Rice shinpaku structure or not?

Rice structure or not rice structure? Extending the review from last post with three more papers.

Key to sake production is the shinpaku or white opaque center. The shinpaku is generally important because of its increased ability to gelatinize during steaming, has a softer center for koji to invade once it breaks through the firmer outer layer, and is more highly convertible by the koji enzymes. All of this is true no matter the milling rate. For these reasons much of the breeding of new rice varieties has involved attempts to improve the significance of the shinpaku. However, as ginjo and daiginjo become more important types of sake, high millability is also becoming more important.

In particular, the papers analyze why some are better suited for high polishing levels while others are not. This characteristic is hugely important for ginjo and daiginjo styles of sake which have been on the rise in importance for some time now. This week I will look at three more articles on the same basic topic. However, before covering the additional papers, I would like to clear up a loose end from the last article.

The papers discussed in the last article, discussed the characteristic type of shinpaku each varietal has. These characteristic types include: non-lined (I think no-shinpaku would be a better name), lined, bellied, dotted, and ellipsoidal. As I mentioned in the article I was not sure what was meant by lined. Actually, I was thinking that it was a dense shell around the shinpaku. However, this was wrong. The lead author on the three papers, Masahiko Tamaki, sent me some nice pictures that make it clear. I don’t have permission to post the pictures so I will attempt to provide a diagram that gets the information across.

In the following diagram there are five characteristics represented with each having a side angle view of a rice kernel on the left and a cross section view looking down the long axis on the right. The first characteristic pattern, non-lined, represents rice without a significant shinpaku (white area in the center of the rice). Most eating rice has this characteristic. Next is the lined shinpaku which is the best structure for high milling levels. The bottom two bellied and ellipsoidal both have larger shinpaku but they are also more brittle. This gets in the way of milling and creates more broken rice. Dotted, is the final characteristic and is somewhere between non-lined and lined in terms of its suitability for high milling levels.

Rice kernel characteristics of shinpaku

OK, now that we have cleared up what was meant in each characteristic it is time to move on to the three additional papers. Masahiko Tamaki is the lead author for this set of papers as well. They are:

The first of these three papers looks at differences between rice kernels with shinpaku and without where the kernels are of the same variety. Two varieties (Senbon nishiki, Yamada nishiki) were analyzed each of which were grown in three different areas of Hiroshima (Shobara, Takamiya, Miwa).

The hardness of the center of each type kernel was measured with no significant difference between the three plots but quite significant difference between the shinpaku and non-shinpaku kernels within the same type. Other locations, four more, were also tested with similar results. In addition, starch characteristics were analyzed finding again, no significant difference between the shinpaku and non-shinpaku kernels. Given all this the conclusion continues to be that the differences in the structure of endosperm cells are responsible for all the properties of the shinpaku.

The second paper looks closer at the differences in hardness of the rice kernel and its shinpaku and their likelihood of breakage. They considered four types of rice: Kairyo omachi, Hattan nishiki No. 1, Senbon nishiki and Yamada nishiki. The first two of these have a significant higher breakage rate as compared to the second two. Very cool pictures taken with a Scanning Electron Microscope (SEM) show that Yamada and Senbon nishiki have much more tightly packed starch than does Kairyo Omachi and Hattan nishiki. This tight packing makes the rice harder and less susceptible to breakage.

Paper three analyzes the same rice varieties as paper two but compares starch properties rather than hardness. This study suggests that the shinpaku tissue may also play a part as well as the temperature of the early ripening period. This is, of course, in addition to the endosperm structure’s demonstrated impact on millability.

Hiroshima’s Hattan Rice Varieties best for Futsu shu but not Daiginjo

Hiroshima’s Hattan Rice Varieties best for Futsu shu but not Daiginjo

This week I thought that I would review a couple of papers on Hiroshima rice. I came across these papers on the analysis of Hattan rice which is grown only in Hiroshima. This piqued my interest because this rice, while only grown in Hiroshima, is sold to 32 Prefectures in 2003 and 24 Prefectures in 2006. I had never heard of this rice (not that this means anything) until I came across the papers so I kept reading to learn more. As it turns out Hattan varieties are well suited for futsu shu (standard table sake) because of the shinpaku (starchy white center in sake rice) but are not as well suited for Daiginjo because of the fragile nature of that shinpaku.

Masahiko Tamaki is the first author on each of the papers I will discuss today. Rie Kiharra and Takao Tsuchiya are also authors on all three papers. There are several other authors but they vary paper to paper. The three papers are:

  1. Varietal Difference of Polishing Characteristics and Suitability for Sake Brewing in “Hattan-Type Varieties” of Rice Suitable for Brewing Original Hiroshima Sake
  2. Properties of Starch and Protein of “Hattan-Type Varieties” of Rice Suitable for Brewing Original Hiroshima Sake
  3. Varietal Differences in Endosperm Structure Related to High-degree Polishing Properties of “Hattan Varieties” of Rice Suitable for Brewing Original Hiroshima Sake

