There is another belief that back to the Age of geographical Discovery, 'hamburger' originally derived from a cooking technique which enabled cooks to make extremely tough dried meat stored in ships as tender and delicious as meat was before dried (this technique was most popular for crew in ships which mainly called at the harbor of Hamburg).
大航海時代、船内で備蓄されていた非常に硬い干し肉を乾燥前の状態に負けないくらい柔らかく美味しく調理するために生み出された調理方法(ハンブルグ港を主な寄港先としていた船舶で最も盛んだった)が発祥という説も有る。 - Wikipedia日英京都関連文書対訳コーパス