Patent Application
20050042333
The invention relates to a frozen aerated product such as ice cream, wherein the fat content of the frozen aerated product comprises vegetable fat containing specified amounts of polyunsaturated and saturated fatty acids. This invention also relates to methods of preparation of such a frozen aerated product.
Fats are triglycerides (ie they are esters of glycerol with three fatty acid moieties). The fatty acid moieties may be the same or different. The fatty acid moieties which have no double bonds are referred to herein as saturated fatty acids (SAFA), fatty acid moieties that contain one double bond are referred to herein as monounsaturated fatty acids (MUFA) and fatty acid moieties that contain two or more double bonds are referred to herein as polyunsaturated fatty acids (PUFA). The relative amounts of saturated, monounsaturated and polyunsaturated fatty acids which are present depend on the source from which the fat has been derived. Traditionally, frozen aerated products such as ice cream have been prepared with fats having a high level of saturated fatty acids, (herein referred to as saturated fats) such as those obtained from dairy products or coconut oil. Saturated fats are solid at ambient temperatures and are relatively easy to formulate into frozen aerated products. Consumers are now looking for frozen aerated products which have all the properties of these traditional products but which are more healthy for them. One concern such consumers have is that eating saturated fats increases the low density lipoproteins (LDL) in their circulation. Increased LDL levels are believed to be associated with increased risk of coronary heart disease and stroke. Replacing the saturated fats in the diet with unsaturated fats has been proposed as one way to reduce the amount of potentially harmful LDLs in the blood. It has not been possible to formulate unsaturated fats which are liquid at ambient temperatures into frozen aerated products which have the desired meltdown characteristics and which provide the desired mouthfeel for the consumer.
Japanese Patent Application 57/036944 describes the production of ice cream using an oil that is liquid at ambient temperatures using a sucrose fatty acid ester as emulsifier. The oils that are exemplified include rapeseed oil, perilla oil, water melon seed oil, sesame oil, rice oil, cotton seed oil, wheat oil, peanut oil, corn oil, soyabean oil, sunflower oil and safflower oil. These oils have a PUFA content in excess of 28%.
French Patent Application 2791870 describes ice creams in which the fat component consists essentially of olive oil. The processing procedures described in this reference produce ice creams that do not have the amounts of de-emulsified fat required by the present invention. Additionally the ice cream produced by the procedure described has poor meltdown initiation times.
In a recipe book written by the French chef, Christian Etienne called “La Magie de la Tomate” (at page 93) there is described an ice cream containing olive oil (50 g), heavy cream (80 ml), milk (170 ml), two egg yolks and sugar (25 g). The presence of dairy products (cream and milk) which are high in saturated fat in this product means that it does not have the desired health benefits.
U.S. Pat. No. 5,478,587 describes frozen desserts which comprise a non-dairy creamer which contains a partially hydrogenated oil but which can contain a partially hydrogenated vegetable oils in addition to the oil in the non-dairy creamer. There is no teaching about the amount of additional vegetable oil that is to be included. Examples of partially hydrogenated oils include canola oil (which is partially hydrogenated) and peanut and olive oils which have not been subjected to hydrogenation.
US Patent Application 2002/0034562 discloses a fat composition (which can be used inter alia to make frozen desserts and filled ice creams) which 15 to 40% by weight of linoleic acid (a polyunsaturated fatty acid) and 20 to 40% of saturated fatty acids. The fat compositions described in this reference have higher content of linoleic acid than envisaged for the present invention.
Definitions
Vegetable Fat
The term “vegetable fat” used herein means a fat obtained from a plant source. Vegetable fats which are liquid at ambient temperatures are often referred to as vegetable oils. In this specification the term “vegetable fat” includes such vegetable oils
Frozen Aerated Product
The term “frozen aerated product” as used in this specification means a frozen product made by freezing a pasteurised mix of ingredients with agitation to incorporate air into the product.
