Yuzu

Yuzu can be offered in small amounts once your baby is ready for solids, at about 6 months. It is high in acid, which can cause a rash where it touches the skin and can cause or worsen diaper rash.

Yuzu is a citrus fruit from East Asia, used in Japanese cooking to add sourness. Its bumpy, dimpled peel turns bright yellow when ripe, and it is also called yuja. It is used much like lemon and lime, bringing a tart, floral flavor to savory dishes and cold drinks. In Japan, the winter solstice yuzu bath, yuzuyu, uses hot water to release the aromatic oils in the peel.

Yuzu has a great deal of vitamin C, a nutrient that supports immunity and helps the body take in iron from plant foods. The peel in particular has many plant compounds that work as antioxidants and against inflammation.

Juice and rind

Fresh yuzu juice works in sauces and marinades, or as a few drops over a finished dish. Freeze leftover juice in ice cube trays and keep the cubes in a freezer bag for up to 6 months. You can also grate the rind.

Do not serve yuzu juice as a drink. Babies should not have juice to drink unless a health provider says so, but a splash used as an ingredient is no problem. Once your child turns one, under 4 ounces (about 120 ml) a day of unsweetened or watered-down juice is acceptable, and waiting until age 2 is better. Regular sweet drinks narrow the variety of foods and raise the risk of cavities.

Digestion

Soluble fiber and pectin are plentiful in yuzu, though people eat so little of it that digestion rarely changes. Stool patterns differ widely between babies. Ask your pediatrician if you are concerned.

Most people only squeeze yuzu for its juice, so choking is not a typical concern. Citrus segments left in their membrane, and seeds, are hazards for babies and children. Remove seeds before offering a wedge and watch your child closely.

Yuzu is not a common allergen. Medical literature does often mention citrus sensitivity that people report themselves. People with pollen food allergy (oral allergy syndrome), especially to grass and some tree pollens, may react to yuzu. That usually means brief itching, tingling or burning in the mouth, and a dangerous reaction is unlikely. Peeling or cooking yuzu reduces the reaction.

Because of the acid, you may see a harmless red patch around the mouth, stomach irritation if a lot is eaten, and diaper rash. Limonene in the peel may give sensitized people an allergic contact dermatitis.

If juice stays on skin and the skin meets sun, a reaction called phytophotodermatitis can follow, with a pigmented, itchy, sometimes blistering and painful rash. Rinsing the skin after contact with citrus and protecting it from the sun will prevent this.