Ginger Milk Pudding [薑汁撞奶]

A friend of mine asked me a couple of days ago if I can try to make ginger milk pudding. Since i had some milk and a ginger in my fridge anyway, and thought it shouldn't be hard to make, why not? I mean there're only 2 main ingredients, right? ginger and milk! However, to my surprise, it wasn't as easy as I thought. I failed! I tried a few times. Boiled the milk, grated the ginger to get the juice. Poured the milk to the juice, but it didn't curdle as it's supposed to be. I ended up getting ginger milk drink instead of ginger milk pudding. Being as curious as curious George, I put it into an investigation. Checked a few websites and read some articles, bought several kinds of milk, and tried and tried... Finally, there you go. I made it! The texture of the ginger milk pudding is very smooth and I enjoy the taste of the ginger hot (辣)  in it, especially we're officially in a cool fall season here.

The texture is somewhat like steamed egg custard with lots of water. It melts in your mouth before you even try to swallow it.

Actually, the process of milk curdling is quite intriguing. Since I've spent quite some time to do the investigation, I would like to share with you in case you're interested as well. (anytime you are falling asleep in the following story, skip to the recipe :P)
First of all, I want to say the creation is amazing. Do you know why milk curdles? It has to because as we know, all mammals drink milk at their young ages. Milk curdling or coagulation plays an important role in them. If milk is not coagulated, it would rapidly flow through the stomach and miss the opportunity for initial digestion of its protein. Thus, in their stomach, they have certain enzymes to do this job. This is also the principle of cheese making. In our case, ginger milk pudding, is the same too. Gingers contain protease, which is the enzyme that coagulates the milk. Also, knowing that the environment in stomach is acidic, which means acidity favors the milk coagulation.
OK, hope this brief explanation may help you understand a little bit more of our food :) most of the time, I enjoy the process of understanding what I am eating than eating itself :P

Ingredients:
Whole fat milk (preferably organic)
1 Tbsp ginger juice
2 tsp sugar (according to your taste)

1. Grate the ginger and extract the juice. I would filter out the impurity with a small sieve.
2. Boil milk in medium heat, add sugar. When the temperature reaches around 67°C, remove from heat immediately and pour into the ginger juice. Remember to stir the ginger juice before pouring the milk to make sure the 'starch' in the ginger juice, which precipitates at the bottom, is mixed thoroughly.
3. Wait for about 10min for the milk to curdle.

Note:

1. Temperature also plays an important role in this process. This chemical reaction is favored in certain temperature. I tried 60+F and 70+F, and noticed the milk curdling did better around 67F. The old method usually tells people to heat the milk when steam starts to appear, then, pour the milk between 2 pots back and forth for a few times (6 times?) in order to achieve this temperature. However, I like to use my cooking thermometer, which makes cooking process like a breeze. No guessing! I use my thermometer for many other recipes, such roast pork and turkey (I always get the most juicy turkey breasts for my guests). my cooking thermometeris about $15, which I believe is a good investment :)
2. I tried several kinds of milk, lactose free, 2% fat, 1% fat, whole fat, organic and non-organic.  For an unknown reason as of now, the whole fat organic milk turns out curdling the best, and it tastes the best too :)
3. Old gingers contain more protease. Young gingers usually produce in summer, and the gingers get 'older and older' as the season approaches to late winter.
4. Adding about 1/4 tsp of vinegar enhances milk coagulation and it shouldn't affect the taste. I tried and it worked. However, later when I used whole fat organic milk, it coagulated pretty well even  without vinegar.
5. I am glad I've learned an interesting chemistry lesson from making this wonderful dessert. Hope you will have fun too ^_^

Here is the ginger juice. 1Tbsp should be enough for 1 cup of milk

I like my cooking thermometer which can tell the exact temperature I want.

I didn't pour the milk from a higher point in order to shove the milk into the ginger juice like some of the people stated in their recipes. Knowing that this process is only trying to mix the milk ginger and milk well, I poured the milk as shown above with a rapid movement and the pudding turned out ok.

These are some of the milk I've tried. The one in the middle, Naturally Preferred Organic Whole Milk, which I got from Ralph's, made the ginger milk pudding most successfully.