GB2342272A

GB2342272A - Acid-stabilised soups

Info

Publication number: GB2342272A
Application number: GB9821759A
Authority: GB
Inventors: Nicholas John Gerard Hazell
Original assignee: Masterfoods CV
Current assignee: Masterfoods CV
Priority date: 1998-10-06
Filing date: 1998-10-06
Publication date: 2000-04-12
Also published as: GB9821759D0

Abstract

Shelf-stable soup products comprise one or more edible acids, other than polymeric food-acceptable acids, in an amount sufficient to provide the soup product with a pH of less than about 4.3, whereby the addition of milk to the soup product provides a palatable soup having a pH of about 4.8 or more. A method for the preparation of such soup products comprises the step of packaging the acidified soup product and stabilising the acidified soup product at a temperature of 85-100{C to render it shelf-stable. The edible acid may be present naturally as a soup ingredient, e.g. vinegar, lemon juice or tomato puree or it may be an inorganic acid, e.g. hydrochloric, or an organic acid, e.g. citric, ascorbic or lactic, that is added to the soup. A package may comprise a first container for the soup and a second container for the milk.

Description

ACID-STABILISED SOUPS The present invention relates to acid-stabilised soup products, processes for the production thereof, and methods of use thereof.

A considerable market exists for shelf-stable packaged soup products that can be used to prepare soups in the home with minimum effort. The term"shelf-stable" indicates a packaged soup product that is stable upon storage at ambient temperature (20-25 C) ior a period of at least one week, preferably at least one month, more preferably at least 3 months, and typically for 6 months to a year or even longer.

Clearly, it is necessary to inhibit microbiological spoilage substantially completely if such shelf-stability is to be achieved.

One method of providing a shelf-stable soup product has been by substantially complete dehydration of the soup to provide a substantially solid, dehydrated soup product that is packaged in moisture-impermeable packaging, and that is rehydrated by the user immediately prior to consumption. Such dehydrated soups present a number of drawbacks, including greatly inferior organoleptic properties as compared to fresh soups, and the need for a relatively lengthy rehydration step before the soups can be consume. Nevertheless, the market demand for shelf-stable soup products is such that even these dehydrated soups have achieved widespread market success.

Shelf-stable soup products have also been provided in cans. Such products are typically prepared as follows: a condensed soup is filled into a can; the can is sealed; and the sealed can is retorted under time-temperature conditions sufficient to provide a sterile product-typically about 1 hour at 11 5 C. Since the canned soup typically has a water content which will support the growth of spoilage organisms, the canned product must be subjected to relatively severe heat processing conditions in order to produce a sterile product. The can prevents ingress of micro organisms into the sterile product, and maintains shelf-stability. However, the severe conditions required for sterilisation result in a soup product having organoleptic properties such as taste and texture that are less than optimal. Nevertheless, such is the demand for shelf-stable prepared soup products that sterile, canned condensed soup products have achieved widespread market success.

It has also been known to stabilise foodstuffs generally by the addition of foodacceptable acids. The microorganisms that cause food spoilage are sensitive to acids in various degrees. Acids may be found in foods as a natural component, produced in foods by fermentation, or added to foods directly as a chemical. Since the acid enhances the lethality of heat on spoilage microorganisms, acidified foods having a pH of 4.6 or less, preferably 4.3 or less, most preferably 4.2 or less, need only be heated generally up to about 95 C to render them shelf-stable. This process of stabilisation is sometimes known as acid-pasteurisation.

