Steeping to hit the numbers

Steeping to hit the numbers

Picture the toji presiding with a stopwatch over kurabito as they steep rice for a batch of daiginjo; pull it out of the water. A 31 second steeping to reach the desired 29% uptake of water into the rice kernels. The precision required is just amazing, but why, why is this so time critical?

We need to back up a little and consider what we are trying to do. The goal is to have our steamed rice weigh 1.38x to 1.4x the pre-steeped rice.1 That is to have the rice take up slightly less than 40% of its weight in water by the time it has completed steaming. Steaming will add another 10% or so water uptake. Backing off to pre-steam levels gives us 1.28x to 1.3x for steeping. So how long will this take and why is it different for different grades of sake?

While there are differences between rice variety and milling rates, it turns out that one of the main contributors to the rate of water uptake during steeping relates to the moisture content the rice starts with. In fact it is this factor that is the main cause for highly polished rice to absorb water so quickly and hence the need for a stop watch.

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  1. These targets may vary a bit from place to place.

The chemistry behind the measurements – San-do and Amino San-do

The chemistry behind the measurements – San-do and Amino San-do

A friend1 helped me to understand the chemistry behind these characteristic sake parameters; san-do (acid level) and amino san-do (amino acid level). It is not that complicated once the basics are explain but without understanding the basics it is impossible to really know what is going on.

Foundational concept: the mole. A mole is a quantity of objects like a dozen. It allows us to map reactions between individual molecules and atoms and more manageable quantities like grams and liters. One mole of hydrogen is 1 gram. Hydrogen is the simplest and lightest atom with one proton and one electron. The electron weight is so small it is insignificant in comparison to the proton. So the proton as hydrogen itself has an atomic weight of 1. Each atom has an atomic weight, ignoring electrons, equal to the number of protons and neutrons it contains. The neutron weighs the same as the proton.

A carbon atom has 6 protons and 6 neutrons and thus has an atomic weight of 12. Because the carbon atom is 12 times that of hydrogen one mole of carbon would also be 12 times the weight of hydrogen or 12 grams.

Foundational concept: molarity or moles/Liter. To create a one molar solution (solution of one molarity) of carbon in water simply place 12 grams of carbon in a one liter container and add water until reaching the one liter level. When we talk about the concentration of elements based on chemical reaction equations we do so in molarity or moles per liter. Continue reading “The chemistry behind the measurements – San-do and Amino San-do”

  1. My fried is Jonathan Musther of New Zealand.

How much sake does a pound of rice make?

How much sake does a pound of rice make?

I recently saw a section in “The Niigata Sake Book” labeled “How Much Sake Is Made out of 1 kg (2.2 lb.) of Rice” and thought this would make a nice topic to cover. I may later do a more in depth look at this but for now we will just get a good idea of the basics.

OK, so if we start with rice, water and some microorganisms how much sake will we get?   Well, let’s start with brown rice as does “The Niigata Sake Book.”  To make sake starting with brown rice the first thing that needs to be done is to polish the rice to a level needed for the type of sake we wish to make. To get down to the edge of junmai ginjo type sake we need to polish the rice to 60% or less. So let’s say we will mill the rice down to 60% of the original brown rice. That is, if we start with 1 lb. of brown rice this will leave us with 0.6 lbs. of white rice.

Now, for this there is a key ratio that needs to be understood. While this ratio will change somewhat for individual sakes, we will simply choose a reasonable example ratio for this analysis. The ratio of water used to the weight of rice added is around 1.3x, so that is what we will use. This implies the water needed for the fermenting mash will be 0.78 lbs. = 0.6 lbs x 1.3. The fermenting mash (the Moromi) will then be 1.38 lbs. = 0.6 lbs. rice + 0.78 lbs. water.

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Super flat rice polishing – A Daishichi special

The level of polishing or milling our rice has a major impact on the characteristics of the sake we produce. The characteristic difference is a function of the amounts of proteins, fats and oils that remain in the rice used for brewing. The more of these that can be removed the more refined the sake. This is why daiginjo has a higher milling rate or lower seimaibuai than ginjo. Sense the proteins, fats and oils have the highest concentrations on the outer portions of rice with steadily dropping concentrations the further from the outer edge you get, going from 90% seimaibuai to 85% has a greater impact than going from 60% to 55% seimaibuai.

However, the methods used to mill our rice determines how effective the milling process is at removing the proteins, fats, and oils without wasting the starch we need. Imagine that the level of concentration declines linearly1 with distance from the surface. Then removing a square unit of the outer 1% will remove more proteins, fats and oils than removing a square unit of the second 1% (from 1% down to 2%). Based on this we would want to mill our rice, such that, we uniformly remove the outer most layer down to the desired seimaibuai. The method to do this is called the Flat Rice Polishing method.

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  1. I don’t know whether the rate of diminishing concentration is linear or some other non-linear function.