WO2024068116A1

WO2024068116A1 - Method for storing a concentrated frozen confection premix

Info

Publication number: WO2024068116A1
Application number: PCT/EP2023/072059
Authority: WO
Inventors: Thomas James BOULTON
Original assignee: Unilever Ip Holdings B.V.; Conopco, Inc., D/B/A Unilever
Priority date: 2022-09-27
Filing date: 2023-08-09
Publication date: 2024-04-04

Abstract

The invention relates to a method for storing a concentrated frozen confection premix, wherein the concentrated premix is an oil-in-water emulsion in liquid form comprising: fat in an amount of 8 wt% to 20 wt%; sugars in an amount of 40 wt% to 64 wt%; protein in an amount of 1.5 wt% to 14 wt%; and water in an amount of 16 wt% to 36 wt%. The method comprises storing the concentrated premix in a closed container for a storage period of up to 84 days, wherein the concentrated premix is not subjected to a temperature: exceeding 37°C for more than 3 days during the storage period; and below 6°C for more than 6 days during the storage period.

Description

METHOD FOR STORING A CONCENRTATED FROZEN CONFECTION PREMIX

Field of the invention

The invention relates to concentrated premixes for the manufacture of frozen confections; in particular, to a method for storing such concentrated premixes. The concentrated premixes are oil-in water emulsions having a high total solids content.

Background of the invention

The manufacture of frozen confections (such as ice cream) is an energy intensive process typically involving several stages, namely: mix preparation (which consists of dosing and mixing of the ingredients); pasteurization and homogenization; ageing; freezing and hardening. Each of these stages requires energy.

The production of frozen confections with sought-after organoleptic properties involves emulsifying the fat in the premix so that it is present in the form of very small droplets. This is typically achieved using homogenization equipment, most commonly a valve-type homogenizer in which the mix is forced through a small valve under high pressure. The usage efficiency of the homogenization equipment is thus a significant contributing factor to the overall energy consumption of the manufacturing process.

The process described in WO 2016/116336 aims to improve the usage efficiency of homogenization equipment. This is achieved by a split stream process in which an emulsion with a high fat content is prepared, and then subsequently diluted with an adjunct composition and aqueous liquid to form the premix. In order to enable storage for longer periods and/or transport over longer distances, the adjunct composition is granulated with the concentrated emulsion as the binder. The granules are said to be much more stable than a liquid emulsion. However, aside from the energy input required to dry the granules to an appropriate moisture level, the drying step can introduce unwanted off-flavours.

Therefore, it would be desirable to provide a concentrated premix in liquid form - as this would avoid both the energy input associated with producing/drying the granules, and the concomitant production of off-flavours. Storage of concentrated oil-in water emulsions in liquid form is not straightforward. Firstly, oil droplet coalescence must be controlled, as small oil droplets are necessary to produce the desired organoleptic properties in the final frozen confection. In addition, there is a need to control Maillard reactions. Maillard reactions are known to affect food quality parameters, including organoleptic properties. For certain food products (such as dairy products) the changes ascribed to Maillard reactions are often undesirable - for example, the products of Maillard reactions may be perceived as off-flavours. The later stages of Maillard reactions include the formation of advanced glycation end products (AGEs) and melanoidins, which cause colour changes, influence sensory properties, and in some cases compromise shelf life. Formation of AGEs and melanoidins can be significantly enhanced by elevated temperatures (such as those used during sterilization or UHT processing), and they are known to accumulate during long-term storage or during transportation. Thus, being able to control Maillard reactions during food production and storage is important. The rate of Maillard reactions may be influenced by several factors including, but not limited to, type of reactants, temperature/time combinations, water activity, and pH.

We have found that carefully controlled storage conditions are required to prevent concentrated emulsions becoming unstable. In particular, it is important to control storage temperature over time.

