GB2428958A

GB2428958A - Snackfood comprising powdered vegetable and/or fruit

Info

Publication number: GB2428958A
Application number: GB0516413A
Authority: GB
Inventors: Paul Ainsworth; Andrew Plunkett
Original assignee: Manchester Metropolitan University
Current assignee: Manchester Metropolitan University
Priority date: 2005-08-10
Filing date: 2005-08-10
Publication date: 2007-02-14
Anticipated expiration: 2025-08-10
Also published as: GB2428958B; GB0516413D0

Abstract

A method of producing a snackfood product comprises the steps of: <SL> <LI>(i) preparing a free-flowing powder mixture comprising <SL> <LI>(a) 5-30% by weight of a powdered fruit and/or vegetable material having a moisture content of less than 10% by weight based on the weight of said material, and <LI>(b) 50-95% by weight of a flour, </SL> said mixture containing at least 80% by weight of (a) and (b) and also containing 10%-20% by weight of moisture based on the total weight of the mixture; <LI>(ii) extrusion cooking the mixture produced in step (i); and <LI>(iii) extruding the cooked mixture at a temperature of 100-150{ C through a die to effect expansion of the mixture and produce a snackfood product having a moisture content of 4-10% by weight, based on the weight of the expanded product, a bulk density of 0.05-0.9 g cm<-3> and a breaking strength of 2-19 N. </SL> A biscuit-like snack is produced. The powdered fruit and/ or vegetable may be citrus peel, pineapple core or broccoli stalks.

Description

* 2428958

I

SNACKFOOD PRODUCT

The present invention relates to a method of producing a snackfood product, i.e. a product that is intended to be eaten as a snack rather than as a substitute for a main meal.

The invention relates more particularly to the production of a snackfood product incorporating vegetable and/or fruit material.

It has long been recognised that the amount of fruit and vegetables eaten by many children is below recommended levels for a healthy diet. The present invention aims to address this problem by providing a snackfood product which incorporates powdered fruit andlor vegetable material and which will appeal to children so as to provide a means of supplementing their fruit and vegetable intake.

Food products prepared using vegetable powder andlor fruit powder are known in a number of forms.

WO 2004/008881 Al (Nestech S.A.) discloses a process for the manufacture of a dehydrated food product which is ultimately intended to be reconstituted with hot or cold water to form a "pulpy-textured" product, e.g. for use as a soup, sauce, porridge or mash.

In the first step of manufacture of the dry food product, a mixture is prepared which comprises: (i) 20-60 parts of vegetable and/or fruit powder; (ii) 20-60 parts of starch; (iii) 15-35 parts of flour; (iv) 0-18 parts of vegetable or fruit pieces; and (v) optionally water.

The mixture has a moisture content of 6-20% and is extrusion-cooked at 60110 C for 20-90 seconds and subsequently extruded through a die. As a result, a part of the water in the mixture is converted to steam and causes an expanded product to be formed.

This expanded product has a water content of 5 to 15% by weight. Finally the expanded product is further dried to a water content of I to 5% by weight.

Thus in the process of WO 2004/00888 1, the mixture (from which the final dry food product is ultimately prepared) includes separate additions of starch and flour (which will also contain starch). The starch (which is added in an amount of 20-60 parts) will gelatinise during the extrusion cooking process and will ensure that the product when reconstituted with hot or cold water has "body" thereby providing a "pulpy-textured" product for use as a soup, sauce, porridge or mash.

The starch used in the process of WO 2004/008881 may for example be potato starch, rice starch, wheat or maize starch or a mixture thereof.

DE-A-29 52 048 discloses a method for manufacturing a preservable and storable food material. The material is produced by producing a mixture of starch or cereal meal (having a carbohydrate content of approximately 70-80%) with vegetable substances such as minced, dried vegetables or Lucerne green meal with marine algae. If fresh vegetables (e.g. carrot) are used, the vegetables are washed, minced (or chopped) and then pressed to remove excess water. Fresh carrots as proposed for use in the process of DE-A-29 52 048 generally contain about 80% moisture (even when excess water that has been used for washing is removed). If using dried vegetables or Lucerne green meal in the process of DE-A-29 52 048, a little water is added to the dried vegetable/green meal to produce a doughy or paste-like composition. The mixture thus obtained comprising the fresh or dried vegetable material and (at this stage) non-digested starch or cereal meal is compacted at relatively high pressures in an extruder with the introduction of saturated steam. The product is extruded through a die, thereby producing an expanded product which is virtually full digested in tenns of the starch content (by virtue of the fact that the starch has been digested by the saturated steam). The product is intended to be dissolved in water so that it can be used to make vegetable soups or vegetable purees.