Each of the following patents discloses treating one or more foodstuffs with one or more acids: JP 62-130644 EP 0012255 UK 2036533 DE 3624035 US 2383907 EP 201266 UK 2174588 US 4789553 US 4181747 US 3886296 US 3985904 US 4741911 US 4542033 US 4191787 US 2291704 US 4818549 US 4740380 US 4675202 US 4564527 US 3446630 US 4814192 US 4762726 US 3366490 US 2992114 US 2790717 US 2819972 US 2819973 US 2434388 The foodstuffs treated in these patents include such items as fruits, vegetables, meats, slurries of vegetable seed fibre, salad dressings, sauces, beverages including juices, and egg yolks. The acids used include ascorbic, acetic, citric, lactic, malic, tartaric, fumaric, adipic, succinic, phosphoric, nitric, hydrochloric, sulphuric, levulinic, gluconic, propionic, hydroxyacetic, maleic, glutaric, palmitic, itaconic, aldonic, sorbic, cinnamic and benzohydroxamic, among others. Unfortunately, each of these low molecular weight, food-acceptable acids confers on the acid-stabilised product a distinct, sharp or pickled flavour, which detracts from the palatability of the product.

W092/03934 describes a method for the preparation of an acid-stabilised foodstuff selected from the group consisting of vegetables, fruits, dairy-based products, egg-based products, sauces, salad dressings, puddings, soups, vegetable beverages and fruit beverages, which comprises heat treating the foods with one or more foodacceptable acids, including at least one polymeric food-acceptable acid, in an amount sufficient to lower pH of the foodstuff below 4.6, for a time of at least five minutes and at a temperature of at least 85 C to effect the acid-stabilisation of the foodstuff. The preferred polymeric food-acceptable acid is alginic acid. The use of the polymeric food-acceptable acid as the principal acidifying additive results in a much less sharp or pickled taste in the product, because the polymeric acids inherently have less impact on flavour. Minor amounts of non-polymeric acids may be used in combination with the polymeric food-acceptable acid as adjuvants or potentiating agents. The resulting acidstabilised food products are palatable and shelf-stable.

It is an object of the present invention to provide a shelf-stable acid-pasteurised soup that does not need to contain added polymeric food-acceptable acid, and that can be used to prepare a palatable soup.

The present invention provides a shelf-stable soup product comprising one or more edible acids other than polymeric food-acceptable acids in an amount sufficient to provide the soup product with a pH of less than about 4.3, whereby the addition of milk to the soup product provides a palatable soup having a pH of 5.0 or more.

Preferably, the shelf-stable soup product is a condensed or concentrated soup.

That is to say, preferably the soup product is a liquid or semi-solid product that is packaged and stored at a substantially lower water content than the water content at which it is preferably consumed. For example, such condensed soups can be manufactured from low water content ingredients such as vegetable purees, or can be prepared by partial evaporation of the water from a conventional soup product.

Preferably, the soup product comprises from 50% to 95% by weight of water, more preferably from 65% to 90% by weight of water, and most preferably about 80% by weight of water. The soup product is preferably diluted by at least 10% on a volume basis, preferably at least 20%, and more preferably at least 50% before consumption.

The soup product may be based on any soup ingredients, for example vegetables, meats, oils and fats, cream, cheese, tomatoes, noodles, etc.

The edible acids used to solidify the soup product may be any food-acceptable acids, other than the polymeric food-acceptable acids described in W092/03934.

Suitable edible acids include ascorbic, acetic, citric, lactic, malic, tartaric, fumaric, adipic, succinic, phosphoric, nitric, hydrochloric, sulphuric, levulinic, gluconic, propionic, hydroxyacetic, maleic, glutaric, palmitic, itaconic, aldonic, sorbic, cinnamic and benzohydroxarnic acids, and mixtures thereof. Preferably, the edible acid comprises ascorbic, acetic, citric, lactic, malic, tartaric, phosphoric, maleic or sorbic acid, or mixtures thereof. More preferably, the acid comprises ascorbic, acetic, citric, lactic or tartaric acid. The most preferred acid is citric acid.

The pH of the shelf-stable soup product according to the present invention is less than about 4. 3, when measured directly on the undiluted soup product using a conventional glass electrode at ambient temperature (say 20 C). Preferably, the pH of the shelf-stable soup product is 4.2 or less, and more preferably is it from 3.8 to 4.2.

