When a large frost covered bag falls out of your freezer as you open it, covered in very pretty but very large ice crystals, it is telling you something.
Do I need to defrost? Stalactites of ice descend from the roof inside my non-frost free freezer. Perhaps my door seal was not working properly, so immediate remedial action is needed to defeat the fearsome ice monster there.
As a food scientist rationally first you take out all the contents of typically frozen meat and vegetables and whatever lurks in those un-labelled packets. If there is no handy empty fridge available then put the items into a large container where they should be safe wrapped in towels for a few hours. As all the boxes and packages are together then they do not normally defrost.
Then large trays of hot water should be put in the freezer to start thawing it. These should be regularly emptied and topped up with more hot water. But sometimes the process is slow and raises fears that the food might be starting to defrost and coming to harm.
Now I have a lovely clean freezer, put back on to refreeze and a stack of food that I am wondering if I have to cook, chuck or re-freeze.
In fact, from a scientific point of view, would food come to harm by re-freezing it? More importantly, are there food safety issues?
My friends over at the Naked Scientists discussed this. As food freezes – whether it is meat, fish or vegetables, the freezing process may rupture the cell walls if it is not quick-frozen. Defrosting may allow some of the liquid from these cells to seep out and refreezing will encourage more crystal growth and potentially a poorer taste and texture when defrosted again after re-freezing.
The Conversation also considers the topic. This is a website where journalists and academics work together presenting clearly about news and topical issues. If the frozen food goes into a fridge, it will only very slowly defrost. Therefore, as long as the fridge with its extra load of food is running at 5°C or below, then no microbiological harm occurs. From a food safety point of view, you can safely re-freeze partially defrosted meat, chicken, or any frozen food as long as the fridge is at the correct temperature.
I then looked at my own stack of frozen and semi frozen food . The following less risky vegetables, fruit and assorted bits were somewhat defrosted and already not so cold :
- One small bag of home grown broad beans
- One large bag of home grown green beans
- One bag of oven baked sliced aubergines
- One small bag of chopped possibly nuts and something else – note to self – do label the bags – now tasted and is hazelnuts
- One bag of egg whites
- One bag with a stick of lemon grass and half a red chilli
- One box of wild miniature blueberries from Poland gone slightly mushy.
- Now the more risky meat and fish:
- A goose leg left over from Christmas
- A rabbit jointed up, a smaller rabbit jointed up
- A small pheasant
- Two muntjac steaks
- Four quails
- Three salmon steaks
- Two rather unidentifiable pieces of white fish, lovingly frozen together in a fishy hug – cod or haddock possibly.
Fortunately all the meat and fish above still had ice on it, so following the advice about refreezing all have been properly labelled stating that they had been partially defrosted, plus the date and put back in the freezer.
However, some items had no ice on them and just felt cold, so rather than suffer loss of texture and possible risk I cooked the following:
- Three chicken breasts
- Three unidentifiable fillets of flat white fish
I could not bear to throw away the blueberries so cooked them gently and refroze them for use later. Half of the egg whites were mixed with the chopped hazelnuts and lemon grass to coat the fish pieces. The rest of the egg whites were mixed with finely shredded chili for the chicken pieces. I then briefly oven baked both of these for re-freezing once cool for future use. The green beans and baked aubergine slices went into a rather creative moussaka.
I now know that I am a freezer hoarder and hate to throw things away. As a foodie I suppose it is not surprising to have such a very strange assortment of food given by friends, grown by ourselves or bartered in some way for pints of beer – hence all the game and rabbits.
So at least the cooking the freezer did not turn out quite as badly as expected….