According to the present invention there is provided a method of providing a snackfood product comprising the steps of: (i) preparing a free-flowing powder mixture comprising (a) 5-30% by weight of a powdered fruit and/or vegetable material having a moisture content of less than 10% by weight based on the weight of said material, and (b) 50-95% by weight of a flour, said mixture containing at least 80% by weight of(a) and (b) and also containing 10%-20% by weight of moisture based on the total weight of the mixture; (ii) extrusion cooking the mixture produced in step (i); and (iii) extruding the cooked mixture at a temperature of 1001500 C through a die to effect expansion of the mixture and produce a snackfood product having a moisture content of 4-10% by weight, based on the weight of the expanded product, a bulk density of 0.05-0.9 g cm3 and a breaking strength of 2-19 N. The method as defined in the previous paragraph produces an expanded snackfood product which may be consumed as a convenient supplemental source of fruit and/or vegetable materials. The product has a good shelf life, e.g. greater than three months, without any significant change in nutritional content. The properties of the expanded snackfood product (in terms of its moisture content, bulk density and breaking strength) provide desirable characteristics with regard to the "initial bite", the "crunchiness", breakdown in the mouth and "toothpack" in the mouth (this is how sticky or how dry the product is in the mouth).

More particularly, step (iii) of the process defined above results in formation of an expanded product partly as a result of water being "flashed-off' as the cooked mixture (at a temperature of 100-150 C) is extruded through the die and the starch in the flour provides a structure forming material to allow the expanded product to form. Additionally the protein and starch present in the flour together provide a degree of "control" over the expansion achieved since the protein will compete with the starch for the limited amount of water and can therefore reduce the starch gelatinisation and thus reduce expansion.

The product resulting from step (iii) has a moisture content of 4-10% (preferably 5-8%) by weight (based on the weight of the expanded product). The product has a good shelf life without the need to lower the moisture content. It will therefore be appreciated that the product of step (iii) of the process of the invention (with its moisture content of 4-10% by weight) may be packaged without further processing, otherwise possibly by cooling and/or cutting to length. We do not however preclude the possibility of the product (of step (iii) being given a post- processing treatment such as flavouring or coating etc prior to packaging but nevertheless the "basic" product would still have a moisture content of 4-10% by weight (preferably 5-8% by weight).

in step (i) of the method, a free-flowing powder mixture is prepared comprising 5- 30% by weight of a powdered fruit and/or vegetable material having a moisture content of less than 10% by weight. An amount of fruit in the range 25-30% by weight will tend to give a product with a biscuit-like texture whereas lowering the fruit content to 5-15% gives a lighter expanded product.

Powered fruit materials that may be used in the invention may be derived from a variety of fruits, e.g. citrus fruits (such as oranges, lemon or grapefruit) pineapples, apples, pears, all berries (e.g. strawberries), tomatoes, mangoes, melons and nectarines.

The powdered fruit may be derived from the flesh of such fruits. However (more conveniently) and depending on the particular fruit under consideration the fruit material for use in the invention may, for example, be derived from peel or core material. Thus, for example, citrus peel such as orange peel is (when dried and powdered) eminently suitable for use in the method of the invention. A further example of fruit material which (when dried and powdered) may be employed in the invention is pineapple cores.

Similarly, the vegetable powder may be derived from a wide range of vegetable materials. The vegetable material may, for example, be leaf, stalk or root material. The vegetable may be broccoli, cauliflower, carrot, onion, celeriac, parsnip, swede, turnip, legumes and beetroot. The vegetable material may, for example, be broccoli stalks.

In all cases the fruit or vegetable material (that is dried and powdered) for use in the invention may be a so-called "co-product", i.e. products that would otherwise be waste from the fruit and vegetable processing industry. Particular examples of such co- products include citrus peel (e.g. orange peel), pineapple cores, broccoli stalks, pea pods, bean pods, cauliflower stem and leaves, carrot peel, parsnip peel and beetroot skins.

For the purposes of the invention, vegetable or fruit material will initially be dried, e.g. to a moisture content of less than 10% by weight, more preferably less than 8% by weight (preferably 5-6% by weight). A variety of drying methods may be used, e.g. osmotic drying, warm air drying or freeze drying. Osmotic drying (possibly in combination with subsequent warm air drying) will be particularly suitable for fruit material that tends to go brown on drying. Example conditions that may be used for osmotic drying include 60% maltodextrin at 50 C for three hours.

