AU2014100059A4 - A method of producing a juiced food product with reduced ammonia and/or ammonium levels - Google Patents

Abstract

A method for reducing the ammonia and ammonium levels in juice products to allow for the use of preservatives such as dimethyl dicarbonate (DMDC). This method includes disinfection of a food product to create a juiced product, acidification of the juiced product, acceleration of the juice aggregation, and removal of the remaining aggregates and dosing of the juiced product with fl k, 111 ---------u ------ - ---

Description

A method of producing a juiced food product with reduced ammonia and/or ammonium levels FIELD OF THE INVENTION [00011 The present invention relates to a method for reducing the ammonia and ammonium levels in juice from fruits or vegetables to allow for the use of preservatives such as dimethyl dicarbonate. BACKGROUND TO THE INVENTION [00021 Dimethyl dicarbonate (DMDC) is a colourless liquid with a sharp odour which is used as a beverage preservative to extend a products shelf life. It is also known as Velcorin@. DMDC acts by inhibiting the enzymes acetate kinase and L-glutamic acid decarboxylase found in microorganisms and it has also been proposed that methoxycarbonylation of the histidine part of the enzymes alcohol dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase by DMDC causes inhibition of these essential enzymes. Use of DMDC does not affect the taste of the beverage. [00031 DMDC is used to stabilize non-alcoholic beverages such as carbonated or non-carbonated juice beverages, isotonic sports beverages, iced teas and flavored waters. [0004] DMDC is added before the filling of the beverage, It then breaks down into small amounts of methanol and carbon dioxide, which are both natural constituents of fruit and vegetable juices. [00051 Once it has been added to beverages, the efficacy of the chemical is provided by the following reactions: [0006] DMDC + H20 - 2 CH30H + 2 C02 [0007] DMDC + Ethanol -+ Ethyl methyl carbonate 100081 DMDC + NH3 -- Methyl carbamate [0009] DMDC + Amino acid -- Derived carboxymethyl [0010] Ammonia is a compound of nitrogen and hydrogen with the formula NH3. The ammonium cation is a positively charged polyatornic ion with the chemical formula NH4+. It is formed by the protonation of ammonia (NH3), These ammonia constituents react with DMDC, not to just reduce its efficiency but also to produce a carcinogen known as Methyl Carbamate. [0011] In the United States, the Food and Drug Administration has approved use of DMDC with the maximum level permitted set at 250 mg/L, and only if there were fewer than 500 yeast cells/mL at time of dosage. It is also approved in the European Union, (where it is listed under the E number E242) and in Australia. DMDC is not currently approved in New Zealand, [0012] The use of DMDC is restricted to fruit and vegetable juices that have very low NH3/NH4 levels, such as in apple, grape and watermelon (see below). Juices such as carrot, grapefruit, beetroot with high level of NH3/NH4, are banned from using DMDC as the carcinogen Methyl Carbamate reaches dangerously unacceptable levels (Victus International Pty Ltd). [00131 Although some fruit and vegetables naturally have excessive NH3/NH4 to warrant the use of Velcorin, other fruit and vegetables normally with low, acceptable NH3/NH4 levels can exceed the acceptable levels through an excessive fertilization programs. In effect, all fruit and vegetables should be analysed for NH3/NH4 prior to using Velcorin for cold sterilizing the juices. Fruitivegetable Ammonia (per 100g edible portion) Apple (raw) 6.8 mg Kaki, Japanese persimmon (non- 8.4 mg astringent, raw) Satsuma mandarin (fruit juices, straight 10 mg fruit juice) Satsuma mandarin (fruit juices, 11mg reconstituted fruit juice Watermelon (raw) mg Japanese pear (raw) 11 mg Grapes (raw) 12 mg Satsuma mandarin (segments, normal 13 mg ripening type, raw) Navel (juice sacs, raw) 19 mg Kiwifruit (raw) 20 mg Pineapple (raw) 21 mg Banana (raw) 21 mg ---------------------------------------------------------------------- --------- --- ---------------- ---- Fig (raw) 22 mg Grapefruit (Juice sacs, raw) 22 mg Natsumikan (juice sacs, raw) 25 mg Melon (open culture, raw) 25 mg Peach (raw) 26 mg [00141 Methyl carbamate (MC) is formed upon hydrolysis of DMDC in the presence of ammonium ions, which may be present in some wines and fruit juices. In an experimental study, MC formed from DMDC added to model solutions and wines containing various amounts of ammonia at different pH-values was detected (recovery of MC by the analytical method employed was 51%) MC-formation increased with increasing NH3-concentration and with increasing pH-value. Under the most extreme conditions in normal commercial practices (pH <to 3.75; NH3-concentration < to 20 mg/l) less than 10 pg of MC per 1 would be formed following the addition of DMDC at 100 mg/. [0015] It is therefore advantageous to reduce the NH3 and NH4 concentrations in raw juices to prevent high levels of MC from forming when using DMDC. Known methods for reducing high NH3/NH4 levels in juice include water or addition of other juices known to have low NH3/NH4 levels. Neat juices with high NH3/NH4 levels could not safely be treated with DMDC and will require other approved sterilization processes such as, filtration, pasteurization, high pressure pasteurization etc. The advantages of using DMDC is that it eliminates the requirement for aseptic filling or sterilized filling containers or caps. Once inside the liquid, DMDC or Velcorin remains active for different lengths of time contingent on temperature. Low temperature reduces the rate of DMDC decomposition whereas higher temperatures accelerate the rate of DMDC decomposition. This allows Velcorin dissolved within the liquid to also sterilise the container and contact cap surface economically. 100161 The object of this invention is to provide a method of removing ammonia from a beverage that alleviates the above problems, or at least provides the public with a useful alternative, SUMMARY OF THE INVENTION 100171 In a first aspect the invention comprises a method of producing a juiced food product with reduced ammonia levels comprising the steps of: disinfecting the food product; juicing the food product to create a juice; acidification of the juice; acceleration of the juice aggregation; and removal of the remaining aggregates. [00181 In a second aspect the invention comprises a method of producing a juiced food product with reduced ammonium levels comprising the steps of: disinfecting the food product; juicing the food product to create a juice; acidification of the juice; acceleration of the juice aggregation; and removal of the remaining aggregates. [00191 In a third aspect the invention comprises a method of producing a juiced food product with reduced ammonia and/or ammonium levels comprising the steps of: disinfecting the food product; dicing and juicing the food product to create a juice; acidification of the juice; inline heating of the juice to a temperature greater than or equal to 45 degrees centigrade; and inline decanting to reduce the solids in the juice to less than but not limited to 0.3%v/v. [0020] In a forth aspect the invention comprises a method of producing a juiced food product with reduced ammonia and/or ammonium levels comprising the steps of: disinfection of the food product by ozone; dicing and juicing the food product to create a juice; acidification of the of the juice; dosing the juice with a fining agent such as but not limited to bentonite slurry; and decanting the juice to remove solids down but not limited to 0.3%v/v.

