JPH0412715B2 - - Google Patents

Description

[Detailed description of the invention]

[Objective of the invention] (Industrial application field) The present invention provides a method for modifying fats and oils, in particular, a method for modifying fats and oils, which maintains the flavor of animal fats and oils that are solid at room temperature.
This invention relates to a method for modifying fats and oils to lower their melting points. (Prior Art) Modification of fats and oils refers to imparting physical properties suitable for the intended use to the fats and oils. As a method for modifying fats and oils, transesterification is one of the typical methods along with hydrogenation used in the production of processed fats such as skimming and margarine. Representative examples of transesterification will be explained below. (1) Method using an alkali metal catalyst This method uses sodium methylate, etc. as a catalyst and reacts dehydrated fats and oils under dry nitrogen.
It is carried out at relatively high temperatures. (2) Method using lipase Lipase is an enzyme that hydrolyzes fats and oils, but when reacted with a small amount (about 1%) of water, a reverse reaction occurs, triglyceride synthesis, resulting in transesterification. The reaction temperature in this case is about 37°C. In order to transesterify a solid fat, a solvent is used to turn the sample fat into a liquid, and a surfactant is used to form micelles so that the hydrophilic lipase mixes with the fat. We are trying to increase reaction efficiency. (Problems to be Solved by the Invention) As described above, the optimal temperature range when using lipase in the transesterification reaction is around 37°C. Here, among fats and oils, pork fat, beef tallow, etc. are used for special cooking because of their flavor, but these animal fats and oils are solid at room temperature and are inconvenient for cooking. In particular, beef tallow has a good flavor as an edible fat, but its high melting point limits its use to hot foods such as grilled meat, and processed meat products such as beef sausages and salami sausages that are eaten cold. It cannot be used because it does not melt in the mouth and cannot develop flavor. In addition, pork fat has low stability, and if it is mixed into cooked foods, there is a limit to how long they can be kept warm. Therefore, when performing the transesterification reaction, animal fats and oils such as pork fat and beef tallow, which are solid fats, cannot be reacted as they are, and require a solvent as described above. This is because in order to cause transesterification in fats and oils, the fats and oils must be liquid. If all of these animal fats and oils were to be melted by heat to promote the reaction by lipase, the lipase would be inactivated or the enzymatic activity would become extremely low. Furthermore, as described above, since lipase is hydrophilic, it does not mix with fats and oils, resulting in a relative decrease in enzyme activity. Therefore, surfactants are used to improve this problem, but another problem is that it is difficult to remove the surfactants at the end of the reaction. The present invention was made in view of the above circumstances, and an object of the present invention is to provide a method for modifying fats and oils, which modifies animal fats and oils, which are solid at room temperature, into liquids while retaining the original unique flavor. There is. [Structure of the Invention] (Means for Solving Problems) As a result of intensive research, the present inventors mixed animal fat and vegetable oil using polyethylene glycol-modified lipase (hereinafter referred to as PEG-modified lipase). They discovered that by transesterifying something, it is possible to lower the melting point of fats and oils, while at the same time maintaining the original flavor. Note that the fats and oils to be mixed in this case are those that have significantly different fatty acid compositions and melting points, such as animal fats and oils that are solid at room temperature and vegetable oils such as corn oil. The present invention will be explained in detail below. First, the lipase before modification is Candida
