Dr. Rudy Schlaf's Group_____________________________________________________

                                       Department of Electrical Engineering - University of South Florida


Last Modified Aug 2013
(c) Rudy Schlaf


How to Make Quark (A Biology Experiment):

Quark is a dish rarely found outside Germany. Quark is essentially curdled and strained sour milk.  Dr. Schlaf tends to need quark when he misses his Vaterland (watching old Schimanski shows sometimes is just not enough...).

Quark is fairly easy to make. All one needs is a standard yogurt maker, a standard in-cable light dimmer (for throtteling the yogurt maker-sour milk cultures like a lower temperature than those used for yogurt), rennet (for curdling the milk), and special sour milk cultures (for making the milk sour in a pleasantly tasting way). The figures on the right show the products Dr. Schlaf uses for his quark production. The salton yogurt maker is nice, since it takes standard quart yogurt containers from the grocery store, but any other brand will also do the job. Malaka brand rennet is a vegetable enzyme, i.e. the resulting quark is acceptable to vegetarians. It is available in many helath food stores. You can of course also use an animal based rennet, which many good grocery stores carry. The ProBiDa sour milk cultures were ordered in Germany from www.nature.de. They ship to the US. One needs only a very small amount of the cultures (a few tiny crumbs suffice), i.e. do not buy too much (seems one of their 6 g packages may last for about 100 quarts of milk), otherwise you will have a lifetime supply.

Once the above equipment and ingredients have been obtained, the actual quark process is quite simple:

1) Adjust the dimmer to ~65-70V (most dimmers require the load to be plugged in for an accurate voltage measurement) and plug in the yogurtmaker. Its light should be lower in intensity than w/o the dimmer.

2) Bring a quart of milk to a boil. This works great in the microwave-use a glass container to avoid leaching of chemicals from plastics into your milk. Closely watch the milk the first time you do it and measure the time it takes to start boiling. Then use this time setting in the future-this will reliably prevent the milk from spilling into your microwave. After the milk has briefly boiled let it cool down to room temperature. The boiling process sterilizes the milk, i.e. creates a clean slate for the sour milk cultures. Once at room temperature, fill the milk into a container that fits into yogurt maker.

3) Add a few drops of rennet and a tiny amount of ProBiDa cultures. A few crumbs are enough. No need to mix or shake. Close container lid.

4) Put container into yogurt maker and close the yogurt maker. Let it run for 12-24 hours (the process is more or less self terminating, i.e. not much happens once the milk is sour and curdled)

5) After incubation, take out the container and strain contents through a kitchen towel (washed with a fragrance free detergent-otherwise your quark might taste like detergent...) until a creamy mass, the quark, remains in the towel. The whey below the towel can be used for baking or just drinking-the protein in it is considered among the best protein sources since it is "universal", i.e. contains all amino acids.

6) Put quark into the fridge until cool, then enjoy plain or with added chives+parsley/salt, or with jam or sugar. Quark can easily stay for several days in the fridge before consumption. If more creamy quark is desired, some of the whey (or cream) can be blended in.

Fig.1: Yogurt Maker used for quark

Fig.2 Rennet-for curdling the milk

Fig.3: Sour milk cultures "ProBiDa" from www.nature.de (they ship worldwide)