thereby stopping alkaline activity and affecting the processing of food. However, at the same time, solution (2) exhibits anti-browning / antioxidant properties without deteriorating the sensory and optical properties of the processed agricultural products.

[0052] In a specific aspect of the present invention, the presence of chelating agents such as EDTA is excluded from the used solution (1) and / or (2), and this is not necessary to achieve the desired effect.

[0053] Solution (1) and solution (2) are generally aqueous solutions, and thus are based on water as a solvent. For the purposes of the present invention, water includes drinking water publicly supplied by local government authorities or privately supplied by food enterprises themselves.

[0054] In addition, other solvents besides water may be used, provided they are water-miscible and suitable as food additives, such as those approved by government regulations, for example, the German Zusatzstoff Zulassungsverordnung (ZZulV) under the German New Food and Food Products Act (Lebensmittel-undFuttemitttelgesetzbuch (LFGB)), or classified as GRAS (Generally Recognized As Safe) food substances by the US FDA. Examples of such other solvents are glycerol and propylene glycol, which are completely miscible with water.

[0055] Solutions (1) and (2) can be applied independently by spraying, sprinkling, rinsing, impregnating or immersing, or a combination thereof, corresponding to steps (c) and (d) of the methods described above.

[0056] The term "spray" in this invention refers to any technical process in which an aerosol is generated and intended to preserve fresh agricultural products. This can be achieved by a pump-driven spray system or a propellant-based spray system. The droplet size of solution (1) or solution (2) is not limited to any size range, but preferably the droplets have a microscopic size.

[0057] The term "spraying" in this invention refers to any technical process in which droplets and / or microdroplets of solution (1) or solution (2) are sprayed onto materials such as fresh agricultural products, for example, by a spraying system.

[0058] The term "rinsing" in this invention refers to any technical process in which a solution (1) or solution (2) is rinsed or poured onto a material such as fresh agricultural products.

[0059] Techniques known as spraying, sprinkling, or rinsing can be applied to fresh produce placed on grates, trays, or conveyor belts, but are by no means limited to these application methods.

[0060] The terms “immersion” and “submersion” in this invention refer to any technical process in which a material such as a fresh agricultural product is introduced into a reservoir of solution (1) or solution (2) in such a way that at least part, but preferably the entire surface, is covered at least temporarily by the solution or in such a way that the fresh food such as the fresh agricultural product floats on the surface of solution (1) or solution (2).

[0061] Furthermore, any other means suitable for covering the surface of fresh food, such as fresh agricultural products, preserved in the solution (1) or solution (2) can be applied in the method of the present invention.

[0062] Preferably, solution (1) and / or solution (2) are applied independently for at least 5 seconds. The application time of solution (1) and solution (2) may vary and / or depend on the processed food. Preferably, solution (1) and / or solution (2) are applied independently for less than 60 seconds.

[0063] The time between the application of solution (1) and solution (2) is preferably no more than 1 hour, more preferably no more than 30 minutes, and most preferably between 30 seconds and 10 minutes. On the one hand, the longer solution (1) remains on fresh food without the application of solution (2), the lower the rate of microbial contamination on the fresh food. On the other hand, fresh food may be eroded and may undergo saponification, leaving unpleasant residues on the processed food. This may also lead to undesirable browning effects on fresh food, especially fresh produce. These side effects are eliminated or inhibited by applying solution (2) to neutralize solution (1).

[0064] The ascorbate-containing solution (2) neutralizes any residues of the hydroxide solution (1). Furthermore, it forms vitamin C derivatives with the remaining sodium and / or potassium ions from the hydroxide solution (1). This neutralization process results in only harmless substances remaining on the food, such as sodium ascorbate and ascorbic acid, for example. Both are widely accepted and used food additives. Solution (2) further prevents browning reactions, enhances structure, and surprisingly even reverses potential browning reactions caused by applying solution (1) to food, particularly fresh produce. Applying ascorbic acid solution (2) alone improves the color of the food and prevents discoloration; however, without pretreatment with solution (1), solution (2) alone will not achieve any reduction in bacterial count. Internal studies and literature indicate that applying fruit acid alone (pH 2.4) does not result in any reduction in bacterial count. The acid further leaves a sour taste on the fresh produce to be consumed; this acidification is preferably avoided to preserve the natural flavor of the food.