It is obtained from Cylindracea, has an extremely high activity of 360000 U/g, and has no triglyceride position specificity during the reaction. The practical decomposition temperature of this lipase is 30 to 40°C, but when it is modified with polyethylene glycol, its action temperature range is expanded and it exhibits sufficient activity even at around 60°C. The activity of PEG-modified lipase is about 70% that of the original lipase, but this value varies somewhat depending on the lot. However, theoretically, as the modification rate increases, the activity decreases, so it is not good if the modification rate is too high. Note that polyethylene glycol-modified lipase itself is known. Next, the sample fats and oils to be subjected to transesterification in the present invention are animal fats and oils that are solid at room temperature, such as pork fat and beef tallow, and vegetable oils that have a low melting point and are tasteless and odorless, such as corn oil. When carrying out transesterification using the above fats and oils, one type of animal fat and one type of vegetable oil are mixed to form a pre-reaction fat and oil. Further, 0.5 to 2% of PEG-modified lipase is prepared for these fats and oils, and the same amount of water is added to increase the activity of the PEG-modified lipase. That is, PEG-modified lipase uses a hydrophobic substrate (oil or fat).
Although it is true that it becomes soluble in water, its activity becomes higher if it is pre-wetted as described above. Dehydrated mixed fats and oils are added to the enzyme (PEG-modified lipase) pretreated in this way. In this case, in order to suppress oxidation by reducing the amount of oxygen that comes into contact with the fats and oils as much as possible, after replacing the air in the reaction vessel with dry nitrogen, the temperature at which all of the fats and oils melts is 24 to 24 minutes.
Perform the transesterification reaction for 72 hours. In this case, the oils and fats are oxidized by ultraviolet rays,
Since rancid odor is likely to occur, it is necessary to cover the reaction vessel with aluminum foil or the like to shield it from light in order to prevent this. The results after the above transesterification are as follows. When pork fat was used as the animal fat and corn oil was used as the vegetable oil, the transparent melting point decreased from 46.1°C to 21.3°C, and although the fat and oil had many white granules visible at room temperature before the reaction. After the reaction, it changes into a homogenized liquid fat or oil. In terms of sensory perception, the flavor of pork fat remained, and it melted in the mouth better than before the reaction. When beef tallow was used as the animal fat and corn oil was used as the vegetable oil, the clear melting point decreased from 41.4°C to 27.2°C, and other physical properties and sensory evaluations obtained the same results as in the case of pork fat. Next, each of the above-mentioned fats and oils was treated with Lichrosorb RP.
The results of triglyceride analysis by high performance liquid chromatography using -18 are shown. The sample fats used were beef tallow, corn oil, a mixture of beef tallow and corn oil, and transesterified fats, and the solvent used was a mixture of acetone:acetonitrile:chloroform in the ratio of 250:200:100. there was. As a result, when looking at the peaks of beef tallow and corn oil, there is little overlap, and when compared with a sample that is just a mixture, a peak that looks like the sum of the peaks of beef tallow and corn oil appears. On the other hand, it was found that when transesterification was performed, the original peaks of beef tallow and corn oil decreased, but a new peak was created in the exact middle of beef tallow and corn oil. This shows that when beef tallow and corn oil are transesterified, new triglycerides never seen before are created.
Furthermore, the newly created triglyceride was proven to be a hybrid of beef tallow and corn oil, with properties that are not biased towards either beef tallow or corn oil. It was also found that there is a large difference in the melting state near the melting point between a mixed fat of lard and corn oil and a fat obtained by transesterifying this fat. In other words, in the case of just mixed fats and oils, the temperature ranges from 10°C lower than its melting point (46.1°C) to around the melting point.
White particles continue to float in the transparent liquid phase,
The white particles disappear completely when the melting point is reached. On the other hand, in the case of transesterified fats and oils, the whole fat is cloudy, but gradually becomes transparent. In short, simply mixed fats and oils contain fewer types of triglycerides than transesterified fats, and each triglyceride melts step by step, whereas transesterified fats and oils contain fewer amounts of each triglyceride. It appears that there are many stages of melting, resulting in homogenization. Note that these facts are supported by analysis using high performance liquid chromatography. Examples will be described below. Transesterification of animal fats and vegetable oils was carried out using PEG-modified lipase. The animal fats and oils used were pork fat and beef tallow, and the ratios were as follows.

