IE44092B1 - Packaged baked goods - Google Patents

Abstract

To produce packaged bakery products having improved storage time, the products are baked and cooled in a film packaging which forms an aseptic barrier and permits the escape of steam during baking. The packaged baked products are then hermetically sealed and pasteurised. Baking is performed in such a manner that a temperature of at least 90 DEG C is reached in the interior of the bakery product for at least 30 minutes. The baking conditions should be selected so that a water activity of less than 0.95 is achieved in the baked product. To produce packaged, partly pre-baked bread, dough is baked at a temperature at which browning is avoided. The packaged, pre-baked products have a high storage stability and, compared with known products, are very stable with regard to attack by micro-organisms.

Description

This invention relates to packaging baked goods and in particular part-baked bread, buns, cake and like baked goods made from dough or pastry prepared from flour and to processes for their preparation.

Bread normally goes stale within a few days of being baked, the crust becoming soft and conversely the crumb becoming hard. It can be stored for longer periods at deep-freeze temperatures, e.g. -20°C or below, but staling occurs, albeit more slowly, even at these low temperatures. Bread can also be part-baked and stored in this condition until the customer is ready for it, when it is given a short, second bake forming a brown crust. Similar considerations apply to other baked goods, whether prepared from a dough base or a pastry base, for example Danish and puff pastry or a batter base, e.g. cakes.

Whatever the method employed, it is highly desirable to protect baked goods in storage from the effects of moisture, air and contamination by micro20 organisms, and to this end methods have been prepared in which the goods are baked wrapped. The present invention provides a process enabling wrapped baked goods to be stored for prolonged periods, in suitable conditions, with markedly little deterioration and, in particular, to be stored in a part-baked condition, from which they can be restored by a second baking to a substantially fresh condition. - 3 The present invention therefore provides a process for the preparation of baked goods having an improved shelf-life, comprising baking the goods enclosed in a foil package providing an aseptic barrier while permitting vapour to escape during baking, cooling and hermetically sealing the foil package and heat-pasteurising the packaged goods. Preferably the escape of vapour during baking is effected through the foil itself, by totally enclosing the goods in foil having a vapour permeability oi at least 800 gms/m2/24 hours of water vapour at 38°C and relative humidity 90%. The baked goods are then sealed, preferably in a separate, outer container made from material of negligible vapour permeability.

The operation of the invention may be as follows: dough or other starting material is baked in a foil package permitting the escape of vapour, especially water vapour, during baking. The package is then allowed to cool before being hermetically sealed, the package serving as an aseptic barrier. Any condensed vapour which would otherwise have provided an active substrate for the proliferation of harmful microorganisms is then rendered innocuous by heat-pasteurising the packaged goods. In this second heating operation comparatively little vapour need be generated, insufficient to burst the sealed package.

When the foil-packaged goods are sealed in an outer container the invention in this specific form overcomes many difficulties inherent in the use of single vapour-permeable packages. While many flexible materials, often of man-made film-forming polymeric materials are nowadays available to serve as aseptic barriers, few among those which are sufficiently 440θ2 - 4 heat-resistant for baking purposes and vapour-permeable can be readily sealed hermetically to resist the ingress of harmful micro-organisms while permitting the escape of vapour and gases during baking. In any case, sufficient moisture usually remains on the surface of the baked dough, in the free space which is invariably present in the package, to provide an active substrate for their proliferation. An important advantage of the invention is that it is then enough to close the inner package temporarily by folding; sufficient protection against infection can be provided by folding the free ends of the foil under the package. The foil package material may comprise uneoated film of a regenerated cellulose product.

Effective protection from contamination after baking is provided by hermetically sealing, as in an outer container, for which a wide range of material is suitable, including plastics film, for example hydrocarbon polymers such as polypropylene, other film20 forming polymeric substances, for example acrylic acid and vinyl polymers and coated regenerated cellulose derivatives, most of which can be heat-sealed.

Baking temperatures for the preparation of partbaked bread and similar leavened goods are preferably 100 to 200°C, for periods preferably from 30 minutes to 1¾ hours, particularly 100 to 175°C for from 40 to 75 minutes, e.g. 120 to 160°C for about an hour, the precise conditions being insufficient to confer a browned appearance to the goods. Preferably the temp30 erature is permitted to fall by 20° to 3o°C during baking. Part-baking should be sufficient to confer rigidity to the goods and prevent their collapse and 4 0 9 2 to effect complete gelatinisatiori of the starch content, at Lfit* same time ensuring that tho action of the .leavening agent is completed and arrested. The water activity of the baked goods, at least for bread, should be below 0.95.

