Fat composition and frothing oil-in-water emulsion

The objects of the present invention are to provide a whippable oil in water type emulsion, which possesses good heat resistance, excellent melting properties in mouth, freshness and cold feeling, and to provide a fat composition suitable for preparing the emulsion. A fat composition, comprising 25-60% of glycerides, of which constituent fatty acid residue has not more than 38 total carbon atoms, 25-50% of glycerides, of which constituent fatty acid residue has 42-46 total carbon atoms, and 5-25% of glycerides, of which constituent fatty acid residue has not less than 48 total carbon atoms was prepared by mixing laurin fats or hydrogenated products thereof which contain fatty acid residues with 16-24 carbon atoms or esters thereof, or a fat being rich in glycerides with fatty acid residues containing 16-24 carbon atoms, transesterifying them by a known method in the presence of a lipase having 1,3-specificity, and, if necessary, extremely hydrogenating them. Then, the fat composition obtained is used to prepare the whipping oil in water emulsion.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a fat composition which has a specific
 composition, and a whippable oil in water (o/w) emulsion prepared by using
 the fat composition.
 2. Description of the Related Art
 A large amount of laurin fats, such as coconut oil and palm kernel oil, and
 hydrogenated products thereof have been used in whippable creams, such as
 whipping cream. Cream prepared by using these fats, solely or with natural
 fresh cream, has been used for cake icing and the like. Many of them have
 superior qualities in their physical properties to natural fresh cream,
 such as excellent melting properties in mouth, freshness and cold feeling,
 but there are still various points to be improved. A particular problem in
 a whipped cream is its poor heat resistance. Especially in summer, the
 whipped cream causes deformation and syneresis, when used to decorate cake
 or the like. Laurin fats, especially coconut oil, contains only a small
 amount of long-chain unsaturated fatty acids, such as oleic acid and
 linoleic acid. Therefore, their heat resistance are not so improved ever
 when extremely hydrogenated. In addition, there is a method to give heat
 resistance to laurin fats by adding a high melting point fraction of
 liquid oils or extremely hydrogenated oils to the laurin fats, but it is
 known that this method deteriorates melting properties of cream in mouth.
 Though a trial has been performed to obtain a hardstock fat of margarine by
 introducing long-chain fatty acids to laurin fat (EP 0170431), no trial
 has been done to improve melting properties in mouth and heat resistance
 of a whippable cream.
 SUMMARY OF THE INVENTION
 The present invention provides a whippable o/w emulsion which has good heat
 resistance and excellent melting properties in the mouth.
 It is believed that excellent melting properties in the mouth, freshness
 and cold feeling of a whippable o/w emulsion prepared by using laurin fats
 are derived from middle-chain fatty acids with 8-12 carbon atoms. Hence,
 the inventors have found that a novel fat composition can be prepared by
 reserving middle-chain fatty acids, which occupy more than half of fatty
 acids especially in their 2-position as they are, and introducing a small
 amount of long-chain fatty acids with 16 or more carbon atoms to the fats,
 and that thereby a whippable o/w emulsion, which is imparted excellent
 melting properties in mouth and heat resistance, can be prepared.
 That is, the present invention relates to a fat composition containing
 25-60% of glycerides, of which constituent fatty acid residue has not more
 than 38 total carbon atoms, 25-50% of glycerides, of which constituent
 fatty acid residue has 42-46 total carbon atoms, and 5-25% of glycerides,
 of which constituent fatty acid residue has not less than 48 total carbon
 atoms. And the present invention relates to a whippable o/w emulsion
 prepared by using the fat composition.
 The fat composition of the present invention contains 25-60% of glycerides,
 of which constituent fatty acid residue has not more than 38 (normally
 30-38) total carbon atoms, 25-50% of glycerides, of which constituent
 fatty acid residue has 42-46 total carbon atoms, and 5-25% of glycerides,
 of which constituent fatty acid residue has not less than 48 (normally
 48-56) total carbon atoms. % value indicating a distribution of number of
 carbon atoms in a glyceride is weight %. That is, the fat composition of
 the present invention is novel in that a content of glycerides, of which
 constituent fatty acid residue has not less than 38 total carbon atoms, is
 less than that in laurin fats and is equal to that in milk fat, and a
 content of glycerides, of which constituent fatty acid residue has 42-46
 total carbon atoms, is more than that in laurin fats and milk fats, and
 that a content of glycerides, of which constituent fatty acid residue has
 not less than 48 total carbon atoms, is less than that in milk fats and
 more than that in laurin fats. The whippable o/w emulsion prepared by
 using the fat composition has excellent melting properties in mouth,
 freshness, cold feeling, and a good heat resistance. When a content of
 glycerides, of which constituent fatty acid residue has not less than 48
 total carbon atoms, are excess, a whippable o/w emulsion has good heat
 resistance, but has inferior melting properties in mouth. Therefore, to
 improve both heat resistance and melting properties in mouth, a content of
 glycerides, of which constituent fatty acid residue has 42-46 total carbon
 atoms, and glycerides, of which constituent fatty acid residue has not
 less than 48 total carbon atoms, should be in the range mentioned above.