Once the fruit/vegetable material has been dried to the appropriate moisture content, it may be milled to a powder using any convenient technique. Powder size is not particularly important but the larger the powder size then the less uniform will be the expansion. Preferably the powder size will be in the range 250-710 /im, more preferably 250-355 tim.

The flour that is employed in the present invention may be one containing 8-12% protein and 70-80% by weight of starch, these percentages being based on the weight of the flour. The flour may for example be a wheat, rice or maize flour.

The flour and powdered fruit and/or vegetable material together comprise at least 80% by weight of the mixture that is subjected to extrusion cooking in step (ii) of the process. This percentage will preferably be at least 85% and more preferably at least 88%. Any additional component(s) of the mixture (to make the total to 100%) will be in powdered form so as to ensure that a free-flowing powder is obtained that may readily be fed to the extruder. One example of such an additional component that maybe employed is a sweetener such as sucrose which may, for example, be employed in an amount of 10- 14% (e.g. about 12%) by weight of the mixture that is subjected to extrusion cooking.

However the use of such additional components is optional and the powdered fruit/vegetable material and flour may together provide all of the mixture that is to be subjected to extrusion cooking.

A further feature of the mixture is that it has a moisture content of 10%20% by weight based on the total weight of the mixture. This moisture will be that which has been retained in the fruit/vegetable material from the drying process and also that which is inherently present in the flour. If it has been found that, during the drying process, the fruit/vegetable material has too low a moisture content to provide the 1 0%-20% required for the mixture then a small amount of additional water may be added to the mixture as it enters the extruder.

The mixture that is obtained in accordance with the above procedures is then subjected to extrusion cooking which may be effected in conventional extrusion cooking apparatus. The extrusion cooking will typically be effected at a temperature of 80-150 C.

Typically the temperature of the mixture will be increased in at least two stages from ambient (e.g. 20-25 C) up to a final temperature in the range 100-150 C at which the product is subsequently extruded through a die. Thus, for example, the mixture may be raised from ambient to a temperature of 70-90 C (e.g. 80 C) and subsequently to a temperature of 110-130 C (e.g. about 120 C) at which the product is extruded through the die.

Extrusion may be effected through one or more dies e.g. circular dies having a diameter of 4mm.

The initial moisture content of the mixture is an important part of the extrusion process in that with more than 20% moisture the product obtained is too hard. In contrast, a moisture content of less than 10% may cause operational problems with the possibility of burning giving undesirable colour and flavour changes and also possibly causing jamming of the extruder. Preferably the initial moisture content of the mixture is 10-17% by weight. Suitable examples within this range are 10-15% by weight and 12- 15%, ideally 13-15%.

The overall conditions of the extrusion process are such that the product obtained has a breaking strength of 2-19 N, a bulk density of 0.05-0.9 g/cm3 and (preferably) an expansion ratio of 1.5-4. A product having a "biscuit-type" texture will generally have a break strength of 10-15 N, a bulk density of 0.5-0.9, an expansion ratio of 1.5-2.5 and a moisture content of 7-10%. A product having a light expanded texture will generally have a break strength of 2-7 N, a bulk density of 0.05-0.3, an expansion ratio of 2.5-4.0 and a moisture content of 4-7%.

For any one extrusion cooking apparatus, the breaking strength, bulk density, expansion ratio and moisture content of the product obtained is a function of the composition of the original mixture, moisture feed, solid feed rate, barrel temperature and screw diameter and speed. It is however well within the ability of the skilled person to arrive at the necessary processing conditions by varying one or more of these parameters to obtain a product in accordance with the invention.

Break strengths as quoted herein are measured on extrudate samples having a length of 80 mn-i using a Stable MicroSystem TA-XT2 texture analyser with a heavy platform, a 3 point bending rig and using a 25 Kg load cell with the two adjustable supports of the base being set at 60mm apart. The break strength was taken as the highest peak recorded.

Bulk density is determined by measuring the mass and volume of a sample of the product and calculating bulk density as mass/volume.

Expansion ratio is determined by measuring a cross-sectional length of the product and dividing that length by the corresponding cross-sectional length of the extrusion die. For example, in the case of a product of circular section the expansion ratio is calculated as: Diameter of product Diameter of die The invention is illustrated by the following nonlimiting Example.

Example

A Werner and Pflederer Continua 37 co-rotating twin-screw extruder was used produce an orange-based snackfood product using the procedure described below. The diameter of the screws and the screw length:screw diameter ratio were 37mm and l/d =27 respectively. The screws were made of self-wiping elements except for a short section consisting of short reverse and forwarding elements. Two circular dies each of 4mm diameter and 19mm length were used.

