Introduction
Market outlets
Packaging
Cooking
Suitable sauces
Freezing
Cold storage
Reheating
Cook-freeze recipes with fish
Haddock or whiting in cheese sauce
Whiting in curry sauce
Shrimp provencale
Sole or plaice in mustard and red pepper sauce
Lemon sole with orange and walnut stuffing
Sauces compatible with fish
Food products that are cooked, packed and frozen at a central production point, distributed frozen, and reheated at the point of consumption are known as cook-freeze products.
This note refers primarily to the use offish in cook-freeze products; a summary of the main market outlets is followed by a description of the process, together with a selection of tested cook-freeze recipes in which the main constituent is fish.
The four most likely outlets for cook-freeze products are the retail frozen food chain, restaurants, institutional caterers, and specialist caterers such as airline caterers.
Products suitable for the retail frozen food cabinet or the home freezer trade can range from simple products like cod in cheese sauce to expensive dishes such as sole with orange and walnut stuffing.
A wide range of cook-freeze dishes stored on the premises enables even the small restaurant to offer elaborate meals from an extensive menu at short notice and with no wastage. In the same way the important and expanding trade in take-away meals can also utilize cook-freeze products.
Caterers in some schools, hospitals and canteens are now using a complete cook-freeze system. Meals are prepared efficiently and hygienically in a central factory kitchen at a steady rate throughout the full working day; the frozen portions are distributed as required from a central cold store to individual schools, canteens or hospital wards where the food is reheated, usually in a forced draught oven, before being served. System catering as it is called, besides being more economic and more efficient, makes portion control and diet control easier, and also gives a wider choice of more palatable and nutritious meals than is possible in conventional mass catering.
There is limited space on aircraft and very little time in which to prepare and serve meals; airline caterers can use cook-freeze dishes which only require reheating during flight; the same system could be used to supply hot meals for example on passenger ships and on fishing vessels.
The style of pack and choice of material must be matched to the product and its proposed outlet. One of the simplest packs is the plastics pouch, and for many applications in institutional catering this may be all that is necessary. Suitable materials include nylon 11 and a range of laminated plastics with high oxygen and water vapour barrier properties. More detailed information on flexible plastics films is given in Advisory Note 51. The range of materials is continually changing and processors should consult film manufacturers about packaging suitable for particular products. However for many products, trays of paper, plastics or aluminium foil are more appropriate. Seamless foil trays are particularly suitable for reheating products in ovens; they are made in many shapes and sizes, ranging from small single portion trays to large catering packs. The top rim can be designed to make the tray more rigid, and to accept a lid. Compartmented trays are available to hold complete meals. Metal foil trays and lids cannot be used in microwave ovens, but here plastics or paper trays are suitable. Sealed packs in most materials can be reheated in steam or hot water.
Traditional cooking methods are suitable for making cook-freeze products, but fish should be slightly undercooked and the process is then completed during reheating. Incidentally, overcooking of fish is a common mistake which results in some loss of eating quality.
Raw fish can be used in some prepared frozen dishes, all the cooking being done after thawing, although this is not strictly a cook-freeze process; a water binding agent must then be included to absorb water released from the fish during cooking, or the appearance and eating quality of the product, particularly the sauce, can be damaged. Where potato is an ingredient, one of the most effective ways of absorbing the water is to put a thin layer of potato powder in the bottom of the tray before the sauce is added.
Devising a suitable sauce for fish and incorporating it in the product, a procedure known as formulation, is an important part of cook-freeze product development. Some of the sauces appropriate to particular species of fish, and recipes for their preparation, are given at the end of this note. Food ingredient manufacturers can make up a sauce mix to meet specific requirements; it can usually be supplied as a powder and reconstituted as required.
It is essential that the sauce does not break down during freezing and thawing. Most sauces contain starch, usually as flour; the starch gel prepared from ordinary wheat flour undergoes structural changes during freezing and thawing and this results in the formation of pools of water, separated from the sauce, and in some curdling. This effect is known as syneresis. The problem is easily solved by using either a flour with a high amylopectin content, for example waxy maize starch, or a chemically modified starch. Modified starch has the additional advantage of giving the sauce a very smooth consistency and a glossy appearance.
The packs should be frozen immediately after cooking and filling, since delay before freezing impairs quality. The temperature of the product should be reduced to - 18°C or lower, typically in an air blast freezer, in 80 minutes or less.
Products should be stored at - 18°C or below. For up to 2 months' storage, - 18°C is satisfactory, and it should be possible to arrange turnover of stock within this period. If a longer storage time is envisaged, the products should be held continuously at - 30°C. Cooked fish and shellfish keep rather better in cold storage than raw fish, particularly with regard to texture. Products made with fatty fish such as herring and mackerel can become rancid unless properly cold stored, and packed in a material that is a good barrier against oxygen. Recommended cold storage practice is described in Advisory Note 28.
Reheating of cook-freeze products, often referred to as conversion, means raising the temperature to serving temperature, that is 80°C in the centre of the pack, without prior thawing. Caterers can accomplish this by heating in special purpose forced draught convection ovens at 180°C for 25 minutes, or in microwave ovens for a very short time, usually about 2 1/2 minutes. Products for home use can be reheated in domestic ovens; times of up to 50 minutes may be necessary. These times are representative of general cook-freeze practice, but the correct time for a particular product should be determined by experiment and appropriate reheating instructions printed on the pack.
