Patent ID: 12213493

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for preserving fresh food, such as in particular fresh produce, comprising the following steps:(a) providing an aqueous solution (1), wherein the solution (1) is an alkaline solution with a pH value 10.0;(b) providing an aqueous solution (2), comprising 0.5% to 25% w/w ascorbate and/or isoascorbate ions;(c) applying the solution (1) on the fresh food; and(d) in a subsequent step applying the solution (2) on the same fresh food.

The fresh food according to the present invention is preferably fresh produce.

The 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, most preferably 12.0. It is most preferred that the alkaline solution (1) has a pH of >11.0, more preferred of 11.5, most preferred of ≥12.0. The alkaline solution (1) must be composed to be effective in order to disinfect the treated fresh food, in particular fresh produce, and should prevent further microbial contamination, delay growth of microorganisms and to a certain extend reduce microorganism contamination on the fresh food. The alkaline solution (1) should be effective against one or more of the group of bacteria, yeasts and fungi, in particular efficacy against at least bacteria and yeasts is desirable. It turned out that sufficient activity against yeasts can be achieved by applying an alkaline solution having a pH of >11.0, preferably of 11.5, most preferred of ≥12.0.

In the sense of the present invention, the pH value of the solutions is measured with a common laboratory pH meter for aqueous solutions at room temperature (20° C.±5° C.), making use of electrochemical determination of pH value.

Suitable alkaline compounds for preparing the alkaline solution (1) can be selected from alkali or earth alkali metal salts, or a mixture thereof. Preferred alkali or earth alkali metal salts used for preparing the 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 for preparing the solution (I).

Among the alkaline compounds, hydroxides are preferred, such as in particular sodium and potassium hydroxide, which are among the alkali metals the strongest, most stable and soluble bases of the hydroxides. Using a strong base can ensure a minimum of microbial infestation on the processed food due to its high antimicrobial and disinfecting potential.

A preferred embodiment of the invention relates to a method for preserving fresh food, wherein the solution (1) comprises at least one hydroxide, selected from the group consisting of calcium hydroxide, sodium hydroxide and potassium hydroxide, or mixtures therefrom, preferably sodium hydroxide and potassium hydroxide, or mixtures therefrom. Although the alkaline solution (1) may comprise the at least one hydroxide in mixture with one or more carbonates, in a preferred embodiment the solution (1) does not comprise a carbonate compound.

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

The upper limit of at least one hydroxide in the 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.

In a further preferred embodiment, the solution (1) comprises at least one hydroxide with a concentration of 0.01% to 5.0% w/w, preferably, with a concentration of 0.1% to 4.0% w/w, more preferably with a concentration of 0.5% to 3.0% w/w and most preferably with a concentration of 1.0% to 2.0% w/w. A suitable range can be selected from the lower and upper values in accordance with the specific process conditions, composition of the solution (2) and the food to be treated.

These concentration ranges and limits allow sufficient reduction of microbial infestations on the processed food on the one hand, without causing irreversible damage and taste deterioration of the processed food on the other hand.

The selected concentration ranges provide a good balance between preservation activity and protection of the treated food against textural or sensorial deterioration.

It is further preferred that the solutions used in the method of the present invention are free of potentially harmful and aggressive disinfectants and that the method does not comprise a disinfection step using such undesired disinfectants. Undesired and avoided disinfectants comprise in particular chlorine-based disinfectants, such as sodium chlorite and other salts of chlorous acid, hypochlorites, hypochlorous acid, and chlorine dioxide, but also peroxyacetic acid, quaternary ammonium compounds, ethyl alcohol, isopropyl alcohol, formaldehyde and hydrogen peroxide. Such undesired disinfectants are potentially harmful for food or for the consumer. The solutions used in the present invention are preferably free of these compounds.

The solution (2) comprises 0.5% to 25.0% w/w ascorbate and/or isoascorbate ions.

Preferably the solution (2) comprises 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 ascorbate and/or isoascorbate ions.

The upper limit of the 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.

More preferably the solution (2) comprises 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.

A suitable range can be selected from the lower and upper values in accordance with the specific process conditions, composition of the solution (1) and the food to be treated.

In principle the ascorbate and/or isoascorbate ions can derive from ascorbic acid and isoascorbic acid. Preferably, a salt of ascorbic acid and/or isoascorbic acid is used for preparing the solutions of the present invention, such as preferably an alkali or earth alkali metal salt of ascorbic acid or isoascorbic acid, or mixtures thereof. Preferred salts are selected from calcium ascorbate, calcium isoascorbate, potassium ascorbate, potassium isoascorbate, sodium ascorbate, sodium isoascorbate, magnesium ascorbate, magnesium isoascorbate, and mixtures thereof. The use of potassium ascorbate, potassium isoascorbate, sodium ascorbate, sodium isoascorbate, or mixtures thereof is particularly preferred. Specifically, these alkali and earth alkali metals are required as essential nutrients by organisms to perform functions necessary for life, as they cannot be synthesized biochemically by the human body. Therefore, the use of these ascorbate and/or isoascorbate salts are beneficial. Further, acerola may be used as a source of ascorbate ions or any other suitable ascorbic acid (vitamin C) rich source.