Summary of the invention

The present invention relates to a method for storing a concentrated frozen confection premix, wherein the method comprises storing the concentrated premix in a closed container for a storage period of up to 84 days, wherein the concentrated premix is an oil-in-water emulsion in liquid form, the oil-in-water emulsion comprising: fat in an amount of 8 wt% to 20 wt%; sugars in an amount of 40 wt% to 64 wt%; protein in an amount of 1 .5 wt% to 14 wt%; and water in an amount of 16 wt% to 36 wt%; and wherein the concentrated premix is not subjected to a temperature:

• exceeding 37°C for more than 3 days during the storage period; and

• below 6°C for more than 6 days during the storage period. Detailed description

The present invention relates to a method for storing a concentrated frozen confection premix. The concentrated frozen confection premix (which, for the sake of brevity, is referred to herein as “concentrated premix”) is an oil-in-water emulsion in liquid form having a high total solids content. The concentrated premix can simply be diluted with an aqueous liquid to produce a premix which contains all the ingredients in the appropriate proportions. Furthermore, the premix can be tailored in the dilution step, for example by adding a small quantity of flavouring and/or colouring.

The concentrated premix is an oil-in-water emulsion comprising fat in an amount of 8 wt% to 20 wt%, sugars in an amount of 40 wt% to 64 wt%, protein in an amount of 1 .5 wt% to 14 wt%; and water in an amount of 16 wt% to 36 wt%.

The method comprises storing the concentrated premix in a closed container for a storage period of up to 84 days. The closed container helps prevent microbiological contamination of the concentrated premix during the storage period. The concentrated premix remains stable for the storage period if the temperature is controlled according to the limits of the present invention. Preferably the storage period is up to 70 days, up to 56 days, up to 42 days, up to 35 days, up to 28 days, or even up to 21 days. The storage period is preferably at least 1 day, at least 5 days, at least 7 days, at least 10 days, or even at least 14 days.

The concentrated premix may be held in one location during the storage period, or it may be transported between locations (e.g. from production factory to finishing factory) for at least part of the storage period.

To prevent Maillard reactions, which can cause unwanted colour changes, and compromise sensory properties, the concentrated premix is not subjected to a temperature exceeding 37°C for more than 3 days during the storage period. Preferably the concentrated premix is not subjected to a temperature exceeding 37°C for more than 2 days during the storage period, more preferably the concentrated premix is not subjected to a temperature exceeding 37°C for more than 1 day during the storage period. It is preferred that the concentrated premix is not subjected to a temperature exceeding 35°C for more than 12 days during the storage period. More preferably, the concentrated premix is not subjected to a temperature exceeding 35°C for more than 6 days during the storage period, and most preferably the concentrated premix is not subjected to a temperature exceeding 35°C for more than 3 days during the storage period.

It is preferred that the concentrated premix is not subjected to a temperature exceeding 30°C for more than 21 days during the storage period. More preferably, the concentrated premix is not subjected to a temperature exceeding 30°C for more than 14 days during the storage period, and most preferably the concentrated premix is not subjected to a temperature exceeding 30°C for more than 7 days during the storage period.

We have surprisingly found that storage of the concentrated premix at low temperatures promotes oil droplet coalescence, which in turn impacts the organoleptic properties of the final frozen confection. In order to limit oil droplet coalescence, the concentrated premix is not subjected to a temperature below 6°C for more than 6 days during the storage period. Preferably the concentrated premix is not subjected to a temperature below 6°C for more than 4 days during the storage period, more preferably the concentrated premix is not subjected to a temperature below 6°C for more than 2 days during the storage period.

It is preferred that the concentrated premix is not subjected to a temperature below 10°C for more than 28 days during the storage period. More preferably, the concentrated premix is not subjected to a temperature below 10°C for more than 21 days during the storage period, and most preferably the concentrated premix is not subjected to a temperature below 10°C for more than 14 days during the storage period.

Preferably the mean temperature of the concentrated premix averaged over the storage period is from 6°C to 37°C, more preferably from 8°C to 35°C, from 10°C to 30°C, or even from 12°C to 27°C.

In order to further control the extent of Maillard reactions and/or inhibit growth of microorganisms, the concentrated premix preferably has a water activity of no more than 0.84, for example from 0.70 to 0.84. Additionally or alternatively, it is preferred that the pH of the concentrated premix is from 5 to 8.