The recipes given here have been used successfully for making cook-freeze fish products. They are meant to serve only as examples; it is expected that processors will devise variations to suit their own requirements.
The quantities given are sufficient to make 12 packs, each containing 225 g offish, that is a serving for two people, plus sauce, in an aluminium foil tray 18 x 11 x 2-5 cm.
|
Sauce ingredients |
|||
|
|
g |
|
g |
|
strong red cheese, grated |
680 |
pepper |
1-0 |
|
modified starch |
140 |
mustard |
0-5 |
|
salt |
2·0 |
|
|
|
|
|
|
ml |
|
|
|
milk |
1650 |
|
|
g |
|
breadcrumbs |
320 |
|
grated cheese |
340 |
Blend the modified starch with the milk and bring the mixture to the boil. Blend in the seasoning, add the grated cheese and blend until smooth. Put pieces of cooked, drained fish in the trays and pour on measured quantities of the sauce. Sprinkle the surface of each pack with the au gratin topping, put on the lid and freeze. Reheat the packs in a convection oven. Remove the lids, grill the topping until crisp and brown, and garnish with tomato before serving.
|
Sauce ingredients |
|||
|
|
g |
|
ml |
|
onion |
1360 |
beef stock or protein hydrolysate |
1700 |
|
red peppers, chopped |
420 |
raisins, coconut, pineapple as required |
|
|
chutney |
185 |
|
|
|
modified starch |
85 |
|
|
|
curry powder |
70 |
|
|
|
cayenne pepper |
0·2 |
|
|
Slice the onions, add the red peppers, and fry them together until the onion is brown. Add the curry powder and starch, and cook the mixture over a low heat for 5 minutes; add the stock gradually and bring to the boil. Add the remaining ingredients and simmer for 45 minutes, stirring all the time to develop the full flavour. Put pieces of cooked, drained fish in the trays, add measured quantities of sauce, put on the lids and freeze. After reheating, serve with a red pepper garnish.
|
Sauce ingredients |
|||
|
|
g |
|
ml |
|
canned tomatoes (drained) |
1700 |
white or red wine |
340 |
|
onions |
900 |
garlic |
4 cloves |
|
parsley |
12 |
|
|
|
salt |
0·5 |
|
|
|
cayenne pepper |
0·5 |
|
|
|
pepper |
0·2 |
|
|
Slice the onions, add salt and garlic, and fry in oil until soft but not coloured. Add the tomatoes, wine, parsley and seasoning, and simmer for 15 minutes. Add 900 g peeled shrimp and simmer for 15 minutes to cook the shrimp and develop the flavour. Pour into foil trays, put on the lids and freeze. After reheating, garnish with parsley and serve with boiled rice.
|
Sauce ingredients |
|||
|
|
g |
|
g |
|
red peppers, chopped |
420 |
salt |
2·0 |
|
mustard |
230 |
pepper |
1·0 |
|
sugar |
175 |
|
ml |
|
modified starch |
140 |
milk |
2300 |
|
|
|
vinegar |
150 |
Blend the starch with the milk and bring to the boil, stirring continuously. Mix the vinegar, sugar, mustard and seasoning together and add to the sauce. Add the pieces of red pepper. Put pieces of cooked, drained fish in trays, add measured quantities of sauce, put on lids and freeze. After reheating, garnish with red pepper and parsley before serving.
Smoked fish kedgeree
|
Ingredients |
|||
|
|
g |
|
g |
|
smoked cod or haddock |
1300 |
salt |
0·5 |
|
patna long grain rice |
710 |
pepper |
0·2 |
|
butter |
453 |
cayenne pepper |
0·2 |
|
12 hardboiled eggs |
|||
Poach the fish in boiling water, remove the bones and flake the flesh. Cook the rice by sprinkling into fast boiling water and simmering until the grains swell and feel soft. Drain the rice. Melt the butter and add the fish, finely chopped egg and seasoning. Mix with the rice, and put portions into foil trays. Put on the lids and freeze. After reheating, garnish with hardboiled egg, tomato and parsley.
|
Ingredients |
||
|
|
g |
|
|
breadcrumbs |
800 |
6 oranges |
|
shelled walnuts |
225 |
36 lemon sole fillets (3 to a tray) |
Line the bottom of the foil trays with a layer of breadcrumbs about 5 mm deep. Grate the zest of the oranges and mix with the finely chopped orange flesh and the juice. Mix in the finely chopped walnuts, and add enough breadcrumbs to make a crumbly stuffing. Spread the stuffing on the side of the raw fillet from which the skin has been removed, and roll up the fillet. Put 3 fillets in each tray, put on the lids and freeze. The product is cooked by heating from the frozen state, and should be garnished with a slice of orange, parsley and walnut before serving.
|
Sauce |
Species |
|
butter |
cod, haddock, whiting, sole, plaice |
|
cheese |
cod, haddock, whiting, hake, scallops |
|
mushroom |
cod, haddock, whiting |
|
curry |
cod, haddock, whiting, shellfish |
|
mustard |
sole, plaice |
|
mustard and red pepper |
sole, plaice |
|
onion |
sole, plaice |
|
hollandaise |
sole, plaice |
|
tomato |
herring, mackerel |
|
cider |
herring, mackerel |
|
gooseberry |
mackerel |
