Mozz won't solidify (too much acid?)

[JoannaH]

I make cheese from raw milk from our goats.  I started making Mozzarella this year, using an "Instantella" recipe modified for goats by a friend, and seemed to be getting better over time. Until this fall when the milk yield went down and the cheese yield per quart went up. Recently I got 1.5 lbs of Mozz instead of the 1 lb I had been getting from 2 gallons of milk,and the Mozz was less stretchy and cohesive than usual.  I thought that might be because the ratio of citric acid to actual cheese was lower.  Then I made a 1.5-gal Mozz with the same amount of rennet(1t) and citric acid (2.5 t) I usually used for a 2-gal batch. The resulting cheese was basically good,highly stretchy and 'plasticy,' and not quite as inclined to hold its shape as some earlier Mozzes. I got just under 1 lb of that cheese. Today I made a 2-gal batch with 3 t of citric acid and 1.25 t of rennet. I got a super-stretchy 'cheese product" that was slightly sticky and wouldn't hold its shape—it stayed together but flowed out flat. I got 1.5 lb of 'cheese product."  I am guessing this is from too much citric acid. If so,I need to figure out how to gauge how much cheese I will get from my milk and how much acid to put in. Do any of you know what weight per gallon is assumed in most home cheesemaking recipes,and how much to adjust ingredients based on weight variation?

I realize there could be some other factor which I am overlooking. I am aware of two slight variations between this batch and the previous one: I added the citric acid when the milk was a little cooler (72 not mid-80s) and when I poured hot water over the recut curds at the end I used 175 F water instead of the 165ish water I used last time.  (The recipe says 170; I assumed there was some wiggle room.) I figure the earlier acid addition might have increased acidification.  I don't know how much difference the water temp should have made.

Below I'm listing the recipe I followed (with today's variations in parentheses.) If you have any thoughts about what might have gone wrong,I would greatly appreciate hearing that.

Cheese:
2 gallons milk
2 1/2 tsp. citric acid powder (used 3 today) dissolved in 1/4 c water
1/4 tsp lipase powder dissolved in 1/2 c water
1 tsp liquid rennet (used 1 1/4 t today)dissolved in 1/4 c water

Brine:1/3c canning salt dissolved in 10c water

Dissolve lipase for 1/2 hr (more like 45mins today)
Add citric acid and lipase solutions to milk as it starts heating (72 F today)
Heat milk to 88
Add rennet,stir 15 sec
Let sit 15 min (Today there was a clean break as usual; also,as often, the curd was a bit grainy; there were more tiny loose particles on top than usual)
Cut into 1/2"-5/8"curds
Rest 5 min
Heat to 108 over 15 min
Remove from heat, (I generally interpret this to mean,remove from double boiler), stir 20 min
Pour into colander, let sit 15 min
Cut into 1" strips,lay crosshatched in bowl
Pour 170 F brine over strips (was 175 today)
Pat cheese into ball, then pull out gently into long rope, return to water, reball and resqueeze; repeat for 10 mins (today I didn't have to squeeze it into a rope-it flowed into one of its own accord if I held it up)
Remove, knead to remove excess whey (Skipped this as by then it wouldn't hold shape)
Shape into ball, submerge in cold water til cool and solid

As I said, this usually works for me—but not today. Any advice greatly appreciated.

[River Bottom Farm]

Your problem is your milk has changed from summer when the animals are off pasture and the weather is cooler they drink less and their diet changes this results in more milk solids and more fats per gallon of milk. You need to figgure out how much rennet to use now that your milk has changed. I would leave the citric acid amount alone (or raise only slightly). I'm sure the last couple batches have had too much citric acid for sure by what you are describing.

Personally I would make a batch or two of fetta and use the floculation "spinning bowl test" (search for it on the forum if you don't  already  know  how  to  do it) to figgure out how much rennet you need to get a 15min floc. (I recommed fetta because the floc can be off quite a bit and you will still get nice fetta). Then use that much rennet (or a tiny bit less) for your mozza.

Good luck and keep at it. Mozza (especially quick mozza) is a tricky cheese to get right, and about the time you have it figgured out the milk will change again!

[JoannaH]

Thank you! It's very helpful to know that I should be increasing the rennet but not the citric acid. (Perhaps this should have been obvious,but it wasn't to me.)

[JoannaH]

Tried Mozz again today using only 2.5 t citric acid to 2 gal milk,otherwise following the same recipe. Curd handled somewhat differently from the previous batch--cut curds held their shape longer, and after draining in cheesecloth the curds were less dense. I poured the hot water on (166 F this time,as usual not poured directly onto the curd but against the side of the bowl) and at first the cheese seemed to be handling well.  But after I had squeezed it into a rope,returned it to the hot water and reballed it a few times--I think 4--the texture changed dramatically; pores visibly opened in the cheese and it began to absorb water and stopped holding its shape and staying adhesive.  I can't figure out what is happening.