It is preferred to effect at least part of the proving of leavened'dough goods in the package, sufficient space therefore being left in the package for this purpose.

After proving, the dough is preferably baked with progressive fall in temperature for 10 to 15 minutes.

Preferably the interior of the package is made commercially sterile by the baking operation. In conventional baking or part-baking of leavened goods the combination of temperature and time normally is insufficient to ensure that the interior is made sterile. Interior temperatures of at least 90°C and preferably in the region of 100°C are desirable according to the present invention, these temperatures being maintained for a period of at least 30 minutes. It may be necessary, in order to ensure that the goods are made homogeneously commercially sterile, to obtain temperature measurements in the interior of the goods.

It will be understood that by commercially sterile is meant a condition in which, while all bacteria may not necessarily be absent, severe pasteurisation has been effected, and substantially only spore-forming bacteria can remain.

After cooling to permit the water vapour to condense, preferably lasting at least 10 minutes, more preferably 20 minutes, the package of baked dough is sealed in a container providing an outer covering - 6 impervious to air, moisture and bacteria and the whole then heated to pasteurise the contents of the container. Vapour should not escape into the outer pack while packing otherwise a partial vacuum is generated likely to lead to the collapse of the container. The cooling step should ensure that this does not occur.

A wide variety of materials is available for the container; while it must be sufficiently heat-resistant to withstand pasteurisation temperatures, these can be less severe than baking conditions. A wider range of materials is thus available and among these can be selected many which meet the remaining requirements and can be conveniently sealed. Preferably a vinyl polymer or copolymer is used which is rigid and affords protection during transport and storage. Other synthetic resins capable of withstanding heat are suitable, including coated regenerated cellulose.

The container and its contents are pasteurised by heating preferably to at least 75°C, especially to about 90°C but preferably to not more than llo°c, for a period of preferably up to 1 hour, at least 10 minutes, preferably at least % hour and especially about 3/4 hour; principally destroying bacteria, moulds and other micro-organisms present between the inner package and the outer container and any that may have entered the inner package. Pasteurisation may also be effected by infra-red heat treatment.

It is a surprising feature of the invention that, providing the baking conditions realise a water activity below 0.95, no spore growth is evident in part-baked bread from its taste after post-baking, when prepared in accordance with the invention, even - 7 after storage for several months at ambient conditions, e.g. 10 to 20°C. Such growth is evident from a ropey taste and soon appears in bread baked in open conditions, even with lower water activity than this.

Shelf-life of the products of the invention may be enhanced by including an accepted preservative in the dough or whatever comestible material is baked. Thus, acetic acid and/or acceptable acetates, e.g. calcium acetate, may be included in suitable amount.

The invention is suitable for the preparation both of part- and fully-baked leavened and unleavened goods such as bread, buns, cakes, scones, muffins, crumpets and pastries. The invention may also be applied to the preparation of packaged cooked meals in predetermined portions which may or may not include baked goods. It is applicable, therefore, to the packaging of cooked comestibles generally.

Several inner packages may be sealed within a common outer container for them all. The inner package and/or outer container may each consist of a preformed bag closed by folding/sealing the mouth, as the case may be. Alternatively, either or both may be formed by wrapping sheet material around the goods or inner package, as the case may be. Again, the inner package and outer container may be made by thermal forming, the outer container at least being heat-sealed at its overlapping edges. Either or both may be made from transparent material. The outer container may be made of laminated material combining strength and imperviousness, e.g. of sheets of aluminium, polyolefine and vinyl polymer or polyamide sheets laminated together . 44098 - 8 The amount of space occupied in the outer container, by the inner package or packages is not critical but it is preferable to avoid cramming.

Example 1 Dough was prepared by kneading together the following ingredients for 20 minutes at 27°C in the parts by weight indicated:- 50 Bread flour 2.5 Yeast 10 1 Salt 1.25 Sugar 1.5 Pat 22.8 Water. Rolls weighing about 55 grams each were prepared 15 from the dough and packed six at a time into cellophane bags having a water vapour permeability of 1200-1300 2 o gms/m /24 hours at 38C and 90% R.H., placed on trays, folded shut and proved at 30°C with a relative humidity 80 to 85% for 35 minutes.

After proving the trays were put in a continuous belt oven for 60 minutes. The temperature profile through the belt oven was as followssPirst 1/4! 138-140°C Sec. 1/4: 142-144°C Third 1/4! 140-142°C Last 1/4: 12O-122°C.

The interior of the packages reached a temperature of 90°C for a period of more than 30 minutes. The baked products were cooled for 20 minutes at a tempera30 ture of approximately 24°C. - 9 Each package of six rolls was placed in a gas and water-vapour impermeable tray, deep drawn from polyvinyl chloride sheet and provided with a lid of similar material which was then sealed on by high frequency means, to provide a hermetically-sealed container .

After a cooling period of 10 minutes or more the packaged containers were placed on the belt of a pasteurisation oven and pasteurised for 45 minutes, with an air temperature inside the oven of 95°C.

After pasteurisation the containers were cooled for at least 1 hour and then packed in cartons. The rolls were firm but white and were stored at 10 to 20°C for a month. They were then unpacked and baked briefly to confer a brown surface crust. The rolls were then tasted and pronounced satisfactory by a tasting panel.

Example 2 The following ingredients for the preparation of French bread were kneaded together as described in Example 1, but at 25°C and the dough was proved in bulk for 20 minutes at 24°Cs- Untreated bread flour 1.25 Yeast 0.50 Salt 0.3 Fat 0.4 Sugar 12.5 Water.

A second proving was carried out for 20 minutes at 28° C with a relative humidity of about 75% on balls of the dough weighing about 210 grams each. The dough pieces were then formed into the final shape of French - 10 440 9« sticks and packed in cellophane bags which were then closed by folding. The permeability of the bag material was as already described in Example 1.

A final proving in the bags was carried out for 5 40 minutes at 30°C with a relative humidity of about 85%.

The pieces were then baked in the cellophane bags for 50 minutes on trays in a belt oven with the following temperature profile:- First 1/4 of the oven. : 15O-155°C 10 Sec. 1/4 It II it t 145-15O°C Third 1/4 II II « « 14O-145°C Last 1/4 II It ll I . 12O-125°C.

Similar internal temperatures were reached as in the previous Example.

The bags were cooled for 20 minutes at about 25°C and packed as before in water- and gas-impermeable deep-drawn trays'each provided with a sealed foil lid.

After a cooling period of at least 10 minutes the sealed containers were pasteurised for 45 minutes in an oven at a temperature of 95°C. After pasteurisation the containers were cooled for at least one hour and then packed in cartons. As before, after storage and final baking to provide a brown crust, the sticks were found excellent to the taste.

Claims (15)

1. CLAIMS:1. Process for the preparation of packaged baked goods having an improved shelf-life, comprising baking the goods enclosed in a foil package providing an aseptic barrier while permitting vapour to escape during baking, cooling and thereafter hermetically sealing the foil package and heat-pasteurising the packaged goods.

2. Process according to Claim 1, in which baking is carried out at a minimum interior temperature of 90°C for at least 30 minutes until the interior of the goods is made commercially sterile.

3. Process according to Claim 2, in which the minimum interior temperature is maintained at approximately 100°C for at least 30 minutes.

4. Process according to Claim 2 or 3, in which a baking temperature is maintained at from 100 to 200°c for a half to 1¾ hours.

5. Process according to Claim 4, in which the baking temperature is maintained at from 100 to 175°C for 40 to 75 minutes.

6. Process according to Claim 5, in which the baking temperature is maintained at from 120 to 160°C for about one hour.

7. Process according to any of the preceding claims, in which the baking temperature is permitted to fall during baking.

8. Process according to claim 7, in which the temperature is permitted to fall by 20 to 30°C.

9. Process according to any of the preceding claims, in which baking conditions are used which realise a water activity in the baked goods below 0.95. 44093 - 12 10. Process according to any of the preceding claims, in which dough is part-baked by baking at a temperature at which browning is avoided. 11. Process according to any of the preceding 5 claims, in which the packaged goods are pasteurised at a temperature of from 75 to 110°C for a period of up to an hour. 12. Process according to Claim 11, in which the packaged goods are pasteurised at a temperature in the

10. Region of 90° C for a period of at least 10 minutes.

11. 13. Process according to any of the preceding claims, in which the foil has a vapour permeability of at least 800 gms/m^/24 hours, of water vapour at 38°C and relative humidity 90%.

12. 15 14. Process according to Claim 13, in which the foil comprises a regenerated cellulose product. 15. Process according to any of the preceding claims, in which after cooling, the foil package is hermetically sealed in an outer container made from 20 plastics film.

13. 16. Proeess according to Claim 15, in which the outer container comprises a rigid vinyl polymer or copolymer.

14. 17. Process according to Claim 15, in which the 25 plastics film comprises a vinyl polymer or polyolefine and polyamide laminate.

15. 18. Process for the preparation of packaged baked goods substantially as hereinbefore described with reference to the accompanying Examples. 30 19. Part-baked packaged bread and like baked dough products whenever prepared by a process as claimed in any of the preceding claims.