The taste you are probably tasting my come from a couple of sources. The first is the milk sugar - Lactose- itself not being converted to lactic acid by the culture. This a real - it depends answer. When I finish a Camembert make and just before I salt them there is a definite sweet smell. Remember that alcohol is a byproduct of fermentation - this might be your ‘ester’ smell. The sweet smell lingers for a few days until the PC takes over. Again this has a lot to do with the pH (acid). Do you have a pH measuring device? This can be either a proper pH meter - which I highly recommend you get - or litmus paper for cheese making. Don’t use the litmus paper from pool chemical suppliers but, source some online that measures pH for 4 to 7.
The other source of a sweet smell might be coming at during the maturing process as the cultures are altering milk proteins (Casein) and producing different Peptides and these have a particular taste profiles.
This explains it way better than I can
https://www.cheesescience.org/cheeseflavorbasics.htmlThe casein breakdown takes a long time so I’m going to go out on a limb here and say that your culture hasn’t consumed enough lactose hence the pH of the curd is still too high and therefore sweet. I would do the following
Given that you mentioned frozen culture added days before you made the cheese I’m suspecting not enough culture left alive consume the lactose.
Did you mean “freeze dried” if so you just keep them in the freezer until needed. They are in a dried powder form and only need about 3 to 5 minutes to rehydrate. I do that in a little dish of the milk just before I add to to the main milk.
Check your cultures’ age - they don’t last forever.
Check your culture itself. Is it the correct type mesophilic or thermophilic.
Check your dosage rates for your amount of Milk.
Check your milk source - it might be pasteurised at way too high a temperature and don’t use longlife, ultra processed. You can use full cream milk powder but I have not tried it and your result will vary.
Check your age of the milk. If you have use by dates try for the freshest possible - I like 10 days before the use by date.
Check your pH at the start that will depend on the milk but around 6.7.
Let me know how you go next time. I’m posting a Camembert make today sometime and have a read of the others I have done to get an idea of the dependencies of milk, culture, time and temperature all play a part in the cheese making process.