On a hot day, there is nothing quite as eagerly anticipated as opening the fridge and pulling out a pitcher of clear, ice-cold cold brew. Many friends often find themselves puzzled when making cold brew: why does it sometimes taste like weak coffee water, and other times bitter and astringent? In fact, making cold brew is like slowly simmering a pot of sweet soup at low temperature. The water temperature is usually between 4 and 10°C, and the aromatic flavors extract especially slowly, relying entirely on time and the interaction of coffee and water to build balance.

What determines whether this cup is smooth or bland is the interplay between extraction yield and concentration. Extraction yield refers to how much flavor material has been drawn out of the coffee grounds, while concentration is the proportion of these substances in the water. If the grind is too coarse or the steeping time is insufficient, the organic acids and sugars have not yet had time to extract, and it will taste thin with hollow flavors; if the grind is too fine or steeped too long, the tail-end off-flavors and woody bitterness are over-extracted, and the whole cup becomes astringent.

If you want the same bag of beans to show a satisfying state, fine-tuning the steeping time is the most intuitive dial. Steeping for around 6 hours often gives a thinner body and aromas that are not cohesive enough; if you steep for a full 24 hours, a slight bitterness easily emerges in the tail end. Usually steeping for 8 to 12 hours makes the flavor appear especially crisp and clean, and if extended to 12 to 16 hours, the sweetness and body become more prominent. As long as you keep it within a reasonable range, you can easily adjust it to be smooth.

Before turning the beans into cold brew, it is worth first getting familiar with their basic character through a regular hot pour-over. Prepare 15 g of coffee grounds, use a 1:15 coffee-to-water ratio, and pour 225 ml of hot water. First bloom evenly with 30 ml of water for 30 seconds, then pour in stages to complete the extraction, keeping the total brewing time at around 2 minutes. Through the aroma and the distribution of acidity and sweetness of this hot cup, you can roughly judge whether this bean is suited to being drunk strong or light.

When selecting beans suitable for cold brew, the flavor direction is especially key. Cold brew is about a transparent, pure low-temperature mouthfeel, and medium-light roasted coffee beans usually better showcase alluring floral notes and fruity acidity. Some beans naturally carry lively citrus and berry notes and are suited to slightly lighter extraction, drinking like iced fruit tea; while beans with pronounced fermentation and prominent sweetness are well suited to being steeped a bit stronger, allowing you to feel the rich smoothness at low temperature.

For those who enjoy a crisp, bright juice-like quality, the Qianjie Yirgacheffe Natural Red Cherry is highly recommended. This classic Ethiopian coffee has highly recognizable floral notes and rich fruit charm. The natural process gives it sweet strawberry and blueberry flavors, accompanied by a faint honey sweetness. When making cold brew with it, steep for around 10 hours then filter; the acidity is lively with a soft sweetness, and gulped down on a hot day, the mouth is full of summer fruit vitality.

If you prefer intense aroma and a rich mouthfeel, Qianjie Mozart will deliver a truly stunning experience. This bean uses a special anaerobic honey process, and opening the bag reveals an immediate bouquet of osmanthus and ripe grape aromas. When making cold brew, let it rest in the fridge for 14 hours, and the slightly tipsy wine aroma from fermentation along with the dark berry sweetness will be fully released, entering the mouth rich and silky with distinct layers of flavor, especially suited as an iced coffee to savor slowly in the afternoon.

For coffee drinkers in pursuit of high sweetness and delicate floral notes, Qianjie Strawberry Candy is a blend not to be missed. It cleverly combines the elegant citrus-honey charm of Panama Geisha with the high sweetness of Costa Rican honey process, and the aroma performance is especially full. When making cold brew, whether steeping for 8 hours to present a crisp, sweet, light-drinking state, or steeping for 12 hours to intensify its rich strawberry gummy-candy sweetness, it can show a refreshing, clean flavor that makes you sip one mouthful after another.

Making cold brew is actually a pleasure full of life's charm. After grinding the coffee grounds, add ten times the amount of room-temperature water, seal it and place it in the fridge to quietly wait for over a dozen hours of low-temperature extraction. After filtering out the coffee grounds, the clear coffee liquid can be drunk straight over ice in big gulps, or stored refrigerated for another day to await the flavor settling brought by slight fermentation. As long as you know how to fine-tune the steeping time according to the bean's character, your home fridge can always serve up a tailored, palatable flavor for you.