The Law Code of Yājñavalkya 3.2.42

3.2.42

lākṣālavaṇamāṃsāni vikrīyamāṇāni sadyaḥpatanīyāni dvijātikarmahānikarāṇi | payaḥprabhṛtīni tu hīnavarṇakarāṇi śūdratulyatvāpādakāni | etadvyatiriktāpaṇyavikraye vaiśyatulyatā | yathāha manuḥ |

Lac, salt, and meat, when sold, cause an immediate fall and cause the loss of the religious acts of a twice-born person. Milk and the rest, however, cause a reduction to a lower class, bringing about equality with a Shudra. In the sale of commodities other than these, there is equality with a Vaishya. As Manu says: