EP0513709B2 - Enzymatic method for reducing the amount of phosphorous-containing components in vegetable and animal oils - Google Patents

Description

The invention relates to a method for reducing the content of phosphorus-containing components in edible oils by enzymatic degradation and separation of the degradation products. The term edible oils includes vegetable and animal, preferably pre-degummed oils.

State of the art

Crude soybean oil and other vegetable crude oils are subjected to a pre-degum treatment, in which Phosphatides such as lecithin and other hydrophilic minor components are removed. This happens through Extracting with water is also called wet degumming. Part of this treatment remains the phosphatide in oil, which is summarized under the term "non-hydratable phosphatide" (NHP) becomes. For the production of edible oils, it is essential to remove this portion; after ruling Opinion, the phosphorus content should not exceed 5 ppm. (See Hermann Pardun, "The Plant Lecithins", Publishing house for chemical industry H. Ziolkowsky KG, Augsburg. 1988, pages 181-194)

The NHP are created by the action of plant enzymes. These are used in the "Alcon process" inactivated by steam treatment of the soy flakes, so that the formation of the NHP is prevented and at the wet degumming of the crude oil the phosphatide content can be almost completely removed.

A substantial part of the NHP can be removed from the pre-degummed oil using aqueous surfactant solutions are extracted, however, one does not usually get below 30 ppm phosphorus. It is more successful Treatment with acids or alkalis, however, requires many steps.

It is known to treat vegetable and animal oils with enzymes, which makes them enzymatic fissile components are to be broken down into water-soluble, easily extractable substances. So be according to DE-A 16 17 001 deodorized fats for soap production with proteolytic enzymes. For clarification Vegetable oils are used according to GB 1 440 462 amylolytic and pectolytic enzymes. After EP-A 70 269 describes animal or vegetable fats or oils in raw, semi-prepared or refined Condition treated with one or more enzymes to remove all ingredients that are not glycerides split and separate. Suitable enzymes are phosphatases, pectinases, cellulases, amylases and proteases mentioned. Phospholipase C is mentioned as an example of a phosphatase. The application of Enzymes for full deglecination or total degumming, how to degum the NHP removal Oil is also not known.

The nature of the NHP is not exactly known. According to Pardun (loc.cit) these are lysophosphatides and phosphatidic acids or calcium and magnesium salts formed therefrom, which are produced by the degradation of Phosphatides arise under the influence of the plant's own phospholipases.

From JP-A 2-153997 it is known to use crude or degummed oil with an enzyme that Has phospholipase A activity to treat. Regulation of the pH is not provided.

With regard to the phosphorus content of the starting material as well as the phosphorus content There is no information in the description of the end product. According to Example 1 is a degummed oil at a temperature of 60 ° C for 48 hours treated with an enzyme solution with 3U phospholipase A activity. The phosphorus content is reduced to 1300 ppm phospholipid. Only after treatment at 105 ° C and 30 Torr with the addition of clay, the phosphorus content can be reduced to 40 ppm phospholipid. According to Example 3, degummed oil with a phosphorus content of 1638 ppm phospholipid 30 minutes, 1 hour, 2 hours or 4 hours at 50 ° C with a high enzyme concentration and with the addition of 100%, 500%, 1000% or 2000% water, based on the amount of oil treated. The phosphorus content after 4 hours depending on the conditions to 266 ppm, 81 ppm, 153 ppm phospholipid, 206 ppm phospholipid or 179 ppm phospholipid decreased.

The method for treating oil known from JP-A-2-153997 has the Disadvantage that it requires a very long reaction time (48 hours) and the phosphorus content is not sufficiently reduced becomes. The variant in which a further reduction in the phosphorus content possible, in which clay is added to the reaction mixture, also has the disadvantage that the process must be carried out in two stages that the second stage takes place at a relatively high temperature and that a vacuum is applied must become. An additional filtration stage is also required. The heating of the oil to a temperature above 80 ° C is disadvantageous. Oxidation reactions take place in the oil and it discolors what to use as an cooking oil is extremely disadvantageous. In addition, the nutritional value of oils partially with a high content of polyunsaturated fatty acids when heated lost.

