GB2447602A - Method for producing a low fat fruit-based food product - Google Patents

Abstract

The invention provides a method of producing a ready-to-eat low fat fruit-based food product comprising the steps of pulping fruit; combining portions of fruit pulp from different fruits; and freezing the combined portions to produce a frozen product, all without adding any or substantially any sweetening or flavouring constituent other than the fruits and/or their juices. A portion of fruit juice may be removed from the pulp, and may optionally be recombined, in part, with the pulp. Further size reduction stages may be provided to adjust rheological properties, while an emulsifier such as lecithin may be added. In particularly preferred methods, the mixture is frozen with a scraped surface heat exchanger and gas, such as nitrogen, may be injected into the mix.

Description

LOW FAT FOODSTUFFS and METHODS for PRODUCING SAME

Field of the Invention

The invention relates to methods of producing low fat foodstuffs, and to foodstuffs produced by such methods.

Review of the Relevant Art Foodstuffs in the form of sorbets, ice-creams, fruit drinks and fruit fLavoured concentrates constitute a well known broad class of product. All are currently in vogue and efforts are continually being made to minimise their fat content in view of what is now known of the benefits of a low fat diet generally.

Of this broad class of product, ice-creams are in many ways the most palatable because they combine an appealing flavour with a creamy viscous texture. But they are known to have a relatively high fat content, of at least 5% and typicaLly some 1% to 14%. Much of the remainder is sugars, thickeners, and flavourings and as a result -and again talking in typical terms -a relatively small proportion of this product consists of edible fruit pulp as such. In many instances, fruit essences are used, or frozen fruit, rather than fruit pulp, is used. Furthermore, many consumers have a desire, or in some instances a need, to reduce or remove dairy products from their diet, and so the desire for a creamy dessert cannot be satisfied by ice cream.

Conventional ice-cream products also have a well-known tendency for their oil/fat constituents to separate if the ice-cream is allowed to melt and left standing for any length of time and this makes it impossible for them to be immediately re-frozen for future serving.

Fruit flavoured juices by contrast have little or none of the fat content problems associated with ice-cream but typically need excessive sweetening, usually by way of added sugars, before the natural sharpness of the pure juice is sufficiently countered to result in a saleable product. This relatively high sugar content is a source of public concern as is the tendency to water down the natural fruit juices so that, for example, one very well known current product contains typically no more than about 12% of real fruit. The vast majority of fruit-flavoured juices and fruit juices contain concentrates in various quantities -in some instances all the fruit is from concentrate; there are concerns that concentration process might lead to loss of nutritional and flavour characteristics.

Fruit flavoured concentrates -conventionally known as "smoothies" -have been developed to overcome the watering-down problem. These contain a proportion of fruit pulp as well as fruit juice. The problem with these is how to converge the relatively chewy fibrous fruit pulp into an acceptably creamy tasting mass. Various additives have been blended in but none of them can be said to be entirely successful. Either the taste of the additive too easily overpowers the natural fruit or it has an unacceptably high carbohydrate content; or both. There may, furthermore be loss of fruit-derived fibre components, known to be beneficial in the diet.

Yet another product in this broad class is the so-called energy drink, typified over many years by the well-known Lucozade product (LUCOZADE is a trade mark) and in more recent times by the widely marketed and advertised Red Bull drink (RED BULL is also a trade mark). These have drawbacks of their own. Lucozade and its direct competitors have a notoriously high sugar content whose energising properties are relatively quickly released into the bloodstream of the drinker. Red Bull and the like rely on what is now beginning to be suspected as an unacceptably high caffeine content.

In summary, individual approaches to the linked problems of this one class of product have not been wholly successful to date; but have all tended to be targeted at individual products and tailored to them alone. No one satisfactory overall approach to the whole class has been successful or even proposed as far as the applicants are aware. Clearly the problem can be regarded as one overall problem and accordingly any series of inventions which are so linked as to solve it must be so linked as to form part of one overall inventive concept.

Summary of the invention

In one broad aspect the invention provides a method of producing a fruit flavoured foodstuff comprising the steps of sending peeled and de-pipped fruit pulp through a juicer; weighing separately the juice, and the de-juiced pulp, so produced; and then blending the juice and the pulp with a soy-based emulsifier to produce an edible foodstuff of desired viscosity and flavour.

A particularly suitable emulsifier is Lecithin and the resultant viscous foodstuff, with blending percentages appropriately tailored to the fruits being used, can have a fat content of no more than about 1% and contain typically of the order of some 35% edible fruit pulp and juice content with as little as (again typically) 0.5% emulsifier and of course a proportion of air.