It is also possible to use derivates of ascorbate and/or isoascorbate, like ascorbate esters or ethers, such as in particular ascorbyl palmitate or ethyl ascorbic ether.

The solution (2) has a preferred pH value of ≤pH 8.0, preferably of ≤pH 7.5, more preferably of ≤pH 7.0, more preferably of ≤pH 6.5, more preferably ≤pH 6.0, more preferably of ≤pH 5.5, more preferably of ≤pH 5.0, more preferably of ≤pH 4.5, even more preferably ≤pH 4.0 and most preferably a pH value between of 3.0 and 5.0.

The solution (2) effects neutralization of the alkaline solution and thereby stops the alkaline activity and impacts on the treated foods. However, at the same time the solution (2) exhibits anti-browning/antioxidant properties without deterioration of the sensory and optical properties of the treated produce.

In a particular aspect of the invention, the presence of chelating agents, such as e.g. EDTA, in either of the used solutions (1) and/or (2) is excluded and not necessary to achieve the desired effects.

The solution (1) and the solution (2) are generally aqueous solutions and are accordingly based on water as the solvent. In the sense of the present invention, water includes drinking water as supplied either publicly by local government authorities or privately by the food business itself.

In addition, further solvents can be used other than water, provided they are water-miscible and suitable as food additives, such as e.g. approved by governmental regulations, for example in the German Food Additive Approval Ordinance (Zusatzstoff-Zulassungsverordnung (ZZuIV)) according to the Foodstuffs and Feedstuffs Code (Lebensmittel- and Futtermittelgesetzbuch (LFGB)), or classified as GRAS (generally recognized as safe) food substances by the FDA. Examples of such additional solvents are glycerol and propylene glycol, which are fully miscible with water.

The solution (1) and the solution (2) can independently be applied by spraying, sprinkling, dousing, dipping or immersion or combinations thereof, which corresponds to steps (c) and (d) of the method described above.

The term spraying according to the invention relates to any technical process in which an aerosol is created and aimed at the fresh produce to be conserved. This may be by a pump spray system or a propellant-based spray system. The droplet size of the solution (1) or the solution (2) is not limited to any size range, but preferably the droplets are of microscopic size.

The term sprinkling according to the invention relates to any technical process in which drops and/or droplets of the solution (1) or the solution (2) are sprinkled onto the material like fresh produce, for instance by a sprinkler system.

The term dousing according to the invention relates to any technical process in which the solution (1) or the solution (2) is doused or poured onto the material like fresh produce.

The technical processes referred to as spraying, sprinkling or dousing can be applied to the fresh produce being positioned on a grid, in a tray or on a conveyor belt, but are in no way restricted by these modes of application.

The terms dipping and immersion according to the invention relate to any technical process in which material like fresh produce is brought into a reservoir of the solution (1) or the solution (2) in a way providing that at least parts, but preferably the entire surface is at least temporarily covered by the solution, or in a way that the fresh food, like fresh produce, is floating on the surface of the solution (1) or the solution (2).

Furthermore, any other means suitable for covering the surface of the fresh food, like fresh produce, to be preserved with the solution (1) or the solution (2) can be applied in the method according to the invention.

Preferably, the solution (1) and/or the solution (2) are independently applied for at least 5 seconds. Application time can vary for solution (1) and solution (2) and/or depending on the processed food. Preferably, the solution (1) and/or the solution (2) are independently applied for less than 60 seconds.

The time between the application of solution (1) and solution (2) preferably does not exceed 1 h, more preferably does not exceed 30 minutes and most preferably is between 30 seconds and 10 minutes. On one hand, microbial infestations on the fresh food are declining more as longer solution (1) remains on the fresh food without the application of solution (2). On the other hand, the fresh food may be etched and saponification may occur, leaving unpleasant residues on the treated food. This can also lead to undesired browning-effects on the fresh food, in particular on fresh produce. These side effects are eliminated or suppressed with applying the solution (2), which neutralizes the solution (1).

The ascorbate-containing solution (2) eliminates any residues of the hydroxide solution (1) by neutralization. Furthermore, it forms derivatives of Vitamin C with the remaining sodium and/or potassium ions stemming from hydroxide solution (1). This neutralization process results in leaving only harmless substances like e.g. sodium ascorbate and ascorbic acid on the food. Both are widely accepted and used food additives. The solution (2) further prevents the browning-reaction, strengthens the structure and surprisingly can even reverse potential browning-reactions induced by the application of solution (1) onto the food, in particular fresh produce. Applying only the ascorbate solution (2) may improve the color of the food and prevents discoloration, however, without the prior treatment with the solution (1) the solution (2) alone will not accomplish any bacterial log reduction. Internal studies and literature show, that the sole application of only fruity acids (pH 2.4) does not lead to any log reduction of bacteria. Acids further leave an acidic taste on the fresh produce to be consumed and it is preferred to avoid such acidification but maintain the natural food taste.

