These a some of my plump & happy kefir grains before going to swim, grow fatter, & reproduce in a new bath of milk. The biggest grains are 15-20mm in size, so will soon need separating in to smaller 5mm grains. The one on the spoon is about the volume of tiny 10g of grains that the rest have grown from to over 700g. I maintain 2-3 batches of 300-400g in rotation in & out of the fridge to prevent them fermenting too quickly. At an ambient temperature 50g of smaller grains, which have a greater surface area, would be enough to ferment 1l of organic whole milk. The softer inside of each grain is protected by a tougher outer layer. When the grains are split. the kefir changes in taste & consistency as different strains of bacteria, yeast & streptococci are exposed to their food source.
More links to follow: chriskresser.com/kefir-the-...
Chris Kresser has an excellent & free e-book on gut health for anyone signing up to his functional medicine email. Please see excerpt below. I've found this information & other free e-books to be a very useful healthy eating & nutrition resource.
I'll add to this as I come across more articles:
ncbi.nlm.nih.gov/pmc/articl... This paper includes photographs of some of the individual lactobacillus, yeast, & streptococci.
NB Water kefir is beneficial for anyone choosing a solely plant based diet, & those with dairy intolerance beyond lactose: