Mulberry Leaf

Physical form is the first grading axis: whole leaf, cut and sifted to a defined sieve range, or milled powder at 80 to 200 mesh. Within each, lots are graded on colour, on stem and petiole content, on the absence of yellowed or diseased leaf and on foreign matter. Harvest timing is a real specification point rather than a marketing one, since young spring leaf carries considerably more 1-deoxynojirimycin and more protein than late season leaf, and the trade prices the two differently.

Processed variants are traded as separate items: steamed and dried leaf for tea, roasted leaf for a darker infusion, freeze dried powder where colour retention matters most, and enzyme-inactivated superfine powder made by blanching and jet milling for use as a green food powder. Frost-fallen leaf, collected after the first frost, is a traditional Chinese grade with its own designation. Organic certified material is widely available, particularly from sericulture regions where pesticide use is already limited because the leaf feeds silkworms. Extracts standardised on 1-deoxynojirimycin or on total flavonoids are made from this material and are a different product.

In the United States mulberry leaf is marketed as a dietary ingredient under the Dietary Supplement Health and Education Act, with manufacture under 21 CFR Part 111, and mulberry leaf tea has a history of consumption as a herbal infusion. The Food and Drug Administration has not issued a food additive regulation or a generally recognised as safe affirmation specific to mulberry leaf, so its use in conventional foods rests on the manufacturer's own determination, and permitted labelling is limited to structure and function statements. Pesticide residues are controlled through tolerances set by the Environmental Protection Agency.

In the European Union the position for Morus alba leaf is recorded in the Commission novel food catalogue and depends on whether the specific preparation was consumed to a significant degree before May 1997; the leaf as a herbal infusion has a stronger case than concentrated preparations, and status should be confirmed for the form being sold rather than assumed for the species. No health claim for mulberry leaf appears on the EU register of authorised claims. Dried leaf is subject to pesticide maximum residue levels applied with a drying factor, and to the contaminant limits of the contaminants Regulation, including the limits on pyrrolizidine alkaloids in herbal infusions and dried botanicals, which arise from co-harvested weed contamination rather than from the leaf itself. Codex maintains general contaminant standards and a code of hygienic practice applicable to dried botanical materials.