Preferably, the solution (2) is applied for at least 5 seconds and can vary depending on the food and the amount and composition of the solution (1) applied on the same fresh food. This minimum duration ensures a comprehensive anti-microbial effect due to the solution (1).

Preferably, there is no additional washing or neutralization step applied between treatment with solution (1) and treatment with solution (2) of the invention. This means, a two-step treatment is preferred.

The duration of the application of the solution (1) can be extended by the addition of ascorbate/isoascorbate ions to the solution (1), as described below in more detail, as well as by the subsequent use of the solution (2).

The composition of solution (2), comprising ascorbate and/or isoascorbate ions, is controlled to have an ascorbate/isoascorbate concentration high enough to neutralize all hydroxides of solution (1). The neutralization vice versa encounters the sour taste of the ascorbate and/or isoascorbate solution.

Optionally, the solution (1) and/or the solution (2) according to the invention furthermore contain one or more excipients suitable for the use in food, in particular fresh produce selected from the group of anti-adherents, binders, colors, flavors, lubricants, preservatives, sweeteners, such as in particular listed in governmental regulations, for example in the German Food Additive Approval Ordinance (Zusatzstoff-Zulassungsverordnung (ZZuIV)) according to the Foodstuffs and Feedstuffs Code (Lebensmittel- and Futtermittelgesetzbuch (LFGB)), or classified as GRAS (generally recognized as safe) food substances by the FDA. Depending on the further excipients the application time of the solution(s) can be shortened or prolonged or the microbial reduction effect can be enhanced.

In a preferred embodiment of the invention, the solution (1) and/or the solution (2) contain less than 30 weight-% of an excipient or excipients, more preferably less than 20 weight-%, even more preferably less than 10 weight-%, and most preferably less than 5 weight-% of excipients.

In a further embodiment the solution (1) may also contain, in addition, ascorbate and/or isoascorbate ions. By adding small amounts of ascorbate and/or isoascorbate ions already to the alkaline solution (1), the process of etching and the browning-reaction on fresh food, in particular fresh produce can surprisingly be delayed significantly while the pH of the solution does not vary due to the buffering effect of the ascorbate and/or isoascorbate ions. It was expected that an alkaline solution (1) additionally containing ascorbate and/or isoascorbate ions would etch the fresh food, in particular fresh produce, in the same amount of time as in case of using a solution (1) without ascorbate and/or isoascorbate ions. The surprising delay of the etching significantly improves the suitability of the process due to the possibility of increasing the application time of the alkaline solution (1) to exceed the disinfection period.

In embodiments, wherein ascorbate and/or isoascorbate ions are added to the alkaline solution (1), it is preferred that solution (1) comprises ascorbate and/or isoascorbate ions in a concentration between 0.1% to 10.0% w/w.

In such embodiments the solution (1) preferably comprises 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 ascorbate and/or isoascorbate ions.

In such embodiments the upper limit of the 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.

More preferably, when ascorbate and/or isoascorbate ions are added to the alkaline solution (1), it is preferred that solution (1) comprises ascorbate and/or isoascorbate ions in a concentration between 0.5% to 5.0% w/w, even more preferably 1.0% to 2.0% w/w.

A suitable range can be selected from the lower and upper values in accordance with the specific process conditions, composition of the solution (1) and the food to be treated.

In a preferred embodiment ascorbate and/or isoascorbate ions are added to the solution (1), until solution (1) has a pH 10.0, more preferred 11.0 most preferred 12.0.

As mentioned above, generally, the process conditions and composition and concentrations of the solutions (1) and (2) of the present invention can be selected and controlled within the claimed ranges to achieve the desired effects. For example, when using a solution (1) with higher pH values, e.g. pH 12.0, a concentration of ascorbate/isoascorbate ions in solution should be selected which is capable to achieve the desired neutralization. In cases of using an alkaline solution (1) with a pH 12.0 and without addition of ascorbate/isoascorbate ions in solution (1) the lower limit of the ascorbate and/or isoascorbate 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) also contains ascorbate/isoascorbate ions, the concentration of the ascorbate and/or isoascorbate ions in solution (2) can be selected from the whole range defined herein, i.e. from 0.5% to 25% w/w.

The pH values of the solution (1) and of the solution (2) should be selected independent of one another. The solution (2) should have a pH low enough (acidic) to reverse the pH of the food products treated with the alkaline solution (1) to neutral pH or below. If no sufficient neutralization or acidification of the treated food is achieved with the solution (2) and in case the treated food products remain with an alkaline pH of e.g. pH>8.0 after the preservation treatment this may lead to undesired deterioration, such as discoloration and browning of the food due to tissue damage. It is therefore desirable to control the pH of the solutions (1) and such that in or after the step of treatment with solution (2) the pH will not become alkaline, but preferably will be ≤pH 8.0, preferably of ≤pH 7.5, more preferably of ≤pH 7.0, more preferably of ≤pH 6.5, more preferably ≤pH 6.0, more preferably of ≤pH 5.5, more preferably of ≤pH 5.0, more preferably of ≤pH 4.5, even more preferably ≤pH 4.0 and most preferably a pH value between of 3.0 and 5.0.