 The fat composition of the present invention has following properties when
 prepared according to a process described below: more than 40%, preferably
 more than 50% fatty acids at 2-position of triglycerides is lauric acid,
 and 1,3-fatty acids are randomly distributed between these positions. And
 also, solid fat content (SFC) is 45-70% (at 20.degree. C.) and 10-45% (at
 30.degree. C.). Slipping point (in the United States, called as Sofning
 point) is 35-45.degree. C.
 An example of preparation of the fat composition of the present invention
 is as follows: The fat composition is prepared by mixing laurin fats or
 hydrogenated forms thereof with fatty acids containing 16-24 carbon atoms
 or esters thereof, or fats rich in glycerides which contain fatty acid
 residues with 16-24 carbon atoms, transesterifying them by a conventional
 method, in the presence of lipase having 1,3-specificity, and extremely
 hydrogenating them according to a conventional method, if needed.
 As for laurin fats, it is most preferred that coconut oil or hydrogenated
 form thereof, wherein lauric acid is most abundant at the 2-position, is
 used.
 As for fatty acids with 16-24 carbons or esters thereof, stearic acid,
 palmitic acid, or ethylester or methylester thereof are exemplified. As
 for fats rich in glycerides which contain fatty acid residues with 16-24
 carbon atoms, vegetable oils, such as soybean oil, rape seed oil, palm oil
 or fractionated oils thereof are exemplified.
 More definitely, when laurin fats or hydrogenated products thereof, and
 fatty acids or esters thereof are raw materials, it is preferred to mix at
 a weight ratio between 60:40 and 80:20 (laurin fats or hydrogenated forms
 thereof : fatty acids or esters thereof). When laurin fats or hydrogenated
 products thereof, and fats rich in glycerides which contain fatty acid
 residues with 16-24 carbon atoms are raw materials, it is preferred to mix
 at weight ratio between 70:30 and 90:10 (laurin fats or hydrogenated
 products thereof: fats rich in glycerides with fatty acid residues
 containing 16-24 carbon atoms).
 As for lipases specific to 1,3-position, known ones, for example from
 Rhizopus, Aspergillus, Penicillium, Candida, Pseudomonas, or Mucor, can be
 used. Procedures for lipases having 1,3-selectivity, lipase preparations,
 or method of transesterification using them, can be performed, according
 to the procedures described in, for example, JP,A,52-104506,
 JP,A,55-71797, JP,A,55-84397, JP,A,56-127094, JP,A,56-163196,
 JP,A,57-78496, JP,A,59-500649, JP,A,60-19495.
 When the fat composition is prepared by random transesterification, the
 composition will contain much triglycerides, such as tristearin, wherein
 each constitutive fatty acid is long-chain and contains 16-24 carbon
 atoms.
 The whippable o/w emulsion prepared by using such a fat composition will
 have heat resistance, but have inferior melting properties in the mouth.
 When a content of triglycerides, which contain both long-chain fatty acids
 and middle-chain fatty acids, i.e., triglycerides consisting of fatty
 acids with different chain lengths, is increased, "firmness" of the
 whippable o/w emulsion (crumbling to make handling difficult) will be
 prevented. Hence, it is preferred that transesterification selective to
 1,3-position is carried out.
 When laurin fats rich in glycerides which contain fatty acid residues with
 16-24 carbons are raw materials, it is preferred that extreme
 hydrogenation is carried out after transesterification of mixed fats. When
 separately hydrogenated fats are transesterified, elevation of the
 reaction temperature and use of solvents are required, which results in
 disadvantage in cost. Hence, it is preferred that fats are extremely
 hydrogenated after transesterification.
 Such fat composition obtained as mentioned above may be used to prepare a
 whippable o/w emulsion.
 In the present invention, "whippable o/w emulsion" is a creamy material,
 prepared by processing basic materials (the fat composition mentioned
 above, proteins, sugars and water) to be an emulsion by an aid of an
 emulsifier. It is also called "cream for whipping". When the whippable o/w
 emulsion is whipped by a foaming apparatus or a mixer for foaming, it
 becomes, what is called, "whipped cream" or "whip cream".
 Fat content of the foaming o/w emulsion of the present invention is
 normally in a range of 20-50% based on whole emulsion.
