We Made a Prototype of Black Tea Using Sweet Potatoes

Agriture has made a prototype of black tea blended with sweet potato. Requests to use dried vegetables and dried fruit as raw materials for blend teas are increasing year by year, but ingredients clearly divide into those whose flavor comes through when mixed with tea leaves and those that come through less than expected. Sweet potato turned out to be a typical example of the latter.

What we learned through prototyping is that sweet potato does not release its flavor unless heated. The starch in sweet potatoes turns into sugar during slow heating, which is what brings out their characteristic sweetness and aroma. When simply dried sweet potato was mixed straight into tea leaves, almost none of the sweetness or aroma transferred during a few minutes of steeping in hot water. The ingredient has high potential, but it is poorly matched to the process of extraction.

So this time we switched to a design built around the toasty flavor of roasted sweet potato, keeping the sweet potato itself to a small proportion. Rather than adding a large amount of the ingredient as the star, the idea is to include a small amount as visual evidence of its presence, and to build the outline of the flavor through a separate design. The result combines a sweet aroma reminiscent of roasted sweet potato with the richness of black tea. Note that the base black tea leaves are sourced externally. Agriture's role is raw material design, that is, how to blend the vegetable and fruit ingredients we dry ourselves; we do not produce the tea leaves themselves.

Pitfalls When Using Dried Ingredients in Blend Teas

In raw material design for blend teas, the first hurdle is whether an ingredient can release flavor in the short process of extraction. Dried vegetables and dried fruit show clear tendencies by ingredient.

• Flavor comes through easily when steeped: citrus peel (essential oils transfer readily into hot water), herbs and aromatic plants, ginger
• Hard to extract: starchy potatoes and root vegetables, ingredients high in sugar but low in volatile aroma compounds
• Color comes through but flavor is weak: leafy vegetable powders

People tend to assume that because potatoes are sweet, tea made with them should taste sweet too, but since the sweetness comes from starch, it does not come through as flavor without saccharification through heating. Making this judgment early in prototyping reduces the need to redo the blend design.

The Design Decision to Use a Small Proportion

When it becomes clear an ingredient cannot be the star, there are two options: give up on the ingredient or change its role. This time we chose the latter.

By limiting sweet potato to a small amount, the product concept of "black tea made with sweet potato" can be maintained while keeping raw material costs down. Being able to see the ingredient when you open the tea bag, and having its name appear on the ingredient label, has value separate from flavor. The point that the amount of flavor an ingredient contributes is not necessarily proportional to how convincing the product is often comes into play in blend design.

Conversely, if you want a product that puts the sweetness of sweet potato front and center, rather than tea, Diced formats that are chewed and eaten, such as ours, or drink designs that dissolve a powder bring out the ingredient's character better. Rechoosing the form to suit the use is the shortest path to making the most of an ingredient.

About Blend Tea OEM and Product Development

At Agriture, we take consultations on raw material design for blend teas combining dried vegetables, dried fruit and herbs. Here are the directions we are most often asked about.

• Seasonal limited-edition flavored teas (sweet potato and chestnut for autumn and winter, citrus for spring, and so on)
• Blend tea series built around Japanese-grown ingredients
• Original teas for souvenirs at pick-your-own farms and farm stands
• House blend development for cafes and restaurants
• Caffeine-free tea drinks (designs based mainly on herbs and fruit tree leaves)

About the minimum prototype lot and processing facility

We accept prototype orders from 1 kg of raw material. Because several variations with different blend ratios can be tested in parallel, the design can be refined while comparing how the flavor comes through. Full production starts from 10 kg, and purchase lots, lead times and packaging formats are worked out through individual consultation.

Processing takes place at our own facility in Kyoto Prefecture. The best-before date is about 6 months from shipping, and we can handle commercial bulk, small bags and light-blocking packaging. The base tea leaves are sourced externally, and we handle blend design with our own dried ingredients, filling and packaging. We do not have in-house equipment for growing or roasting tea leaves or for extracting or concentrating coffee, so please consult with us in advance about projects that include those processes.

Dried Ingredients That Are Easy to Use in Blends

Here are the ingredients we are most often asked about as blend tea raw materials. Building around ingredients whose aroma comes through easily when steeped reduces design failures.

• Dried yuzu (citrus whose essential oils transfer easily into hot water)
• Dried sudachi (sharp acidity and a refreshing quality)
• Dried ginger (noticeable heat and aroma)
• Dried Osmanthus (a floral ingredient with a bright aroma)
• Dried Cardamom (for chai-style designs)
• Dried Lavender (a star ingredient in herbal teas)

Agriture also handles raw material design for blend teas that make use of dried vegetables and dried fruit, and prototypes of commercial raw materials. You can consult with us from the stage of asking how much of an ingredient's flavor will come through or which form is best.

Dried turnip can be expected to attract commercial interest as a material for soups, simmered dishes, and pickles, and if processed into powder, it can also be used as a raw material for baby food and nursing-care food. Turnip's characteristic gentle flavor is a material well compatible with children's foods and products for the elderly.