@Madhoo ji,
GOLDEN SUNRISE healthy blessings for your tip.
You can take these serum energies by directly requesting VK as you do, when there is no possible to charge food at other's house.
Every serum should be charge one by one only not in a single request when charging water, food and other items.
YOU CAN ALSO USE THIS METHOD;
In this method you don't need to remove VK from hand and also no need to rotate VK.
You can charge food and water by wearing VK in your hand just say serum name 3 times and put your hand (wearing VK) over food/water for 1 minute upto 1ltr or follow your inner guidance.
You can charge serums/energies like this one by one.