 As proteins, much proteins from non-fat solids are normally used. Non-fat
 solids are necessary to stabilize the emulsified state as an o/w emulsion
 as well as to impart milk flavor to the cream. Examples of these non-fat
 solids are skim milk powder, whole milk powder, raw cream, milk and
 sweetened condensed milk. Other proteins, such as casein, lactalbumin and
 vegetable proteins can be used. Alternatively, skim milk powder or whole
 milk powder may be Maillard-treated. Such non-fat solids are used in an
 amount of 1-15%, preferably 3-8% based on the total weight.
 Sugars are essential when the whippable o/w emulsion of the present
 invention is transported as fillings for breads or cakes at room
 temperature or under chilled condition. That is, to preserve the whipped
 materials for long time, decrease in water activity is required,
 therefore, addition of sugars is needed. Examples of sugars are glucose,
 maltose, sorbitol, sucrose, fructose, saccharified reduced starch, various
 thick malt syrups and the like. One of these sugars may be used, or more
 than one of them may be mixed to be use. In such cases, it is preferred
 that the amount of sugars to be added is less than 50% based on whole
 emulsion, calculated in an anhydrous material, and that a suitable amount
 of sugars is added according to the use. When more than 50% of sugars are
 used, viscosity of the whippable o/w emulsion increases, and various
 problem, such as a trouble in transportation by a pump in production step,
 will occur.
 Furthermore, emulsifiers, various salts, stabilizers and flavors, which are
 used in known synthetic cream, may be co-existed in the whippable o/w
 emulsion. As emulsifiers, for example, a suitable amount of soybean
 lecithin, sucrose fatty acid ester, polyglycerin fatty acid ester,
 sorbitan fatty acid ester and the like may be used. As salts, a suitable
 amount of alkali metal salts of phosphoric acid, alkali metal salts of
 citric acid and the like may be used. As stabilizers, a suitable amount of
 xanthan gum, guar gum and the like may be used.
 The whippable o/w emulsion of the present invention can be prepared
 according to procedures for preparing normal field creams or imitation
 creams, and can be sterilized if necessary. Homogenization or stirring can
 be preformed after or before sterilization. Homogenization may be done by
 either pre-homogenization or post-homogenization, otherwise combination of
 both.
 The whippable o/w emulsion prepared as mentioned above is suitable as
 fillings in breads and cakes, and can be used as nappe for a normal
 decorated cakes or as cream for preparing imitation flowers.
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
 As embodiments of the invention, the fat compositions and the whippable o/w
 emulsions were prepared by conventional methods according to Example 1.
 Furthermore, occurrence of thickened state after incubating the whippable
 o/w emulsions at 20.degree. C. for 2 hours and stirring them, over-run
 after foaming them for 5 minutes using a kenwood mixer, syneresis and
 maintenance of shape at 20-30.degree. C., and melting properties in mouth,
 were estimated. Results obtained from comparative experiments are also
 described in Comparative Example 1 and 2.

Following examples are to be construed as merely illustrative, and not to
 be limitations of the spirit of the invention. In addition, parts in
 formulation are represented by weight.
 EXAMPLE 1
 Eighty parts of palm oil was mixed with 20 parts of rape seed oil, and
 transesterification selective to 1,3-position was preformed, then extreme
 hydrogenation was carried out by a conventional method to obtain a fat
 composition (fat A). Composition and physical properties of fat A is shown
 in Table 1. Then, according to the formulation below, a whippable o/w
 emulsion was prepared by using fat A. Firstly, an oily phase was prepared
 by warming fat A to 70.degree. C., and adding soybean lecithin thereto.
 Separately, an aqueous phase was prepared by warming water at 60.degree.
 C., adding sodium hexametaphosphate and sodium bicarbonate thereto to be
 dissolved, then dissolving or dispersing therein skim milk powder, thick
 malt syrup and sorbitol in this order. Then, the oily phase and the
 aqueous phase were mixed together, and sucrose fatty acid ester, xanthan
 gum and flavor were added thereto, and the mixture was stirred and
 pre-emulsified at 65-70.degree. C. for 20 minutes using a homomixer.
 Thereafter, the mixture was homogenized under a pressure of more than 100
 kg/cm.sup.2, treated by ultra high temperature sterilization (UHT) at
 1400-150.degree. C. for 4 seconds, and again homogenized under a pressure
 of 45 kg/cm.sup.2, cooled to 12.degree. C., then subjected to aging.