The amount of edible acid needed to achieve a pH in this range will depend upon the initial pH of the soup product before acidification, and also on the pKa of any added edible acid. Some concentrated soup products containing naturally acidic ingredients such as tomato puree, vinegar, wine or lemon juice may exhibit a pH of less than 4.3 without the addition of further acid. However, preferably, the edible acid is added in an amount of from 0.05 to 2% w/v, more preferably 0.2 to 1% w/v. This refers to added acid, and not to edible acid present naturally in the soup ingredients.

It is a feature of the acid-stabilised soup products according to the present invention that they are generally unpalatable, due to the sharp, tart or pickled flavour imparted by the added edible acid. In use, the soup products are rendered palatable by the addition of milk in an amount sufficient to raise the pH of the soup, typically to a pH of 5.0 or more. The pH of whole milk is approximately 6.9, and milk has a considerable acid-base buffering capacity.

Accordingly, the present invention further provides a method of preparation of a palatable soup, comprising the steps of : providing a shelf-stable soup product according to the present invention; and adding milk to the said product to provide the palatable soup having a pH of 5.0 or more.

Typically, the milk will be added before, during or after heating the soup product to produce a hot, palatable soup. It is an advantage of the shelf-stable soup products according to the present invention that they are substantially instant soup products. lt is merely necessary to add milk to the soup product with heating, e. g. in a microwave oven, to provide a palatable soup. The milk may be any suitable liquid or powdered milk product, including skimmed milk, sterilised milk or cream.

Preferably, the milk is added to the soup product in an amount of at least 25% by volume, based on the volume of the soup product. More preferably, the milk is added in an amount of at least 50% by volume, and still more preferably in an amount of 100% by volume or more. Preferably, the milk is added in an amount sufficient to provide the palatable soup with a pH greater than 5.5, preferably a pH of 6.0 or more.

The present invention also provides a process for the preparation of a shelfstable soup product, comprising the steps of : providing a concentrated soup product having a pH of less than 4.3; packaging the acidified soup product in a microorganismimpermeable container; and stabilising the acidified, packaged product at a temperature of 85-100 C.

Preferably, said step of providing comprises adding one or more edible acids other than polymeric food-acceptable acids to the soup product in an amount sufficient to lower the pH of the soup to less than about 4.3.

Preferably, the soup product is a condensed soup product as hereinbefore defined. The edible acid may be added to the soup product either before or after evaporating water from the soup product to provide the condensed soup product. The edible acids are preferably as hereinbefore defined, and added in amounts as hereinbefore specified. The acidified soup product is preferably packaged in a microorganism-impermeable sachet, a glass jar or a can. An advantage of the acidified soup product according to the present invention is that they can be heat stabilised at atmospheric pressure, without retorting. This in turn broadens the range of packaging formats that are available from cans to include glass jars similar to those used for packaging sauces, or even plastic film sachets.

A preferred packaging format is a twin-pack comprising a first container for the soup product and a second container for a shelf-stable milk or cream product, the first and second containers being packaged in combination for mixing shortly before consumption. The first and second containers can, for example, be thermoformed from one piece of plastic, or they could be snap-fitted together to form the twin-pack. The twin-pack packaging format enables both the quantity and the composition of the neutralising milk or cream to be optimised. The milk or cream component may be sterilised at a higher temperature and shorter time in conventional fashion, before being combined with the soup product in the twin-pack.

The packaged, acidified soup product is heat stabilised for a time, and at a temperature, sufficient to achieve the desired degree of shelf stability. Preferably, the product is treated at a temperature of from 90-100 C, more preferably about 95 C.

Preferably, the heat treatment is continued for a period of from 5 minutes to 2 hours, preferably for 10-40 minutes.

The packaging for the soup products according to the present invention preferably bears instructions directing the user to add milk before consumption.

Specific embodiments of the present invention will now be described further, by way of example, as follows.

