Kimchi

No you don’t need pear or apple. The amount of time it takes depends on things like the temp of your room (the cooler the room the longer it takes) and the recipe. In my experience sugars like apple or pear and starches like rice flour (which convert to sugar) in porridge will speed fermentation because if feeds the bacteria. But it’s not necessary. It can take 1 to 5 days. Look for bubbles. And taste it occasionally, like daily, to see if it’s getting sour. When it tastes like you want it to taste it’s ready for the refrigerator.

The only added sugar in mine is what occurs naturally in the onions and carrots. At 70F-75F its ready for the fridge in no more than 3 days. Without a amylase enzyme starches wont convert to sugar.

I make kimchi all the time without any porridge and have not had a batch fail yet. After 2-3 days at room temp and 2 weeks in the fridge they are plenty sour. Never needed any added to sauerkraut either. Ive been making it for over 20 years.

Amylase is naturally found in all vegetables (and fruits too for that matter) so don’t worry about that. The starch will convert to sugar and feed the bacteria. I only had one batch that took 5 days (radish kimchi) and it was in winter and the house was cooler than usual. Usually takes no more than 3 days.