Overrun
Overrun is defined as in Ice Cream—W. S. Arbuckle—AVI Publishing, 1972, page 194. Several ways of calculating the overrun are given in this book. In this specification overrun is measured according to the formula
% Overrun=100×[Wtmix−Wtproduct]/Wtproduct
in which Wtmix is the weight of a certain volume of the mix from which the frozen product is to be prepared and Wtproduct is the weight of the same volume of the product after it has been frozen and aerated.
Meltdown Initiation Time
The meltdown initiation time is defined as the time that elapses before 4% of the initial weight of the sample has dropped into the collecting vessel in the experimental procedure described hereinafter.
De-Emulsified Fat
De-emulsified fat is known by many different names (for example destabilised fat, agglomerated fat, aggregated fat, partially coalesced fat, flocculated fat, extractable fat). It is generally believed that fat de-emulsification is responsible for establishing a three dimensional agglomeration of fat globules throughout a frozen aerated product which contributes to the structural integrity of the product. The process of de-emulsification occurs when the partially crystalline fat globules present in the mix from which the frozen aerated product is to be made undergo partial coalescence during the whipping and freezing process. The shear forces applied to the mix during aeration and freezing cause the fat globules to collide and interact, eventually leading to a fat structure to be formed that contributes greatly to the texture and meltdown properties of the product. This fat network is made up of partially coalesced fat particles that have been de-emulsified from the original mix. Measurement of the extent of fat de-emulsification therefore provides a measure of the structural integrity in the frozen aerated product.
Several methods exist to measure the amount of de-emulsified fat in ice cream. The method used herein is the so called Mastersizer technique which is described in more detail hereinafter, and has previously been described in EP 1 094 718.
Stabilisers
Stabilisers are defined as in Arbuckle, W. S., Ice Cream, 4th Edition, AVI publishing 1986, chapter 6, pages 84-92.
Emulsifiers
Emulsifiers are defined as in Arbuckle, W. S., Ice Cream, 4th Edition, AVI publishing 1986, chapter 6, pages 92-94.
In accordance with a first object of the invention there is provided a frozen aerated product comprising water, 0.1 to 35 w/w % sweetener and 2 to 20 w/w % vegetable fat component of which up to 20% by weight of the fatty acids are polyunsaturated fatty acids, less than 15% by weight of the fatty acids are linoleic acid and up to 50% by weight of the fatty acids are saturated fatty acids; said frozen aerated product being characterised in that the amount of de-emulsified fat expressed as a percentage of the total fat present is greater than 20% by weight.
It has been found that the frozen aerated products of the invention have a good mouthfeel.
Preferably the percentage by weight of the polyunsaturated fatty acids in the fat component lies in the range 2 to 20%, more preferably 3 to 17.5%, most preferably 4 to 15%.
Preferably the percentage by weight of the saturated fatty acids in the fat component lies in the range 5 to 50%, more preferably 7 to 45%. The lower the amount of saturated fat, the greater the health benefit.
Preferably the ratio of the weight of saturated fatty acids to the weight of monounsaturated fatty acids in the fat component lies in the range 0.05 to 1.5, more preferably 0.10 to 1, most preferably 0.15 to 0.5.
Preferably the frozen aerated product comprises 0 to 1 w/w % emulsifier.
Preferably, the frozen aerated product according to this invention is an ice cream.
