[0001] This invention unveils a novel procedure for the dyeing and stabilizing of kiwi through a series of steps and with the use of dyeing and stabilizing agents and auxiliaries to obtain a final product with a stable non-bleeding proper color, appropriate firmness and desirable organoleptic features that are able to withstand thermal or chemical processing, light and time and thus are suitable for its use in fruit products.

Background Art

[0002] A strong loss of color and firmness takes place when kiwi fruit is canned and pasteurized under normal conditions. The natural magnesium chlorophyll is a very unstable pigment that fades quickly upon heating and consequently the heated fruit turns yellowish. The yellowish color is explained by the presence of carotenoids or xanthophylls that withstand the heating process.

[0003] Also, during the heating process a great loss of firmness occurs, which can be explained mainly by the diffusion of the natural fruit stabilizing-thickening agents (vegetable gums) to the packing syrup. This explains why today canned kiwi pieces or slices are manufactured using unripe fruit. When unripe fruit is selected for preservation, important quality features such as flavor are sacrificed in favor of firmness and pulp hardness.

[0004] We have, after studying processes for coloring and stabilizing kiwi and other types of fleshy fruits, found a simple process based on the use of stabilizing agents and natural colorants for preparing a very stable, firm, non-bleeding naturally colored kiwi with natural texture and flavor. That is to say, we have succeeded in obtaining a very stable product that withstands thermal and or chemical sterilization processes, light and time without the loss of color, texture and hardness or flavor.

Disclosure of Invention [0005] A) Pulp exposure A.1) The desired level of ripeness for the process disclosed on the invention is that which renders the most intense flavor attributes and aptness for direct consumption.

• A.2) Customary processes for the industrial preconditioning of the fruits are recommended, such as selection, washings, removal of stems and leaves, etc.

• A.3) The kiwi must be peeled and/or cut to allow the direct exposure of the pulp to the coloring/dyeing, stabilizing and fixing agents. Preferable, peeled kiwi slices are used for further processing.

[0006] B. Alkalinizing, Stabilizing and Dyeing

B.1) Surprisingly, the present inventors have identified that the kiwi pieces can be alkalinized in a certain way in which many of its attributes, like flavor / aroma and texture are not affected. Thus, after peeling and cutting, the kiwi slices are alkalinized. This process can take place simultaneously with the stabilizing processes. The alkalinizing stabilizing solution can be used in a weight ratio between 10:1 and 0.8:1 (solution to fruits), preferably between 2:1 and 1 :1 and most preferably of 1.1 :1.

B.2) The alkalinization is provided by a suitable alkalizing agent, which can be of organic or inorganic nature. Examples of suitable alkalizing agents are (but not limited to): sodium hydroxide, potassium hydroxide, calcium carbonate, sodium carbonate, magnesium hydroxide, ammonium hydroxide, amides, and their mixtures. More preferred alkalinizing agents are: sodium hydroxide, potassium hydroxide and ammonium hydroxide. Preferably, the alkalinization takes place so that the pH of the pulp is between 7 - 13, with pH 8 - 11 being preferable. In the most preferred embodiment, the pH of the pulp is 9.5 to 10.5.

B.3) Surprisingly, the present inventors have identified that the infusion under this alkaline condition of certain hydrocolloids that form gels in acidic conditions and/or in presence of polyvalent cations like calcium (gelling stabilizing), can restore or maintain the texture of the fruit and add or maintain their firmness and hardness, even in high temperature conditions like pasteurization or after freezing and thawing cycles like in the IQF kiwi. Examples of such gelling stabilizing agents are (but not limited to): Alginic acid and its salts (sodium, potassium, ammonium and propylene glycol), gellan gum, calcium reactive pectins (low-ester pectin and amidated pectin), carrageenans (iota and kappa forms) and its salts (ammonium, potassium, or sodium) and carboxymethyl cellulose. Preferably, the amount of gelling stabilizing agents by weight in the alkalinizing stabilizing solution is between 0.005% and 5%, more preferably 0.01 % and 2%, and in the most preferred embodiment 0.02% and 1%.

B.4) The said gelling stabilizing agents can be added in combination with other secondary thickeners, stabilizers, and/or gelling agents to increase the firmness of the fruit. The said secondary stabilizing agents may include vegetable, algal and microbiological hydrocolloids like agar-agar, carrageenan, processed eucheuma seaweed, arabinogalactan, cassia gum, locust bean gum, oat gum, guar gum, tragacanth, acacia gum, xanthan gum, karaya gum, tara gum, gum ghatti, glucomannan, pectins. Also, complex carbohydrates like starches, modified starches and modified cellulose polymers like methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxy propyl methyl cellulose, ethyl methyl cellulose, carboxymethyl cellulose, sodium carboxy methyl cellulose and enzymically hydrolysed carboxymethyl cellulose can be used as secondary thickeners, stabilizers, and/or gelling agents.