The concentrated premix only needs to be diluted with an aqueous liquid (such as water) to produce a premix for a frozen confection. As such, the concentrated premix comprises fat in amount of 8 wt% to 20 wt%, and preferably comprises fat in an amount of 9 wt% to 19 wt%, 10 wt% to 18 wt%, or even 11 wt% to 17 wt%. The fat is preferably dairy fat (such as butter fat) or vegetable fat (such as coconut oil, palm oil, palm kernel oil, or a mixture thereof). It is preferred that the fat is vegetable fat, and particularly preferred that the fat is coconut oil.

High concentrations of sugars may contribute unwanted sweetness and/or calories to the frozen confection that is ultimately prepared from the concentrated premix (following dilution and freezing). Conversely, low concentrations of sugars may be inappropriate if the frozen confection that is ultimately prepared from the concentrated premix is a scoopable product, since low concentrations of sugars tend to result in a frozen confection with a high ice content. Therefore, the concentrated premix comprises sugars in an amount of 40 wt% to 64 wt%, and preferably comprises sugars in an amount of 42 wt% to 62 wt%, 44 wt% to 60 wt%, or even 46 wt% to 58 wt%. As used herein the term “sugars” includes monosaccharides, disaccharides and oligosaccharides (which are formed from 3 to 10 monosaccharide units). Monosaccharides include glucose, fructose, galactose and mannose. Disaccharides include sucrose, lactose and trehalose. Oligosaccharides include raffinose. The term “sugars” does not include polysaccharides, which comprise >10 monosaccharides. Some ingredients commonly included in frozen confections may contribute to the amount of sugars. An example is corn syrup (sometimes called glucose syrup) - which is a mixture of monosaccharides, disaccharides and oligosaccharides.

The concentrated premix comprises protein in an amount of 1.5 wt% to 14 wt%, and preferably comprises protein in an amount of 1.6 wt% to 12 wt%, 1.7 wt% to 10 wt%, 1.8 wt% to 8 wt%, or even 1.9 wt% to 6 wt%. Preferably the protein is milk protein or plant protein, or a mixture thereof. If the emulsion becomes too concentrated it may become difficult to handle in subsequent processing, in particular it may become difficult to pump. On the other hand, a low water activity can mean that the concentrated premix has a longer shelf-life. The concentrated premix comprises water in an amount of 16 wt% to 36 wt%. Preferably the concentrated premix comprises water in an amount of at least 17 wt%, at least 18 wt%, or at least 19 wt%. Preferably the concentrated premix comprises water in an amount of no more than 32 wt%, no more than 29 wt%, no more than 28 wt%, no more than 27 wt%, or even no more than 26 wt%. The concentrate premix of the present invention has a high total solids content. The total solids content is the sum of all the ingredients other than water. Since the concentrated premix comprises water in an amount of 16 wt% to 36 wt%, the total solids content of the concentrated premix is 64 wt% to 84 wt%. The total solids content of the concentrated premix affects the viscosity, with higher total solids leading to higher viscosity. This can be advantageous, since higher viscosities are associated with better oil droplet breakup. However, the power input required to achieve emulsification of the oil also increases with viscosity, and at very high viscosities there is a risk of the emulsification equipment being overloaded. Therefore, there is a need to balance these competing technical considerations. Preferably the total solids content of the concentrated premix is at least 68 wt%, at least 71 wt%, at least 72 wt%, at least 73 wt% or at least 74 wt%. Preferably the total solids content of the premix is no more than 83 wt%, no more than 82 wt%, or no more than 81 wt%.

