Piccalilli recipe problem

[shivvy]

I have used the below recipe to make piccalilli however in the second part where I heat the mustard micture with the vinegar, although it started off the expected bright yellow colour, it turned into a brown colour as it thickened. Have I done something wrong or do the shop-bought piccalillis have colouring in them to assist with the vibrant yellow colour?
Thanks

Piccalilli

Ingredients
700ml Malt vinegar
2 tbsp Coriander seeds
500g Cauliflower, broken into 3cm florets
2 Onions, peeled and chopped
3 tbsp English mustard powder
3 tbsp Plain flour
1 tbsp Turmeric
2 tsp Ground ginger
150ml Cider vinegar
100g French beans, trimmed and cut into 1cm slices
� Cucumber, quartered lengthways and cut into 1cm slices
2 Garlic cloves, peeled and sliced
200g Granulated sugar
Method
1. Place the malt vinegar and coriander seeds in a large preserving pan and bring to a boil. Add the cauliflower and onion and simmer for 5 minutes until slightly softened but still crunchy. Meanwhile, put the mustard, flour, turmeric and ginger in a small bowl and gradually whisk in the cider vinegar until smooth. Add the remaining vegetables, garlic and sugar to the pan and stir over the heat for 2�3 minutes until the sugar has dissolved. Drain over a large bowl to collect the vinegar.
2. Put the mustard mixture in the pan and bring to the boil. Gradually add the drained malt vinegar and simmer for 10 minutes, until thick enough to coat the back of the spoon. Add the drained vegetables and take off the heat. Spoon into sterilised jars � if they're not kilner jars, cover them with plastic discs and elastic bands rather than metal lids, which can sometimes react with the vinegar.

[guerrilla]

not encountered this problem before, but saying that major brands prob do use some colourings for that extra vibrancy. the recipe below is similar to the one i used to use in one of gary rhodes restaurants and works great. just make sure your tumeric is reasonably fresh and not stale, you can also use fresh tumeric root if you can find some!!!!

2 cauliflowers-in florets
1 kg onions-sliced
1 kg carrots-julienne
4 cucumbers-deseeded & sliced
2 bagsfrozen pearl onions thawed
2 litres white wine vinegar
1 litre malt vinegar
� litre water
750 g castor sugar
100 g mustard powder
50 g turmeric
6 tablespoons corn flour
200 g salt
2 red chillies-chopped
method salt the onions,cauliflower & carrots over night, in the morning wash well and dry
salt the cucumber for 10 mins then wash well and dry, mix all the vegetables together well.
boil the vinegars and water together with the chopped chilli then allow to cool for 30 minutes then strain into clean pan
mix the sugar,flour, turmeric, mustard powder & corn flour together and let down to a paste with a little of the vinegar mixture
bring the vinegar mixture back to the boil and whisk in the mustard mixture and cook until thick over gentle heat, when thick pour over the vegetables and allow to cool .