The method of preserving food, in particular fresh produce, according to the invention is preferably carried out at ambient temperature/normal conditions. In any case, the temperature of the solution (1) and/or the solution (2) should not exceed boiling temperature and should be controlled to avoid boiling or cooking or otherwise temperature-induced deterioration of the fresh food, in particular fresh produce. The temperature of the applied solutions is preferably ≤50.0° C., more preferably is ≤40.0° C., even more preferably is ≤30.0° C. and most preferably is room temperature (20° C.±5° C.). It is also possible to carry out the process at temperature below 20° C. with cooled fresh food, in particular cooled fresh produce, however freezing of the solution(s) must be avoided.

A temperature below the boiling point is preferred, as this way the water retention of the food, in particular fresh produce, does not destroy the structure of the treated food. Even lower temperatures are preferred, such as below 40-50° C., because on one hand, depending on the temperature, proteins and/or vitamins in the fresh food, in particular in fruits and vegetables, may denature or be destroyed at higher temperatures and the treated food may be therefore less nutritious and on the other hand, the structure of the fresh food may soften at such temperature leading to loss of its crunchy structure, as for example with apples or nectarines. At a temperature of 20° C. and especially at a temperature around 20° C. or below, it can generally be ensured that the treatment has little to no effect regarding the structure of the food, in particular fresh produce, especially with regard to alkaline treatment and acidic treatment. Furthermore, the lower temperature of the treatment, especially of the solution (1), but also of the solution (2), allows a longer treatment period, since etching, the browning-reaction and degradation of the structure occurs later. The longer treatment time allows the microbial infestation to be further reduced without having negative impact on the structure of the fresh food, in particular fresh produce.

It is known to use alkaline solutions for treating fruits and vegetables. However, known alkaline treatments aim at chemical peeling of fruits and vegetables and are usually carried out with significantly higher concentrations of the alkaline compound and under steam or high temperatures. In contrast the method of the present invention is neither used nor suitable for such an alkaline/chemical peeling process. The present method differs in the processing conditions such as lower temperatures and lower alkali concentrations.

In the process of the present invention no final washing step is necessary, as the alkaline solution (1) and the acidic solution (2) neutralize each other. This is a clear procedural advantage with respect to saving time and resources.

The process of preserving food, in particular fresh produce, described herein may comprise one or more further steps selected from step (e) drying, sieving, centrifuging, air-blowing, draining, packaging, or confectioning and combinations thereof.

In the sense of the present invention the term “food” relates to any food which may be prone to oxidation. The term “food” comprises processed food like cut, sliced, or peeled vegetables or fruits. The invention particularly relates to fresh food, more particularly to fresh produce. Nevertheless, it is also possible to apply the method of the invention to dried or semi-dried fruits and vegetables.

Fresh produce in the sense of the invention, relates to fresh food such as vegetables, fruits and herbs. In the sense of the invention fresh food relates to food, that was not processed with chemical or physical preservation measures, such as in particular the above excluded chemical preservation methods or heat or steam conservation methods. In the sense of the present invention, fresh produce taxonomically belonging to fungi, such as champignons, mu err, porcino, chanterelle and any other mushrooms, are considered to be comprised by the term vegetables.

In the sense of the present invention, the term “fresh produce” in particular comprises fresh fruit and vegetables. Primarily, but not exclusively, such fresh fruit and vegetables are farm-grown.

In the sense of present invention, the term “fresh produce” further comprises fruits and vegetables that are either in the same state as they were harvested, or have been peeled, sliced, chopped or submitted to any means for reducing size or providing bite-size portions of fruits and vegetables, such as slicing, chopping, cutting or peeling. Herbs may be also be present in cut form.

In a preferred embodiment the method of preserving the food, in particular fresh produce, is applied to fresh cut produce. Especially, fresh cut produce is prone to etching and/or browning. Treatment of fresh cut produce with solution (1) and solution (2) in accordance with the process of the present invention protects this cut produce in particular.

Fresh produce and/or fresh cut produce to be preserved with the method of the present invention may be selected from the group of fresh fruits comprising apples, avocados, rhubarb, melons, pineapple, cherries, strawberries, nectarines, peaches, kiwi, lemons, oranges, apricot, coconut, grapes or dragon fruit; fresh produce and/or fresh cut produce from the group of fresh vegetables may be selected from the group comprising pears, potatoes, carrots, lettuce, leeks, onions, rutabaga, kale, mushrooms, garlic, peppers, tomatoes fennel, asparagus, beans, peas, broccoli, cauliflower, Brussel sprouts, cabbage, celery, chard, corn, endive, leafy greens, okra, chili, beetroot, turnip, ginger, radish, squashes, courgette, pumpkin, artichoke, sweet potato, ginger, turmeric, eggplant or zucchini as well as fungi (as defined above); fresh produce and/or fresh cut produce from the group of fresh herbs may be selected from basil, parsley, mint, dill, sage rosemary, thyme, cilantro, fennel, chamomile, lemongrass, oregano, chives, or watercress.

The method for preserving fresh cut produce is preferably applied to:fresh cut produce selected from fruits consisting of apple, rhubarb, melon, pineapple, coconut, strawberries, grapes or kiwi;fresh cut produce selected from vegetables consisting of carrots, tomatoes, peppers, zucchini, leafy greens, mushrooms or eggplant;fresh cut produce selected from herbs consisting of basil, parsley, mint, cilantro or chives.

The method for preserving fresh cut produce is preferably applied to:apples, melon, pineapple, strawberries, coconut, grapes, or leafy greens.

The invention further relates to a combination of a solid composition (1) and a solid composition (2), ready for dissolution in a suitable solvent, preferably water or mixtures of water with other water miscible solvents as defined above, for providing the solution (1) and/or the solution (2) as defined herein. Alternatively, the invention covers a combination of the ready-to-use solutions (1) and (2) for carrying out the herein described process.

A further aspect of the invention relates to a kit-of-parts combination (kit-of-parts product) comprising:a) the solution (1) as defined above;b) the solution (2) as defined above;in a separated special arrangement; and optionally one or more ofc) an instruction leaflet, and/ord) container for the parts to be treated like a box or a bag, for example made from plastic, or any other suitable container made from any other suitable material or single-use devices for carrying out the process of the invention, like tubes, falcons, cuvettes, bottles, syringes, dispenser, phials etc. made from plastic, glass, or other suitable materiale) optionally a container for packaging and/or storing the parts to be treated or the parts after treatment.

In a further embodiment the invention relates to a kit-of-parts combination (kit-of-parts product) comprising:a) the compounds, in particular salts, for preparing the solution (1) as defined above;b) the compounds, in particular salts, for preparing the solution (2) as defined above, in a separated special arrangement;c) optionally solvents as defined above for dissolving the compounds for solution (1) and (2); andd) an instruction leaflet, and/ore) container wherein the compounds a) and/or the compounds b) can be dissolved for preparing the solutions (1) and (2), like tubes, falcons, cuvettes, bottles, phials etc., made from plastic, glass, or other suitable material; and/orf) container for the parts to be treated like a box or a bag, for example made from plastic, or any other suitable container made from any other suitable material or single-use devices for carrying out the process of the invention, like tubes, falcons, cuvettes, bottles, syringes, dispenser, phials etc. made from plastic, glass, or other suitable material;g) optionally a container for packaging and/or storing the parts to be treated or the parts after treatment.

This embodiment is particularly preferred, if the solvent for preparing solution (1) and (2) is water, which then needs not to be included in the kit-of-parts.

The instruction leaflet may in particular comprise instructions for preparing the solutions (1) and (2) and for the treatment conditions of the fresh food.

The kit-of-parts described herein are intended for the use in a method for preserving fresh food, in particular fresh produce as described herein.

EXAMPLES

The present invention is further illustrated by the following examples, without being limited thereto.

A. Microbial Log Reduction Test and Sensorial Evaluation

Microbial log reduction can be carried out with the following test conditions:I. Preparation of (solid) agar-plates according to instruction paper (if necessary adapt to pH-value with NaOH or HCl):1 VRBD-Agar:41.5 g/l distilled water; sterilization 118° C. for 15 min.2. YGC-Agar:40.2 g/l distilled water; sterilization 121° C. for 15 min.3. LB-Agar:10 g/l Tryptone5 g/l NaCl5 g/l Yeastextract 2.5 g/lGlucose15 g/l AgarpH 7.5distilled water; sterilization 121° C. for 21 min.II. Weighing of products (fruits/vegetables); add preferred amount of liquid medium and pestle until receiving a homogenous mixture. Easiest is to use 1 ml per gram product, since then the titer is directly cfu/g product. If there is not enough liquid present, use a higher amount of medium. Take care to adjust the titer appropriately.III. Preparation of serial dilution (0, −1, −2, −3 . . . ; depending on the expected bioburden)IV. Plating of content of 1.5 ml reaction tubes (e.g.) on (solid) agar plates by transferring 100 μl of a measured homogenous mixture of the test sample (e.g. fruits/vegetables) on the agar surface; if Enterobacteriaceae are to be detected, preparation of a fresh VRBD-Agar-solution is needed, that is to be poured on top (between 45° and 50° C.) to create an anaerobic layer to ensure a fermentation process.V. After 18-24 hours (VRBD)/48 hours (LB)/(3-)7 days (YGC) at 37° C. (VRBD), resp. room temperature (LB, YGC) colony forming units per ml (CFU/ml) are counted; the titer is determined. LB gives the mesophilic aerobic total bacterial count, VRBD the one forEnterobacteria, and YGC the total count for fungi. For YGC a differentiation between yeasts and fungi has to be done optically. For VRBD, disregard colonies growing on the surface. Violet colonies in the agar suggest acid production, light colonies do not produce acid.

The tests are based on the official procedure for evaluation of bacterial contamination. Differences are the medium used for total bacterial count and the incubation temperature for LB and YGC (room temperature instead of 25° C.).

