COMPOSITION AND PROCESS FOR OBTAINING PEELED PRICKLY PEARS COATED WITH AN EDIBLE FILM BASED ON CELLULOSE DERIVATIVES

Abstract

The present invention is related to a composition to obtain peeled prickly pears coated with an edible film based on cellulose derivatives; process to obtained peeled prickly pears with the cellulose derived edible composition; and its use to coat the peeled prickly pears to delay the fruit dehydration and decomposition.

Claims

1. A process to obtain edible film coated peeled prickly pears, the process comprising the following steps: a) removing the thorns from the prickly pears after the harvest; b) selecting the prickly pears without thorns, discarding the damaged prickly pears; c) calibrating the selected prickly pears according to size; d) sanitizing the prickly pear with the peel; e) peeling the prickly pear; f) sanitizing the peeled prickly pear; g) applying a sterile edible coating composition, comprised of hydroxypropyl methylcellulose, glycerol and citric acid over the surface of the peeled prickly pear; h) externally drying the coated prickly pear; i) packing the coated and externally dried prickly pear; and j) keeping the prickly pear under cold in a modified atmosphere.

2. The process of claim 1, wherein removing the thorns is done by rubbing.

3. The process of claim 1, wherein selecting is performed discarding those that are damaged.

4. The process of claim 1, wherein the prickly pears are calibrated by size, homogenizing the volume to maintain a stable industrial process, controlling the amount of prickly pears that enter the process, calculating the necessary supplies needed during the process, so that at the end of said process, the final product is obtained with the same conditions.

5. The process of claim 1, wherein the sanitizing in d) is performed with a 150-200 ppm sodium hypochlorite solution for 2 minutes and the sanitizing in f) is performed with a 200 ppm sodium hypochlorite solution and a solution made of 170 ppm of hypochlorous acid, 25 ppm of hypochlorite ions and 700 ppm of chloride dioxide 700 ppm, for 2 minutes.

6. The process of claim 1, wherein in step e) the prickly pear is peeled in a mechanical or manual form.

7. The process of claim 1, wherein in step g) the sterile edible composition is applied by immersion, aspersion or casting wherein said solution is made of hydroxypropyl methylcellulose (HPMC) in a solution at 2-5% w/v, 0.5-3% w/v glycerol, and 0.5-3% w/v citric acid.

8. The process of claim 1, wherein in the step h) the drying comprises the application of cold and dry air over the fruit under sterile conditions.

9. The process of claim 1, wherein in the step i) the packaging is performed individually in a package with a gas barrier, in a sterile environment, where the normal atmosphere is replaced by a modified atmosphere, by decreasing the content of O.sub.2 to 3-5% and increasing the content of CO.sub.2 to 2-3%.

10. The process of claim 3, wherein in the step j) the packed prickly pear is kept under refrigeration between 2-4° C., in a modified atmosphere over 30 to 45 days.

11. An edible composition to coat a peeled prickly pear, comprising 2-5% w/v hydroxypropyl methylcellulose (HPMC) solution, 0.5-3% w/v glycerol, and 0.5-3 w/v citric acid.

12. The edible composition of claim 11, wherein, once dry, the composition forms a tasteless, odorless and colorless film.

13. Use of an edible composition according to claim 11 to coat peeled prickly pears, thereby delaying the dehydration and decomposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0020] To carry out this invention, it is necessary to prepare the edible composition under sterile conditions, whose components are hydroxypropyl methylcellulose (HPMC) in solution, which is a cellulose ether in which about ⅓ corresponds to hydroxyl groups, HPMC being the most hydrophilic of the methylcelluloses, glycerol and citric acid.

[0021] To perform the production process the following steps are considered: [0022] 1. To harvest the prickly pears in state ripe for consumption, in order to later remove the thorns from the prickly pears. [0023] 2. To select the prickly pears, separating the damaged units. [0024] 3. To calibrate the prickly pears by size, so all of them have the same volume, allowing to control the amount of prickly pears that enter to the process, calculate the necessary supplies, and to obtain a final homogeneous product. [0025] 4. To wash the prickly pears using sanitizers to avoid the entrance of the bacteria or other organisms affecting the fruit decay; [0026] 5. To peel or remove the skin of the prickly pears. [0027] 6. To perform a second sanitization of the peeled prickly pears. [0028] 7. To apply the coating solution, that has been prepared under sterile conditions. [0029] 8. To dry the prickly pears to eliminate the residual surface humidity. [0030] 9. To pack the prickly pears individually in packages with a specific barrier to CO.sub.2 and O.sub.2, replacing the natural atmosphere by a composition of different gases (modified atmosphere). [0031] 10. To store the prickly pears already packaged in a refrigerated environment.