 Estimation of the whippable o/w emulsion prepared is shown in Table 2

Formulation (%; w/w)
 fat A 23.6%
 skim milk powder 4.0%
 sugars (*1) 35.0%
 water 36.04%
 emulsifier (*2) 0.58%
 stabilizer (*3) 1.38%
 salts (*4) 0.32%
 flavor 0.08%
 (*1) sorbitol, thick malt syrup
 (*2) soybean lecithin, sucrose fatty acids ester, sorbitan fatty acid ester
 (*3) xanthan gum
 (*4) sodium hexametaphosphate, sodium bicarbonate
 EXAMPLE 2
 A fat composition (fat B) was prepared by mixing 70 parts of hydrogenated
 palm oil with 30 parts of stearic acid, and transesterifying selectively
 to 1,3-position of the glycerides. Composition and physical properties of
 fat B are shown in Table 1. Then, a whippable o/w emulsion was prepared
 according to Example 1, except that fat B was used instead of fat A.
 Estimation of the whippable o/w emulsion prepared is shown in Table 2.
 EXAMPLE 3
 A fat composition (fat C) was prepared by mixing 70 parts of palm oil with
 30 parts of rape seed oil, transesterifying selectively to 1,3-position,
 and preforming extreme hydrogenation by a conventional method. Composition
 and physical properties of fat C are shown in Table 1. Then, a whippable
 o/w emulsion was prepared according to Example 1, except that fat C was
 used instead of fat A. Estimation of the whippable o/w emulsion prepared
 is shown in Table 2.
 COMATIVE EXAMPLE 1
 fat composition (fat D) was prepared by mixing 60 parts of coconut oil with
 40 parts of rape seed oil, transesterifying selectively to 1,3-position,
 and performing extreme hydrogenation by a conventional method. Composition
 and physical properties of fat D are shown in Table 1. Then, a whippable
 o/w emulsion was prepared according to Example 1, except that fat D was
 used instead of fat A. Estimation of the whippable o/w emulsion prepared
 is shown in Table 2.
 COMATIVE EXAMPLE 2
 One hundred parts of coconut oil was extremely hydrogenated to obtain fat
 E. Composition and physical properties of fat E are shown in Table 1.
 Then, a whippable o/w emulsion was prepared according to Example 1, except
 that fat E was used instead of fat A. Estimation of the whippable o/w
 emulsion prepared is shown in Table 2.
 In reference to Table 2, the whippable o/w emulsion from Examples 1-3 had
 good heat resistance and excellent melting properties in mouth. The
 whippable o/w emulsion from Comparative Example 1 had heat resistance as
 good as from Examples 1-3, but had inferior melting properties in mouth,
 therefore it was intolerable as food. The whippable o/w emulsion from
 Comparative Example 2 had melting properties as good as from Example 1-3,
 but had very poor heat resistance.
 EFFECT OF THE INVENTION
 The present invention provides a whippable o/w emulsion used in whipping
 cream and the like, which possesses good heat resistance as well as
 excellent melting properties in the mouth, freshness and cold feeling, and
 provides a fat composition suitable to be applied to the emulsion.
 TABLE 1
 Compositions and physical properties of fat A-E
 distribution
 of number of slipping
 carbon atoms SFC (%) point
 fat -38 42-46 48- 20.degree. C. 30.degree. C.
 (.degree. C.)
 Example 1 A 39.9 33.0 13.8 63.6 32.6 36.2
 Example 2 B 34.5 36.6 17.3 63.4 37.7 36.0
 Example 3 C 30.5 36.4 22.0 68.2 39.7 42.0
 Compar- D 22.5 38.5 28.5 72.0 46.0 46.0
 ative
 Example 1
 Compar- E 75.8 11.0 2.3 45.4 7.5 31.0
 ative
 Example 2
 TABLE 2
 Estimation of the whippable o/w emulsions
 maintenance
 state of melting
 viscosity occurrence of time for of shape
 syneresis* properties
 fat (CPS) thickened state foaming O.R.(%) 20.degree. C.
 25.degree. C. 30.degree. C. 20.degree. C. 25.degree. C. 30.degree. C. in
 mouth
 Example 1 A 880 no 9'29" 140 AA AA A
 -- -- -- excellent
 Example 2 B 980 no 10'38" 144 AA AA A
 -- -- -- excellent
 Example 3 C 850 no 12'28" 150 AA AA A
 -- -- -- excellent
 Comparative D 938 no 14'09" 150 AA AA A
 -- -- -- inferior
 Example 1
 Comparative E 920 no 12'15" 148 A B C
 .+-. + + excellent
 Example 2
 *maintenance of shape, state of loss of water; represent the states when
 imitation flowers (prepared using a whipped material) were kept at
 20.degree. C., 25.degree. C. and 30.degree. C. for 24 hours.
 maintenance of shape
 AA: best, without disintegration
 A: good, almost without disintegration
 B: with slight disintegration
 C: bad, with disintegration
 state of syneresis
 +: occurred
 .+-.: slightly occurred
 -: not occurred