A mixture was prepared comprising 30% orange peel powder, 58% rice flour and 12% sucrose, the percentages being by weight. The mixture contained 13% by weight moisture based on the total mixture weight was fed into the extruder at a feed rate of 30Kg/hr. The extruder was subdivided into 3 temperature zones. The first zone was at ambient temperature and allowed progression of the mixture, the second zone was heated at 80C, and the third zone was heated at 120C. Screw speed was 300rpm. The mixture This gave an extruded product with a final moisture content of 5%. A ready to eat extruded crisp biscuit like snack was produced.

Break strength = 4.7N Bulk density = 0.18 g/cm3 Expansion ratio = 2.5

Claims

1. A method of providing a snackfood product comprising the steps of: (i) preparing a free-flowing powder mixture comprising (a) 5-30% by weight of a powdered fruit and/or vegetable material having a moisture content of less than 10% by weight based on the weight of said material, and (b) 50-95% by weight of a flour, said mixture containing at least 80% by weight of(a) and (b) and also containing 10%-20% by weight of moisture based on the total weight of the mixture; (ii) extrusion cooking the mixture produced in step (i); and (iii) extruding the cooked mixture at a temperature of 100-150 C through a die to effect expansion of the mixture and produce a snackfood product having a moisture content of 4-10% by weight, based on the weight of the expanded product, a bulk density of 0.05-0.9 g cm3 and a breaking strength of 2-19 N.

2. A method as claimed in claim 1 wherein the fruit material is derived from a citrus fruit, pineapple, apple, pear, berry, tomato, mango, melon and/or nectarine.

3. A method as claimed in claim 2 wherein the fruit material is citrus peel.

4. A method as claimed in claim 3 wherein the fruit material is orange peel.

5. A method as claimed in claim 2 wherein the fruit material is derived from pineapple.

6. A method as claimed in claim 5 wherein the fruit material is derived from pineapple core.

7. A method as claimed in claim I wherein the vegetable material is derived from broccoli, cauliflower, carrot, onion, celeriac, parsnip, swede, turnip, legumes and/or beetroot.

8. A method as claimed in claim 7 wherein the vegetable material is derived from broccoli stalks.

9. A method as claimed in any one of claims ito 8 wherein the flour contains 8-12% by weight of protein and 70-80% by weight of starch.

10. A method as claimed in any one of claims 1 to 9 wherein the flour is wheat, rice or maize flour.

ii. A method as claimed in any one claims I to 10 wherein the mixture that is subjected to extrusion cooking in step (ii) comprises at least 85% by weight of the flour and powdered fruit and/or vegetable material.

12. A method as claimed in claim 11 wherein the mixture that is subjected to extrusion cooking in step (ii) comprises at least 88% by weight of the flour and powdered fruit and/or vegetable material.

13. A method as claimed in any one of claims I to 12 wherein the mixture prepared in step (i) contains 10-14% by weight of a sweetener.

14. A method as claimed in claim 13 wherein the sweetener is sucrose.

15. A method as claimed in any one of claims 1 to 14 wherein the fruit andlor vegetable material used in step (i)(a) contains less than 8% by weight moisture.

16. A method as claimed in any one of claims Ito 15 wherein the mixture produced in step (i) contains 10-15% by weight moisture.

17. A method as claimed in any one of claims I to 16 wherein the extrusion cooking is effected at a temperature of 80-150 C.

18. A method as claimed in claim 17 wherein, during extrusion cooking, the temperature of the mixture is increased in at least two stages from ambient to a final temperature in the range 100-150 C.

19. A method as claimed in claim 18 wherein the mixture is raised from ambient to a temperature of 70-90 C and subsequently to a temperature of 100-130 C.

20. A method as claimed in any one of claims 1 to 19 wherein the product of step (iii) has a breaking strength of 10-15 N, a bulk density of 0.5-0. 9 and an expansion ratio of 1.5-2.5.

21. A method as claimed in claim 20 wherein the product of step (iii) has a moisture content of 7-10%.

22. A method as claimed in any one of claims 1 to 19 wherein the product of step (iii) has a breaking strength of 2-7 N, a bulk density of 0.05-0.3 and an expansion ratio of2.5- 4.0.

23. A method as claimed in claim 22 wherein the product of step (iii) has a moisture content of 4-7%.

24. A method as claimed in any one of claims 1 to 23 wherein the product of step (iii) is subjected to optional further processing steps and then packaged whilst having a moisture content in the range 4-10% by weight.