The concentrated premix preferably comprises stabilizer in an amount of 0.3 wt% to 3 wt% and/or emulsifier in an amount of 0.1 wt% to 2 wt%. Preferably the concentrated premix comprises stabilizer in an amount of 0.2 wt% to 2 wt%, 0.4 wt% to 1.5 wt%, or even 0.6 wt% to 1.0 wt%. The stabilizer is preferably selected from the group consisting of alginates (E400-E405), carrageenan (E407), locust bean gum (E410), guar gum (E412), xanthan gum (E415), tara gum (E417), pectin (E440), sodium carboxymethyl cellulose (E466), and mixtures thereof. Preferably the concentrated premix comprises emulsifier in an amount of 0.2 wt% to 1.5 wt%, 0.3 wt% to 1.2 wt%, or even 0.4 wt% to 1.0 wt%. A single emulsifier or a mixture of emulsifiers may be used. For example, mono-/diglycerides (E471), which are commonly used as emulsifiers in frozen confections. The concentrated premix of the present invention may be susceptible to microbiological spoilage. A common approach to limiting such spoilage is refrigerated storage. However, this is not appropriate for the concentrated premix of the present invention, as it has unexpectedly been found to promote coalescence of oil droplets. Therefore, it may be appropriate to utilise a different approach to inhibit spoilage microorganisms. As such, the concentrated premix is preferably subjected to a sanitisation step (such as pasteurisation) prior to storage. Following such a sanitisation step, the method may comprise aseptically dosing the concentrated premix into the container prior to closing the container and storing the concentrated premix for the storage period. This step is most likely to be appropriate where a long shelf life is required (i.e. several weeks). However, in practice this step is not usually required. Indeed, it is preferred that, following the sanitisation step, the concentrated premix is dosed into the container before being cooled (typically referred to as “hot filling”).

The concentrated premix may optionally comprise a preservative. Addition of a preservative may be appropriate if a long shelf life of several weeks is required, and may provide a cheaper and/or more convenient alternative to aeseptic dosing of the concentrated premix. The concentrated premix preferably comprises 0.02 wt% to 0.5 wt% preservative, and the preservative is preferably sorbic acid (E200) or a salt thereof. Suitable salts include sodium sorbate (E201), potassium sorbate (E202), and calcium sorbate (E203). A successful preservative inhibits spoilage microorganisms without interfering with the sensorial properties of the final frozen confection product. It should be noted that the level of preservative in the concentrated premix will not be the level of preservative in the final frozen confection product, since the concentrate premix will be diluted prior to being used to prepare a frozen confection. This means that a relatively high level of preservative can be added to the concentrated premix without compromising the sensorial properties of the final frozen confection. However, it is preferred to keep the level of preservative as low as possible, whilst still including a sufficient amount to inhibit spoilage microorganisms. Thus, the concentrated premix preferably comprises the preservative in an amount of 0.02 wt% to 0.5 wt%, 0.06 wt% to 0.4 wt%, 0.1 wt% to 0.3 wt%, or even 0.12 wt% to 0.2 wt%. The method comprises storing the concentrated premix in a closed container. The concentrated premix can be stored in any suitable container. Non-limiting examples of potential containers include pouches, tanks, bottles, kegs, barrels, drums, jerry cans, and intermediate bulk containers (IBCs). The volume of the container is preferably at least 500 ml, and more preferably 1 L to 2000 L. In particular, the container is preferably a rigid or flexible intermediate bulk container having a volume of up to 2000 L, preferably from 250 L to 2000 L.

An advantage of the concentrated premix is that it can be shipped to a remote location during the storage period and then simply diluted with an aqueous liquid (preferably water) at the remote location before being frozen in a conventional manner to produce a high quality frozen confection in a finishing factory. This means that the finishing factory does not need to be equipped with a mix plant capable of handling and blending multiple ingredients.

In circumstances where the concentrated premix will be transported between locations (e.g. from a hub factory to a finishing factory), the container is preferably an intermediate bulk container (preferably having a volume of 250 L to 2000 L) or a tanker truck (preferably having a volume of 10,000 L to 44,000 L). Tanker trucks usually comprise a cylindrical tank lying upon the body of the truck in an essentially horizontal manner. The tank will typically comprise multiple compartments and/or baffles to prevent load movement destabilizing the vehicle during transit. The tanker truck should be suitable for transporting food-grade material, and will typically be equipped with a pumping system to allow for loading and unloading of the liquid load.

It is also envisaged that the concentrated premix may be transported to a retail outlet rather than a factory. For example, this scenario may occur where the concentrated premix is for a soft-serve ice cream product. Such products are made in a small ice cream freezer, for example in an ice cream van or a cafe, and eaten immediately. As such, the container is likely to be smaller, and is preferably a bottle or a pouch with a volume of 500 ml to 50 L, more preferably 500 ml to 10 L, or even 500 ml to 2 L. It is preferred that a diluent liquid is added to the concentrated premix at the end of the storage period. The diluent liquid is an aqueous liquid, preferably water. The ratio of concentrated premix to diluent liquid is preferably 1 :1 to 1:3.

The dilution step provides a premix which can be frozen to produce a frozen confection. The premix can be tailored in the dilution step by adding a small quantity of flavouring and/or colouring.

Unless otherwise specified, numerical ranges expressed in the format "from x to y" are understood to include x and y, and in specifying any range of values or amounts, any particular upper value or amount can be associated with any particular lower value or amount.

Except in the examples and comparative experiments, or where otherwise explicitly indicated, all numbers are to be understood as modified by the word “about”. As used herein, the indefinite article “a” or “an” and its corresponding definite article “the” means at least one, or one or more, unless specified otherwise.

Figures

By way of example, the present invention is illustrated with reference to the following figures, in which:

Figure 1 is a plot of oil droplet size data from Example 1;

Figures 2a and 2b are plots of colour change data from Example 1.

Examples

The examples are intended to illustrate the invention and are not intended to limit the invention to those examples perse.

Example 1

Preparation of a concentrated premix

A concentrated premix having the formulation shown in Table 1 was prepared. Briefly, the aqueous phase was prepared by adding hot water (at 80°C) to a mixing vessel, followed by sucrose, stabilizer, corn syrups, fructose, dextrose monohydrate, skimmed milk powder, and whey protein concentrate. The mixer was set at 3000 rpm during aqueous phase ingredient addition, with heating at 60°C to 75°C to ensure complete dissolution/dispersion of the ingredients. The oil phase was prepared by melting the coconut oil and combining it with the emulsifier. A concentrated oil-in-water emulsion was prepared by adding the oil phase to the aqueous phase and passing the mixture through a rotor-stator mixer set at 4200 rpm. The rotor-stator mixer had a rotor diameter of 0.145 m and a shearing clearance of 0.5 mm. The concentrated premix was pasteurized.

Table 1 : concentrated premix formulation

Storage trials

The concentrated premix was separated into containers, and the containers were sealed. Containers were stored at a constant temperature of 5°C, 20°C, 25°C, 30°C, 35°C, or 40°C, and the trials were run for up to 84 days. Oil droplet coalescence was investigated at 5°C or 20°C over a storage period of up to 28 days. Colour changes were investigated at various storage temperatures (20°C, 30°C, 35°C, 40°C) over a storage period of up to 21 days, with samples being analysed periodically from 3 days storage onwards. In addition, microbiological growth was investigated at 25°C (chosen as being the most favourable temperature for yeast and mould growth); the concentrated premix showed no spoilage due to growth of mould for storage periods up to and including 84 days. Oil droplet size

The effect of the storage trials on oil droplet size was determined. Oil droplet size was measured using a Malvern Mastersizer 3000 equipped with a wet dispersion unit to determine surface weighted mean droplet size (Da,2). The premix samples were diluted 10-fold in a solution of sodium dodecyl sulphate (SDS) and urea (6.6 M urea, 0.1% SDS, pH 7), and subjected to 1 minute of full power sonication within the dispersion unit prior to the start of particle size measurement. This treatment ensures that any weakly bound or flocculated oil droplets are separated into individual oil droplets to give a more accurate representation of the oil droplet size (such treatment cannot break up fully coalesced or aggregated oil droplets).

The effect of storage temperature over time on oil droplet size is shown by the data in Figure 1 , with the dashed line representing storage at 20°C and the solid line representing storage at 5°C. The results show that oil droplet size remains constant (at less than 1 pm) when the concentrated premix is stored at 20°C. In contrast, storage at 5°C leads to a marked increase in droplet size over time, indicating coarsening of the emulsion. Although not included in Figure 1 , the oil droplet size remains constant for significantly longer than 15 days when the concentrated premix is stored at 20°C (i.e. for a storage period of at least 28 days).