In preferred embodiments of the present invention the frozen aerated product may comprise 5 to 12%, more preferably 8 to 10% fat component. The fat component may comprise a vegetable fat which is a liquid at ambient temperatures (hereinafter referred to as liquid vegetable fat) or a mixture of liquid vegetable fat with other fats provided that the amount of polyunsaturated fatty acids in the mixture does not exceed 20% of the fatty acids present, that the total amount of linoleic acid does not exceed 15% of the fatty acids present and the amount of saturated fatty acids in the mixture does not exceed 50% of the fatty acids present. The fatty acid content of vegetable fats can be found in standard reference works such as “The Lipid Handbook”, Second Edition, Authors Frank D Gunstone, John L Harwood, Fred B Padley, Published by Chapman & Hall 1994 from which the data in this specification are taken unless otherwise indicated. Suitable liquid vegetable fats that may be used on their own include those listed in Table 1. The notation “(USDA)” in Table 1 indicates that the data was obtained from the United States Department of Agriculture National Nutrient Database for Standard reference. The notation “(Erasmus)” indicates that the data was obtained from Fats that heal, fats that kill, Erasmus, U., Alive Books, 1993. The notation “(FBFD)” denotes that the data was obtained from the Fat Blend Formulation Database. The exact fatty acid composition of liquid vegetable fats varies between sources and the numbers given are typically averages. Because of this, and because of rounding errors, the total MUFA+PUFA+SAFA may not be exactly 100% in every case.
The fat component of the frozen aerated products of the present invention may comprise the vegetable fats in Table 1 in admixture with one or more of the other vegetable fats listed in Table 1 or with any other vegetable fat which results in the fat component of the frozen aerated product having the required PUFA, SAFA and linoleic acid content.
It will be appreciated by those skilled in the art that the desired PUFA and SAFA levels may be achieved when mixing two vegetable fats when one component of the mixture has a high SAFA content and the other has a high MUFA content provided that neither of the components contributes excessive amounts of PUFA or linoleic acid. Vegetable oils having large PUFA or linoleic acid content can only be used in mixtures suitable for use in the present invention if they are present in relatively small amounts.
Examples of suitable mixtures include mixtures of olive oil (OV) and coconut oil (CNO) whose composition is 6.2% MUFA, 1.6% PUFA, 92.3% SAFA, 1.6% linoleic, and mixtures of OV and CNO in admixture with other vegetable fats for example linseed oil, rice bran oil, grape seed oil, cotton seed oil, ground nut oil, high oleic rapeseed oil or poppy seed oil. Some specific examples of such mixtures are given in Table 2 by way of example only but it will be appreciated by those skilled in the art that mixtures having different proportions of the OV, CNO and other fats could be formulated to have the desired PUFA, SAFA and linoleic acid content. It will also be appreciated that all or part of the OV, CNO or other fat identified in Table 2 could be replaced by other vegetable fats or that other vegetable fats may be added in addition to the OV, CNO and other fat identified in Table 2 to give frozen aerated products having the PUFA, SAFA and linoleic acid levels specified in the present invention.
Table 3 gives further examples of mixtures of fats that give the required levels of PUFA, SAFA and linoleic acid. Many other combinations are possible as will be apparent to those skilled in the art.
The frozen aerated products of the present invention may additionally contain milk solids not fat (MSNF) in an amount of 0.25 to 20% w/w. MSNF contains milk proteins and lactose. MSNF may be provided by using dried skimmed milk and/or dried whey
The sweetener of the invention is a mono-, di- or oligo-saccharide, or a sugar alcohol, for example sucrose, fructose, glucose, lactose, dextrose, invert sugar and sorbitol, and can be included in the pre-mix in either crystalline or liquid syrup form. Alternatively, or additionally, the sweetener is a corn sweetener in either a crystalline form of refined corn sugar (dextrose and fructose), a dried corn syrup (corn syrup solids), a liquid corn syrup or a mixture thereof.
In the frozen aerated products of the present invention, stabilisers are preferably used. The amount of stabiliser is in the range 0 to 1%, preferably 0.05 to 0.8%, more preferably 0.1 to 0.5% by weight of the frozen aerated product. Examples of known stabilisers include alginates, gum arabic, gum ghatti, gum karaya, gum tragacanth, locust bean gum, carrageenan, xanthan gum, guar gum, gelatine, agar, sodium carboxymethylcellulose, microcrystalline cellulose, methyl and methylethyl celluloses, hydroxypropyl and hydroxypropylmethyl celluloses, low and high methoxyl pectins and mixtures thereof. It has been found that stabilisers can improve the mouthfeel of the products.
The amount of emulsifier is preferably in the range 0.05 to 0.8 w/w % emulsifier, more preferably 0.1% to 0.5% by weight of the frozen aerated product. Examples of known emulsifiers include mono- and di-glycerides of saturated or unsaturated fatty acids (for example monoglyceryl palmitate—MGP), polyoxyethylene derivatives of hexahydric alcohols (usually sorbitol), glycols, glycol esters, polyglycerol esters, sorbitan esters, stearoyl lactylate, lactic acid esters, citric acid esters, acetylated monoglyceride, diacetyl tartaric acid esters, polyoxyethylene sorbitan esters, lecithin and egg yolk and mixtures thereof.
The amount of de-emulsified fat in the frozen aerated products of the present invention is preferably in the range 20 to 80%, more preferably 25 to 70%, most preferably 30 to 60%. The amount of de-emulsified fat is determined using a Malvern Mastersizer model 2000 (Malvern Instruments UK).
The amount of de-emulsified fat in the frozen aerated products of the present invention was determined in the following way. The percentage of the fat present that is de-emulsified is the percentage by volume when measured by the Mastersizer method of the fat particles in the frozen aerated product that have a particle size larger than the d(0,9) diameter measured on the mix from which the frozen aerated product is made before it is frozen.
In order to ensure that the measurement is only of the fat droplet size distribution, any milk protein micelles must be broken down before the measurements are taken. A solution of urea (to disintegrate casein micelles by disrupting hydrophobic bonds) and sodium dodecyl sulphate (SDS) (to displace protein at the oil/water interface and to dissociate the micelles) is used. The solution used in the method that is described herein is prepared by adding urea (198.2 g 98%— Sigma U5378) to water (around 250 ml) and stirring for twenty minutes. SDS (0.5 g—Prod 44244 from BDH Chemical Ltd) is added and the volume made up to 500 ml with water. The mixture is stirred until clear (around 10 minutes). The resulting solution is referred to herein as “the urea/SDS solution”.
To determine the fat droplet size distribution in the mix from which the frozen aerated product is made before it is frozen, a sample (10 ml) of the cooled, homogenised and pasteurised mix is added to the urea/SDS solution (20 ml) in a 50 ml glass beaker. The mixture is stirred for 15 minutes at 20° C. The resulting mixture is added dropwise by pipette to the large bath of the Mastersizer 2000 machine to an obscuration of 10-15% and the integral ultrasound is applied at 100% power for one minute. The machine measures the particle size distribution and determines the fat droplet diameter d(0,9) below which the diameters of 90% by volume of the fat droplets are found.
To determine the fat droplet size distribution in the frozen aerated product after it has been frozen, a sample (20 ml) is taken from the centre of the frozen aerated product using a cork borer having a diameter of 18 mm. The sample is added to the urea/SDS solution (20 ml) in a 50 ml glass beaker. The mixture is stirred for 15 minutes at 20° C. The resulting mixture is added dropwise by pipette to the large bath of the Mastersizer 2000 machine to an obscuration of 10-15% and the integral ultrasound is applied at 100% power for one minute. The machine measures the particle size distribution and determines the percentage volume of fat particles with a size greater than the d(0,9) value obtained for the unfrozen mix above. This is the percentage of de-emulsified fat reported herein. According to this definition, the percentage of de-emulsified fat for the unfrozen mix is 10%. Consequently, and allowing for experimental error (which is typically a few percent), values of the de-emulsified fat from frozen products of less than 20% are considered to show that the frozen product does not contain significantly more de-emulsified fat than the unfrozen mix. Values greater than 20% are considered to show that the frozen product does contain significantly more de-emulsified fat than the unfrozen mix.