Example 1 A condensed tomato and basil soup product was prepared by mixing the following ingredients: Tomatoes 188 g Water 144 g Tomato paste 41 g Starch 5 g Salt 5 g Sugar 5 g Olive oil 5 g Herbs and 7g 400 g The resulting concentrated soup product had a pH of 4.17, when measured directly with a glass electrode at 20 C. The soup product was unpalatable, having an excessively strong and acidic taste for consumption as a soup.

The soup product was packaged into glass jars of the type conventonally used to package pasta sauces. The sealed jars were heated at 95 C for 20 minutes to acidpasteurise the the soup product. The resulting packaged soup product was shelf-stable after three months at ambient temperatures.

A sample of the soup product (400 g) was warmed and mixed thoroughly with 270 ml of whole fresh milk to give a palatable soup having a measured pH of 5.0.

The above embodiments have been described by way of example only. Many other embodiments falling within the scope of the invention will be apparent to the skilled reader.

Claims

CLAIMS 1. A shelf-stable soup product comprising one or more edible acids other than polymeric food-acceptable acids in an amount sufficient to provide the soup product with a pH of less than about 4.3, whereby the addition of milk to the soup product provides a palatable soup having a pH of about 4.8 or more.
2. A shelf-stable soup product according to claim 1, wherein said edible acids comprise added edible acids in addition to edible acids present naturally in the food ingredients of the soup product.
3. A shelf-stable soup product according to claim 2, wherein said added edible acids are selected from the group consisting of citric acid, tartaric acid, fumaric acid, acetic acid, ascorbic acid, lactic acid, malic acid, adipic acid, succinic acid, phosphoric acid, nitric acid, hydrochloric acid, sulphuric acid, levulinic acid, gluconic acid, propionic acid, hydroxyacetic acid, maleic acid, glutaric acid, palmitic acid, itaconic acid, aldonic acid, sorbic acid, cinnamic acid, benzohydroxamic acid, or mixtures thereof.
4. A shelf-stable soup product according to claim 1 or 2 which is a condensed soup.
5. A shelf-stable soup product according to claim 1, 2 or 3 which is packaged in a microorganism-impermeable container.
6. A shelf-stable soup product according to claim 4 which is substantially stable against spoilage on storage for three months at 20 C.
7. A shelf-stable soup product according to any preceding claim, wherein said product has a pH of 4.2 or less.
8. A shelf-stable soup product according to any preceding claim, wherein said product is substantially unpalatable prior to addition of said milk.
9. A method of preparation of a palatable soup, comprising the steps of : providing a shelf-stable soup product according to any one of claims 1 to 8; and adding milk to said product in an amount sufficient to provide the palatable soup having a pH of 4.8 or higher.
10. A method according to claim 9, wherein the volume of said added milk is at least 50% of the volume of said soup product.
11. A method according to claim 10, wherein the volume of said added milk is at least 100% of the volume of said soup product.
12. A method according to claim 9,10 or 11, wherein said palatable soup has a pH of 5.0 or higher.
13. A process for the preparation of a shelf-stable soup product, comprising the steps of : providing a soup product; adding one or more edible acids other than polymeric food-acceptable acids to the soup product in an amount sufficient to lower the pH of said soup product to less than 4.3; packaging said acidified soup product; and stabilising said acidified soup product by heat treatment at a temperature of 85100 C.
14. A process according to claim 13, wherein said edible acids are added in a total amount of from 0. 05% to 2% by weight, based on the weight of the soup product.
15. A process according to claim 13 or 14, wherein said acidified soup product is stabilised at about 95 C.
16. A process according to claim 13,14 or 15, wherein said heat treatment is continued for a period of from 5 minutes to 2 hours.
17. A packaged shelf-stable soup product comprising: a first container having a shelf-stable soup product according to any of claims 1 to 8 packaged therein; and a second container having a milk or a cream packaged therein, said first and second containers being packaged in combination, whereby said soup product and said milk or cream can be stored separately for mixing shortly before consumption.