Example A-1: Control

Sliced parts of pineapple without any treatment for five days constitute the control.After five days a significant growth of bacteria, yeast and fungi and sensorial deterioration was detected.

Comparative Example A-2: Treatment with Ascorbic Acid Solution (pH 2.4)

Sliced parts of pineapples, similar as in Example A-1, were treated by applying an ascorbic acid solution (pH 2.4) with a concentration of 6% w/w.A significant growth of bacteria, yeast and fungi, but lesser sensorial deterioration was detected.

Comparative Example A-3 Treatment with 0.4 PPM ClO2Solution

Sliced parts of pineapples, similar as in Example A-1, were treated by applying 0.4 ppm ClO2solution (6% w/v). The quotient corresponds to the permitted value determined by the

Drinking Water Ordinance (TrinkwV) of the Federal Republic of Germany and is commonly used as a disinfectant.A 0.5 log reduction of bacterial, yeast and fungi infestation, but sensorial deterioration after 5 days was detected.

Comparative Example A-4: Treatment with 80 PPM Peroxyacetic Acid Solution

Sliced parts of pineapples, similar as in Example A-1, were treated by applying 80 ppm peroxyacetic acid solution. The quotient corresponds to the permitted value determined by the US FDA limitation for washing fruits and vegetables and is commonly used as a disinfectant in the area of use.A log reduction of 1 of bacterial, yeast and fungi infestation, but sensorial deterioration after 5 days was detected.

Comparative Example A-5: Treatment with 1% (w/w) Sodium Hydroxide Solution

Sliced parts of pineapples, similar as in Example A-1, were treated by applying 1% (w/w) sodium hydroxide solution [corresponding to solution (1) of the present invention].A log reduction of 1-2 of bacterial, yeast and fungi infestation, but significant sensorial deterioration was detected.

Comparative Example A-6: Treatment with 0.4 PPM C102 Solution and Subsequent Treatment with Ascorbic Acid Solution (pH 2.4)

Sliced parts of pineapples, similar as in Example A-1, were treated by applying 0.4 ppm ClO2solution (6% w/v) and afterwards ascorbic acid solution (pH 2.4) with a concentration of 6% w/w [corresponding to solution (2) of the present invention] was applied on the same test material.A 0.5 log reduction of bacterial, yeast and fungi infestation, but lesser sensorial deterioration was detected.

Comparative Example A-7: Treatment with 80 PPM Peroxyacetic Acid Solution and Subsequent Treatment with Ascorbic Acid Solution (pH 2.4)

Sliced parts of pineapples, similar as in Example A-1, were treated by applying 80 ppm peroxyacetic acid solution and afterwards ascorbic acid solution (pH 2.4) with a concentration of 6% w/w [corresponding to solution (2) of the present invention] was applied on the same test material.A log reduction of 1 of bacterial, yeast and fungi infestation, but lesser sensorial deterioration was detected.

Example A-8: Treatment with 1% (w/w) Sodium Hydroxide Solution [Solution (1)] and Subsequent Treatment with Ascorbic Acid Solution (pH 2.4) [Solution (2)]

Sliced parts of pineapples, similar as in Example A-1, were treated by applying 1% (w/w) sodium hydroxide solution [corresponding to solution (1) of the present invention] was applied on the test material and afterwards ascorbic acid solution (pH 2.4) respectively with a concentration of 6% w/w [corresponding to solution (2) of the present invention] was applied on the same test material.A log reduction of 2 of bacterial, yeast and fungi infestation and better sensorial character for up to 8 days was detected.

Reverse Effect of Discolored Fresh Produce

Comparative Example B-1.1: Treatment of Onions with 1% (w/w) Sodium Hydroxide Solution [Solution (1)]

1% (w/w) sodium hydroxide solution [corresponding to solution (1) of the present invention] was applied onto sliced parts of onions which caused immediate discoloration over the entire storage time of 14 days.

Example B-1.2: Treatment of Onions with 1% (w/w) Sodium Hydroxide Solution [Solution (1)] and Subsequent Treatment with Ascorbic Acid Solution (pH 2.4) [Solution (2)]

The test material was treated with the hydroxide solution (1) according to Example B-1.1 and subsequently an ascorbic acid solution (2) (pH 2.4) with a concentration of 6% w/w [solution (2)] was applied onto the same test material immediately thereafter. Surprisingly, the discoloration was not only stopped but even reversed and the test material took the original appearance as before the hydroxide treatment. This appearance was maintained during the entire storage time of 14 days.

Comparative Example B-2.1: Treatment of Sliced Apples with 1% (w/w) Sodium Hydroxide Solution [Solution (1)]

1% (w/w) sodium hydroxide solution [corresponding to solution (1) of the present invention] was applied onto sliced parts of apple which caused significant discoloration within 1-2 minutes over the entire storage time of 21 days.