It has been found that amounts of de-emulsified fat in these ranges produce products with good mouthfeel.
The frozen aerated products of the present invention preferably show resistance to meltdown and to serum leakage for extended periods of time on exposure to a temperature above the melting point of the product. Resistance to meltdown and to serum leakage is determined by measuring the meltdown initiation time as described hereinafter. The frozen aerated products of the present invention satisfy the condition that the meltdown initiation time is greater than 25 minutes, preferably greater than 40 minutes, more preferably greater than 45 minutes when measured at 20° C. in the test described below.
The meltdown initiation times were determined in the following way. Tests were performed on a stainless steel wire mesh grid having a size of 25×25 cm, with 2.5 mm holes, 1 mm thick wire. The grids are placed on a 600 funnel with a bore size of 2 cm suspended over a collecting vessel (of large enough volume to collect the entire sample tested) placed on balances for weighing the material collected in the vessel. The balances are connected to a data logging system to record the mass collected. The grids were placed in a meltdown cabinet set at a constant temperature environment of 20° C., which was capable of holding up to 12 of these grids simultaneously.
For each formulation listed hereinafter in the examples, melting tests were performed on three samples of each product at 20° C. Each sample was in the form of a rectangular block measuring 14.5×9×3.8 cm and was placed on the grid with one of its larger flat faces in contact with the grid. Before placement in the cabinet the ice cream samples were equilibrated in a freezer at −25° C., and then weighed on a zeroed balance containing the mesh grid. They were then arranged randomly over the available positions in the meltdown cabinet. Once all samples were in place, the data logging system measured the amount of collected material every minute.
From the mass of the sample collected over this period, the percentage mass loss of the samples is calculated using the following formula.
wherein:
The meltdown initiation time for each sample of each formulation was observed. This is defined by the time that elapses before 4% of the initial weight of the sample has dropped into the collecting vessel.
Preferably the frozen aerated products of the present invention have an overrun of between 10% and 250%, more preferably between 50% and 150%, most preferably between 80% and 110%. Products with overruns in these ranges are particularly acceptable to consumers.
In accordance with a second aspect of the present invention there is provided a process for manufacturing a frozen aerated product comprising:—
It has been found that products prepared according to this process have a good mouthfeel.
Preferably emulsifiers are included in the range 0 to 0.5% w/w.
Preferably stabilisers are included in the range 0 to 1% w/w.
This process is particularly applicable to the manufacture of frozen aerated products in which 2 to 20%, preferably 3 to 17.5% by weight of the fatty acids in the fat component are polyunsaturated fatty acids and 5 to 50%, preferably 7 to 45% by weight of the fatty acids in the fat component are saturated fatty acids, and in which the ratio of the weight of saturated fatty acids to the weight of monounsaturated fatty acids lies in the range 0.1 to 1.5 preferably 0.1 to 1.
Conveniently the premix may be produced by mixing the other ingredients and the sweetener and then adding the fat component.
The processes of this invention includes the step of homogenising and pasteurising the mix. The mix may be homogenised using equipment and conditions commonly known in the industry for example a single or double stage valve homogeniser. Pasteurisation of the homogenised mix can be conducted using any method and condition that is well known to a person skilled in this field for example high temperature short time (HTST) or low temperature long time (LTLT) pasteurisation. In a preferred homogenising and pasteurising step according to the processes of the present invention the temperature of the premix is raised to the pasteurisation temperature, the premix is homogenised and then held at the pasteurisation temperature for sufficient time to complete the pasteurisation.
After homogenisation and pasteurisation the mix is preferably held at a temperature below 0° C. for a period between 2 and 72 hours preferably with agitation. More preferably the mix is held at a temperature around −2° C. with agitation for 2 to 48 hours, or most preferably for 4 to 24 hours. It has been found that including this step in the process produces products which have improved mouthfeel.
