I made some Cantonese style mooncakes with red bean paste a couple of days ago. The crust of Cantonese mooncakes is rather thin, like paper thin, and has a dough/filling ratios of 1 to 4. The deep color of the filing makes the wrapping process very tricky as any unevenness will simply show through. To make my life easier, I’ve changed the ratios to 1 to 3.
To enhance the red bean flavor, I’ve added maltose and red bean powder when I prepared my red bean paste. It tasted so much better than the filling I made for my snowskin mooncakes last year. Unlike lotus seed paste, red bean paste feels rather soft in texture. Therefore I recommend chilling the filling ahead of time before use. Adding toasted and chopped nuts into the filling would be a great idea as well. Just make sure to maintain the weight of the filling.
For the dough, I incorporated skim milk powder to add more flavor. In fact I have tested with both cake and all-purpose flour. I prefer all-purpose flour as it tends to produce a pattern that is much clearer. Perhaps this is due to the higher gluten content. I made my own golden syrup (recipe link will be provided below). Agave syrup and honey both worked equally well in my previous trials. Each yields a slightly different taste which is likely unnoticeable as the crust is so thin. There is another ingredient, namely kansui, which is used only in a minimal amount. I’m not sure if there is anyone like me who wonders if kansui can be skipped. I was so curious to find out why kansui is needed so I did an experiment last week on my sugar-free mooncakes. What I discovered was that it took a very long time for the mooncakes to brown without the presence of kansui. By the time my mooncakes finally turned golden brown, the mooncakes just got too hot in the oven and the filling bursted out of the crust! Kansui, according to online references, is a mixture of sodium carbonate and potassium carbonate. It raises the alkalinity (pH) by balancing out the acids in the golden syrup. It also serves to soften and puff up the crust of mooncakes (from Baidu). With a raised alkalinity (pH), Maillard reaction will be promoted, resulting in faster browning. Baking soda (which is sodium bicarbonate) does the trick too, but it has a weaker pH so is a lot less powerful than kansui. I didn’t buy any kansui last year as unlike baking supply stores in Hong Kong, kansui is sold in big bottle at Asian grocery stores here in Toronto and the smallest bottle I could get is 500ml. So I followed Harold McGee’s method to make a substitute by making baked baking soda. Simply by baking, baking soda would be transformed into sodium carbonate that is more potent. I was very satisfied with the result and will include some pictures at the end of this blog post.
月餅皮方面，EC在麵粉中加添了脫脂奶粉，而低筋及中筋麵粉EC也試過了，個人經驗是中筋麵粉比較能做出漂亮的花紋，應該是筋度較高的緣故吧！金黃糖漿是自己煮的，EC試過改用龍舌蘭蜜和蜜糖，效果差不多，只是月餅的味道有少許不同(其實餅皮那麼薄是很難察覺的)。至於另一種材料一梘水，或許大家會問，梘水份量那麼少，不加可以麼？愛研究及求真的EC又怎會沒想過這個問題呢？上星期製作無糖月餅時EC便做了實驗，結果發現沒加梘水的月餅要焗很久才上色，當焗至上色時月餅早已因為中心溫度過高而過度膨脹，以致餅皮爆裂了！翻查資料，梘水是以碳酸鉀和碳酸鈉為主要成份的鹼性混合物，作用包括中和糖漿的酸性、令餅皮軟化和鬆軟等(有關更多梘水資料可參考百度百科)。梘水也可增强餅皮的pH值，從而促進梅納反應(Maillard reaction)的發生，令月餅更金黃。除了梘水，梳打粉也有類似功效，可是梳打粉的鹼度沒梘水般强，去年EC沒有購買梘水(加拿大的梘水是不能像香港烘焙店般少量購買的，最少的份量也要500毫升！)，所以便依Harold McGee的方法將梳打粉烘乾做成鹼性更高的碳酸鉀(sodium carbonate)，效果真的十分不錯！EC在網誌末段也會附上照片給大家看看。
Red Bean Mooncakes
Makes 10 mini mooncakes (50 g each)
For the Dough
68 g all purpose flour, plus extra for dusting
4 g skim milk powder
40 g golden syrup (see homemade golden syrup recipe here)
18 g grapeseed oil
1/4 tsp kansui
For the Filling
370 g sweet red bean paste (see recipe here)
For the Egg Wash
1 large egg yolk
1/2 large egg white
For the Dough 月餅皮
In a large bowl combine golden syrup, grapeseed oil and kansui. Stir with a spatula until incorporated (the mixture may emulsify if homemade golden syrup is used). Sift in the flour and milk powder then stir gently to form a dough. Shape dough into a log then wrap with plastic wrap. Let rest in the fridge for an hour.
For the Filling 餡料
Divide red bean paste into 10 equal portions (37 g each). Shape each into a ball and chill thoroughly before use.
For the Egg Wash 蛋黃液
In a small bowl whisk together the egg white and yolk until combined. Strain then set aside.
For Shaping 造型
Divide dough into 10 equal portions (13 g each). Shape each into a ball then set aside.
Take a portion of dough and roll it out into a disc between two pieces of plastic wrap. The dough should be slightly thinner around the edges. Remove plastic wraps and place a red bean paste ball in the middle. Wrap then seal edges by pinching them together. I held the dough with one hand and used my purlicue (the space between my thumb and my forefinger) of the other hand to seal the edges while turning the dough slightly. Shape the stuffed dough into a ball again. Poke air pocket, if any, with a toothpick. Coat slightly with flour. Repeat with remaining portions.
Brush a thin layer of flour on the inside of a 50-g mooncake mold to prevent sticking then tap off excess. Insert dough into the mold, seam side out. Flatten the dough slightly to fill up the mold. Place mold upright onto a parchment paper lined baking tray then press down firmly onto the plunger for 5 seconds to make an imprint. Press the plunger down again to release the mooncake. Repeat with the rest of the dough. Chill shaped mooncakes for 15 minutes. In the meantime, preheat oven to 400℉/200℃.
Spray mooncakes with water to prevent the surface from cracking. Bake for 8 minutes to set the crust. Remove and let cool for 10 minutes. With a small pastry brush, brush tops with a thin layer of egg wash. Let dry for 10 minutes then brush on a second coat of egg wash. Continue baking at 350℉/175℃ for another 10 to 12 minutes or until the mooncakes are golden brown. Cool completely on a cooling rack.
Store mooncakes in an air-tight container for two to three days so the oil can seep through the skin of the mooncakes. When the skin becomes soft and shiny the mooncakes are ready to be served.
The dough of these red bean mooncakes I made last year was made with agave syrup and baked baking soda. The dough made up 30% of the weight of the mooncake.