Archive for the 'science' Category

Fritter science, non-best-practice version

Tuesday, March 27th, 2012

I like to do my culinary science the right way. Standardisation, controls, a well-thought-out experimental design. This isn’t always possible to achieve on the fly, however, so tonight’s dinner should be considered as exploratory experimental work that will require rigorous follow-up. Fortunately fritters lend themselves to this kind of experimentation, as you can fry a couple, taste, modify the batter, fry another couple, modify again, and so on.

I felt like corn and zucchini fritters for dinner, and wanted to try making them with besan flour. I prepped the vegetables: corn, zucchini, scallions, coriander leaves and chili flakes. I then made up a batter based on this recipe: besan flour, plain flour, salt and water. Mixed the vegetables and the batter, fried the first batch of four, and split one with Ted for a taste test. Not bad! They were particularly good hot off the pan, crispy on the outside and light and toasty inside. I wondered, however, whether they might not be better with a little bit of feta crumbled in. So I added some feta to the mix, and cooked up another four. These were also good straight off the pan, though the feta was a little dominating in flavour. Still, the cheese was in there now, so we pressed on and cooked another four, leaving the rest on a plate underneath a tea-towel to stay warm until we were ready to sit down.

We were pretty peckish at this point, so while cooking we split another one of the first feta fritters once they had cooled down a bit, and actually the flavour was pretty good – more appealing than the no-feta version. Both the feta-free and feta-ful versions, however, were getting slightly lumpen as they cooled. There was enough mixture left for two more fritters, so I added about a quarter of a teaspoon of baking powder to this before frying them off. Ah ha! Now we see a difference – there were a few little bubbles rising to the surface as we cooked the first side, and the fritters were puffier and had straighter sides. Fresh off the pan, the first one of these that we shared was softer and lighter than the previous versions, and tasted great.

We sat down to eat a few more, with some salad and roast tomatoes. After about 5 minutes, when all of the fritters had had a chance to cool down a bit, we did a side-by-side tasting of the three versions. The first version (no feta, no baking powder) was ok, but quite dense. The second (feta, no baking powder) was noticably softer than the first version, and the feta added some more interest to the flavour. The third (feta, baking powder) was quite similar to the second, but still a little lighter.

So, the secret is feta and/or baking powder, right? Perhaps, but I am tormented by the confounding variables. The feta-free fritters were cooked earliest, so were the coldest, and maybe that’s why they seemed less good. What if I cooked the different batches for different times, so that the first set were actually just overcooked? What if the performance of the batter improves with sitting – some fritter recipes do call for a resting period before you start cooking. There’s no way to disentangle these factors! I need to make three batters in parallel, rest them the same amount of time, and then fry a fritter from each batter in the same pan at the same time, using the same amount of batter for each one. Only then will I know the truth. Until then, the recipe below is the one I currently hypothesise to be the best. Further testing required (and I will be happy to oblige – these were damn good fritters).


Corn, zucchini and besan flour fritters

2 medium zucchini, finely julienned on a mandoline
kernels cut from 2 cobs of corn
4 scallions, finely sliced
2 large handfuls of coriander leaves, chopped
2 large pinches of chili flakes, or to taste
150 g besan flour
3 tablespoons plain flour
1 heaped teaspoon baking powder
salt and pepper
170-200 ml water
80 g feta, crumbled
olive oil

Sprinkle the julienned zucchini well with salt, and leave to drain in a colander or sieve for 30 minutes. Squeeze out excess water, the spread out over a tea-towel, roll it up lengthwise, and twist to squeeze out all the remaining liquid. Put the zucchini into a bowl with the corn, scallions, coriander leaves and chili flakes, and mix.

In another bowl, sieve together the besan flour, plain flour, baking powder, salt and pepper. Stir in the water, to make a thick batter. Combine this with the vegetables and the feta. The mixture should be thick but not excessively stiff. Add a little extra water to thin if necessary.

Heat a little olive oil in a frypan over moderate heat. Spoon fritter-sized portions of batter into the pan, and flatten them out so they are about 1 cm thick. Allow them to cook until browning on the bottom, then flip and continue to cook until golden on the other side and cooked in the middle. Remove to a plate and keep warm.

Makes about 14 fritters (about 7-8 cm in diameter).

We ate the fritters with some roast cherry tomatoes  and some snow peas and pea shoots (all harvested from our garden! I was overly pessimistic about our chances of getting more ripe tomatoes on the weekend).


