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From the Field

What’s with these New Meso-Thermo Blend Cultures for Cottage Cheese?

A trend has emerged in the cottage cheese making world to use a blend of cultures to make cottage cheese curd rather than to use just the traditional “all mesophilic” lactic acid producing cultures, Lactococcus lactis and Lactococcus cremoris strains. Why is that? The answer simply is because the meso-thermo blend is faster in producing lactic acid to lower the pH and more comparable to bulk starter time wise! And thermophilic strains appear to be more robust in fighting phage attack than mesophilic strains. Streptococcus strains will no doubt produce lactic acid faster than Lactococcus strains. The faster the lactic acid is produced, the shorter the time period that phage can attack and overtake the cottage cheese culture. Let’s do a quick review and compare set times and set temperatures.

Everyone knows that if you make an all mesophilic bulk starter made from L. lactis and L. cremoris and add 1.5 – 2% of this starter to your skim milk to be set at 88 – 92F° to make cottage cheese, you should be cutting that coagulum in 4 to 4.5 hours from the time the starter is added.

Adding a frozen all mesophilic DVI (direct to the vat inoculum) at the same set temperature of 88-92F° gives about a 6 to 6.5 hr. set. Remember those old frozen metal cans? It seems like they took forever to make cheese, right? Thus direct setting had no advantage over using bulk starter because the incubation time was significantly longer.

Though cultures are pelletized now, using an all meso pelletized culture will still have about a 5.5 to 6 hour set time when setting cottage cheese skim milk at 88-92F°. Using a blend of culture, a mesophilic-thermophilic blend offers several advantages. We call these our CHOOZIT® MCT cultures. First of all, the set temperature can be raised from 92F° to a set temperature of 96 – 100F° to favor the thermophilic cultures in the blend. They will produce acid at a faster rate than the mesophilic cultures do, especially at the elevated setting temperature. Now, set times are reduced using this pelletized blended culture to 5 to 5.5 hours, and in some cases 4 hour sets can be achieved! This makes the meso-thermo blend culture’s set times much closer to traditional bulk starter. No long sets anymore!

The second advantage of using a blended culture is that more moisture is trapped in the curd piece giving you a higher “dry curd weight”, when cooked to the same cookout temperature, (if your customers will accept that). Granted, everyone is used to a certain curd texture or firmness and using a blended culture may require you to cook your cottage cheese curd 6-10F° higher to get the same curd firmness depending upon if you use cooking acid or not. Since faster acid production is achieved with the thermo portion of the culture blend, whey pHs will be somewhat lower, causing a reduction in amount of cooking acid added than when using an all meso culture; usually ½ to ¼ the amount of cooking acid is necessary, and in most cases, no cooking acid at all is needed! A higher dry curd weight, even though the extra “weight” is trapped moisture, increases dry curd cottage cheese yields (usually by 0.75% to 1.5% of the dry curd weight). Combine that with equal amounts of dressing and now you are talking about 2-3% more finished cottage cheese going into the cup, which can add up to a lot of money over a year’s time. Take a plant that produces 10 million pounds of cottage cheese per year. That adds up to 75,000 lbs. more dry curd produced over the course of a year’s time, and 150,000 lbs. more finished cheese in the cup, assuming a 50%/50% dressing to curd ratio. Figuring a production cost of $.90/lb. for 1 lb. of finished cottage cheese, and now you are talking about an extra $135,000 worth of product that ends up being produced each year by your dairy company! That more or less pays for the cost of the MCT cultures and then some!

The third advantage is that faster acid production and shorter incubation times when using DVI cultures can also equate to better phage protection. Why? As you may know, phage attack is a race against incubation time. When phage comes to visit it is replicating inside the lactic acid producing bacterial cell nucleus replicating phage at a much faster rate than that cell’s binary fission cell replication can occur. Usually this occurs at a ratio of 200 phage produced to 1 bacterial cell reproduced. Time is on the side of the phage! The longer the incubation takes in the vat, the more of a chance the phage can overtake the lactic acid culture, kill it, and stop lactic acid production! The faster the cheese culture can produce lactic acid, the less time the phage has to overtake it. Let’s face it; even though the cheese starter culture is growing slowly, it has several tens of millions of cells of a head start against the phage. Besides with a blend, you have two bacterial culture strains producing lactic acid rather than just one (Lactococcus and Streptococcus strains). Be careful so that the thermophilic strain doesn’t get attacked by phage, because if we favor that strain with a higher set temperature, the mesophilic portion may not be robust enough to lower the pH by itself to the proper cut pH, and it may take a very long time!

So why not try some of the newer pelletized “blended meso-thermo cultures” in your plant today? If your plant has a tough time making an all meso cheese due to regular phage attack, then our CHOOZIT® MCT blended cultures are for you! We offer 9 strains from MCT 170, 171, 172, 176,177,178,180,182, and 184. You’ll probably be glad you did!

We also offer the traditional all meso pellets in the same numbered strains as above called our CHOOZIT® MC series with the same 9 strain numbers offered dropping the “1” designation as listed above, i.e. MC 70, MC 71, MC 72, etc.. Each bag of culture sets 1,000 gallons of cottage cheese skim milk, so typically for a 4,000 gallon vat of cottage cheese skim to be set, you would use 4 bags of either our MC or MCT culture (MC = mesophilic culture, MCT = mesophilic culture with the thermophilic culture added). We look forward to showing you what these cultures can do in your plant!

Branching Out in the Future!

DuPont has many cultures available to make all kinds of aged and fresh cheeses such as mozzarella, provolone, cheddar, parmesan, asiago, feta, Swiss, and Romano to name a few. While this newsletter and me in specific, concentrate on grade A applications, I will be performing technical service in the future in cheese plants also. During my stint as a sales representative for DuPont Nutrition & Health, I have had the pleasure and opportunity to work with many cheese manufacturers on the very cheeses mentioned above. In fact, I had cheddar, pasta filata, Swiss cheese and feta cheese plants in my sales territory when I had sales responsibilities for 7 years. So as my technical service “road show” goes out into the field, you may happen to see a familiar face show up in your cheese plant as well… to help demonstrate what our cultures and ingredients can do for you to make any particular cheese you would like. Call us first and take a look at what we have to offer.