FOOD PRODUCTS WITH REDUCED SALT LEVELS

TECHNICAL FIELD The present invention relates to food products. In particular, it relates to food products having reduced salt levels and to a method of reducing salt levels in food products .

BACKGROUND OF THE INVENTION

Salt or sodium chloride is an essential nutrient (Lindemann B., Physiol. Rev. 1996, 76, 718-766) . It is, however, consumed in Western societies at relatively high levels, which are thought to be positively related to high blood pressure and related diseases, e.g. strokes and ischemic heart disease (He F.J., MacGregor G. A., Hypertension 2003, 42, 1093-1099) . In the DASH (Dietary Approaches to Stop Hypertension) sodium study, people on a low sodium diet were followed, and results showed a linear relation between salt intake and blood pressure (Appel, L. J. et al . New

England Journal of Medicine 1997, 336, 1117-1124) . Public health and regulatory authorities, such as the World Health Organisation (WHO) and the Food and Drug Administration (FDA) , recommend lowering of the dietary intake of salt and salt reduction programmes have been initiated.

One of the main functions of salt is the salty taste that it imparts. It is also important as a general taste enhancer, contributing to the overall flavour profile of a food product.

Most technologies for reducing sodium levels in foods depend on the direct substitution of sodium cations by other cations or by novel molecules. In particular, potassium salts have been used to replace sodium salts. A clear disadvantage of using potassium salts is the

bitterness and the metallic off-taste that it causes in the complete food product, when more than about 20% of the sodium ions are replaced with potassium ions. One of the other functionalities of salt is that it is a general bitter masker (R.S.J. Keast et al . , Chimia 2001, 55, 441- 447) . The implication of this is that at reduced salt levels only limited amounts of potassium chloride can be masked by salt.

Possibilities for suppressing the bitterness of KCl have been investigated for many years, but only with limited success, which is in part due to the side tastes imparted by maskers, such as for sweeteners, e.g. taurine (US-A-5 631 299), lactose and/or dextrose (US-A-3 860 732) . Other bitter maskers and salt substitutes include autolysed yeast (US-A-4 297 375), AMP and IMP (US-A-6 540 978) and lysine monohydrochloride (US-A-5 897 908) .

An alternative approach is to use non-salt containing fillers so that less salt is required in the total product. US-A-4 988 521 describes ready-to-eat cereals with reduced salt content but whose taste profile is organoleptically equivalent to conventional cereals having higher salt concentrations. The salt reduction is achieved by distributing the reduced salt content between a portion being distributed uniformly throughout the cereal piece and a second portion being uniformly topically applied to the cereal pieces' exterior. US-A-5 094 862 describes a salt substitute granule comprising a core composition made with a non-sweet carbohydrate bulking agent and a coating on the core comprising sodium chloride. US-A-5 098 724 describes a low sodium salt composition which tastes, handles and flows like a table salt and which contains sodium chloride, a bulking agent and optionally a binder.

In water-containing products, oils or fats can be used as fillers. However, according to Malone et al . [Food Hydrocolloids 2003, 17, 775-784] and Yamamoto & Nakabayashi [Journal of Texture Studies 1999, 30, 581-590], when a portion of the water in the aqueous phase is replaced with oil and the same salt concentration in the aqueous phase is maintained, a decrease in saltiness perception is obtained due to the mouth coating effect of the oil. Furthermore, adding oils/fats to foods contribute to the increase in the total calories of the product.

There is a constant need for new or alternative food products having reduced salt levels to help consumers to lower their daily sodium intake. It is therefore an object of the present invention to provide such food products. It is a further object of the invention to provide a process for the preparation of such food products having reduced salt levels and to provide a method of reducing the salt level in a food product.

It was surprisingly found that the object can be achieved by the edible product of the invention, which comprises homogeneously distributed gas bubbles in an aqueous phase containing sodium ions. It is surprising that unlike the oil, gas bubbles do not give a decreased taste perception.

SUMNLARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a food product having a reduced salt level, comprising 5 to 40 vol.% of a gas in the form of bubbles.

A second aspect of the invention relates to a method of reducing the salt level in a food product whereby 5 to 40 vol.% of a gas is incorporated into a food product to reduce the salt level of said food product.

A third aspect of the invention relates to the use of a gas in an amount of 5 to 40 vol.% of a gas in a food product to reduce the salt level of said food product.

DETAILED DESCRIPTION OF THE INVENTION

According to a first aspect, the present invention relates to a food product which contains an aqueous phase with sodium ions and a discrete phase which is made up of gas bubbles and which are homogeneously distributed in the aqueous phase. The gas bubbles have a volume mean diameter in the range of 1 to 1,000 micrometer, preferably from 40 to 600 micrometer, more preferably from 60 to 400 micrometer.

