(a.k.a. Refractometers) The Baumé hydrom-eter is used to measure the density of sugar in a liquid, and the Brix hydrometer (refractometer) is used to measure the percentage of sugar in a liquid. This liquid should ideally be at 20°C / 68°F; higher temperatures will not produce an accurate reading since the hydrometers are sensitive to temperature. They are used for wine making, beer making, and for syrups used to make sorbet bases. Hydrometers are an inexpen-sive substitute for a refractomer, but are not as accurate or clear to read.
The Baumé hydrometer must be carefully placed in the liquid to be measured, since agita-tion will produce bubbles in its interior that will not give a correct reading. Hydrometers contain a graduated scale and mercury and work similar-ly to a thermometer, in which the mercury rises and drops depending on the liquid’s density.
They measure from 0° to 50° degrees Baumé, notated variously as: degrees Baume, degrees Baumé, B°, Be°, Bé°, and Baume, where 0 has no density and 50 has the highest possible density.
A refractometer is used to measure refraction.
In other words, it can measure the density of a particular liquid by how the light refracts through it. When a straw is placed into a glass of water, the straw appears bent. If the same straw is placed
into a glass of water containing dissolved sugar, the straw appears even more bent because sugar
“thickens” water (it makes it denser) and therefore has a magnifying effect. This is known as the prin-ciple of light refraction. Refractometers measure this refraction of light and are based on the princi-ple that as the density of a substance increases, its refractive index (how much the straw appears to be bent) rises proportionately. If the liquid is thin, the angle of refraction is large. If the liquid is thick, the angle of refraction is small. The refractometer measures in the Brix (0° up to 32°) scale.
There are many different kinds of refrac-tometers, ranging from economical to very ex-pensive, and each one has a particular use and range. For frozen dessert purposes we will use only the refractometer for sorbets and granités, which is to say, it measures from 0° up to 32°
Brix. Any sorbet base higher than 32° Brix will be too sweet. On the other hand, refractometers can also be used for candy making, where Brix measurements tend to be higher, so it is a good idea to have a refractometer that can read up to 90° Brix, and will therefore have more than one use in the pastry kitchen. (For availability, see the resources list on page 425.)
Brix is more straightforward than Baumé.
Each degree Brix is equivalent to 1 percent of sugar in a liquid, so if the hydrometer measures 16 degrees, it means that the liquid contains 16 percent sugar. Baumé degrees are based on
Baumé hydrometer Brix hydrometer (refractometer)
the specifi c gravity of a substance, where each degree Baumé represents approximately 1.75 percent sugar in the liquid.
There is no accurate formula for conversion between the two measures, since Baumé is a unit of relative density and Brix is a unit of pro-portion. However, you may fi nd recipes that call for a Baumé measure and you might only have a refractometer, or vice versa. You can use the following formula to get fairly good conversion approximation:
Brix degrees / 1.8 = Baumé degrees or
Baumé degrees × 1.8 = Brix degrees
EXAMPLE: 22° Brix / 1.8 = 12.22.
The true value of 22° Brix is 12.2° Baumé.
The result will be slightly off by fractions of the correct amount, which won’t be as detri-mental for sorbet or granité production but can have a devastating effect in wine or beer making.
Most sorbets range from 30° to 32° Brix (16.6° to 17.7° Baumé). Granités range from 16° to 19° Brix (8.8° to 10.5° Baumé). These measures apply only to nondairy frozen desserts. Dairy contains proteins that throw off Brix and Baumé mea-sures, simply by the effect they have on liquids.
STRAINERS
An 18/10 stainless steel re-inforced fi ne-mesh strainer or bouillon strainer with a fi ne mesh will produce the best results.The strained liquid will have no undesired large solids left in it, making it an evenly smooth (or clear, depending on what is being strained) prod-uct. A conical strainer (see photo) will be more effi cient than round fi ne-mesh strainers, since gravity forces the liquid to the base of the cone, which makes it easier for it to pass through the fi ne mesh.
Medium-mesh or perforated strainers will not give the same results, since they will let larger solids through. These strainers are better suited for sifting dry ingredients, such as fl our.