Quince science

Monday, June 13th, 2011

Cooking quinces is culinary magic. You start out with fruits that are yellow, hard and astringent. Three or four (or five) hours of gentle poaching later, they are fragrant, grainily soft, sweet and – most impressively – deep pink. Unless, that is, they have been cooked by me in the last year or so. I used to have the knack: see these beautiful specimens I cooked when I lived in the UK (and I made many similar-looking in Ireland, too, and I think I used to in Australia). But the last few times I’ve cooked them, they have refused to change colour, and after three or four hours of poaching I’ve been left with quinces the colour of bandaids. Not very appetizing! The liquid always goes at least a little pink, but not the jewel-pink it does when the fruit themselves also change colour.

Each time I’ve been confronted with beige quinces, I’ve scoured the internet looking for information on what could be going wrong. I haven’t found anything conclusive, but did see brief suggestions on a couple of cooking forums that absence of colour change could be due to one of two faults with the poaching liquid: (a) low sugar concentration, or (b) not adding lemon juice. Now, although I did make one beige batch with a lighter sugar syrup than usual, I’ve also had non-colour changing quinces when using the same sugar concentration that I’ve always used. So I thought it probably wasn’t the sugar. The lemon suggestion struck a chord, though.

When I was first cooking quinces, and for many years thereafter, I was a good, dutiful woman and followed Stephanie Alexander’s poached quince recipe to the dot. This included dropping the peeled and cored quinces into acidulated water (water with a good squeeze of lemon juice), before adding them to a light sugar syrup (1 part sugar to 2 parts water). A couple of years ago, though, I got uppity and started to think there was no point in the acidulated water, the stated purpose of which was to stop the quinces discolouring. What did I care if they discoloured a little? Once they turned dark pink you wouldn’t be able to see any discolouration, anyway. So I stopped doing that step, and began just tossing the quince quarters directly into the sugar syrup once I’d finished trimming them. Although I can’t pin it down precisely, in retrospect I do believe that it was around the same time I started doing this that my quinces stopped turning colour so successfully.

Last time I was faced with beige quinces, I found the lemon suggestion online, and, three hours into the cooking time, squeezed the juice of half a lemon into the poaching liquid. When I looked again, an hour later, the quinces were a lovely, reasonably deep pink. Ah ha!! But, being a scientist and generally sceptical, I wondered whether perhaps it was just the extra hour of cooking that had wrought the change, and the lemon had had nothing to do with it. So I decided to do….. Quince Science.

First, I obtained some experimental subjects.

Next, I thought about my experimental design. I wanted to test two hypotheses: (a) that low sugar concentration in the poaching liquid reduces quince colour change, and (b) that lack of lemon juice in the poaching liquid reduces quince colour change. I was also curious about whether sugar and lemon interacted somehow – for example, sugar and lemon might each boost colour a little bit, but both of them together would be required for full colour change. So I decided to set up four treatments:
– low sugar/no lemon
– low sugar/with lemon
– high sugar/no lemon
– high sugar/with lemon
This would let me separate out the effects of each of the variables, while also checking for an interaction.

I also thought about other sources of potential variation that might affect my results. The main ones I could think of were (a) random variation between quinces and (b) consistent variation between quince varieties. I could deal with the first fairly easily. Instead of cooking one quince in high sugar/no lemon, a second quince in high sugar/with lemon, etc, I decided to cut each quince into quarters, and cook each quarter in a different treatment. That way if one of my quinces was a weird one that would never change colour under any circumstances, I wouldn’t be misled into thinking that it was the treatment that was at fault for causing no colour change. The second source of variation was a bit more tricky. I know that there are about a dozen different quince varieties grown in Australia alone, and more overseas. But they’re never labelled, and I’m not sure which ones I’ve used for any particular batch of quinces. I know the last batch I cooked had waxy, fuzz-free skin and were and pear-shaped, while the ones I bought at the farmers’ market for this experiment were fuzzy, and two were pear-shaped and one more spherical. I wasn’t actually prepared to spend days driving all over Brisbane to source a wider variety of quince types for this experiment, so decided to just press ahead with what I had.

So I set up my laboratory. I usually poach quinces in the Le Creuset in the oven, but have occasionally done it on the stovetop. I don’t own four Le Creusets (or equivalents), unfortunately, so had to do this on the stove.

Here’s another potential confounding factor: different pot volumes and burner strengths. I tried to deal with this by making sure that all the treatments had ample liquid, and tweaking the burners throughout the experiment to make sure that all the pots were simmering very, very gently. And after all, I am not going to be publishing this in Nature.