The mix is then frozen and aerated. This may be achieved in any equipment suitable for this purpose and commonly known in the industry. One of ordinary skill in the art will readily be able to determine the required aeration pressure and throughput rate of the mix to obtain the desired aerated product.
The conditions of aeration are chosen to achieve an overrun of about 10% to about 250%. Preferably the overrun for the preferred ice cream products is between 50% and 150%, more preferably 60% and 120% and most preferably between 80% and 110%.
The aerated mix is then extruded, preferably directly, into containers, hardened at a temperature of, for example, −35° C. and stored in a commercial freezer at a temperature of, for example, −25° C.
Examples of the products of the invention and comparative examples will now be described by way of illustration only, and not to limit the invention.
The PUFA, SAFA and linoleic content given in the Examples are taken from data given in “The Lipid Handbook”, Second Edition, Authors Frank D Gunstone, John L Harwood, Fred B Padley, Published by Chapman & Hall 1994.
Formulations containing the components listed in Table 4 were prepared by the method described below.
Water was placed in a jacketed mix tank at 85° C., then skimmed milk powder, whey, locust bean gum, guar gum, carrageenan, emulsifier, sucrose, corn syrup and the olive oil and (if present) coconut oil were dissolved by mixing with a high shear mixer. Hot water was circulated in the jacket of the tank to maintain a premix temperature of 65° C.
The premix was heated using a plate heat exchanger to a temperature of 83° C., homogenised using a the first stage of a Crepaco double stage valve homogeniser at pressures of 140 bar. After holding the mix at 82 to 85° C. for 12.1 seconds, the mix was cooled using a tubular heat exchanger to −2° C. and held at this temperature for at least 24 hours before freezing. The colour and flavour were added to the cooled mix.
The mix was processed through a continuous ice cream freezer (type APV Technohoy MF75) fitted with an open dasher rotating at a speed of 300-500 rpm and operating with a barrel pressure in the range 1-4 bar. The products were produced with a mix flow rate of 0.4 l/min, with an overrun of 100% and an extrusion temperature in the range −6° C. to −8° C. The frozen aerated products were collected in 500 ml waxed paper cartons and then hardened in a blast freezer at −35° C. for a period of 2 hours. The hardened products were then stored at −25° C.
The de-emulsified fat content and the meltdown initiation time at 20° C. given in Table 4 were determined by the methods described previously.
Formulations containing the components listed in Table 5 as disclosed in the example in FR 2791870 were prepared by the method described below.
Water was placed in a jacketed mix tank at 85° C., then skimmed milk powder, whey protein, sucrose, glucose, olive oil, maltodextrin and oligofructose were dissolved by mixing with a high shear mixer. Hot water was circulated in the jacket of the tank to maintain a premix temperature of 65° C.
The premix was heated using a plate heat exchanger to a temperature of 83° C., homogenised using the first stage of a Crepaco double stage valve homogeniser at pressures of 140 bar.
After holding the mix at 82 to 85° C. for 12.1 seconds, the mix was cooled using a tubular heat exchanger to 2° C. and held at this temperature for 8 hours before freezing.
The mix was processed through a continuous ice cream freezer (type APV Technohoy MF75) fitted with an open dasher rotating at a speed of 300-500 rpm and operating with a barrel pressure in the range 1-4 bar. The products were produced with a mix flow rate of 0.4 l/min, with an overrun of 100% and an extrusion temperature in the range −5° C. to −9° C. The frozen aerated products were collected in 500 ml waxed paper cartons and then hardened in a blast freezer at −35° C. for a period of 2 hours. The hardened products were then stored at −25° C.
The de-emulsified fat content and the meltdown initiation time at 20° C. given in Table 5 were determined as described previously.
The above formulation had a de-emulsified fat content of 3% and gave a meltdown initiation time of 7 minutes at 20° C. These values do not give a quality ice cream.
| Number | Date | Country | Kind |
|---|---|---|---|
| 03255097.2 | Aug 2003 | EP | regional |