ICE BATHS
When a frozen dessert base requires heat for it to be made (a.k.a. heat transfer), it is necessary to cool it down to a temperaturethat is considered food safe (below 5°C / 41°F) before freezing. Dairy-based products will be more sensitive to bacteria growth than those without, because bacteria love protein. The quicker a dairy-based mix is cooled down, the better, because this will reduce the propagation of bacteria. All heated liquids need to be cooled before storing and before churning or freezing.
It is not a good idea to pour a hot liquid into a batch freezer to cool it down, because this will overwork the machine and, while this will not have immediate consequences, the machine will quickly deteriorate.
A granité base, which is mostly protein-free but might have been heated in order to infuse a liquid, should not be placed directly in the freezer to begin its crystallization. The steam it gives off will result in condensation that will harden inside the freezer. Its heat will also raise the interior temperature of the freezer, which will overwork the compressor and raise the tempera-ture of other items in the freezer.
The equipment used to cool down the base depends on the amount made, but the principle is the same regardless. The liquid is poured into a container (preferably thin stainless steel) large enough to have the most amount of exposed surface possible without going to extremes
(such as using a sheet pan, which has the most exposed surface area, but the liquid inside it will easily spill with any movement). The more the liquid is spread out, the more room the heat has to escape. This container is then placed in an ice bath. The ice bath should be part of the mise en place that has to be done before any cooking oc-curs, so that when the mix is ready to come out of the pot, it has a place to go so that the cook-ing process is stopped immediately and bacteria growth is prevented.
Ice alone will not get the job done. A proper ice bath should have equal amounts of ice and water. If there is too much water, the ice will melt quickly, and if there is too much ice, the product will take longer to cool down, since the container won’t be surrounded completely by chilled water.
Think of how much surface an ice cube has. This minuscule surface will be in contact with the hot container’s surface. Logic would dictate that the ice would melt, but the process isn’t as quick as you’d think. By the time the ice melts enough to
become chilled water, a considerable amount of time will have gone by. The ice bath should be big enough to fi t the container with the hot liquid and have room left around its border. Care must be taken when deciding the amount of ice and water.
It is best when the ice and water mix come up to the same level as the liquid inside the container.
When the level of ice and water is lower, there is an amount of hot liquid that is not being cooled down. It is also important to make sure that the ice and water mix does not come in direct contact with the hot liquid, for no other reason than it will become diluted and affect the fi nal result. For very large amounts of base, it is recommended to have more than one ice bath ready. Smaller amounts cool down faster than large ones.
It isn’t enough to leave the hot liquid in the water bath to cool down. Constant whisking or stirring will distribute the cooler liquid that is closer to the stainless steel pan surface (because its exterior is in direct contact with the ice water) throughout the rest of the hot liquid.
This section refers to machines used to freeze all varieties of machine-churned frozen desserts for small-batch production. These include ice cream, gelato, sherbet, and sorbet. Small-batch production should not be confused with what one would make at home for personal consump-tion, either in the amount produced or the ma-chines used. Home ice cream mama-chines are not recommended for restaurant or hotel production because they are slow and inconvenient and of-ten yield poor results.
The amount that is needed in a 50-seat restaurant will be different than that needed in a 300-seat restaurant or a hotel, but both cases are still considered small-batch production if a batch freezer is used and the human element plays a big part in its production. If a 5000-room hotel in Las Vegas makes its own ice cream, is it still small-batch production? It can be. In small-batch production, there is an actual per-son involved in most of the process (weighing
machine, storing the frozen product, and cleaning the machine). There are batch freezers that can churn up to 41 liters (11 gallons approximately) per batch, and 190 liters (50 gallons) per hour. It all comes down to the type of machine used.
There are many brands of machines, but we will focus on the two types of machines available for small-batch production. Each type operates in its own distinct way.
PACOJET
Pacojet machines work by pour-ing the ice cream, sorbet, sherbet, or gelato base into special beakers that are placed in a freezer set to −20°C / −4°F for 24 hours. The time is considerably reduced if using a blast freezer that can drop to −38°C / −36°F. Once the product is completely frozen, the beaker is then attached to the Pacojet, which is fi tted with a spiral blade that literally “shaves” the frozen base into very thin sheets about 2 microns thick at a speed of 2000 rpm. When the beaker is attached and theMachines
into the frozen base and then come back up.