[0021] In preference, a further step in which the juice is dosed with dimethyl dicarbonate. [0022] It should be noted that any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below as appropriate. BRIEF DESCRIPTION OF THE DRAWINGS [0023] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows. 10024] Figure 1 is a flow chart demonstrating the process of reducing ammonia and ammonium levels in a juice product. DETAILED DESCRIPTION OF THE INVENTION 10025] The following detailed description of the invention refers to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration. [0026] The invention relates to the production of beverages in which the ammonia levels are reduced in order that DMDC may be used as a disinfectant this allows for the preservation of the beverage resulting in increased shelf life. By way of example, the following description refers to the production of carrot juice, however it is to be understood that the invention can be applied to the production of other types of beverages, particularly fruit and vegetable juices with high NH3/NH4 (ammonia) levels. [0027] The known production of carrot juice includes the mechanical peeling and dicing of the carrots. The carrots are then pasteurised by heating and decanted to remove solids down to 0.3% v/v. However, the resulting carrot juice is high in ammonia and therefore the use of DMDC on carrot juice would produce an excessive amount of the Methyl Carbamate carcinogen. Therefore, DMDC could not be safely used in the production of carrot juice, and therefore carrot juice does not have the advantages of DMDC produced juices, including long shelf life and appealing look and taste. Furthermore, carrot juice produces by such a process settles to produce coloured solid sediment and a straw coloured plasma or serum fraction that is not aesthetically acceptable to consumers and required vigorous shaking to cause resuspending of the solids. [00281 The invention therefore includes a new method for the production and treatment of carrot juice. Firstly, the fresh whole carrots are sorted to remove mould or rotten carrots and then they are chemically disinfected using chlorine, hydrogen peroxide or ozone wash to obtain a oxidation redox potential (ORP) of greater than 700mv . At room temperature, pure water at pH = 7.0 containing 1 ppm ozone will have a disincentive efficiency of 99.99% if the carrots or other fruit were retained in solution for 57 seconds. To achieve pasteurisation efficiency, both the ozone concentration and time of contact could be tailored to give at least a 5 log reduction in microbial and pathogenic load. Ozone gas can also be mixed with 85% humid air and used to fumigate the carrots to achieve a 5 log reduction in microbial load including pathogen load reduction. The carrots are then peeled and diced. then squeezed to create the carrot juice itself. The carrot juice then undergoes a process of acidification which reduces the pH of the juice from 6.3 to a final pH of 4.5 or lower. The acidified juice is then processed using inline heating to a temperature of at least 45C0. The final step comprises inline decanting of the carrot juice to reduce the solids in the juice to less than 0.3%v/v. [0029j This new process and production of carrot juice reduces the level of ammonia in the final juiced product so that DMDC can be safely used to disinfect in the production or bottling process. Furthermore, the juice produced using this process remains suspended at all times, requiring minirnal shaking for total suspension to occur. This is an advantage in that DMDC acts as an antimicrobial measure, increasing the shelf life of a product. Currently, non-pasteurised carrot juice has a shelf life for up to one day, and pasteurised carrot juice is visually and organoleptically less appealing. Therefore, the new process increases the shelf life, look and taste of the product as it reduces the ammonia to levels acceptable to use DMDC.