[0065] Preferably, the solution (2) is applied for at least 5 seconds, and this duration can vary depending on the food and the amount and composition of the solution (1) applied to the same fresh food. This minimum duration ensures the full antimicrobial effect of the solution (1).

[0066] Preferably, no other washing or neutralization steps are applied between treatment with the solution (1) of the present invention and treatment with the solution (2) of the present invention. This means that a two-step treatment is preferred.

[0067] The application time of solution (1) can be extended by adding ascorbate / isoascorbate ions to solution (1) (as detailed below) and by subsequently using solution (2).

[0068] The composition of the solution (2) containing ascorbate and / or isoascorbate ions is controlled to have a sufficiently high ascorbate / isoascorbate concentration, thereby neutralizing all hydroxides in the solution (1). Conversely, neutralization counteracts the acidity of the ascorbate and / or isoascorbate solution.

[0069] Optionally, the solutions (1) and / or (2) of the present invention further contain one or more excipients suitable for food, particularly fresh agricultural products, selected from anti-adhesion agents, binders, colorants, flavoring agents, lubricants, preservatives, sweeteners, such as those listed in particular government regulations, for example, German Zusatzstoff Zulassungsverordnung (ZZulV) under the German New Food and Food Products Act (Lebensmittel-und Futtemitttelgesetzbuch (LFGB)), or substances classified as GRAS (Generally Recognized As Safe) by the US FDA. Depending on additional excipients, the application time of the solution may be shortened or prolonged, or the microbial reduction effect may be enhanced.

[0070] In a preferred embodiment of the invention, the solution (1) and / or solution (2) contain less than 30% by weight of one or more excipients, more preferably less than 20% by weight, even more preferably less than 10% by weight, and most preferably less than 5% by weight of excipients.

[0071] In another embodiment, solution (1) may also additionally contain ascorbate and / or isoascorbate ions. By adding a small amount of ascorbate and / or isoascorbate ions to the alkaline solution (1), the corrosion and browning reactions of fresh foods, especially fresh produce, can be surprisingly and significantly delayed, while the pH of solution (1) remains unchanged due to the buffering effect of the ascorbate and / or isoascorbate ions. It is expected that the alkaline solution (1) additionally containing ascorbate and / or isoascorbate ions will corrode fresh foods, especially fresh produce, in the same amount of time as when using solution (1) without ascorbate and / or isoascorbate ions. Since the application time of the alkaline solution (1) may be extended beyond the sterilization time, the surprising delay in corrosion significantly improves the applicability of the process.

[0072] In embodiments in which ascorbate and / or isoascorbate ions are added to an alkaline solution (1), the solution (1) preferably contains ascorbate and / or isoascorbate ions at a concentration between 0.1% and 10.0% w / w.

[0073] In such embodiments, the solution (1) preferably contains at least 0.2%, at least 0.3%, at least 0.4%, at least 0.5%, at least 0.75%, at least 1.0%, at least 1.5%, at least 2.0%, at least 2.5%, at least 3.0%, at least 3.5%, at least 4.0%, at least 4.5%, at least 5.0%, at least 5.5%, at least 6.0%, at least 6.5%, at least 7.0%, at least 7.5%, at least 8.0%, at least 8.5%, at least 9.0%, at least 9.5% w / w of ascorbate and / or isoascorbate ions.

[0074] In such embodiments, the upper limit of ascorbate and / or isoascorbate ions in solution (1) is 10.0% w / w, preferably 9.5%, 9.0%, 8.5%, 8.0%, 7.5%, 7.0%, 6.5%, 6.0%, 5.5%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5% or 1.0% w / w.

[0075] More preferably, when ascorbate and / or isoascorbate ions are added to the alkaline solution (1), the solution (1) preferably contains ascorbate and / or isoascorbate ions at a concentration between 0.5% and 5.0% w / w, or even more preferably between 1.0% and 2.0% w / w.

[0076] Depending on the specific process conditions, the composition of the solution (1), and the food to be processed, a suitable range can be selected from the lower and upper limits.

[0077] In a preferred embodiment, ascorbate and / or isoascorbate ions are added to solution (1) until the pH of solution (1) is ≥10.0, more preferably ≥11.0, and most preferably ≥12.0.