【table】

[Table] For transesterification, in each case above,
After 1.0 g of PEG-modified lipase was activated by moistening it with 1.0 ml of water, the above-mentioned oils and fats were reacted. In this case, the temperature was 58°C, the reaction time was 48 hours, and the reaction was carried out in a light-shielded state after replacing the air in the reaction vessel with dry nitrogen. Furthermore, fats and oils that are a mixture of animal fat and corn oil,
The following two tests were conducted to determine how the sensory evaluation changes due to transesterification. In the sensory evaluation, a comparison was made between a simple mixture of transesterified products using sodium methylate and transesterified products using PEG-modified lipase. In the sensory evaluation, the unmodified lipase and the one after transesterification using the PEG-modified lipase were compared with a simple mixture. Each case is shown below.

【table】

[Table] In each of the above cases [] and [], the oils and fats that were simply mixed without transesterification had poor mouth melting, and were significantly different from those that had undergone transesterification. Moreover, in each case, no difference was observed depending on the transesterification method. Examples of processing and cooking using transesterified fats and oils are shown below. () Comparison of beef sausages Sausages were manufactured using the following materials in a conventional manner.

【table】

[Table] However, transesterified fat is a mixture of equal amounts of beef fat and salad oil, and transesterified using polyethylene glycol modified lipase. As a result of the sensory evaluation of the above products, the test group had a good taste and was mellow.
Beef flavor was expressed and was clearly superior to the control group. () Fried rice using pork fat and corn oil A prototype of fried rice was made using the following ingredients. Then, it was left at room temperature for 10 minutes and a sensory test was conducted.

【table】

[Table] Sample oils and fats A: Pork fat B: A mixture of equal amounts of pork fat and corn oil and transesterification C: A mixture of equal amounts of pork fat and corn oil D: Corn oil sensory test results (b) When using only pork fat, some of the fat will crystallize and become whitish when it cools down a bit, and it will not melt in your mouth. The same thing can be said about just mixed fats and oils. (b) Ester-exchanged fats and oils have a better texture in the mouth than pork fat, and retain the unique flavor of pork fat. (c) Corn oil alone does not show any characteristics. (iv) When using lard, it is difficult to measure because it is a solid, but transesterified fats and oils are soft and can be used more easily. () White sauce using beef tallow and corn oil A prototype white sauce was made using the following ingredients. After preparation, a sensory test was conducted at 60°C.

[Table] Sample oils and fats A: Beef tallow B: Beef tallow and corn oil mixed in equal amounts and transesterified C: Beef tallow and corn oil mixed in equal amounts D: Corn oil sensory test results (a) Products made using only beef tallow are very hard, have a fishy smell, and don't melt in the mouth. (b) The one made with corn oil was soft, but I felt it was unbalanced, as if the flour and fat were separating in my mouth. (c) Oils and fats that are simply mixed without transesterification have a fishy smell and do not melt in the mouth. (d) Ester-exchanged fats and oils mix well with flour, eliminate fishy odor, and melt in the mouth. Note that butter is usually used for white sauce, but by making use of the butter-like aroma of beef tallow to create transesterified oil, beef tallow, which is not commonly used today, can be used as a butter substitute for white sauce. Can be used effectively. In general, pork fat, beef tallow, and the like are fats and oils that each have a unique flavor, and depending on the cooking, the flavor is used to make the most of the flavor. but,
Animal fats and oils have a high melting point and do not melt at body temperature, so they do not melt in the mouth and have an unpleasant texture. Furthermore, even if animal fats and oils are mixed with vegetable oils such as corn oil, which have a low melting point, the melting point is the same as that of animal fats and oils, resulting in a poor texture. However, as mentioned above, when transesterification is performed, the melting point is lowered and becomes lower than body temperature, so it melts in the mouth and improves the texture. Note that the polyethylene glycol-modified lipase used in the present invention is soluble both in organic solvents and in hydrophobic substrates (oils and fats). Due to this, solvents and surfactants were required when transesterifying solid fats, but now
This was made possible using only oil, PEG-modified lipase, and a small amount of water, and the reaction proceeded at the melting temperature of animal fat. Here, we conducted a storage test on oils and fats, and measured changes in acid value and peroxide value over time. The results are shown below. The test conditions were 47°C for about 45 days. First, the acid value was higher at 0 hours than the transesterified fat and the mixed fat, which was compared and contrasted. However, while the acid value of pork fat rapidly increases around the 30th day, there is almost no change in the acid value of transesterified fats. In addition, the peroxide value of pork fat increases sharply from around the 10th day and that of corn oil from around the 30th day, whereas the value of transesterified fats and oils increases relatively slowly and is low. In general, as the peroxide value increases, the rancid odor increases in sensory terms, but even if the peroxide value is the same, pork fat is overwhelmingly more rancid than corn oil. There is a lot of odor. However, by mixing pork fat and corn oil and transesterifying the mixture, it was possible to maintain the flavor of pork fat and obtain odor stability that could not be obtained with pork fat alone. [Effects of the Invention] As explained above, according to the present invention, since the PEG-modified lipase is used to transesterify fats and oils, the melting point is lowered while retaining the flavor of animal fats, and as a result, the range of use has been expanded. Modified fats and oils are obtained.

Claims (1)

[Claims] 1. After moistening polyethylene glycol-modified lipase with water, adding dehydrated mixed fats and oils,
A method for modifying fats and oils, characterized by replacing air in a reaction vessel with nitrogen and performing transesterification in a light-shielded state. 2. Claim 1, characterized in that the fat is a mixture of animal fat and vegetable oil.
Modification method described in section.