The process described in Example 3 has the disadvantage that large enzyme and amounts of water are required, which are determined by the Oil must be separated again. Such conditions are technical and not economically sensible, since huge amounts of waste are generated and there is a risk that stable oil-in-water emulsions form. In addition, with a Except the phosphorus level is not sufficiently lowered, even at a very high one Phospholipase A activity, except for one example where 500% water, based on the oil is used.

JP-A 2-49593 describes a similar enzyme treatment of oils, which, however, does not the degumming of the oil, but aimed at the extraction of lysolecithin. Here is the setting special pH values are superfluous. The process according to EP-A 328 789 is also about the conversion of soybean oil lecithin to lysolecithin by phospholipase A in the production of mayonnaise-like Products.

Task and solution

The aim of the invention is to further reduce the phosphorus and iron content Ingredients in pre-degummed animal or vegetable oils to a phosphorus content below 5 ppm due to enzymatic degradation.

It has been found that the treatment of animal or vegetable oils which have a phosphorus content of 50 to 250 ppm with a phospholipase A ₁ , A ₂ or B in a continuous process leads to phosphorus contents below 5 ppm if the enzyme is in the form of a treated into fine droplets of emulsified aqueous solution at a pH of 4 to 6. Phosphorus levels below 5 ppm and iron levels below 1 ppm were achieved. The low iron content is beneficial for the stability of the oil.

The drastic reduction in the phosphorus content is surprising in that the phospholipases A ₁ , A ₂ and B have a pH optimum in the neutral to weakly alkaline range. The process goal cannot be achieved with phospholipase C or D.

The invention therefore relates to a process for reducing the content of phosphorus-containing constituents in animal or vegetable oils by enzymatic degradation by means of a phospholipase. A pre-degummed animal or vegetable oil with a phosphorus content of 50 to 250 ppm is stirred with an organic carboxylic acid and the pH of the mixture formed is adjusted to 4 to 6; an enzyme solution containing phospholipase A ₁ , A ₂ or B is added to the mixture in a mixing vessel with turbulent stirring and formation of fine droplets, an emulsion containing 0.5 to 5% by weight of water, based on the oil, is formed, which is passed through at least one subsequent reaction vessel with turbulent agitation for a reaction time of 0.1 to 10 hours at temperatures in the range from 20 to 80 ° C., and the treated oil, after separating off the aqueous solution, has a phosphorus content below 5 ppm having.

Implementation of the invention

Since the phospholipases A ₁ , A ₂ or B would attack lecithin, it does not make sense to use oils with a high lecithin content, such as crude soybean oil, in the process according to the invention. The starting material is therefore preferably pre-degummed oils, especially edible oils, which are generally characterized by a phosphorus content between 50 and 250 ppm. Oils with fluctuating quality can be processed on the same system. Pre-degummed oils, especially sunflower oil; Rapeseed oil and especially soybean oil are used. It is not necessary to dry the oil beforehand.

The phospholipase is advantageously used in an aqueous solution which is as fine as possible in the oil is emulsified. The enzymatic reaction is expected to occur at the interface between the oil phase and the Water phase take place. It is mixed intensively, e.g. through turbulent stirring and additionally promoted by the addition of surfactants. The degradation products of the NHP have a higher hydrophilicity and therefore go into the water phase. They are therefore, like the metal ions, simultaneously with the Water phase removed from the oil.

Phospholipase A ₁ , A ₂ and B are known enzymes; (See Pardun, loc.cit. Seiton 135-141). Phospholipase A ₁ cleaves the fatty acid ester group on the G ₁ atom of a phospholipid molecule. It is found, for example, in rat liver and in the pancreas. An enzyme with phospholipase A ₁ activity could be isolated from mold cultures of Rhizopus arrhizus.