[0078] As described above, in general, the process conditions, compositions and concentrations of the solutions (1) and (2) of the present invention can be selected and controlled within the claimed range to achieve the desired effect. For example, when using solution (1) having a higher pH, for example pH ≥ 12.0, the concentration of ascorbic acid / erythorbate ions in solution (2) should be selected to achieve the desired neutralization. Where an alkaline solution (1) with pH ≥ 12.0 is used and no ascorbate / erythorbate ions are added to solution (1), the lower limit of ascorbate and / or erythorbate ions in solution (2) is preferably at least 0.75%, at least 1.0%, at least 1.5%, at least 0.75%, at least 2.0% w / w. However, in embodiments wherein the alkaline solution (1) further contains ascorbate / erythorbate ions, the concentration of ascorbate and / or erythorbate ions in solution (2) may be selected from the entire range defined herein, that is 0.5% to 25% w / w.

[0079] The pH values of solution (1) and solution (2) shall be selected independently of each other. Solution (2) should have a sufficiently low pH (acidic) to reverse the pH of food treated with alkaline solution (1) to a neutral pH or lower. If sufficient neutralization or acidification of the treated food is not achieved with solution (2), and the treated food maintains an alkaline pH of, for example, pH > 8.0 after preservation treatment, this may lead to undesirable spoilage, such as discoloration and browning of the food caused by tissue damage. Therefore, it is desirable to control the pH of solutions (1) and (2) such that during or after the treatment step with solution (2), the pH will not become alkaline, but preferably < pH 8.0, more preferably < pH 7.5, still more preferably < pH 7.0, more preferably < pH 6.5, more preferably < pH 6.0, more preferably < pH 5.5, more preferably < pH 5.0, more preferably < pH 4.5, even more preferably < pH 4.0, and most preferably the pH is between 3.0 and 5.0.

[0080] The method for preserving food, particularly fresh produce, according to the present invention is preferably carried out at ambient temperature / normal conditions. In any case, the temperature of solution (1) and / or solution (2) shall not exceed the boiling temperature, and shall be controlled to avoid boiling or cooking or other temperature-induced spoilage of the treated fresh food, particularly fresh produce. The temperature of the applied solution is preferably < 50.0°C, more preferably < 40.0°C, even more preferably < 30.0°C, most preferably room temperature (20°C ± 5°C). The process can also be carried out at temperatures below 20°C using cooled fresh food, particularly cooled fresh produce, however, freezing of the solution must be avoided.

[0081] Temperatures below the boiling point are preferred because this ensures that the water-holding capacity of the food, especially fresh produce, is not compromised, thus preserving the structure of the processed food. Even lower temperatures are preferred, such as below 40°C to 50°C, because, on the one hand, depending on the temperature, proteins and / or vitamins in fresh foods, especially fruits and vegetables, may denature or be destroyed at higher temperatures, and the processed food may therefore be nutritionally unsatisfactory; and on the other hand, the structure of fresh foods may soften at such temperatures, resulting in the loss of their crispness, for example, in apples or nectarines. At temperatures of 20°C, especially around 20°C or lower, it is generally ensured that the treatment has little effect on the structure of the food, especially fresh produce, particularly with regard to alkaline and acidic treatments. Furthermore, lower treatment temperatures, especially lower temperatures for solutions (1) and (2), allow for longer treatment times, as corrosion, browning reactions, and structural degradation occur later. Longer treatment times allow for further reduction in microbial contamination without negatively impacting the structure of fresh foods, especially fresh produce.

[0082] It is known to use alkaline solutions to treat fruits and vegetables. However, known alkaline treatments are intended for the chemical peeling of fruits and vegetables and are typically carried out at steam or high temperatures with significantly higher concentrations of alkaline compounds. In contrast, the method of the present invention is neither intended for nor suitable for such alkaline / chemical peeling processes. The difference in the method of the present invention lies in the processing conditions, such as lower temperatures and lower alkali concentrations.

[0083] In the process of this invention, since the alkaline solution (1) and the acidic solution (2) neutralize each other, a final washing step is not required. This is a significant process advantage in terms of saving time and resources.

[0084] The processes described herein for preserving food, particularly fresh agricultural products, may include one or more additional steps selected from step (e) drying, sieving, centrifugation, blowing, draining, packaging or shaping, and combinations thereof.

[0085] In the context of this invention, the term "food" refers to any food that may be easily oxidized. The term "food" includes processed foods such as cut, sliced, or peeled vegetables or fruits. This invention particularly relates to fresh foods, and more particularly to fresh agricultural products. However, the methods of this invention can also be applied to dried or semi-dried fruits and vegetables.

[0086] In this invention, "fresh agricultural products" refers to fresh foods such as vegetables, fruits, and herbs. In this invention, "fresh foods" refers to foods that have not been processed using chemical or physical preservation methods, such as chemical preservation methods or heat or steam preservation methods, particularly those excluded above. In this invention, fresh agricultural products taxonomically belonging to fungi such as shiitake mushrooms, wood ear mushrooms, porcini mushrooms, chanterelles, and any other mushrooms are considered to be included in the term "vegetables."

[0087] In the context of this invention, the term "fresh produce" specifically includes fresh fruits and vegetables. Primarily, but not exclusively, these fresh fruits and vegetables are farm-grown.

[0088] In the context of this invention, the term "fresh produce" further includes fruits and vegetables that are either in the same condition as when they were harvested, or that have been peeled, sliced, chopped, or subjected to any means for reducing the size of the fruits and vegetables or providing bite-sized portions, such as slicing, chopping, cutting, or peeling. Herbs may also be present in cut form.

[0089] In a preferred embodiment, the method for preserving food, particularly fresh agricultural products, is applied to freshly cut agricultural products. In particular, freshly cut agricultural products are susceptible to spoilage and / or browning. According to the process of the invention, treating freshly cut agricultural products with solutions (1) and (2) particularly protects the cut agricultural products.

[0090] The fresh produce and / or fresh cut produce preserved by the method of the present invention may be selected from the group consisting of fresh fruits, including apples, avocados, rhubarb, melons, pineapples, cherries, strawberries, nectarines, peaches, kiwis, lemons, oranges, apricots, coconuts, grapes, or dragon fruit.

[0091] Fresh produce and / or freshly cut produce from the fresh vegetables group may be selected from the following groups: pears, potatoes, carrots, lettuce, leeks, onions, rutabagas, kale, mushrooms, garlic, peppers, tomatoes, fennel, asparagus, beans, peas, broccoli, cauliflower, Brussels sprouts, cabbage, celery, leaf beets, corn, chicory, leafy greens, okra, peppers, beets, turnips, ginger, radishes, squash, baby zucchini, squash, artichokes, sweet potatoes, ginger, turmeric, eggplant or densely packed zucchini, and fungi (as defined above);

[0092] Fresh produce and / or freshly cut produce from the group of fresh herbs can be selected from basil, parsley, mint, dill, sage, rosemary, thyme, coriander, fennel, chamomile, lemongrass, oregano, chives or watercress.

[0093] Methods for preserving freshly cut agricultural products are preferably applied to:

[0094] Choose freshly cut produce from a variety of fruits, including apples, rhubarb, melons, pineapples, coconuts, strawberries, grapes, or kiwis.

[0095] Choose fresh, cut produce consisting of a variety of vegetables, such as carrots, tomatoes, peppers, densely packed zucchini, leafy greens, mushrooms, or eggplants.

[0096] Choose fresh, cut produce from herbs such as basil, parsley, mint, cilantro, or chives.

[0097] Methods for preserving freshly cut agricultural products are preferably applied to:

[0098] Apples, melons, pineapples, strawberries, coconuts, grapes, or leafy green vegetables.

[0099] The present invention further relates to combinations of solid compositions (1) and (2), which are prepared to be dissolved in a suitable solvent, preferably water or a mixture of water and other water-miscible solvents as defined above, for providing solutions (1) and / or solutions (2) as defined herein. Alternatively, the present invention covers combinations of ready-to-use solutions (1) and (2) for performing the processes described herein.

[0100] Another aspect of the invention relates to a kit assembly (kit product) comprising components a) and b) in a separate, specially arranged manner:

[0101] a) Solution (1) as defined above;

[0102] b) Solution (2) as defined above;

[0103] and one or more of the following

[0104] c) Instructions and / or

[0105] d) Containers for the parts to be treated, such as boxes or bags made of plastic, or any other suitable containers made of any other suitable material, or disposable devices for performing the process of the present invention, such as tubes, centrifuge tubes, cuvettes, bottles, syringes, dispensers, vials, etc. made of plastic, glass or other suitable materials (optionally, containers for packaging and / or storing the parts to be treated or the parts after treatment).

[0106] e) Optional containers for packaging and / or storing the parts to be processed or the parts after processing. In another embodiment, the invention relates to a kit assembly (kit product) comprising components a) and b) in separate, specially arranged arrangements:

[0107] a) Compounds, especially salts, used to prepare solutions (1) as defined above;

[0108] b) Compounds, especially salts, used to prepare solutions (2) as defined above;

[0109] c) An optional solvent as defined above, used to dissolve the compounds in solutions (1) and (2); and

[0110] d) Instructions and / or

[0111] e) Containers in which compounds a) and / or b) can be dissolved to prepare solutions (1) and (2), such as tubes, centrifuge tubes, cuvettes, bottles, vials, etc., made of plastic, glass or other suitable materials;

[0112] and / or

[0113] f) Containers for the parts to be processed, such as boxes or bags made of plastic, or any other suitable containers made of any other suitable material, or disposable devices for performing the process of the present invention, such as tubes, centrifuge tubes, cuvettes, bottles, syringes, dispensers, vials, etc. made of plastic, glass or other suitable materials;

[0114] g) Optional containers for packaging and / or storing parts to be processed or parts after processing.

[0115] If the solvent used to prepare solutions (1) and (2) is water, this embodiment is particularly preferred and does not need to be included in the kit.

[0116] The instructions may specifically include instructions for the preparation of solutions (1) and (2) and for the processing conditions of fresh food.

[0117] The kits described in this article are intended for use in preserving fresh food, particularly in methods for preserving fresh produce as described in this article. Example

[0118] The present invention is further illustrated by the following embodiments, but the present invention is not limited thereto.

[0119] A. Microbial logarithmic reduction test and sensory evaluation

[0120] The reduction of the microbial logarithm can be carried out under the following experimental conditions:

[0121] I. Prepare (solid) agar plates according to the instructions (adjust the pH with NaOH or HCl if necessary):

[0122] 1. VRBD-Agar:

[0123] 41.5 g / L distilled water; sterilize at 118°C for 15 min.

[0124] 2. YGC-Agar:

[0125] 40.2 g / L distilled water; sterilize at 121°C for 15 min.

[0126] 3. LB agar:

[0127] 10g / L tryptone

[0128] 5g / l NaCl

[0129] 5g / L yeast extract

[0130] 2.5g / L glucose

[0131] 15g / L agar

[0132] pH 7.5

[0133] Distilled water; sterilize at 121℃ for 21 min.

[0134] II. Weigh the product (fruit / vegetable); add the preferred amount of liquid medium and grind until a homogeneous mixture is obtained. It is easiest to use 1 ml / g of product, as the titer at this point is directly CFU / g.

[0135] Product. If there is not enough liquid present, use a larger volume of medium. Carefully adjust the droplet size appropriately.

[0136] III. Preparation of a series of dilutions (0, -1, -2, -3…; depending on the expected bioburden)

[0137] IV. Transfer a homogeneous mixture of 1000 measured test samples (e.g., fruits / vegetables) onto an agar surface, or spread the contents of a 1.5 ml reaction tube onto a (solid) agar plate; if Enterobacteriaceae are to be detected, a fresh VRBD-agar solution needs to be prepared and poured on top (between 45°C and 50°C) to create an anaerobic layer, thus ensuring the fermentation process.

[0138] V. Placed at 37°C (VRBD) and separately at room temperature (LB, YGC) for 18 to 24 hours (VRBD).

[0139] After 48 hours (LB) / (3 to) 7 days (YGC), count the colony-forming units (CFU / ml) per ml; determine the titer. LB gives the total count of thermophilic aerobic bacteria, VRBD gives the total count of Enterobacteriaceae, and YGC gives the total count of fungi. For YGC, optical methods must be used to distinguish yeasts from fungi. For VRBD, colonies growing on the surface are ignored. Purple colonies in agar indicate acid production, while light-colored colonies do not produce acid.

[0140] The test was based on the official procedure used to evaluate bacterial contamination. The difference was in the culture medium used to examine the total bacterial count and the incubation temperature of LB and YGC (room temperature instead of 25°C).

[0141] Example A-1: ​​Control

[0142] Pineapple slices were left untreated for five days to serve as a control group.

[0143] Five days later, significant growth and sensory deterioration of bacteria, yeast, and fungi were detected.

[0144] Comparative Example A-2: Treatment with ascorbic acid solution (pH 2.4)

[0145] Pineapple slices similar to those in Example A-1 were treated with a 6% w / w ascorbic acid solution (pH 2.4).

[0146] Significant growth of bacteria, yeast, and fungi was detected, but there was little sensory deterioration.

[0147] Comparative Example A-3: Treatment with 0.4 ppm ClO2 solution

[0148] Pineapple slices, similar to those in Example A-1, were treated with a 0.4 ppm ClO2 solution (6% w / v). This coefficient corresponds to the permissible value determined by the German Federal Republic's Drinking Water Ordinance (TrinkwV) and is commonly used as a disinfectant.

[0149] Bacterial, yeast, and fungal infections were detected with a 0.5 log reduction, but sensory deterioration occurred after 5 days.

[0150] Comparative Example A-4: Treatment with 80 ppm peracetic acid solution

[0151] Pineapple slices, similar to those in Example A-1, were treated with an 80 ppm peracetic acid solution. This coefficient corresponds to the permissible value determined by the US FDA's limits on washing fruits and vegetables and is commonly used as a disinfectant in the field of application.

[0152] The number of detected bacterial, yeast, and fungal infections decreased by 1, but sensory deterioration occurred after 5 days.

[0153] Comparative Example A-5: Treatment with 1% (w / w) sodium hydroxide solution

[0154] Pineapple slices similar to those in Example A-1 were treated by applying a 1% (w / w) sodium hydroxide solution [corresponding to solution (1) of the present invention].

[0155] The number of detected bacterial, yeast, and fungal infections decreased by 1 to 2, but sensory deterioration was obvious.

[0156] Comparative Example A-6: Treatment with 0.4 ppm ClO2 solution, followed by treatment with ascorbic acid solution (pH 2.4).

[0157] Pineapple slices similar to those in Example A-1 were treated with a 0.4 ppm ClO2 solution (6% w / v), and then an ascorbic acid solution (pH 2.4) [corresponding to solution (2) of the present invention] at a concentration of 6% w / w was applied to the same test material.

[0158] Bacterial, yeast, and fungal infections were detected with a 0.5 log reduction, but sensory deterioration was minimal.

[0159] Comparative Example A-7: Treatment with 80 ppm peracetic acid solution, followed by treatment with ascorbic acid solution (pH 2.4).

[0160] Pineapple slices similar to those in Example A-1 were treated with an 80 ppm peracetic acid solution, and then an ascorbic acid solution (pH 2.4) at a concentration of 6% w / w [corresponding to solution (2) of the present invention] was applied to the same test material.

[0161] The number of detected bacterial, yeast, and fungal infections decreased by 1, but sensory deterioration was less.

[0162] Example A-8: Treatment with 1% (w / w) sodium hydroxide solution [solution (1)] followed by treatment with ascorbic acid solution (pH 2.4) [solution (2)].

[0163] Similar to Example A-1, the pineapple slices were treated by applying a 1% (w / w) sodium hydroxide solution [corresponding to solution (1) of the present invention] to the test material, and then applying a 6% w / w ascorbic acid solution (pH 2.4) [corresponding to solution (2) of the present invention] to the same test material.

[0164] The detection log reduction of bacterial, yeast, and fungal infections was 2, and it exhibited better sensory properties for up to 8 days.

[0165] The reversal effect of discolored fresh produce:

[0166] Comparative Example B-1.1: Onion treatment with 1% (w / w) sodium hydroxide solution [solution (1)]

[0167] Applying a 1% (w / w) sodium hydroxide solution [corresponding to solution (1) of the present invention] to sliced ​​onions immediately caused discoloration throughout the 14-day storage period.

[0168] Example B-1.2: Onions were treated with 1% (w / w) sodium hydroxide solution [solution (1)] followed by ascorbic acid solution (pH 2.4) [solution (2)].

[0169] The test material was treated with a hydroxide solution (1) according to Example B-1.1, and then immediately a 6% w / w ascorbic acid solution (2) (pH 2.4) [solution (2)] was applied to the same test material. Surprisingly, the discoloration did not merely stop, but even reversed, and the test material presented its original appearance as before the hydroxide treatment. This appearance was maintained throughout the entire 14-day storage period.

