The Maillard reaction that creates toast's golden-brown color begins at precisely 310°F, when amino acids and reducing sugars combine. Professional kitchens use infrared thermometers to achieve the ideal 16% moisture loss that yields crispness without dryness. Interestingly, vertical toasters brown bread more evenly than horizontal ones due to better heat circulation. A 2021 study found that the optimal toast thickness is 14mm - thin enough to crisp thoroughly but thick enough to maintain chewiness. The distinctive "toast aroma" comes from 40+ volatile compounds released during heating, with 2-acetyl-1-pyrroline being the key molecule humans find irresistible.