Parameters and Conditions

[0032] In the process to coat fruits, such as a peeled prickly pears, is possible to delay their dehydration and decomposition, maintaining their biochemical processes as if they were fresh fruit. [0033] 1. Visual Inspection and selection: The skin color is a maturity index, which in this case corresponds to a slightly yellowish green coloration. This level of maturity that can be characterized as “firm”, in which the fruit already presents the appropriate organoleptic characteristics for consumption, but keeps a compact texture, without softened areas, especially in the bottom part, opposite to the apical end, tolerates well the mechanical handling and the thorns can be remove without it suffering physical damage. By being peeled, the fruit maintains the integrity of the pulp structure, which is firm and compact, but tender. Later the thorn removal is performed by rubbing the fruits with a surface able to remove the thorns not damaging the skin. Generally is a relatively rough fabric. This process can be performed manually with brooms, or automated. Once the thorns have been removed, they are separated by means of an air stream. [0034] 2. Raw material selection: it is done by visual inspection, separating the fruits presenting damage, deformities, excess of maturity, over ripped areas, etc. [0035] 3. Calibration: is performed in a mechanical manner, using the equatorial diameter as reference. Depending on the variety, the fruits are grouped as small, medium and large to be separately process. The selection by size is important for the packaging of the final product. [0036] 4. Washing and disinfection: are performed by water showers with the addition of sanitizer and brushing using rotating roll systems, comprised of soft bristles, until the dirt has been completely removed from the skin surface. This is necessary to avoid the transference of microorganism to the surface of the pulp during the peeling stage. The sanitizers used are sodium hypochlorite, and a solution containing hypochlorous acid, hypochlorite ions, and chloride dioxide. The solutions are each applied for two minutes in a separate sequential manner. [0037] 5. Peeling: consists in cutting the ends of the fruit and performing a longitudinal cut of the skin, to later remove it from the pulp, completely separating it. [0038] 6. Second disinfection of the peeled fruits: is performed using the disinfectant formulations that have demonstrated efficacy eliminating the microbiological contamination that may have remained from the peeling operation. The sanitizer used is sodium hypochlorite, and a solution containing hypochlorous acid, hypochlorite ions, and chloride dioxide. The solutions are each applied for two minutes in a separate sequential manner. [0039] 7. Sterilization of the coating solutions and application of the sterilization is performed in an alternative way by means of pasteurization at 80° C. or exposure to UV radiation, among other options, to eliminate the microbiological contamination. The application of the edible coating is performed at room temperature under sterile conditions, wherein the prickly pears without skin or peel are put in contact with the edible composition.

[0040] The coating can be apply in three manners; these are immersion, aspersion or casting. The immersion process consists of the application of the edible matrixes submerging the food in the coating solution. The aspersion process is a technique based on the application of the pressurized coating solution. This allows for a fine and uniform coating. Finally, casting consists in the obtaining of a uniform dispersion made of biomolecules, plasticizers, and water. It is then poured over a plate made of inert material (stainless steel) wherein it is let to dry to allow the film form. [0041] 8. The drying is done by air stream to evaporate the remnant water on the fruits when applying the coating solutions. [0042] 8. The packaging is performed using packages with a specific barrier to CO.sub.2 and O.sub.2 (Bags B-2620 from Sealedair). The normal atmosphere is replaced by a modified atmosphere, decreasing the content of O.sub.2 to 3-5% and increasing the content of CO.sub.2 to 2-3%. [0043] 8. The refrigerated storage is made at 2-4° C. for a period of 30 to 45 days.

Sanitizing Solution Composition:

[0044] The process requires the use of sanitizer products in a two-step process. The prickly pear is sanitized when it has the peel as well as when it has been peeled. In each step of the sanitization process two solutions are used. The first solution is made of 150-200 ppm of sodium hypochlorite. The second solution is made of 170 ppm of hypochlorous acid, 25 ppm hypochlorite ions, and 700 ppm chlorine dioxide. The prickly pears are submerged in both solutions for 2 minutes each.

Coating Solution Composition:

[0045] The components of this solution are 2-5% w/v solution of hydroxypropyl methylcellulose (HPMC), 0.5-3% w/v of glycerol and 0.5-3% w/v of citric acid; this later with the objective of delaying the darkening of the prickly pears under study. Furthermore, this coating solution once is dry, forms a tasteless, odorless and colorless film, which maintains the fruit's own characteristics.

Examples

Example 1: Preparation of the Edible Coating Composition

[0046] The selection of the coating that presented the best properties and results regarding the microbiological contamination of the prickly pears was based on studies performed before the present invention. The selected coating was based on 2-5% w/v of microcrystalline hydroxypropyl methylcellulose (HPMC). The preparation of the HPMC consisted in the dissolution of the solute in distilled water previously sterilized, with the addition of 0.5-3% w/v of glycerol, at a temperature of 80° C. for 30 minutes, using a magnetic agitator. At the same time a solution of 0.5-3% w/v of citric acid was prepared, which was incorporated to the solution of HPMC-glycerol. The use of citric acid has the objective of delaying the darkening of the prickly pears.

Selection of the Proper Disinfectant as Preventive Treatment.

[0047] Sodium hypochlorite, hypochlorous acid, hypochlorite ions, and chloride dioxide solutions were used as disinfectants on the prickly pears and the used distilled water, to later coat the prickly pear with a coating solution based on HPMC. These disinfectants were prepared in the following concentrations: 200 ppm sodium hypochlorite, which was prepared with 16 mL of sodium hypochlorite in 4 L of distilled water, and a solution of 170 ppm of hypochlorous acid, 25 ppm hypochlorite ion and 700 ppm of chloride dioxide.

Example 2: Coating of Peeled Prickly Pears with the Edible Coating Solution

[0048] 100 kilograms of prickly pears were harvested, using the skin color as a maturity index, which in this case is a slightly yellowish green coloration. The thorns of these prickly pears were then removed by rubbing the fruits. The thorn removal was performed manually with brooms and/or automated, obtaining losses of 0.5 kilograms. Once the thorns were detached, these were removed by an air stream. The remnant of the raw material, 99.5 kg, was stored at temperatures of 2 to 4° C. and then was selected by visual inspection, separating the fruits presenting damage, deformations, excess of ripeness, over ripe areas, etc. After this, the raw material was mechanically calibrated, using the equatorial diameter as reference. Depending on the variety the fruits were grouped in small, medium and large caliber to be separately process.

[0049] After that, the prickly pears without thorns were disinfected with a 150-200 ppm sodium hypochlorite solution, by means of showers with water with added disinfectant, as well as brushing the fruit using a rotating rolls system comprised of soft bristles, until the dirt adhered to the surface of the skin has been completely removed. After this step, the damaged fruits were eliminated, losing 5 kg. The remaining 94.5 kg of fruits were separated in similar size batches.

[0050] Subsequently, the fruit peeling was performed, in which 94.5 kg of prickly pears were manually or mechanically peeled. In this stage a loss of 29 kg was obtained. The amount of raw material, 65.5 kg of peeled prickly pears, were disinfected a second time with a 0.02% w/v sodium hypochlorite, 0.07% w/v hypochlorous acid solution, and a solution made by three disinfectants: 170 ppm hypochlorous acid, 25 ppm hypochlorite ions, and 700 ppm chloride dioxide, to later apply the coating composition. The coating composition used is a mycrocrystallinehydroxypropyl methylcellulose solution assayed in the concentration range of 2-5% w/v, citric acid assayed in the range of 0.5-3% w/v, and glycerol assayed in the concentration range of 0.5-3% w/v, all dissolved in sterile water. Following this step, a dry air stream was applied to evaporate the excess of water from the fruit surface.

[0051] Finally, the peeled and coated with HPMC 2-5% v/v prickly pears were individually packaged in Sealedair B-2620 bags, replacing the normal atmosphere by a modified atmosphere, decreasing the content of Otto 3-5% and increasing the content of CO.sub.2 to 2-3%.

Example 3: Breathing Analysis

[0052] For all the treatments performed, the breathing analysis consisted of the measurement of gases (O.sub.2 and CO.sub.2) to observe the behavior of the packaged fruit in the barrier bags to these gases, in order to compare the respiratory activity with that of the untreated fresh fruit, expecting to obtain a decrease in the level of O.sub.2 and an increase in the level of CO.sub.2. The results indicated that the fruit continued breathing at a moderate rate, where the percentage of oxygen was reduced and the percentage of carbon dioxide increase in the interior of the package. The average value of all the samples in each treatment can be seen in table No. 1:

TABLE-US-00001 TABLE N.sup.o 1 Data on breathing assessments Chlorine + hypochlorous acid, hypochlorite Hypochlorous ions, acid, hypochlorite and chloride ion and dioxide Chlorine chloride dioxide Environment Control Days CO.sub.2% O.sub.2% CO.sub.2% O.sub.2% CO.sub.2% O.sub.2% CO.sub.2% O.sub.2% CO.sub.2 O.sub.2 5 5.46 13.16 1.96 19.06 9.41 6.51 0.24 20.05 8.32 11.34 10 6.37 9.92 0.6 18.78 14.9 3.47 0.39 20.21 13.87 4.71 15 8.39 8.49 0.4 17.85 14.73 3.47 0.42 20.2 16.23 3.79 20 9.41 6.51 5.9 15.84 17.61 0.26 0.43 20.19 18.39 4.04

Example 4: Microbiologic Analysis

[0053] Analyses were performed under strict sterile conditions, to avoid any type of contamination different than the one that could be found in the packaged product. This evaluation was made under a laminar flow cabinet with a burner, in order to maintain the sterility and to avoid potential contamination from the surrounding air. The microorganisms to analyze are indicated in the Chilean Sanitary Regulation for Foods, detailed in Specifications for “pre-made ready for consumption edible fruits and vegetables”. These consider the count of Escherichia coli, Staphylococcus aureus, mesophilic Aerobes (RAM), Enterobacterium, fungus and yeast, as well as Salmonella (table No. 3).

[0054] The microbiological analyses were made at 5, 10, 15, 20, 25, and 30 days after packaging and after the breathing measurements of the packaged samples were made, where it was determined the presence or absence or microorganism based on the count of colony forming units (CFU/g). For this assays prickly pears from Til-Til, Melipilla, and Romeral were used. The results shown in table No. 2 were obtained following established parameters. All the assays were done in duplicate. The control for the microorganisms present in pre-made fruits and other edible vegetables corresponds to the contamination limits specified in the Sanitary Regulation of Foods, table No. 3 (RSA, 2010).

TABLE-US-00002 TABLE N.sup.o 2 Count of colony forming units in peeled and coated prickly pears measured at 5, 10, 15, 20, 25 y 30 days after its package. Count (UFC/g) Days Fungus stored Mesophilic Entero- and Source at 4° C. Aerobes Coliforms E. coli bacterium S. aureus yeast Salmonella TIL-TIL 5 <10 <10 <10  10 50 1000  NEG 10 <10 <10 <10 <10 20 7000  NEG 15 <10 <10 <10 <10 <10 20 3.2 × 10.sup.5 1.8 × 10.sup.3 <10 <10 <10 <10 NEG 25 4.3 × 10.sup.5 1.6 × 10.sup.3 <10 <10 <10 <10 NEG 30 3.6 × 10.sup.5 1.4 × 10.sup.3 <10 <10 <10 <10 NEG MELIPILLA 5 700 <10 <10 <10 <10 600 NEG 10 1800  900 <10 1100  40 3.6 × 10.sup.5 NEG 15 <10 <10 <10 <10 <10 20 5.7 × 10.sup.5 8.0 × 10.sup.4 <10 200 <10 <10 NEG 25 3.6 × 10.sup.5   2 × 10.sup.3 <10 100 <10 <10 NEG 30 1.3 × 10.sup.5 2.6 × 10.sup.3 <10 200 <10 <10 NEG ROMERAL 5 3.4 × 10.sup.4 540 <10 800 <10 400 NEG 10 100 9000  <10 <10 <10   2 × 10.sup.5 NEG 15   2 × 10.sup.5 5.5 × 10.sup.3 <10 8.3 × 10.sup.3 300 20   2 × 10.sup.5  30 <10 <10 <10 <10 NEG 25 1.6 × 10.sup.5 1.6 × 10.sup.3 <10 <10 <10 <10 NEG 30 4.2 × 10.sup.5 <10 <10 3.6 × 10.sup.4 <10 <10 NEG

TABLE-US-00003 TABLE N.sup.o 3 Specifications for the limits of microorganisms presents in pre-made fruits and other edible consumption ready vegetables. Limit per gram Parameter m (UFC/g) M (UFC/g) RAM 5 × 10.sup.4 5 × 10.sup.5 Enterobacterium 5 × 10.sup.3 5 × 10.sup.4 E. coli 10 102 S. aureus 10 102 Salmonella in 25 g 0 — m = value of the microbiological parameter at which or under which the food does not represent a risk to the health; M = value of the microbiologic parameter over which the food represents a risk to the health;