How to make old yogurt at home?

Original yogurt 200g

Whole milk 1L

Whole milk powder125g

30 grams of sugar

How to package the old yogurt at home?

Mix the milk powder and sugar evenly.

Pour in fresh milk heated to 40 degrees and stir well.

Add the original yogurt and stir well.

In a sealed bottle.

Put the sealed bottle into a thermos bottle with 45 degrees water, and the water level is less than four fifths of the height of the bottle.

Keep the temperature about 10 hour, take it out and put it in the refrigerator for 24 hours before eating.