The setup:
1. Rear left: high sugar/no lemon: A 1:2 sugar syrup, 2 cups sugar: 4 cups water.
2. Front left: low sugar/no lemon: A 1:4 sugar syrup, 2 cups sugar: 8 cups water.
3. Front right: high sugar/lemon: A 1:2 sugar syrup, 3 cups sugar: 6 cups water, plus the juice of half a lemon.
4. Rear right: low sugar/lemon: A 1:4 sugar syrup, 2 cups sugar: 8 cups water, plus the juice of half a lemon.

In go the quinces, to simmer gently for 3 hours.

After three hours, the differences were clear:

Fortunately this is science rather than art, so ugly flash photography is A-OK.

The bowls are in the same arrangement as the saucepans were on the stove. The two treatments with lemon are on the right, and are clearly a lot pinker than the treatments without lemon. There’s no obvious difference between the high and low sugar treatments with lemon. There’s a colour difference between the two non-lemon treatments, but I think that’s because the low-sugar treatment was on the front, wok burner, and so simmered a little harder than the back saucepan despite my trying to even them out.

Conclusion: Lemon is required for quinces to turn properly pink! Sugar concentration has no noticeable effect at the levels tested here.

I then went on to try a couple of further experiments.

First, I wanted to see whether I could get the lemon quinces to turn even darker pink, and whether this could be achieved simply by longer cooking, or if it required (or could be facilitated by) more lemon juice. I combined the two lemon treatments then split them back into two saucepans, to even out the different sugar levels, since I no longer believed this to be an interesting variable. I then added the juice of another half a lemon to one saucepan, left the other as it was, and simmered them both for a further hour.

There was no visible difference between the quinces with extra lemon and the ones without. Both sets, however, were noticeably darker and glossier after the extra hour of cooking. The syrup was also much thicker and darker. (I think the apparent glossiness of the fruits is just due to being coated in the beautifully cooked-down syrup.) You can’t really see an enormous amount of difference in the photos above, but trust me, there was a very clear change! I should have kept back some of the 3-hour quinces to use as a comparison in the photo, but I was too keen and rushed on without thinking my experimental design through, tch tch.

Finally, I wanted to confirm that a pot of beige-y quinces could be rescued at the last minute by the addition of lemon, for the benefit of anyone reading this after searching for answers to their quince troubles. So I combined then split the non-lemon quinces into two pans, added the juice of half a lemon to one of them, and simmered for a further hour. After that hour, the quinces cooked without lemon were pale pink (so at least no longer beige). But the quinces with the late-added lemon were utterly indistinguishable from the ones that had been cooked with lemon from the start. Both sets were equally dark pink and glossy. There was a difference, however, in flavour. The quinces that had been cooked with lemon from the start seemed to have a stronger flavour, that was more consistent all the way through. The ones that had had lemon added at the end were entirely fine, but less flavourful in the middle of each piece of fruit. I think the lemon may heighten flavour, and cooking with lemon for 4 hours rather than just 1 gives it a chance to penetrate all the way in.

Final conclusions: Long-cooking (at least 4 hours) contributes strongly to quince pinkness, as we all knew. For maximum colour change, add lemon juice during cooking. For the best flavour and earliest colour change, add the lemon at the start of cooking, rather than towards the end.

Future research directions: While waiting for these quinces to poach, I browsed the internet for more quince information, and came across this incredibly useful site from NSW DPI: Quince Growing. Table 1 lists 15 varieties of quinces grown in NSW, and includes information on what colour they are when cooked. This ranges from ‘yellowish’ to ‘deep pink’. I wonder whether some varieties really can’t be turned pink with cooking, even with lemon, or whether other varieties turn pink without lemon. Clearly an area that needs further research! I will just have to scour farmers’ markets for further specimens from a wider variety of cultivars. Maybe I can get ARC funding for it.


Happy Ada Lovelace Day

Wednesday, March 25th, 2009

Yes, I’ve managed to survive grant-writing season, hurrah!  (Now we just wait for 8 months to see if funding will be forthcoming.)  I should be getting back to cooking soon.

In the meantime, here is a diversion for you: some of my favourite posts from Ada Lovelace Day (yesterday, 24th of March).

Jean Bartik, ENIAC programmer

Valerie Aurora, Linux kernal programmer

Hedy Lamarr(!), co-inventor of spread spectrum frequency hopping

Mary Somerville and Agnes Clarke, interpreters and communicators of science

Enid Mumford, sociotechnologist

Addison Berry, Drupal developer and mobilizer

Jane McGonigal, game designer and futurist

Karen Spärk Jones, computational linguist

Ada Lovelace (1815-1852) wrote the first computer programs, for Charles Babbage’s analytical engine. And Ada Lovelace Day is an international day of blogging to celebrate women in technology. You can track down loads of other ALD posts via Technorati or the Ada Lovelace Day Collection – many of them are worth a read.