Comparative Example B-2.2: Treatment of Sliced Apples with Ascorbate Solution (pH 2.4) [Solution (2)]

An ascorbate solution (pH 2.4) with a concentration of 6% w/w [corresponding to solution (2) of the present invention] was applied onto sliced parts of apple which only prevented discoloration to a certain extent, as some apple slices still turned brown.

Example B-2.3: Treatment of Sliced Apples with 1% (w/w) Sodium Hydroxide Solution [Solution (1)] and Subsequent Treatment with Ascorbic Acid Solution (pH 2.4) [Solution (2)]

The test material was treated according to Example B-2.1 and an ascorbic acid solution (2) (pH 2.4) with a concentration of 6% w/w [solution (2)] was applied onto the same test material immediately thereafter. The discoloration was prevented more effectively. This appearance was maintained during the entire storage time of 21 days. The sodium ions of the sodium hydroxide solution significantly improved the anti-browning effect and prevented the discoloration more effectively.

The results are summarized in Table 1 as follows:

TABLE 1Exam-Exam-ExampleExampleplepleExampleExperimentB-1.1B-1.2B-2.1B-2.2B-2.3Solution1%+++−+(1)(w/w)NaOHSolutionAscorbic−+−++(2)acid (pH2.4/6%w/w)SolventwaterwaterwaterwaterwaterDeterioration/Etching++ReversedDiscoloration/++Reversed+++—BrowningPreservedPreservedup to 14up to 21daysdays
B. Comparative Tests

Comparative experiments with compositions described in the prior art U.S. Pat. Nos. 6,500,476 and 5,919,507 (Table 1) have been carried out to show the improvements and surprising effects achievable with the new method of the present invention over the claimed range (Table 2 and 3).

Test Conditions:

Storage: 5-8° C. Packing type: Plastic TraysPiece size: Very thin slices, machine cutTest duration: 6 Days

Pieces of fresh cut carrots are treated with the different test solutions and evaluated with respect to their log reduction as described in Example A above.

Further, the optical appearance was examined by a visual (optical) evaluation of the treated test pieces and the anti-browning rate was determined according to the following formula
100−(number of test pieces affected by browning/total number of test pieces)×100=anti-browning rate [%].

Therein, the anti-browning rate (%) indicates the proportion of test pieces without browning. This means that a higher anti-browning rate correlates to a better anti-browning performance.

FIGS.1,2and3illustrate the results of the following Tables 1 to 3 further.

TABLE 1231Comparative Example overComparative Example overSolution/ControlU.S. Pat. No. 6,500,476U.S. Pat. No. 5,919,507Composition%g/Solution%g/Solution%g/SolutionSolution (1)100.00%2000Water0.42%8Na2CO34.20%84NaHCO30.08%2NaHCO3pH1150% NaOHSolution (2)100.00%2000Water0.60%12Citric acid0.60%12Isoascorbic acid2.40%48Na-Isoascorbate0.80%16Na-Citrate0.10%2EDTA0.10%2CaCl2Solution (3)2.00%40Na-Isoascorbate0.10%2EDTA0.10%2CaCl2CommentTo verify effectiveness of“Best solution” according to“Best solution” according to Comparativeother solutions over neutralU.S. Pat. No. 6,500,476Example over U.S. Pat. No. 6,500,476water treatmentand U.S. Pat. No. 5,919,507Dipping time2 dips, 1 minute each1st: 30 s; 2nd: 15 s; 3rd: 15 s1std: 120 s; 2ndd: 60 sConductivity b. [mS]07.13.86.51 d: 53 | 2 d: 8.25Conductivity a. [mS]0.606.054.06.91 d: 49.5 | 2 d: 12.5pH Value before7.5510.385.35.71 d: 11.0 | 2 d: 4.69pH Value after7.2510.35.35.341 d: 11.22 | 2 d: 8.96Mibi results Ø n = 4Day 0Day 3Day 6Day 0Day 3Day 6Day 0Day 3Day 6Enterobacterales3.25E+034.99E+034.51E+042.19E+031.86E+041.86E+058.77E+026.76E+025.23E+04anti-browning rate100%70%65%100%82%80%100%65%50%

TABLE 2456Solution/FF-1 6% Asc.FF-1 0.5% pH 12FF-1 25% Asc.Composition%g/Solution%g/Solution%g/SolutionSolution (1)1.00%40 mL50%pH 125.5 mL50%1.00%40 mL50%NaOHNaOHNaOHSolution (2)6.00%120Ascorbic0.50%10Ascorbic25.00%500AscorbicacidacidacidCommentPresent inventionPresent inventionPresent inventionLower middle of claimed rangeLower limit of claimed rangeUpper limit of claimed rangein Solution (2)in Solution (2) and Solution (1)in Solution (2)with pH 12.0Dipping time2 dips, 1 minute each2 dips, 1 minute each2 dips, 1 minute eachConductivity b.1 d: 140 | 2 d: 1.451 d: 4.5 | 2 d: 0.61 d: 140 | 2 d: 2.0[mS]Conductivity a.1 d: 65 | 2 d: 1.41 d: 4.2 | 2 d: 0.6221 d: 65 | 2 d: 2.28[mS]pH Value before1 d: 12.9 | 2 d: 2.661 d: 12.0 | 2 d: 3.381 d: 12.9 | 2 d: 2.35pH Value after1 d: 12.5 | 2 d: 3.051 d: 11.96 | 2 d: 3.611 d: 12.5 | 2 d: 3.11Mibi results Ø n = 4Day 0Day 3Day 6Day 0Day 3Day 6Day 0Day 3Day 6Enterobacterales3.83E+012.88E+028.95E+034.30E+021.66E+032.02E+04<10<101.60E+02anti-browning rate100%90%85%100%75%70%100%100%95%