Phospholipase A ₂ , formerly also called lecithinase A, cleaves the fatty acid ester group on the C ₂ atom of a phospholipid molecule. It occurs, mostly in association with other phospholipases, in almost all animal and plant cells. It is abundant in the snake venom of the rattlesnake and the cobra, as well as in the bee and scorpion venom. Technically, it can be obtained from pancreatic glands after activity-inhibiting accompanying proteins have been broken down with trypsin.

Phospholipase B is widespread in nature. It acts on the lysolecithin caused by the action of phospholipase A ₁ by splitting off the second fatty acid ester residue. In some cases it is also regarded as a mixture of the phospholipases A ₁ and A ₂ . It occurs in rat liver and is also produced by some molds, such as Penicillium notatum.

Phospholipase A ₂ and B are available as commercial products. The use of purified enzymes is generally not necessary for technical applications. A phospholipase preparation which is obtained from ground pancreatic pulp and which contains above all phospholipase A ₂ is suitable for the process of the invention. Depending on the activity, the enzyme is used in amounts of 0.001 to 1% by weight, based on oil. A good distribution of the enzyme in the oil is ensured if it is dissolved in an amount of water of 0.5 to 5% by weight, based on oil, and emulsified in this form in the oil into droplets of less than 10 μm in diameter (weight average) becomes. Turbulent stirring at radial speeds above 100 cm / s has proven itself. Instead, the oil can be circulated in the reactor using an external centrifugal pump. The enzymatic reaction can also be promoted by means of ultrasound.

The enzyme effect is achieved by adding an acid, preferably an organic carboxylic acid, increased, which is added before the enzyme treatment, Citric acid is preferred. It can be in the form of the free acid or in combination as a buffer system with their salt, such as an alkali salt (e.g. sodium citrate), an alkaline earth salt (e.g. calcium citrate) or a Ammonium salt can be used. Suitable amounts are 0.01-1% by weight, based on on oil, optimally 0.1% by weight. The pH is adjusted to a value of 3 to 7, preferably 4 to 6, with the acid. The The optimum is around pH 5: Surprisingly, this pH is also optimal when the Phospholipase is used in the form of an enzyme complex from the pancreas. The pancreatic enzyme complex otherwise has a pH optimum of 8 and is hardly effective at pH 5. Apparently it turns out to be Phase interface where the enzyme action occurs, a higher pH than within the aqueous phase a.

In order to dissolve the phospholipases A ₁ , A ₂ and B from fatty pancreatin or pancreatic products, emulsifying additives are helpful. Water-soluble emulsifiers, in particular those with an HLB value above 9, such as sodium dodecyl sulfate, are suitable. It is effective in an amount of, for example, 0.001% by weight based on oil if it is added to the enzyme solution prior to emulsification in the oil.

The addition of other enzymes, especially proteinases and amylases, often has an advantageous effect. Also Protein additives can be advantageous due to a certain surfactant effect.

The temperature in the enzyme treatment is not critical. Temperatures are between 20 and 80 ° C suitable. A temperature of 50 ° C is optimal, but it can also be briefly heated to 70 ° C. The duration of treatment depends on the temperature and can be shorter with increasing temperature being held. Times of 0.1 to 10, preferably 1 to 5 hours are usually sufficient. A step program, in which the first step at a temperature of 40 to 60 ° C and the second stage is carried out at a higher temperature in the range of 50 to 80 ° C. For example, the mixture is first stirred at 50 ° C. for 3 hours, then at 75 ° C. for one hour.

After completion of the treatment, the enzyme solution together with the degradation products contained therein the NHP is separated from the oil phase, preferably by centrifugation. Because the enzymes get through a high stability and the amount of degradation products absorbed is low same enzyme solution can be reused several times.

