Open a packet of hojicha and you may find mostly leaves or mostly slender stems. Products on the same hojicha shelf do not necessarily begin with the same material before roasting.
Product examples and research offer ways to explore those differences. Rather than deciding whether stems or leaves are better, the starting point is to identify what is actually being compared.
One maker can use both leaves and stems
Maruhachi Seichajo uses leaves for its Kaga Hojicha and stems for its Kenjō Kaga Bōcha. Sharing a maker does not mean sharing the same ingredients. Put the product names side by side, then check what each contains: it changes where the comparison begins.
If they taste different, that difference cannot automatically be put down to roast level alone. These products are made from different materials. Before asking how deeply a tea was roasted, there is another question: what was roasted?
The stems are separated before roasting
In the Kaga bōcha process described by Japan’s Ministry of Agriculture, Forestry and Fisheries, steaming, rolling and drying produce aracha, or unrefined tea. The stems are then separated and roasted. Leaves and stems are selected before roasting, rather than being separated by the roasting itself.
This process collects the stems mixed into the tea material and puts them to use. When drinking bōcha, tracing the work back beyond roasting to that separation makes the choice of stems more concrete.
Some products combine leaves and stems
Marukyu Koyamaen’s Gosho Kaori combines sencha with karigane from tea grown for matcha, then roasts the mixture. In the company’s product categories, karigane refers to stem tea. Leaves or stems are not the only two options: different teas can also be combined.
The useful detail is not simply that this is a blend. The description identifies sencha and stems from matcha tea material. Separate the part of the plant from the tea it came from, and a single line about ingredients supplies two pieces of information.
The same roasting conditions do not produce the same aroma
Joint research presented by the Industrial Research Institute of Ishikawa found differences in the composition of aroma compounds when stems and leaves were roasted under the same conditions. The starting material also matters to the aroma after roasting.
That comparison used samples under controlled conditions. Commercial products can differ in both their materials and processing, so it does not create a ranking in which stems always have one particular aroma or taste better than leaves. A research comparison and a choice between products in a shop do not hold the same things constant.
Different materials can call for different heating conditions
A 1999 study of tea aroma found that the roasting conditions judged suitable differed between tea containing stems and tea made only from leaves. The distinction between stems and leaves appears not only in the finished aroma, but also in how heat is applied.
The research settings cannot be transferred directly to kitchen equipment. They do, however, show a connection between selecting the raw material and roasting it. Looking for leaves or stems is a way to understand what a tea was made from, rather than to rank its taste.