TABLE 3789Solution/FF-1 pH 11.5FF-1 Iso-Asc.FF-1 Iso-Asc. 2Composition%g/Solution%g/Solution%g/SolutionSolution (1)pH 11.50.64 mL50%1.00%40 mL50% NaOH1.00%40 mL50%NaOHNaOHSolution (2)6.00%120Ascorbic0.60%12Iso-Ascorbic0.10%2Iso-acidacidAscorbicacid2.40%48Na-Isoasc.2.90%58Na-IsoascCommentPresent inventionPresent inventionPresent inventionSolution (1) pH 11.5Solution (2) like in Composition 3Solution (2) like in Composition 3(U.S. Pat. No. 5,919,507)(U.S. Pat. No. 5,919,507), slightly acidicDipping time2 dips, 1 minute each2 dips, 1 minute each2 dips, 1 minute eachConductivity b.1 d: 2.0 | 2 d: 1.451 d: 140 | 2 d: 6.351 d: 140 | 2 d: 7.21[mS]Conductivity a.1 d: 1.3 | 2 d: 1.41 d: 65 | 2 d: 8.751 d: 65 | 2 d: 9.93[mS]pH Value before1 d: 11.5 | 2 d: 2.661 d: 12.9 | 2 d: 5.11 d: 12.9 | 2 d: 6.04pH Value after1 d: 11.0 | 2 d: 3.051 d: 12.5 | 2 d: 10.71 d: 12.5 | 2 d: 11.3Mibi results Ø n = 4Day 0Day 3Day 6Day 0Day 3Day 6Day 0Day 3Day 6Enterobacterales5.59E+021.15E+033.05E+049.17E+015.50E+013.37E+031.75E+018.00E+013.25E+03anti-browning rate100%95%90%100%70%60%100%40%30%
Discussion of the Results:

TheFIGS.1,2and3further illustrate the results over the test range of 0 to 6 days.

Microbial Assessment:

The solutions according to the prior art (U.S. Pat. Nos. 6,500,476 and 5,919,507; test solutions 2 and 3 in Table 1) both show a higher microbial load ofenterobacteriacompared to the (“FF”) test solutions according to the invention (test solutions 4 to 9) over the test period of 6 days.

Table 1 further shows that the microbial load of the prior art solutions (U.S. Pat. Nos. 6,500,476 and 5,919,507; test solutions 2 and 3) is similar to that of a simple wash with water (Control) or even worse than water.

A comparison of test solutions 4 and 7 show, that a higher pH value provides even higher antimicrobial effects.

Test solution 8 further confirms the relevance of the pH value. Although comparative test solution 3 is nearly identical to test solution 8 according to the invention, the comparative test solution 3 provides significantly worse microbial results which leads to the conclusion that the higher pH value of solution 8 is the decisive factor here.

The results are illustrated inFIGS.1and2, whereinFIG.1compares the results on days 0, 3 and 6, whileFIG.2shows the final results on day 6. The superiority of the preservation treatments according to the invention is particularly apparent from this final result onFIG.2.

Optical Evaluation:

Again, most test solutions according to the invention (“FF” samples) are superior over the test solutions according to the prior art (U.S. Pat. Nos. 6,500,476 and 5,919,507; test solutions 2 and 3 in Table 1).

Test solution 5 provides an example according to the invention with the solutions (1) and (2) having a concentration of active components covering the lower limits of the invention as defined herein and having a significantly higher pH value (pH 12) compared to the prior art solutions (U.S. Pat. Nos. 6,500,476 and 5,919,507; test solutions 2 and 3 in Table 1). This example according to the invention shows that the increased pH provides superior antimicrobial efficacy but nevertheless allows to maintain an acceptable anti-browning rate, which is still better than the results achieved with the prior art solution according U.S. Pat. No. 5,919,507 (test solution 3).

Overall, the prior art solution according to U.S. Pat. No. 5,919,507 (test solution 3) does not provide any good optical results at all and is even worse than the water control (test solution 1 in Table 1).

The results of the optical evaluation are illustrated inFIG.3comparing the results on days 0, 3 and 6.

DESCRIPTION OF THE FIGURES

FIG.1Microbiological load of comparative preservative solutions and solutions according to the invention on day 0, 3 and 6.

FIG.2Microbiological load of comparative preservative solutions and solutions according to the invention on day 6.

FIG.3Optical evaluation (anti-browning evaluation) of comparative preservative solutions and solutions according to the invention on day 0, 3 and 6.