Colour analysis

The later stages of Maillard reactions include the formation of advanced glycation end products (AGEs) and melanoidins, which cause colour changes, influence sensory properties, and in some cases compromise shelf life. In order to assess the effect of Maillard reactions on the concentrated premix, LAB colour analysis was used to identify any colour changes which occurred during the storage trials.

A digital colour imaging system (Digieye, VeriVede) was used to measure colour and appearance of samples. Samples were photographed using a Nikon AF-S Nikor in a VeriVede cabinet under standardised D65 light without UV, with lighting set to diffuse and no internal mirrors. Camera settings were as follows:

Camera zoom: 35 mm,

Focus: Auto Focus, Measurement mode: Diffuse Mode, d90 diffused,

Chart type: Digitizer Chart V3.94,

Aperture: 8,

Shutter: 1/6.

Calibration Wizard was run before measurements were taken to ensure consistent calibration (maximum <10, median <1 , RGB values = 210 ± 10). CIE76 colour values were generated from representative regions of photographs of the samples. Change between CIE76 colour values for sample and reference are reported independently, and used to calculate AE colour change values, which can range from 0 to 100. AE values greater than 1 indicate a perceivable difference in colour between samples.

The data in Figures 2a and 2b show the colour changes that occurred over time at storage temperatures of 20°C, 30°C, 35°C, and 40°C for two different storage trials. In both cases, samples stored at a temperature of 20°C show almost no change in colour over time. In contrast, samples stored at a temperature of 40°C show significant colour change - even after very short periods of time.

Claims

1 . A method for storing a concentrated frozen confection premix, wherein the method comprises storing the concentrated premix in a closed container for a storage period of up to 84 days, wherein the concentrated premix is an oil-in-water emulsion in liquid form, the oil- in-water emulsion comprising: fat in an amount of 8 wt% to 20 wt%; sugars in an amount of 40 wt% to 64 wt%; protein in an amount of 1.5 wt% to 14 wt%; and water in an amount of 16 wt% to 36 wt%; and wherein the concentrated premix is not subjected to a temperature:

• exceeding 37°C for more than 3 days during the storage period; and

• below 6°C for more than 6 days during the storage period.

2. The method as claimed in claim 1 wherein the concentrated premix is not subjected to a temperature exceeding 35°C for more than 12 days during the storage period.

3. The method as claimed in claim 1 or claim 2 wherein concentrated premix is not subjected to a temperature exceeding 30°C for more than 21 days during the storage period.

4. The method as claimed in any one of the claims 1 to 3 wherein the concentrated premix is not subjected to a temperature below 10°C for more than 28 days during the storage period.

5. The method as claimed in any one of claims 1 to 4 wherein the mean temperature of the concentrated premix averaged over the storage period is from 6°C to 37°C.

6. The method as claimed in any one of claims 1 to 5 wherein the concentrated premix has a water activity of no more than 0.84, preferably from 0.70 to 0.84.

7. The method as claimed in any one of claims 1 to 6 wherein the pH of the concentrated premix is from 5 to 8. The method as claimed in any one of claims 1 to 7 wherein the concentrated premix comprises stabilizer in an amount of 0.3 wt% to 3 wt% and/or emulsifier in an amount of 0.1 wt% to 2 wt%. The method as claimed in any one of claims 1 to 8 wherein the concentrated premix comprises 0.02 wt% to 0.5 wt% preservative, and the preservative is preferably sorbic acid or potassium sorbate. The method as claimed in any one of claims 1 to 9 wherein the concentrated premix is subjected to a sanitisation step prior to storage. The method as claimed in claim 10 wherein the method comprises aseptically dosing the concentrated premix into the container prior to closing the container and storing the concentrated premix for the storage period. The method as claimed in any one of claims 1 to 11 wherein the volume of the container is at least 500 ml, and preferably 1 L to 2000 L. The method as claimed in any one of claims 1 to 12 wherein the container is a rigid or flexible intermediate bulk container having a volume of up to 2000 L, and preferably from 250 L to 2000 L. The method as claimed in any one of claims 1 to 13 wherein a diluent liquid is added to the concentrated premix at the end of the storage period. The method as claimed in claim 14 wherein the ratio of concentrated premix to diluent liquid is 1 :1 to 1 :3.