Each portion or scoop takes around 20 seconds to make. An entire beaker takes 4 minutes to process. It can be programmed to produce however many portions are needed at a time, up to 12 per beaker. The fi nal temperature of the frozen base is −12°C / 10°F to −15°C / 5°F. At this point it is reserved, frozen, for service. The company makes only one type of machine, but there are a total of four variations on it. All four machines are the same; the only difference is the kind of voltage required to use them. A machine that works in the United States will not work in Europe, and vice versa.
According to the president of Pacojet AG, the motor, though rated at 1,000-watt power, has the capacity to output over 1600 watts, after which it cuts out. This is what enables the Paco-jet to pacotize virtually anything that is deep-fro-zen, at a constant rpm and downward penetra-tion speed, regardless of hardness. The primary reason for the quality in consistency and texture is a combination of constant rpm, constant shaft progression, and blade geometry. If one of the three were out of synch or faulty, the end result would be compromised.
PROS
•
• Cuts the churning time to a fraction of what a regular machine takes to freeze a quart of prod-uct (20 seconds for one portion, 4 minutes for a whole beaker). Keep in mind, however, that this machine doesn’t “churn,” it “shaves.”
•
• Finished item has a very smooth consistency, is easy to scoop, and has an excellent texture and mouth feel.
•
• Because of the way it shaves the frozen product, it is not necessary to use any kind of stabilizer or emulsifi er to obtain a smoother, more freezer-resistant product. In other words, its ice crystals remain small and are not prone to increase in size. This will have a direct effect on maintaining a consistent texture for hours at a time.
•
• The amount of sugar in a sorbet can be sig-nifi cantly reduced and the result will still be smooth. In other machines, if there is not enough sugar in a sorbet base it will be icy, and if there is too much sugar it will be too soft. It is possible to use the same amount of sugar and still obtain positive results. This machine is ideal for savory ice creams and sor-bets, because sugar content will not determine the size of the ice crystals; only the machine’s thorough blending will determine that.
•
• It is reasonably priced compared to other small-batch ice cream machines.
•
• The beakers can be fi lled and kept frozen for long periods of time, and processed when needed.
•
• You decide how many portions to “shave” by pressing a button. You can process one portion or up to the entire beaker.
•
• It takes up very little space. Its dimensions are 20 cm / 8 inches wide by 36 cm / 15 inches deep by 50 cm / 20 inches tall, and it weighs only 14 kg / 30 lb.
•
• The cleaning process is just as fast as the paco-tizing process.
•
• It is not used exclusively for frozen desserts. It can also be used for pâtés, terrines, mousses, and for grinding spices, nuts, etc., through its blending action.
The blade and beaker of a Pacoject
CONS
•
• If the machine should break down, there aren’t many technicians who repair Pacojets.
If the machine has to be sent away for repair, it often requires at least a month to get back.
For this reason it is a good idea to have a second Pacojet as backup. One of the main reasons a machine will need repair is because of improper handling and misuse. It needs to be cleaned properly on a consistent basis.
The “drill” needs to be thoroughly cleaned at least once a day for sanitary purposes, as well as to prevent any product from accumulating on it that will prevent it from drilling properly through the rock-hard product.
•
• Should there be any product that has already been shaved left in the beaker, it can be frozen to −20°C / −4°F to shave again, but the fi nal result is not very good. The second shaving incorporates too much air into the product, which makes it hard to scoop, and in turn makes the scoops not look very good. The orig-inal optimal consistency is not there anymore.
•
• There are many small components that tend to get lost very easily.
•
• The spiral blade needs to be sharpened at least once a year.
•
• The Pacojet does not pasteurize the base, which is a key step in frozen dessert produc-tion. For products that will be pacotized, pas-teurization should take place during the cook-ing process.
•
• It is mostly convenient for small restaurants and hotels because of the quantities that can be made at one time. I would discourage the use of a Pacojet for operations with more than 120 seats because the amount of beakers that have to be frozen and pacotized ahead of time would take up too much freezer space. In many estab-lishments, space is a luxury.
In this book, all ice creams, sorbets, and sherbets that do not contain any stabilizers and/or emulsifi ers, as well as all savory items, will be processed using a Pacojet machine. They can also be churned in a batch freezer, but the
Pacojet will produce frozen desserts with better texture and mouth feel. Although gelatos can be put through the Pacojet, it is better to churn them in a batch ice cream maker, in which it is easier to control the amount of air that is incor-porated into the product (see gelato on page 53 and overrun on page 63).