The aim of the invention is to provide a food product having a reduced salt level. By the term "salt" we mean sodium salts, in particular sodium chloride.

The food product according to the present invention may suitably take any physical form. In particular, it may be a liquid or a spreadable, spoonable solid or a supplement. For instance, it may be a soup, a sauce, a beverage, a spread, a dressing, a dessert or a mayonnaise. Preferably, the product is a soup, a sauce or beverage. A conventional soup will typically have a salt content in the range of 20- 800 mg/100 ml, a conventional sauce will typically have a salt content in the range of 40-1,200 mg/100 ml and a typical savoury beverage will typically have a salt content in the range of 10-500 mg/100 ml. It will be understood that if one would incorporate for example 30 Vol.% gas bubbles into such product, the salt level can be significantly reduced to about 70% of the original salt content.

A soup product in accordance with the invention containing 30 Vol.% gas bubbles will typically have a salt content in the range of about 14-560 mg/100 ml. A sauce in accordance with the invention containing 30 Vol.% gas bubbles will typically have a salt content in the range of about 28-840 mg/100 ml. A beverage in accordance with the invention containing 30 Vol.% gas bubbles will typically have a salt content in the range of about 7-350 mg/100 ml. In any case, the products of the invention will have a lower limit for the salt content of at least about 4 mg/100 ml.

If the product is a spread, it is preferably in the form of an oil-in-water emulsion. The term "spread" as used herein encompasses spreadable products such as margarine, spreadable cheese based products and processed cheese, but also hydrolysed yeast extracts such as Marmite™. If it is a beverage it typically contains at least 90 wt . % water and 0-10 wt .% of dispersed fat.

The foamed product should be stable such that creaming and bubble growth are prevented. Creaming arises when the gas bubbles rise to the surface of the aqueous phase due to the buoyancy of the bubbles. To prevent creaming, the aqueous phase must have either an apparent yield stress or viscosity. Common ingredients that provide a yield stress or increased viscosity are xanthan gum, starches, agar, carrageenan, pectin, alginate, galactomannans such as guar gum, gelatin, gelling proteins such as whey protein, fibres such as those of fruit or vegetable origin, carboxy methyl cellulose and/or mixtures thereof.

Bubble stability can be achieved by using suitable surface active agents. Examples of surface active agents are proteins such as caseinate and whey, protein hydrolysates, saponins, hydrophobins and surface active particles. Examples of surface active particles can be found in

WO2007/068344 which discloses stable foams comprising a surface-active material that comprises fibres which have been modified so as to impart surface-active properties onto said fibres and giving it a contact angle between 60° and 120°, wherein the fibres have an aspect ratio of more than 10 to 1,000.

The yield stress agent (s) and/or thickener (s) and surface active agents used are preferably tasteless or have no strong off-taste or are used in such low concentrations that they have no influence on the taste.

The gas bubbles can be incorporated into the aqueous phase by known methods, such as by high speed whipping using food blenders or rotary mixers. The bubble characteristics such as their size and volume fraction can be controlled by varying the mixing time and speed. Usually, all of the ingredients are present in the final food composition before the gas bubbles are incorporated by the whipping process. Mixing or whipping leads automatically to the homogeneous distribution of the gas bubbles. However, some ingredients, such as liquid fat, can interfere with the stability of the bubbles such that no foam can be formed during whipping. In this case, a foamed composition, comprising mostly of water and the surface active agent, can be whipped separately and then the foamed composition is thoroughly mixed into the rest of the composition. After the desired gas bubble structure has been created, the application of high shear force on the total composition is preferably avoided.

Examples of gas include air, nitrogen, carbon dioxide, nitrous oxide, oxygen or mixtures thereof. These gases can also be loaded with volatile flavour compounds.

An example of a stable foam can be found in WO2007/068127 which discloses a method to prepare wet foams exhibiting long-term stability, wherein colloidal particles in a suspension are used to stabilize the gas-liquid interface and wherein the particles are present in amounts of at least about 1% by volume referred to the volume of the suspension, and wherein the whole of the suspension is homogeneously foamed.

The incorporation of the gas bubbles into the aqueous phase which contains sodium ions does not preclude the use of other salts such as potassium or other cations or novel molecules or bitter maskers or other salt substitutes in the aqueous phase to further reduce the sodium content of the overall product.

Foam stability and the spatial distribution of the bubbles in the product can be determined by visual method by observing the product in measuring cylinders. Further methods that can be used are optical microscopy and light scattering technique. For example, the Turbiscan Tlab measurement system (Formulaction, France) as described in US-A-20070116848, which analyses both the backscattered and transmitted light from the aerated sample of interest, can be conveniently used.

According to a second aspect, the present invention relates to a method of reducing the salt level in a food product, whereby 5 to 40 vol.% of a gas is incorporated into a food product in the form of bubbles, to reduce the salt level of said food product.

A third aspect of the invention is the use of a gas in an amount of 5 to 40 vol.% of a gas in a food product to reduce the salt level of said food product.

This invention will now be described in more detail by means of the following Examples, in which percentages are by weight unless indicated otherwise.

Example 1 relates to a gelled product with 40% volume of gas incorporated by high shear mixing of the whole composition .

Example 2 relates to a soup product with up to 30% volume of gas incorporated via post dosing of the gas bubbles into the non-aerated aqueous phase. Figure 1 shows a sensory evaluation of soups.

Example 1 A soft gel, containing 40 Vol.% (volume fraction) of gas bubbles, was prepared according to Table 1. A solution of water with 1OmM potassium chloride and sodium chloride (according to Table 1) was heated to 90 ⁰ C. 0.5% Xanthan and 0.25% agar were then added and the solution was stirred for one hour. The solution was then cooled to 50 ⁰ C and 1% Bipro 95 whey protein was then added. The solution was then beaten using a Silverson mixer at 8,000 rpm for 5 minutes to get 40% volume fraction of gas bubbles. The resulting foam was then cooled down in an ice bath to induce gelation of the agar to keep the foam stable. The foams were kept in a fridge (4°C) for a night before the panel sessions. Sensory panelling was performed by eleven trained panellists, who evaluated the samples in triplicate. The scale was from 0-15. An analysis of variance (ANOVA) with product, panellist and session as factors, was performed to identify significant differences between the products (p<0.05) . The saltiness scores of the foams are shown in Table 1. The foam with 40% less salt gave the same salty taste as the control (100% salt with 0 Vol.% foam) . When the salt content in the foam was the same as the control, a significantly higher salty taste was obtained.

Table 1: Description of foams and their saltiness scores. Base contains water, 1OmM potassium chloride, 0.5% xanthan, 0.25% agar and 1% Bipro 95 whey protein. Samples with the same letter (a or b) are not significantly different from each other.

Example 2

A premix soup composition was prepared according to Table 1. A ready to eat thickened chicken soup was prepared by mixing 2 1 of water per 127 g premix soup composition. This was brought to boil and it was simmered for 5 minutes. One soup was prepared with 25 % less sodium.

Table 2: premix soup composition

Foam was prepared separately by adding 0.1 wt. % saponin (Desert King Ultra Dry 100) to lOOg freshly boiled water. The mixture was beaten in a Kenwood kitchen mixer (KMC550) at maximum speed for 10 minutes.

Foam was added to the soup and stirred in gently by hand, according to Table 3. For the 10 Vol.% foam sample 20 ml foam was added to 180 g soup.

Bubble size was estimated using the soup containing 20% VoI foam. The soup was sampled at two different locations and transferred to an optical microscope. The volume weighted mean diameter of the bubbles at both locations was approximately 180μm.

Table 3: description of samples

Description of sensory test

20 ml of hot soup (~70°C) was added to plastic cups (50 ml), just prior to evaluation. Panel members received each time the reference (labelled reference) and a blind sample (coded with a random 3 digit code), according to Table 3.

Two evaluation sessions were organised, with 4 and 5 panel members, respectively. Panel members in the same session received the same order of samples, according to a randomised design. The panel consisted of 9 expert tasters who frequently evaluate food products. The panellist had to score the samples on the following attributes: saltiness, chicken, flavour intensity, creaminess and mouthfeel. The assessors could also indicate any comments on appearance and other sensations.

The samples were rated on a linear scale from 0-10. The reference soup was anchored at a score of 5 on this scale for each attribute. All samples were compared to the reference soup for each attribute. Water and crackers were used to rinse the mouth in between samples.

Results

Attributes saltiness, flavour intensity and creaminess can explain the differences between the products. All samples with added foam (with up to 30 Vol.% foam) have the same saltiness (see Figure 1) . It is slightly lower than that of the reference, but well within the experimental error. The same trend is seen for flavour intensity. The sample with 25 % less salt is scored much lower on saltiness than all other samples. All samples were scored similarly on creaminess. The soups became whiter in appearance upon addition of increasing amounts of foam. Samples with higher amounts of foam (≥ 20 Vol.%) were described as ^λ aerated' or foamy.

Overall, the evaluation shows that up to at least -15 Vol.% foam can be added to soup with only minor changes to the sensory profile.