B.5) Surprisingly, the present inventors have identified that under the said alkaline condition copper complexes of chlorophyllin and optionally curcumin and norbixin can be infused into the pulp and after exposure of the alkalinized and dyed fruit to acidic conditions or to polyvalent cations like calcium, a non-bleeding natural green kiwi color can be obtained. Copper complexes of chlorophyllin, curcumin and norbixin are soluble and stable under alkaline conditions but precipitate in presence of acids and/or polyvalent cations like calcium. Preferably, the dyeing takes place so that the color intensity of the alkalinizing dyeing solution is between 0.01 and 1 , with 0.05 to 0.8 being preferable. In the most preferred embodiment, the color intensity of the alkalinizing dyeing solution is 0.1 to 0.5. Color intensity is defined as the absorbance of a 1 % alkalinized solution (pH>8) in distilled water, at the wavelength of maximum absorbance for the colorant (\ _ma x copper chiorophyiiin = 405 nm, max curcumin ^— 425 nm, A _ma x norbixin = 453 nm).

B.6) The temperature of the alkalinizing stabilizing dyeing processes should be as low as possible to avoid damage to the fruit. Preferably, temperature range is between 0°C and 40°C, more preferably between 4°C and 25°C and most preferred between 6°C and 12°C.

B.7) The length of the alkaline step depends on the ripeness of the kiwi, the temperature of the solution and the desired final color. Preferably, time range of exposure is between 20 min and 24 hours, preferably between 1 and 8 hours and most preferably between 2 and 4 hours.

B.8) The order of the addition of the components (stabilizing agents, dyes, etc) of the alkaline solutions is not relevant, provided that the complete solubility of the dyes and the stabilizing agents are guaranteed.

C. Fixation

C.1) Once the alkaline dyeing process is finished, the treated kiwi pieces must be immersed in a fixing acid solution containing certain substances that facilitate the precipitation of the soluble dyes and the gelling of the stabilizing agent.

C.2) This fixing acid solution should be used in a weight ratio between 10:1 and 0.8:1 (solution to fruits), preferably between 3:1 and 1 :1 and most preferably of 2:1.

C.3) The gelling stabilizing agents and dyes infused into the fruit during the alkaline step are fixed by the acid present in the fixing acid solution. The acid condition allows the formation of gels and precipitation of the dyes. The acid conditions are provided by means of suitable inorganic and/or organic acids such as: hydrochloric acid, sulphuric acid, phosphoric acid, nitric acid, citric acid, fumaric acid, acetic acid, tartaric acid, malic acid, oxalic acid, tannic acid, benzoic acid, propionic acid, lactic acid, ascorbic acid, etc. Among these the following are preferred: ascorbic acid, citric acid, lactic acid, malic acid and tartaric. Preferably, the acidification takes place so that the pH of the pulp is between 2 - 7, with pH 3 - 5 being preferable. In the most preferred embodiment, the pH of the pulp is 3 to 4.

C.4) The gelling stabilizing agents and dyes infused into the fruit during the alkaline step are fixed by polyvalent cations that allows the formation of gels and precipitation of the dyes. The rheological property of the gel formed by the stabilizing agents and the color distribution and hue of the precipitated dyes depends on the type of polyvalent cation, their concentration and on the combinations of the cations used. Preferably, calcium is used as the main gelling/fixing polyvalent cation because it allows obtaining gels with satisfactory rheological properties and a homogeneous green color. Other suitable polyvalent cations are (but not limited to): aluminum, tin, iron, copper, nickel, zinc or magnesium. Preferably, polyvalent cation salts are those in the forms of citrates, lactates, malates, propionates, chlorides, etc. Most preferred are calcium lactates and chlorides. Hardness (express as calcium) target values are between 100-20,000 ppm, preferably between 1 ,000-10,000 ppm and most preferably between 2,000-8,000 ppm.

C.5) The temperature of the fixing processes should be as low as possible to avoid damage of the fruit. Preferably, temperature range is between 0°C and 40°C, more preferably between 4°C and 25°C and most preferred between 6°C and 12°C.

C.6) Preferably, time range of exposure to the fixing acid solution is between 20 min and 24 hours, preferably between 1 and 8 hours and most preferably between 2 and 4 hours.

C.7) The order of the addition of the components of the fixing solution is not relevant. The acid could be added first, and then the cation donors, or vice versa, or they also could be added simultaneously. Optionally, calcium ions and/or polyvalent cations can be infused into the kiwi pieces prior the infusion of the stabilizing and dyeing agents.

[0008] D. Optional auxiliary processes

[0009] In case the stabilized kiwi pieces are canned for pasteurization or other sterilization treatment, it may be desirable to add certain additives to improve the shelf life and palatability of the preserved kiwi pieces. These optional additives could be infused during any of the processing stages or in the packing syrup. These may comprise the following:

D.1) Antioxidant agents, such as, but not limited to: ascorbic acid and its salts, erythorbic acid and its salts, rosemary extract, flavonoids, etc.

D.2) Flavoring agents, such as, but not limited to natural flavorings, identical to natural flavorings, artificial flavorings, fruit juices, etc.

D.3) Preservatives, such as, but not limited to: lactic, sorbic, propionic, formic and benzoic acids and their salts (sodium, potassium, calcium, etc.) and derivatives, sulfites (in any chemical form), etc.

D.4) Acidity regulators such as, but not limited to: lactic, citric, malic, fumaric, tartaric, succinic and ascorbic acids and its salts (sodium, potassium, ammonium, calcium, etc.), etc.

D.5) Sweeteners and flavor enhancers such as, but not limited to: acesulfame potassium, aspartame, isomalt, isomaltitol, saccharin and its sodium, potassium and calcium salts, sucralose, alitame, thaumatin, glycyrrhizin, neohesperidine dihydrochalcone, stevioside, neotame, lactitol, xylitol, mannitol, glycerol, sucrose, fructose, honey, etc.

D.6) Firming agents such as, but not limited to: calcium, magnesium or aluminum organic or inorganic salts like calcium hydrogen sulfite, monocalcium citrate, dicalcium citrate, calcium citrate (tricalcium citrate), monocalcium phosphate, dicalcium phosphate, tricalcium phosphate, calcium chloride, magnesium chloride, magnesium sulfate, aluminium sulphate, aluminium sodium sulphate, calcium gluconate, etc.

D.7) Dyes such as, but not limited to: synthetic dyes like, FD&C Blue N° 1 (Brilliant Blue FCF E133), FD&C Blue N° 2 (Indigotine E132), FD&C Green N° 3 (Fast Green FCF E143), FD&C Yellow N°5 (Tartrazine, E102), FD&C Yellow N°6 (Sunset Yellow FCF, E102), etc., and natural dyes like, magnesium or copper complexes of chlorophyllin, gardenia blue, gardenia yellow, carthamus, saffron, riboflavin, betacarotene, lutein, caramel, etc.

E. Preservation Processes [0011] Several preservation options are available to get an acceptable shelf life for the final product. Alternatives are: pasteurization, high pressure treatments, freezing, vacuum, chemical or osmotic inhibition and irradiation or any other means to stop microbiologic spoilage. Most preferred methods are pasteurization and high pressure pasteurization or processing (HPP).

Mode(s) for Carrying Out the Invention

[0012] V. Examples

[0013] The present invention is furthered explained in detail in the following

Examples. However, the invention is not limited to these Examples

[00 4] Example 1. Disclosed Method

[0015] Ten (10) kg of ripe kiwi pieces were selected using the criteria of flavor, and then were peeled and sliced in rounds of approximately 5 mm width.

[0016] An alkalinizing dyeing solution was prepared according to the following table:

[0017] Table 1. Alkalinizing stabilizing dyeing solution:

Table 1

[0018] The alkalinizing stabilizing dyeing solution was cooled to a temperature below 12°C.

[0019] The kiwi pieces were immersed in the alkalinizing stabilizing dyeing solution in a weight ratio of 1.1 :1 (solution to fruits) and were left there for 3 hours.

[0020] A fixing acid solution was prepared according to the following table:

[0021] Table 2. Fixing acid solution: Table 2

[0022] Once the alkaline process was finished, the kiwi pieces were immersed in the fixing acid solution in a weight ratio of 2:1 (solution to fruits) that was kept at a temperature below 12°C, for 3 hours.

[0023] The kiwi pieces were then rinsed with clean water and packing syrup was prepared according to the table 3:

[0024] Table 3. Packing solution:

Table 3

[0025] The fruits were immersed in suitable recipients with the packing syrup, in a weight ratio of 2:1 (solution to fruits).

[0026] The fruits in the packing syrup were pasteurized at 95°C for 10 minutes.

[0027] After allowing the solution to cool, the kiwi pieces were evaluated in their sensory features. The color was brilliant, homogeneous, and very similar to the natural one; the firmness and texture was adequate and resembled that of the ripe fruit; the flavor profile was according with the expected quality.

[0028] Example 2 Control trial: untreated kiwi slices

[0029] Unprocessed kiwi used as control parameter.

[0030] Description of the Sensory tests

[0031] Firmness: Measured with a fruit pressure tester (also known as penetrometer) using a 1 ,3 mm diameter plunger. [0032] Texture: The texture was tested by an expert panel, with a qualitative scale from 1 to 5, being 5 the more similar texture to the fresh ripe fruit and 1 the less similar.

[0033] Color: The color was determined using a Hunter Lab instrument.

[0034] Flavor and aroma: The flavor and aroma were tested by an expert panel; with a qualitative scale from 1 to 5, being 5 the more similar flavor profile to the fresh ripe fruit and 1 the less similar.

[0035] Bleeding: Measured by determination of the direct absorbance of the syrup with a Shimadzu Mini UV 1240 spectrophotometer at 520 nm wavelength using a 1cm square cell.

[0036] The compared results of the sensory tests are shown in the next tables.

[0037] Table 4. Sensory results before Pasteurization: Comparison of the Disclosed

Method to untreated kiwi pieces

Table 4

[0038] Table 5. Sensory results after Pasteurization: Comparison of the Disclosed Method to untreated kiwi pieces

Table 5

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.