[0170] Comparative Example B-2.1: Apple slices treated with 1% (w / w) sodium hydroxide solution [solution (1)]

[0171] Applying a 1% (w / w) sodium hydroxide solution [corresponding to solution (1) of the present invention] to apple slices caused significant discoloration within 1 to 2 minutes over the entire 21-day storage period.

[0172] Comparative Example B-2.2: Apple slices treated with ascorbate solution (pH 2.4) [solution (2)]

[0173] Applying a 6% w / w ascorbate solution (pH 2.4) [corresponding to solution (2) of the present invention] to the apple slices only prevented discoloration to a certain extent, as some apple slices still turned brown.

[0174] Example B-2.3: Apple slices were treated with 1% (w / w) sodium hydroxide solution [solution (1)], followed by treatment with ascorbic acid solution (pH 2.4) [solution (2)].

[0175] The test material was treated according to Example B-2.1, and then immediately a 6% w / w ascorbic acid solution (2) (pH 2.4) [solution (2)] was applied to the same test material. This prevented discoloration more effectively. This appearance was maintained throughout the entire 21-day storage period. Sodium ions in the sodium hydroxide solution significantly improved the anti-browning effect and prevented discoloration more effectively.

[0176] The results are summarized in Table 1 below:

[0177] Table 1:

[0178]

[0179] B. Comparative Test

[0180] Comparative experiments were conducted on the compositions described in prior art US6,500,476 and US5,919,507 (Table 1) to demonstrate the improvements and surprising effects of the novel method of the present invention within the claimed scope (Tables 2 and 3).

[0181] Test conditions:

[0182] Storage: 5℃ to 8℃

[0183] Packaging type: Plastic pallet

[0184] Slice size: Ultra-thin slices, machine-cut

[0185] Trial duration: 6 days

[0186] Freshly cut carrot pieces were treated with different test solutions, and their log reduction was evaluated as described in Example A above.

[0187] In addition, the optical appearance was examined by visual (optical) evaluation of the treated test blocks, and the browning resistance rate was determined according to the following formula.

[0188] 100 - (Number of test blocks affected by browning / Total number of test blocks) × 100 = Browning resistance rate [%).

[0189] The browning resistance rate (%) represents the proportion of test blocks that did not brown. This means that a higher browning resistance rate is associated with better browning resistance performance.

[0190] Figure 1 , Figure 2 and Figure 3 The results are further shown in Tables 1 to 3 below.

[0191] Table 1

[0192]

[0193] Table 2

[0194]

[0195]

[0196] Table 3

[0197]

[0198] Discussion of Results:

[0199] Figure 1 , Figure 2 and Figure 3 The results were further shown within the experimental range of 0 to 6 days.

[0200] Microbiological assessment:

[0201] During the 6-day test period, the prior art solutions (US6,500,476 and US5,919,507; test solutions 2 and 3 in Table 1) showed higher Enterobacterial loads compared to the test solutions of the present invention (“FF”) (test solutions 4 to 9).

[0202] Table 1 further shows that the microbial load of the prior art solutions (US6,500,476 and US5,919,507; test solutions 2 and 3) was similar to, or even worse than, the microbial load of simple washing with water (control).

[0203] A comparison of test solutions 4 and 7 showed that higher pH values ​​provided even greater antimicrobial effects.

[0204] Test solution 8 further confirms the correlation of pH. Although comparative test solution 3 is almost identical to test solution 8 of the present invention, comparative test solution 3 provides significantly worse microbiological results, leading to the conclusion that the higher pH of solution 8 is the decisive factor here.

[0205] The results are shown in Figure 1 and Figure 2 Among them Figure 1 The results on day 0, day 3, and day 6 were compared, and Figure 2 The final results for day 6 are displayed. The superiority of the preservation process of this invention lies in… Figure 2 This is particularly evident in the final results.

[0206] Optical evaluation:

[0207] Similarly, most of the test solutions of the present invention (“FF” samples) are superior to the test solutions of the prior art (US6,500,476 and US5,919,507; test solutions 2 and 3 in Table 1).

