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Tremendous point of view: Hiire (Pasteurization) Methods at Nanbubijin Brewery

Nanbubijin is proud to introduce their unique approach to Hiire, a traditional sake pasteurization technique that involves heating brewed sake. Their methods, particularly for the crucial initial heating stage called Hon-Hiire, differ significantly from conventional practices.

Traditional Hiire: A Trade-Off Between Safety and Quality

The standard Hiire process heats sake between 70°C and 75°C, followed by transferring it to a tank. Once the tank is full, the transfer hose is sealed, and water is sprayed to cool the sake and eliminate Hiochi bacteria, known to cause spoilage.

This textbook method, developed in a time without refrigeration, ensures safe storage at room temperature. However, it comes at a cost: sacrificing the sake's original taste and aroma. The lengthy heating (30-40 minutes for a 10,000-liter tank) and subsequent cooling (half to a full day) significantly degrade the delicate flavors. Imagine wanting to enjoy a hot, fresh sake, only to be presented with a cold beverage that has lost its essence – a consequence of prioritizing safety over sensory experience.

Nanbubijin's Innovation: Plate Heater Rapid Cooling and Warming

Recognizing these drawbacks, Nanbubijin implemented the "Plate Heater Rapid Cooling and Warming" process for most of their sake (excluding Dai Ginjo). This method prioritizes preserving the sake's freshness and fruitiness while maintaining pasteurization effectiveness.

The core concept lies in significantly reducing the time the sake spends at high temperatures. Here's a breakdown of the process:

  • The Plate Heater: This machine utilizes three plates for heating and cooling.

  • Heating and Cooling Cycle:

  • Cold sake is placed on the middle plate.

  • Hot water on the left plate heats the sake to 60-65°C.

  • The warmed sake returns to the middle plate, mixing with the original cold sake, before rapidly cooling down to 35°C.

  • Finally, the right plate with a cold water circulation system cools the sake down to its final storage temperature of 10°C.

This rapid heating and cooling process effectively preserves the sake's quality. However, a crucial limitation exists – it cannot completely sterilize the storage tank itself. Traditionally, hot sake achieved this sterilization; however, the new method utilizes cold sake (10°C) to prevent activating dormant "Hiochikin" that could cause spoilage.

Therefore, refrigerated storage becomes mandatory for sake processed with this method. Additionally, reheating is necessary before bottling to prevent clouding and spoilage. While these extra steps require vigilance, we believe this method offers the best balance between preservation and taste.

Bottle Storage for Special Sake

For Dai Ginjo, Junmai Dai Ginjo, and Junmai Ginjo sake, Nanbubijin employs a method called Bottle Storage (瓶貯蔵). This approach is ideal for smaller quantities and aims to minimize the risk of spoilage within the tank while maximizing fragrance and taste preservation. It involves heating the bottled sake in hot water (60-65°C) followed by rapid cooling in cold water, similar to the traditional method.

While this method takes longer than the Plate Heater (20-25 minutes for heating and 15-20 minutes for cooling), we believe a single heating best preserves the delicate qualities of these premium sakes.

Timing is Key: Heating Sake at its Peak

Beyond the heating method itself, Nanbubijin prioritizes the timing of Hiire. Traditionally, sake was produced in large batches and heated for storage during the winter before the chief brewers departed for spring. While this approach maximized production efficiency, it resulted in delayed heating, leading to flavor deterioration due to "Namahine" (a peculiar sweetness associated with spoilage).

Modern sake brewing emphasizes prompt Hiire to lock in the desired flavors. We adhere to the following heating timeframes:

  • Dai Ginjo & Junmai Ginjo: Within 3-7 days after squeezing

  • Junmai & Ginjo: Within 7-14 days after squeezing

  • Special Junmai: Within 10-20 days after squeezing

  • Honjozo: Within 10-20 days after squeezing

  • Regular Sake: Within 30 days after squeezing

Precise Hiire timing is crucial for maintaining sake quality. Without proper Hiire, sake rapidly deteriorates and develops off-flavors.

Nanbubijin's Dedication to Quality Sake

At Nanbubijin, we take immense pride in our innovative Hiire methods. We believe these techniques allow us to deliver sake that is both safe and exceptionally flavorful. We are committed to continuous improvement and hope to see our methods adopted more widely within the sake brewing industry.

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