Introduction to Sake Studies | The World of Sake-Making Becomes More Fascinating the More You Learn

Why Learning About Sake is Fascinating | Sake-Making is a Fusion of Science and Art

Sake is an exceptional fermented beverage in which infinite variations are born from just three raw materials: "rice," "water," and "koji." Unlike wine, where flavor is determined by grape varieties and terroir, sake's flavor changes through countless decisions made during the production process, from ingredient selection to each step of fermentation. This depth is precisely what makes sake such a compelling subject to learn about.

In recent years, interest in "sake studies"—the systematic study of sake—has grown rapidly. In 2018, Niigata University established the world's first "Sake Studies Center," initiating programs to research sake from multiple perspectives including fermentation science, history and culture, and economics. Additionally, the number of certified sake sommeliers (kikizakeshi) has reached approximately 45,000 domestically and internationally, and demand among general consumers to enhance their sake literacy is expanding.

Learning about sake goes beyond simply increasing one's knowledge of alcohol. Sake serves as a gateway to diverse academic fields: agriculture through rice cultivation, microbiology through the workings of koji mold, geography through water quality, and cultural anthropology through the history of each brewery. Let's explore together the world of knowledge that unfolds beyond a single cup of sake.

The Science of Sake Rice | Why Yamada Nishiki is the "King of Brewing Rice"

Rice used in sake-making is called "sake-brewing-suitable rice" and possesses characteristics clearly distinct from food-grade rice. As of 2024, approximately 130 varieties of brewing rice are registered, but "Yamada Nishiki" dominates with overwhelming market share. It accounts for approximately 35% of total brewing rice production, and rice from Special Grade A districts—specifically Miki and Kato cities in Hyogo Prefecture—commands the highest prices as premium products.

Yamada Nishiki's superiority lies in the "shinpaku" (white center), a white opaque portion in the core of the rice grain. The shinpaku has a coarse starch density, allowing koji mold hyphae to penetrate easily for efficient saccharification. Additionally, its large grain size (approximately 27g per 1,000 grains compared to 22g for food rice) allows it to withstand high polishing rates, making it ideal for premium daiginjo sake production.

Other notable varieties include "Gohyakumangoku," born in Niigata, which produces a clean, crisp sake profile and holds about 25% of the national market share. Nagano Prefecture's "Miyamanishiki" creates well-balanced flavors, while Okayama Prefecture's "Omachi" produces robust sake with wild character. In recent years, each prefecture has developed its own brewing rice varieties, and new cultivars expressing regional terroir—such as Yamagata Prefecture's "Yukimusume," Toyama Prefecture's "Tomikaori," and Ehime Prefecture's "Shizukuhime"—continue to emerge.

The Mechanics of Fermentation | The Magic of Parallel Multiple Fermentation Found Only in Sake

The most noteworthy aspect of sake fermentation is "parallel multiple fermentation," a unique fermentation method found nowhere else in the world except sake. In wine, yeast directly converts sugars present in grapes into alcohol through "single fermentation." In beer, starch is first converted to sugar by malt enzymes, followed by alcohol fermentation by yeast—"sequential multiple fermentation." However, in sake, "saccharification" (koji mold converting starch to sugar) and "fermentation" (yeast converting sugar to alcohol) occur simultaneously within a single tank.

This mechanism allows sugar produced during saccharification to be swiftly converted to alcohol, naturally generating high-concentration alcohol (17–20% in the final product)—among the world's highest alcohol content for fermented beverages.

Simplified, the fermentation process follows this sequence: rice polishing → washing and soaking → steaming → koji production → starter culture preparation → main mash preparation → pressing → pasteurization → storage → bottling. Particularly crucial is the "three-stage brewing," where rice, koji, and water are added to the mash tank in three separate stages. The first stage is called "hatsu-zoe" (initial addition), the second day is "odori" (rest day where nothing is added but yeast propagates), the third day is "naka-zoe" (second addition), and the fourth day is "tome-zoe" (final addition). This staged approach prevents stress on yeast and ensures stable fermentation.

The Art of Sake Tasting | Mastering the Fundamentals of Tasting

To enjoy sake more deeply, master the basic techniques of sake tasting. Professional sake sommeliers evaluate tasting systematically across four elements: appearance, aroma, flavor, and finish.

First, appearance. Pour sake into a white ceramic cup with a snake-eye pattern and observe its color and clarity. New sake is nearly colorless and transparent, while aged sake takes on golden to amber hues. Also observe the presence of turbidity or sediment.

Next, aroma. Gently smell the glass without swirling to capture the first impression (initial aroma). Fruity ginjo aromas (apple, banana, melon, etc.), grain-like aromas (freshly cooked rice, chestnut), dairy aromas (yogurt, cheese), and aged aromas (honey, caramel, nuts)—sake's aroma comprises over 200 aromatic compounds.

When evaluating flavor, be mindful of five taste elements (sweetness, acidity, umami, bitterness, astringency) and mouthfeel (texture). Roll the sake across your entire tongue to sense how each taste element balances. While sake meter value (dry-sweet spectrum) and acidity measurements provide objective reference points, ultimately trust your own palate's impressions.

Sake Credentials and Learning Opportunities | Knowledge That Can Build a Career

For those wanting to systematically build sake knowledge, credential acquisition is recommended. The most well-known credential is "Sake Sommelier" (Kikizakeshi), certified by the Japan Sake Service and Sommelier Institute (SSI). The correspondence course costs approximately ¥58,800, with total fees including exam registration around ¥79,000. The pass rate is approximately 80%, making it relatively accessible for acquisition. Beyond the beverage industry, general learners increasingly pursue this credential for cultural enrichment.

For a more accessible starting point, the "Sake Knowledge Test" is available. Also administered by SSI, it ranges from Level 5 to Level 1. Level 3 exam registration is reasonably priced at ¥3,650 and can be prepared for through textbook study. Upon passing, a certification card is issued, serving as proof of foundational sake knowledge.

As an international credential, "SAKE DIPLOMA" is gaining attention. Certified by the Japan Sommelier Association (JSA), known for wine sommelier credentials, the exam fee is ¥29,600. It consists of a primary exam (written) and secondary exam (tasting), with a pass rate around 40%, making it somewhat challenging. Its distinctive feature is sake education modeled on wine knowledge frameworks, with increasing numbers of international wine professionals taking the exam.

As venues for learning, "brewery seminars" held by sake breweries throughout the country are invaluable. The opportunity to taste sake while listening directly to fermentation masters (toji) provides living knowledge unavailable from textbooks. Participation fees typically range from ¥2,000 to ¥5,000, and considering complimentary tastings, the cost-performance is excellent. SOROU.JP also shares information about sake-related events and seminars, so please use it as your first step into sake learning.