Such a product is not a form of ice-cream, for reasons which will be obvious when the background above is visited by the reader. Although it can be frozen and then have a shelf life of approximately up to one year like ice-cream, it is more accurately described as a "Melt" because of its low emulsifier content and lack of dairy-based ingredients and it is best chilled, stored, and served as a healthy alternative to ice-cream in the Latter's traditional form. Preferably, there would be no addition of exogenous sugars such as fructose, glucose syrup or sucrose.

If such a foodstuff is allowed to melt, following production, deliberately; and more soy-based emulsifier (such as lecithin) is added and the whole then whisked; then the result is a smoothie-type drink. This is another aspect of the invention, clearly so linked to the previous one as to form directly, part of the same inventive concept. The non-separation properties of the Melt, due to its almost negligible fat content, make this aspect possible.

In another broad aspect of the invention a fruit juice product is produced by juicing the peeled and de-pipped fruit pulp and then weighing, separately, the juice and the de-juiced pulp so produced and blending them with a sweetener which is itself another natural fruit juice.

With appropriate percentaging of the constituents this gives a juice product with typically some 25% pulp-and-juice constituent and the use of another natural fruit juice as the sweetener, rather than refined, isolated sugars, minimises its sugar content or at least restricts it only to those natural sugars in the fruit itself.

In yet another aspect of the invention an energy drink is produced by juicing and then blending in 50/50 proportions avocado and pineapple pulp, the juicing of each being carried out separately and then the separately juiced fruit pulps being brought together to give a drink with slow-release energy properties and without an abnormally high carbohydrate content.

In non-public experiments such a product has been found to have bruise-healing properties as well as energy releasing qualities.

In any aspect of these several inventions if a natural fruit sweetener is used then a particularly preferred sweetener is the fruit known as Soursop (Annona muricata) which is found in the Caribbean as a distant relative of the pawpaw. This particular fruit has a unique and very pleasant flavour with sour citrus notes contrasting with an underlying creamy roundness of texture reminiscent of coconut or banana. When its seeds, and pockets of soft flesh and fibrous membranes are removed, the edible white pulp can be juiced and used to flavour the product.

Like banana, Soursop is high in carbohydrates but without the overpowering taste of the banana fruit. It also contains significant amounts of vitamins and is believed to have inherent herbal and medicinal qualities, Its combination of fructose content, creamy smooth taste, and ability to counteract the contrasting sharpness of many natural fruits make it an ideal additive.

The juice obtained from Soursop is known as a flavouring for sorbets and ice-creams in the Caribbean but, as has been pointed out, the present invention is not concerned with making ice-creams or sorbets. The foodstuff products produced in accordance with the inventive concept are Melts, smoothies, pure fruit juices and energy drinks. Using this fruit in these contexts is believed to be entirely new and as such is therefore inherently inventive.

The invention also provides a method of producing a ready-to-eat low fat fruit-based food product comprising the steps of: (I) pulping fruit to produce a fruit pulp; (ii) combining portions of fruit pulp from a plurality of different fruits; and (iii) freezing said combined portions to produce a frozen product, all without adding any -or substantially any -sweetening or flavouring constituent other than the fruits and/or their juices.

Preferably, following pulping at step (i), fruit pulp is sieved to remove a portion of juice before combining with other fruit pulps at step (ii). More preferably, an aliquot of said removed juice is recombined with the pulp. This allows acidity and for sweetness to be adjusted without the use of additional sugars or flavourings.

In any aspect of the method, it is preferable that said combined portions of pulp are subjected to a further size reduction step.

Also in any aspect of the method, it is preferable that an emulsifier is added to said combined portions of pulp. Preferably, said emulsifier is lecithin.

Also in any aspect of the method, it is preferable that soursop (Annona muricata) is added to said combined portions of pulp.

Also in any aspect of the method, it is preferable that freezing is carried out by use of a scraped surface heat exchanger.

Also in any aspect of the method, it is preferable that gas is incorporated into said combined pulp before freezing. Preferably, the gas is nitrogen.

Also included within the scope of the invention is a method of producing a (ow fat fruit-based food product substantially as described herein, with reference to and as illustrated by any appropriate combination of the accompanying drawings.

Also included within the scope of the invention is a low fat fruit-based food product obtainable by a method described herein.

Also included within the scope of the invention is a low fat fruit-based food product substantially as described herein, with reference to and as illustrated by any appropriate combination of the accompanying drawings.

Specific Examples Embodying the Invention

Example 1

Initially separate batches of mango, clementine, and pineapple which had been peeled and de-pipped as necessary were each fed to a respective juicer through which the batch passed via a mesh of appropriate coarseness or fineness. Each batch of the resulting and separated pulp and juice flows emerging from the juicer was weighed and the flows were then brought together in appropriate relative percentage by weight amounts.

A carefully metered amount of lecithin was added to act as an emulsifier and the blend was further adjusted for taste by sweetening it with white or black seedless grape juice or sharpening it with pure lemon juice.