[0208] Test solution 5 provides an embodiment of the invention, wherein solutions (1) and (2) have active ingredient concentrations covering the lower limit of the invention as defined herein, and have a significantly higher pH (pH 12) than prior art solutions (US6,500,476 and US5,919,507; test solutions 2 and 3 in Table 1). This embodiment of the invention demonstrates that the increased pH provides excellent antimicrobial efficacy while still allowing acceptable anti-browning rates to be maintained, which are still superior to the results obtained with the prior art solution (test solution 3) according to US5,919,507.

[0209] In summary, the prior art solution (test solution 3) according to US5,919,507 does not provide any good optical results at all, and is even worse than the water control (test solution 1 in Table 1).

[0210] The results of the optical evaluation are shown in Figure 3 The results of day 0, day 3, and day 6 were compared. Attached Figure Description

[0211] Figure 1 The microbial load of the preservative solution and the solution of the present invention was compared on days 0, 3, and 6.

[0212] Figure 2 The microbial load of the preservative solution and the solution of the present invention was compared on day 6.

[0213] Figure 3 Comparative optical evaluation of the preservative solution and the solution of the present invention on days 0, 3, and 6.

[0214] (Evaluation of resistance to browning)

Claims

1. A method for preserving fresh food, the method comprising the following steps: (a) Provide an aqueous solution (1), wherein the aqueous solution (1) is an alkaline solution with a pH value ≥ 12.0; (b) Provide an aqueous solution (2) containing 0.5% to 25% w / w ascorbate and / or isoascorbate ions; (c) Apply the aqueous solution (1) to the fresh food; as well as (d) In a subsequent step, the aqueous solution (2) is applied to the same fresh food; The presence of EDTA was excluded. The fresh foods mentioned therein are selected from a group consisting of vegetables, fruits, and herbs.

2. The method for preserving food according to claim 1, wherein the aqueous solution (1) contains at least one hydroxide.

3. The method for preserving fresh food according to claim 1, wherein the aqueous solution (1) contains at least one hydroxide selected from the group consisting of calcium hydroxide, sodium hydroxide and potassium hydroxide or mixtures thereof.

4. The method for preserving fresh food according to claim 3, wherein the aqueous solution (1) contains at least one hydroxide selected from sodium hydroxide and potassium hydroxide or a mixture thereof.

5. The method for preserving fresh food according to claim 1, wherein the aqueous solution (1) contains at least one hydroxide at a concentration of 0.01% to 5% w / w.

6. The method for preserving fresh food according to claim 1, wherein the aqueous solution (1) further comprises 0.1% to 10% w / w ascorbate or isoascorbate ions.

7. The method for preserving fresh food according to claim 1, wherein the aqueous solution (2) has a pH value of ≤8.

8. The method for preserving fresh food according to claim 6, wherein the aqueous solution (2) has a pH value of ≤6.

9. The method for preserving fresh food according to claim 6, wherein the aqueous solution (2) has a pH value of ≤4.

10. The method for preserving fresh food according to claim 6, wherein the aqueous solution (2) has a pH value of 3.0 to 5.

0.

11. The method for preserving fresh food according to claim 1, wherein the temperature of the aqueous solution (1) and the temperature of the aqueous solution (2) are ≤30°C.

12. The method for preserving fresh food according to claim 1, wherein the aqueous solution (1) and / or the aqueous solution (2) further comprises one or more excipients suitable for use in food.

13. The method for preserving fresh food according to claim 1, wherein the aqueous solution (1) and / or the aqueous solution (2) is applied for at least 5 seconds.

14. The method for preserving fresh food according to claim 1, wherein the time between the application of the aqueous solution (1) and the application of the aqueous solution (2) does not exceed 1 hour.

15. The method for preserving fresh food according to claim 1, wherein the aqueous solution (1) and / or the aqueous solution (2) is applied to the fresh food by spraying, sprinkling, rinsing, soaking or immersing or a combination thereof.

16. The method for preserving fresh food according to claim 1, the method comprising additional steps (e) of drying, sieving, centrifuging, blowing, draining, packaging or shaping the fresh food, and combinations thereof.

17. The method for preserving fresh food according to claim 1, wherein no additional washing or neutralization step is applied between the application of the aqueous solution (1) and the aqueous solution (2).

18. The method for preserving fresh food according to claim 1, wherein the presence of a chelating agent is excluded.

19. The method for preserving fresh food according to claim 1, wherein the fresh food is cut agricultural product.

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