Hattan type rice goes back to at least 1875 when private growers were breeding rice based on Hattanso.  Not long after this in 1907 the Hiroshima Prefecture Agriculture Experiment Station began working on producing better strains of Hattan-type rice. The primary goal for the improved strain was to produce rice with a more prominent shinpaku, better disease resistance, lodging resistance and higher yield. Initially, in 1921 this led to the development of Hattan No. 10. It had a low yield, was susceptible to lodging and rice blast and had a long culm, none of which are advantages. Despite these disadvantages it was used for breeding material. In 1962, this continued work produced Hattan No. 35 from Hattan No. 10 by introducing rice blast resistance. Later in 1965 Hattan No. 40 was bred. Much later, or much more recently, in 1984 two new varieties were bred from Hattan No. 35 by improving its yield; Hattan-nishiki No. 1 bread for hilly areas and Hattan-nishiki No.2 bred for altitudes above 400m. These last two both have the same high yield and lodging resistance as does table rice (non-glutinous rice).

The breeding program has succeeded in producing rice with larger grain size, higher percentage shinpaku and a higher percentage of the grains having this characteristic shinpaku. It also resulted in rice characteristics that are advantageous of sake brewing; better absorption of water and higher digestibility (that is the koji enzymes can convert more of their starch to sugar and protein to amino acids). These characteristics have made Hattan No. 35, Hattan-nishiki No. 1 and No. 2 well suited for sake brewing.

However, both Hattan-nishiki No. 1 and No. 2 are easily broken during polishing while Hattan No. 35 has a smaller harder shinpaku that is not easily broken. The level of breakage for No. 1 and No. 2 make them unsuitable for ginjo and daiginjo brewing, so only Hattan No. 35 is used for this. But Hattan No. 35 is by no means ideal because its cultivation characteristics are lacking.

It seems that one characteristic of the shinpaku between those that are fragile and those that are less so, is a “lined-white-core” or, in the terminology I have been using, a “lined-shinpaku.” I am not sure what a lined-shinpaku is, I will have to watch for more on this. Yamada-nishiki also seems to have just such a shinpaku, a lined-shinpaku that is.

The analysis in these papers show that the starch and protein composition of the various Hattan varieties are virtually the same so the composition does not account for the fragility. Maybe the endosperm structure can account for the fragility? The final paper looks at just this question. It concludes, yes, the structure seems to be the main cause. Hattan-nishiki No. 1 and No. 2 both have large shinpaku but also large number of interstices (gaps in the structure) while Hattan No. 35 has fewer gaps. In addition Hattan No. 35 has a lined-shinpaku while Hattan-nishiki No. 1 and 2 do not.

Comparing the Hattan-type rice with Yamada-nishiki the authors find that Yamada-nashiki has the same lined-shinpaku as Hattan No. 35 but with even fewer gaps. All of this (lined-shinpaku with low number of gaps) leads to less fragility for Yamada-nishiki than Hattan No. 35.

So, while a large shinpaku is important for sake brewing it is not enough by itself to make a rice type suitable for daiginjo.


P.S. Furukawa, S. is referenced in the 2ed paper 🙂

I finally did it! My book, Brewing Sake, is out.

I finally did it! My book, Brewing Sake, is out.

Brewing Sake hit Amazon around the 20th and is making it into the channels. It can take up to 6 weeks to fully make its way through the channel. I am told that at least one person has been able to order it in Denmark through a standard retailer, so it is working its way into the channel nicely; a bit quicker than I had expected.

Brewing Sake: Release the Toji Within is here on Amazon and interestingly enough, the used copies are asking 2.5 times the price of the new copies. J Are there really any used copies? I wouldn’t think so.

I believe that I have pulled together a lot of material that is pretty hard to come by for those of us who don’t speak, and more importantly don’t read, Japanese. The table of content is below. The overall layout is a quick introduction on sake brewing and the equipment needed as well as a step by step walk through to begin with. This is followed by details on each of the ingredients and chief measurable characteristics. Next, is a bit about how to protect the sake. Then I dive head long into each step of the process. After this we look into the details of analyzing your sake for each of its measurable characteristics. This is followed by a brief look at sake’s enemy, Hiochi-kin. I have then provided a significant glossary containing more than 170 entries. Finally, I give a list of links to places where you can find specific pieces of equipment.

If you get a copy I hope you will also write a review on the Amazon page on what you think about the book.

Table of Contents:
Introduction 1
How Saké is Brewed 5
Brewing Equipment 11
Quick Start Saké Brewing 23
Rice – Kome (米) 37
Koji (麹) 47
Yeast – Kobo (酵母) 57
Water – Mizu (水) 65
Nihonshu-do (日本酒度) or Saké Meter Value (SMV) 71
Sando ( 酸度 ) – Acidity 77
Amino Sando (アミノ酸度 ) – Amino Acid 79
Protecting your Homebrew Saké from light 81
Sanitation 85
Seimai (精米) or Rice Milling / Polishing 89
Rice Preparation 101
Koji Making 105
The Moto 111
The Buildup – San-Dan-Jikomi (三段仕込み) 135
The Main Ferment – Moromi (諸味) 145
So you like the Honjozo (本醸造) 151
Time for Shibori ( 搾り ) 157
Final Steps in Saké Brewing 161
Measuring Your Homebrew Saké 163
Spoilers and Trouble Shooting 189
Glossary 191
Links and Contacts 209