Soursop was then added, again in carefully metered quantities until an acceptable combination of viscosity and flavour had been achieved. The resultant melt was then pasteurised before being chilled arid stored under appropriately low-temperature conditions.

Example 2

Peeled and de-pipped grapes were treated as outlined above but were juiced specifically in a "blank"( i.e. non-mesh-strained) juicer.

Example 3

Raspberries were treated as previously outlined but were juiced through a relatively course-mesh-filtering juicer.

Example 4

Strawberries in this example we used as the basic fruit pulp and were fed through a relatively fine-mesh filter in the first stage of the process.

Example 5

A fruit juice product was produced in accordance with the invention by juicing the fruit pulp through a relatively coarse mesh in order to let relativeLy high amounts of pulp through and then adding lemon juice, pineapple juice, and/or Soursop to adjust the flavouring and the final product was gently pasteurised in order for it to be supplied to retail outlets as a shelf-life of six weeks, as fresh-taste product intended to be drunk within two to three days of opening.

The intended skilled addressee of this specification will be able to determine, without inventive thought or experiment, the percentages and other variable parameters appropriate to any given instance in which he wants to put the invention into practice in any of its aspects within the overall inventive concept.

Production Process Figure 1 is a schematic diagram illustrating a production process for preparing fruit prior to manufacture of products of the present invention. Fruit is initially prepared by removing stones or pips that might interfere with subsequent processing, or might impart an unpleasant taste or texture to the product. For example, the stones of mangoes and avocado pears would be removed, as would stones of smaller fruits such as cherries. Much smaller seeds, such as those found on the surface of strawberries or raspberries may be removed in subsequent stages, if required.

If the fruit has a thick or unpalatable skin, this may also be removed. Fruits such as mango, avocado and orange would fall into this category.

There then follows a pulping and sieving stage, to produce up to two process streams: a pulp stream and -depending on the nature of the fruit -a juice stream. Methods for fruit pulping wilt be generally known to the skilled addressee. Having obtained a pulp stream and a juice stream, a proportion of the juice may be re-mixed with the pulp to obtain a desired viscosity and sweetness. The sugar and acid content of fruits varies with variety and with ripeness, and so this stage of the process allows the operators to tailor the final organoleptic properties of the product. It is envisaged that incoming fruits may be tested for sugar and acid content to guide the amount of re-mixing required. Alternatively, the pulp and juice may be tasted by a skilled operator, to judge the appropriate proportions required. We refer to this mixture of pulp and juice (or the pulp alone if no juice is either removed or added back) as "let-down pulp".

Depending on the composition of the required product, a number of different types of fruit may be combined at the pulping and sieving stage if they have similar physical characteristics: for example, raspberries and blackberries require similar degrees of applied forces to reduce them to pulp, and they may therefore be processed together.

Alternatively, fruit ingredients may be pulped and sieved individually, and the stage of juice re-addition carried out independently before eventual mixing. This provides greater control over the eventual flavour and rheological properties of the let-down pulp.

Figure 2 illustrates, schematically, a further stage of the process for manufacturing products of the present invention. The let-down pulp is, by preference, subject to a further size-reduction process to achieve the desired viscosity. The size reduction process itself leads to an increase in viscosity of the let-down pulp. Two process options are illustrated in Figure 2: in one option, illustrated on the top left-hand side of Figure 2 (box A), let-down pulps of different fruit types or varieties are blended in proportions to achieve the desired flavour characteristics of the required product before the further size reduction step. In another option (box B), fruit of different types (if required) are subjected to a size reduction process before being blended. The choice of "blending before size reduction" as opposed to "size reduction before blending" will depend on the physical characteristics of the fruit pulps to be employed for any particular desired fruit combination. As before, puips with similar degrees of mechanical strength may be usefully size-reduced together; dissimilarly strong pulps may be size-reduced individually before blending.

This secondary size reduction process (i.e. following pulping) has the effect of increasing the viscosity of the fruit mixture, which is highly beneficial in the subsequent stages of processing.

A particularly preferred form of size reduction for this stage is hornogenisation by use of a high shear mixer, such as those sold under the registered trademark Silverson. In especially preferred embodiments of the process, size reduction (such as homogenisation) is carried out at an elevated temperature such as above 30 C, or preferably above 40 C, above 50 C, or at an especially preferred temperature of above 60 C. The temperature should not exceed about 80 C, as this would result in deterioration of product quality.

If it is desired to increase the shelf-life of the product, or should specific problems of microbial load on the fruit be of concern, then the size-reduced let-down pulp may be subjected to a microbial-load-reduction stage such as pasteurisation. If pasteurisation is to be used, a guide would be to hold the product at 79 C for 15s. To this end, the process stream of size-reduced material may be passed through a heat exchanger, such as a plate heat exchanger.