The method is preferably carried out continuously. With an expedient continuous The oil is emulsified in a first mixing vessel with the enzyme solution, in one or several subsequent reaction vessels, if necessary with increasing temperature, under turbulent Movement allowed to react, and then the aqueous enzyme solution separated in a centrifuge. To avoid an accumulation of the degradation products in the enzyme solution, a part of it can be running replaced with fresh enzyme solution and the rest returned to the process.

The oil obtained has a phosphorus content below 5 ppm and is therefore for physical refining suitable for cooking oil. Thanks to the low iron content that has been achieved, it has good preconditions for Refining to achieve high resistance to oxidation.

EXAMPLES example 1

1 l wet degummed soybean oil with a residual phosphorus content of 110 ppm is heated to 75 ° C in a round bottom flask. With vigorous stirring with a 5 cm diameter paddle stirrer at 700 rpm, 10 ml of water containing 1 g of citric acid are added and stirring is continued for 1 hour. The mixture is then cooled to 40 ° C. and a solution of 0.1 g of phospholipase A _{2 of} the quality given in Example 1 and 50 mg of calcium chloride in 20 ml of 0.1 molar acetate buffer pH 5.5 are added. After a further 5 hours of intensive stirring, the water phase is centrifuged off. The oil obtained contains 2 ppm P and is suitable for physical refining. The following table shows the change in the other key figures: Starting oil treated oil phosphorus 110 ppm 2 ppm iron 3.3 ppm <0.1 ppm Calcium 65.4 ppm 5.3 ppm magnesium 38.4 ppm <0.1 ppm Peroxide number 18.3 18.50 Acid number 0.91 1.10 Saponification number 191.2 190.4

Example 2

The procedure according to Example 1 is repeated with the difference that 1 g of a pancreatic preparation (pancreatin, 800 phospholipase units / g) is used instead of phospholipase A ₂ . The preparation contains phospholipase A ₂ , proteinase, amylase, lipase. The phosphorus content drops below 1 ppm. Due to the influence of lipase, there is only a slight increase in the acid number from 0.91 to 1.49.

Example 3

9 l wet-degummed rapeseed oil with a phosphorus content of 72 ppm is mixed with a solution of 8.6 g citric acid in 250 ml water and heated to 60 ° C. The mixture is homogenized by circulating it once per minute using an external centrifugal pump. Then the pH of the aqueous phase is adjusted to 5.0 with 30 g of 10% sodium hydroxide solution. Now 9 g of phospholipase A ₂ with an activity of 400 U / g are added together with a little calcium chloride and the mixture is circulated for 3 hours at 60 ° C. in the manner indicated. After centrifugation, a phosphorus content of 3 ppm is found.

Claims (4)

1. A process for reducing the content of phosphorus-containing ingredients in animal or vegetable oils through enzymatic degradation using a phospholipase, in doing so a previously-deslimed animal or vegetable oil with a phosphorus content of 50 to 250 ppm is stirred with an organic carbonic acid and the pH value of the resultant mixture is set at 4 to 6; an enzyme solution containing phospholipase A₁, A₂ or B is added to the mixture in a mixing vessel, whilst being subjected to turbulent stirring with the formation of fine droplets, wherein an emulsion is formed with 0.5 to 5 wt. % water, relating to the oil, which is passed through at least one subsequent reaction vessel, undergoing turbulent stirring, during a reaction time of 0.1 to 10 hours at temperatures in the range of 20° to 80° C, and wherein the treated oil has a phosphorus content of less than 5 ppm after separation of the aqueous solution.
2. A process according to claim 1, characterised in that an oil is used from which mucilage has been removed beforehand.
3. A process according to claim 1 or 2, characterised in that a citric acid is used as an organic carbonic acid in the form of the free acid or as an alkali metal, calcium or ammonium citrate.
4. A process according to one or more of claims 1 to 3, characterised in that an emulsifier is additionally used.