[0030] The method is illustrated in Figure 1, beginning with the raw food product and ending with the bottling of the juice. The in-line process and steps are as follows: [0031] 1. Sorting and removal of rotten fruit or vegetables. The unsuitable fruit is disposed of or used for compost; [0032] 2. Sanitization/wash step i.e. Ozone, Peroxide or Chlorine bath, 5 log reduction achieved; Can include clean wash step to remove chemical residue when necessary [0033] 3. Skin removal or peeling; [0034] 4. Dicing/crushing/juicing; [0035] 5. Acidification pH adjustment pH =4 with lemon juice or other organic food acid; [00361 6. Heating or pasteurization >45 Celsius OR bentonite fining without subsequent heat; 10037] 7. Rapid cooling; [00381 8. Decanting or centrifugation; [0039] 9. Velcorin dosing 250mg/L; and [0040] 10. Bottling & Capping. [00411 Each step of the new process has been tested and found necessary for the final result. Laboratory research of raw carrot juice revealed that acidification of carrot juice alone as a measure, from pH = 6.3 to Ph = 4.5, or pH = 4.0, or pH = 3.8, produced a juice that will settle over the course of one or two hours at room temperature. Aggregation of otherwise soluble constituents was accelerated by heating this acidified carrot juice (ph < natural carrot ph) to near 40"C in a rocking heated water bath. [00421 The precipitation or aggregation occurred more rapidly when higher temperatures up to 93*C were used. This aggregation did not occur with non-acidified carrot juice where heated under similar conditions. This acidification of juices affects the solubility of the juice constituents and subsequent heating, catalyses the aggregation reaction to occur more rapidly. This process, followed by decanting or centrifugation, removes juice constituents that would otherwise precipitate from the juice in the course of the juice remaining still as would happen in a supermarket. [00431 The treated juice remains completely suspended for long periods of time without settling or separation of solids from the serum of the juice as would normally occur without the new treatment. Carrot juice prepared as described remained suspended for many days and required only an optional shake to produce a commercially acceptable looking juice. This effectively makes the juice more appealing to the consumer. [0044] DMDC treated juice that had been processed as outlined above, in contrast to tunnel pasteurized juice (20 PSU, 10 minutes at 63*C), appealed to a panel of expert tasters, showing less heat treated aromatic notes and closely resembling freshly squeezed juice. [00451 The use of lemon juice or lime juice to acidify the carrot juice added naturally occurring vitamin C which helped produce a superior coloured carrot juice that was high in antioxidant activity. This juice when placed at 4*C remained stable and acceptable for consumption for 30 days and remained free of microbial load even without preservatives. However, any food grade acid can be used to acidify the juice reducing the pH by any other means such as ion exchange etc. will be appropriate for this protocol. [00461 Disinfecting incoming fruit or vegetables using a washing step containing either, ozone, chlorine or hydrogen peroxide reduces the microbial load of the fruit or a vegetable destined for juicing and effectively, improves the reliance on Velcorin as a final disinfecting step in juice production. It is possible to obtain a 5 log reduction in microbial numbers using this chemical wash step of the incoming fruit or vegetables that still contain the skin or peel. Such a process is equivalent to a pasteurization step but does not affect the taste of the resultant juice produced. This wash step remains most effective if rotten fruit or vegetables are removed prior to it. [00471 The reader will now appreciate the benefits of the present invention, which primarily reduces the ammonia or ammonium content of a juiced product such as carrot juice, making the juice safe to use DMDC as a rneans of disinfecting the juice. The invention also reduces heat treating measures, therefore decreasing the cost of production of the juice and the increase of the quality of the juice. The process also reduces the formation of Methyl Carbamate which is a known carcinogen in juices when DMOO is used, The mechanism by which ammonia/ammonium is reduced may involve altering the charge of proteins through H+ addition to the protein, effectively, obtaining the iso-electric point of the protein. The heat would then