At this stage, the process stream may be frozen, producing a stable product that may be used to produce fruit "smoothies".

Alternatively, the stream may be further processed to produce the "Melt" described above.

To produce a Melt, the stream is introduced into a scraped surface heat exchanger (SSHE), often used in the ice-cream and margarine industries, for cooling and subsequent freezing.

Batch-mode SSHEs may be employed for smaller quantities of material. Alternatively, continuous or semi-continuous SSHEs can be used for processing larger quantities.

The use of a scraped surface heat exchanger for freezing the product is particularly advantageous to create a frozen product having the creamy texture and other characteristics discussed above, without the need to introduce fat into the mixture. SSHEs aUow for a rapid freezing of the product where it is in contact with the cold surface; the continual mixing and scraping of the product against the cold surface ensures that the product freezes evenly and quickly, and that the ice crystal size within the frozen product remains small. The production of small ice crystals is a key factor in producing the creamy texture. It is especially preferred that the majority of ice crystals (by mass) have a size of less than 50microns. The inventors have found that a cooling rate that can bring the temperature of the product down to -18 C within 2 minutes from a chiLled state (i.e. below 4 C) is particularly effective. After freezing, storage at -25 C or below is particularly advantageous to maintain the product structure.

The use of SSHEs for the freezing stage also introduces air into the product, creating a foamed structure (i.e. gas bubbles dispersed throughout the fruit pulp matrix). The foamed nature of the product improves the mouthfeel of the Melt, and makes it "soft and creamy" rather than ice-like. To this end, especially preferred embodiments of the process include a step of introducing gas into the fruit pulp before freezing to increase the effect. Air may be introduced to the pulp, for example, at the inlet of the SSHE. More preferably, however, other gases may be used: the use of Nitrogen, for example, leads to more stable bubble formation due to its reduced solubility in the fruit pulp. The use of Carbon Dioxide also has advantages: although it is more soluble than Nitrogen (and especially so at low temperatures), when the product is eaten, the elevated temperature of the mouth causes the CO2 to come out of solution, so producing a fizzing effect in the mouth. The combination of a creamy initial texture and a subsequent fizziness has particular appeal making it more attractive to consumers, thus increasing the likelihood that they will consume more of the fruit-based product and benefit from the known health advantages of fruit consumption.

For a very soft product, providing increased bulk and volume for a given mass of product, an air (or other gas) content of up to 80%(v/v) is envisaged. For a more solid texture, an air content of approximately 25%(v/v) is envisaged. Air contents between these values provide a range of textures. Air contents in the range of 30-50%(v/v) are particularly preferred.

The increase of viscosity of the process stream, imparted by the size reduction stage has the effect of increasing the product's ability to stabilise the foam structure created by the introduction of air or other gases. In alternative embodiments, however, a surf actant stabiliser may also be used. A particularly preferred stabiliser is lecithin, and especially soya bean lecithin. The inventors have found that the use of lecithin at a concentration of approximately O.025%(w/w) is particularly suitable. It is envisaged, however, that concentrations up to O.1%(w/w) would also be effective. The stabiliser is preferably added at the size-reduction stage.

Claims (13)

1. A method of producing a ready-to-eat low fat fruit-based food product comprising the steps of: (I) pulping fruit to produce a fruit pulp; (ii) combining portions of fruit pulp from a plurality of different fruits; and (iii) freezing said combined portions to produce a frozen product, all without adding any -or substantially any -sweetening or flavouring constituent other than the fruits and/or their juices.

2. The method of claim 1 wherein, following pulping at step (i), fruit pulp is sieved to remove a portion of juice before combining with other fruit pulps at step (ii).

3. The method of claim 2 wherein an aliquot of said removed juice is recombined with the pulp.

4. A method according to any preceding claim wherein said combined portions of pulp are subjected to a further size reduction step.

5. A method according to any preceding claim wherein an emulsifier is added to said combined portions of pulp.

6. A method according to claim 5 wherein said emulsifier is lecithin.

7. A method according to any preceding claim wherein soursop (Annona muricata) is added to said combined portions of pulp.

8. A method according to any preceding claim wherein freezing is carried out by use of a scraped surface heat exchanger.

9. A method according to any preceding claim wherein gas is incorporated into said combined pulp before freezing.

10. A method according to claim 9 wherein the gas is nitrogen.

11. A method of producing a low fat fruit-based food product substantially as described herein, with reference to and as illustrated by any appropriate combination of the accompanying drawings.

12. A low fat fruit-based food product obtainable by a method according to any preceding claim.

13. A Low fat fruit-based food product substantially as described herein, with reference to and as iLlustrated by any appropriate combination of the accompanying drawings.