Making Kiwi Distilled Spirits
Our distillery has been producing kiwi distilled spirits since its establishment. Kiwi is also grown in Ibaraki Prefecture, where our distillery is located. Many agricultural products, including fruits, do not make it to the market due to minor damage or failure to meet size standards. I’ve heard that Japan’s standards are particularly strict. Utilizing these off-spec agricultural products is one way to address the challenges facing our agricultural industry.
When we first started distilling kiwi, it was challenging to capture its aroma. However, through a series of improvements, we have succeeded in extracting the distinctive scent of kiwi.
The biggest breakthrough came when we began using fully ripe kiwis. This was made possible when a nearby farmer provided us with overly ripened and soft kiwis that could no longer be sold. In Japan, most kiwis available on the market are still firm and not fully ripe, making it difficult to source fully ripened ones. When using firm kiwis, we have to ripen them ourselves. Fully ripened kiwis have a stronger aroma, which can be expected to impart a rich fruity character to the distilled spirit.
The story of an accident that happened when I was peeling kiwii
General Precautions for Distilling Fruit-Infused Liquids
- Effects of Pectin Gelation on Distillation Equipment
Kiwi contains a high amount of pectin, which may gel during the heating process of distillation. This can cause clogs or scorching in the equipment.
Gelation can occur under acidic conditions with high sugar concentrations (50% or more) or in the presence of calcium ions. This mechanism is referred to as the “egg-box model.” Pectin gelation tends to progress during the heating and cooling process. Countermeasures:- Adding pectinase (a pectin-degrading enzyme) beforehand can clarify the juice and prevent gelation.
- Excessive heating can break down pectin and hinder gelation. Since distillation involves prolonged high-temperature heating, I believe gelation is not a significant concern in our process.
- Duration of Fruit Infusion
When infusing kiwi in alcohol, prolonged exposure may result in excessive breakdown of the fruit, leading to bitterness or astringency. It’s generally recommended to keep the infusion time to a few days to a week.
However, I prefer an infusion period of 10 days to two weeks. While this does result in some bitterness, I find it acceptable as part of the spirit’s unique character. If you’re comfortable with this flavor profile, extending the infusion time can be a viable option. - Bitterness from Seeds
Crushing kiwi seeds can transfer bitterness to the distilled spirit. If possible, lightly filtering the mixture to remove the seeds and pulp is advisable.
In our method, we transfer the entire fruit mixture, including the infused fruit, into the still for distillation. As mentioned earlier, there is a slight bitterness in our distillate, though its origin—whether from the infusion period or the seeds—has not yet been confirmed. - Scorching of Pulp Inside the Still
To prevent the fruit pulp from scorching inside the still, it’s recommended to filter the infusion liquid before distillation. Insufficient maintenance of the still can result in burnt smells or off-flavors. Special care should be taken when working with fruit, and thorough cleaning is essential.
Currently, I am satisfied with our distillation methods. However, I believe it’s important to adhere to these precautions and continually explore ways to improve the process. Identifying areas for improvement and working to enhance the flavor of our spirits is an ongoing commitment we must uphold.
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