catalyse the precipitation of constituents associated with NH3/NH4. The iso-electric point of most proteins lies between pH 4.0 and 6.0. [0048] In an alternate embodiment of the invention, the raw carrots are disinfected to kill common pathogens by ozone according to dose and time and temperature outlined in known scientific literature. The carrots are then diced, juiced and acidified to pH = 4.5, pH = 4.0, pH = 3,8 and dosed with bentonite slurry solution (10% in water), followed by decanting to remove solids down to 0.3 % v/v. This alternate process also reduces the ammonia levels in the juice to allow for the use of DMDC. [0049] An optimum dose of bentonite in unheated carrot juice can be determined by dose-response trials to optimize constituent NH3/NH4 removal from the carrot juice and maintaining carrot flavour and taste. Centrifugation post bentonite addition results in a juice low in protein. Furthermore, the ammonia concentrations are much reduced and this process produces a juice suitable for DMDC use at bottling. [0050] The further advantage of this alternate embodiment is that no heating of the juice was necessary to remove the proteins. This process will be equally efficient with other protein fining agents as a rneans of reducing the ammonia levels to a level acceptable for DMDC use. [0051] In order to keep microbial load in the carrot juice below 500 cfu/ml, disinfection of the whole carrot to a protocol producing a 5 log reduction can be implemented. This is achieved using chlorine, hydrogen peroxide or ozone to wash the carrots prior to juicing whilst skins were intact. Visually and organoleptically, the carrot juice remained stable for 30 days at 4C with acceptably low numbers of microbes found. Alternatively, the heating of juice after acidification can be set at a temperature and time that would traditionally pasteurise the juice. [0052] The second embodiment highlights the elimination of juice heating for achieving a safe and disinfected juice. Each time juice is heated, the aroma and taste undergo changes contingent on the level and duration of heating. Maximum juice quality remains when juice is not heated at all. The problem with non-pasteurized juices is an increased risk of pathogenic organisms being present that may cause disease to the consumer. [0053j The reduction of proteins/fibre and other soluble constituents either by acidification and gentle heating or by acidification and fining treatment results in a juice that is resistant to settling. This is commercially favourable as often consumers are not aware that juice separation can result in the raw colourless serum and solids, a sight that is harmless but not appealing to the consumer. [0054] The removal of ammonia, and predominantly the proteins, reduces the substrate for microbial growth. In addition, acidification of juice to pH = 4.5 and below, i.e. pH =38; produces a negative environment for pathogens to grow, thus assisting DMDC effectiveness further. [00551 Reducing the pH of the juice affects the equilibrium between NH3 and NH4 as follows: NH3 (arnmonia) + H+ = NH4 (ammonium). When pH is reduced, there is more NH4 produced. Treating juices to reduce the NH3/NH4 levels, allows cold sterilization using DMDC, thus eliminating the requirements of aseptic filling and sterile caps and bottle requirements. This occurs as a result of DMDC remaining active in the juice long enough to allow it to kill organisms found in the cap or bottles. The only requirement is for all the surfaces within the sealed container to be wet by the juice. [0056] Disinfection of raw fruit and vegetables prior to juicing assists in reducing the microbial load of the resultant juice to within the specifications of DMDC to sterilize juice, If the initial load is higher than this, DMDC cannot completely destroy all microorganisms. Disinfection by the first embodiment involves washing the raw carrots with a powerful oxidizing agent or even heating the juice to pasteurization temperatures such as 63 C for 10 minutes to achieve a 5 log reduction in microbial counts. [00571 Acidification of a juice changes the charge of the juice constituents and causes aggregation or settling. Often this iso-electric point can be determined by bench trials (acidification final pH) and protein and NH3/NH4 analysis (chemical analysis through established laboratory methods) of the juice to determine when the optimum amount of acidification is achieved to cause maximurn precipitation of the major juice constituents that precipitate.

100581 Each juice type will have varying and differing constituents that aggregate and the iso-electric point or level of acidification or alkalisation requirements will differ. Most proteins will precipitate within a pH range of 4 to 6. [00591 Fining agents have an electrical charge. If this charge is opposite to that of the protein or other aggregating constituents, it will bind and neutralize in charge. The charge of proteins can be affected by acidification or alkalisation and at the iso-electric point; the proteins are not charged and can aggregate. If the acidification is below the iso-electric point of the protein, the proteins are negatively charged and will bind to fining agents that are positively charged. Thus any such fining agent opposite in charge will bind constituents and have such an effect. The functioning of a fining agent can be optimized by affecting the charge of the proteins through acidification either below or above the iso-electric point of the protein and using the appropriately oppositely charged fining agent to absorb proteins. The fining agents then gather an increase in size and these can then be removed by methods such as decanting, centrifugation, settling and other available methods. [0060] It is not known if bentonite reduces NH3/NH4 directly or indirectly through adsorbing the charged protein. [00611 The reader wil now appreciate the present invention which is a method of reducing ammonia and ammonium levels in a juicing process to allow for the safe use of DMDC. This is achieved primarily through the vital steps of acidification of the juice to change the electrical charge of the constituents that contain ammonia or ammonium, then stirring and heating to accelerate juice aggregation (heating is not necessary but preferred to catalyse the aggregation reaction) and the physical removal of aggregates in the constituents or fining agents by such methods of decanting, centrifugation or settling. [00621 Therefore, carrot juice when produces according to the present invention and the addition of DMDC, improves the taste, appearance, quality and shelf life of the product to the benefit of manufacturers and consumers. [00631 Further advantages and improvements may very well be made to the present invention without deviating from its scope, Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field. [0064] In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Claims (5)

1. A method of producing a juiced food product with reduced ammonia levels comprising the steps of: disinfecting the food product; juicing the food product to create a juice; acidification of the juice; acceleration of the juice aggregation; and removal of the remaining aggregates.

2. A method producing a juiced food product with reduced ammonium levels comprising the steps of: disinfecting the food product; juicing of the food product to create a juice; acidification of the juice; acceleration of the juice aggregation; and removal of the remaining aggregates.

3. A method of producing a juiced food product with reduced ammonia and/or ammonium levels comprising the steps of: disinfecting the food product; dicing and juicing the food product to create a juice; acidification of the juice; inline heating of the juice to a temperature greater than or equal to 45 degrees centigrade; and inline decanting to reduce the solids in the juice to less than but not limited to 0 3%v/v.

4. A method of production of a juiced food product with reduced ammonia and/or ammonium levels comprising the steps of: disinfection of the food product by ozone; dicing and juicing the food product to create a juice; acidification of the of the juice; dosing the juice with a fining agent such as but not limited to bentonite slurry; and decantng the juice to remove solids down but not limited to 02%v/v,

5. A method according to any of the above claims in which the juse is dosed ith di methyl icarbonate.